diff --git a/.dockerignore b/.dockerignore
index 87239fb0a2..5e9711a8f9 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -5,6 +5,7 @@
 # these entries just stop the heavy/irrelevant trees from bloating the context.
 **/node_modules
 **/dist
+**/.next
 **/types
 **/.vite
 **/.vite-plus
diff --git a/docs/content/docs/features/custom-schemas/container-blocks.mdx b/docs/content/docs/features/custom-schemas/container-blocks.mdx
new file mode 100644
index 0000000000..d9b56d1216
--- /dev/null
+++ b/docs/content/docs/features/custom-schemas/container-blocks.mdx
@@ -0,0 +1,194 @@
+---
+title: Container Blocks
+description: Learn how to create custom blocks that contain other blocks
+---
+
+# Container Blocks
+
+You can create custom blocks that contain other blocks, such as panels, callouts, and column layouts. Take a look at the demo below, in which we add a custom panel to a BlockNote editor, as well as a custom [Slash Menu item](/docs/react/components/suggestion-menus#changing-slash-menu-items) to insert it. Each panel can contain paragraphs, headings, lists, or any other blocks in the editor.
+
+<Example name="custom-schema/container-block" />
+
+## Creating a Container Block
+
+Use the `createReactBlockSpec` function to create a container block, just like a [Custom Block](/docs/features/custom-schemas/custom-blocks). For the panel below, we set `content` to `"none"` and add the `children` option to let it contain other blocks:
+
+```tsx
+import { createReactBlockSpec } from "@blocknote/react";
+
+export const createPanel = createReactBlockSpec(
+  {
+    type: "panel",
+    propSchema: {},
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    render: (props) => (
+      <div className="panel" ref={props.contentRef} />
+    ),
+  },
+);
+```
+
+### Block Config
+
+The block config defines the content and child blocks your container can hold:
+
+`content:` Works the same as for [Custom Blocks](/docs/features/custom-schemas/custom-blocks#block-config-customblockconfig). When using the `children` option, choose `"none"`, `"inline"`, or `"plain"`.
+
+`children.allow:` Set to `"blocks"` to accept the editor's block types. You can also restrict a container to specific container types, as explained in [Restricting Children](#restricting-children).
+
+`propSchema:` Defines the container's props, just like for other custom blocks. Use these to customize its appearance or behavior.
+
+### Block Implementation
+
+`render:` Your React component defines how the block should look. With `content: "none"`, attach `contentRef` where the child blocks should appear. With `content: "inline"` or `"plain"`, attach it to the block's own editable text. You can add icons, buttons, or other elements around it:
+
+```tsx
+render: (props) => (
+  <div className="panel">
+    <span contentEditable={false}>💡</span>
+    <div ref={props.contentRef} />
+  </div>
+),
+```
+
+You can style the component with CSS, just like any other React component:
+
+```css
+.panel {
+  display: flex;
+  gap: 12px;
+  padding: 16px;
+  border-left: 4px solid #507aff;
+  border-radius: 6px;
+}
+```
+
+## Adding Container Blocks to the Editor
+
+Add your container to a [BlockNote schema](/docs/features/custom-schemas#creating-your-own-schema):
+
+```typescript
+import { BlockNoteSchema } from "@blocknote/core";
+import { createPanel } from "./Panel";
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    panel: createPanel(),
+  },
+});
+```
+
+You can then create an editor with this schema, as explained on the [Custom Schemas](/docs/features/custom-schemas) page. Use `children` to set the blocks inside a panel:
+
+```typescript
+import { useCreateBlockNote } from "@blocknote/react";
+
+const editor = useCreateBlockNote({
+  schema,
+  initialContent: [
+    {
+      type: "panel",
+      children: [
+        { type: "heading", content: "Getting started" },
+        { type: "paragraph", content: "Follow these steps to get set up." },
+        { type: "checkListItem", content: "Create an account" },
+      ],
+    },
+  ],
+});
+```
+
+If you create a panel without specifying its children, it starts with an empty paragraph. To let users insert panels themselves, add a [custom Slash Menu item](/docs/react/components/suggestion-menus#changing-slash-menu-items), as shown in the demo.
+
+## Combining Content and Child Blocks
+
+A block can have both its own text and child blocks. Use this for a question followed by hints, a checklist item with detailed instructions, a code sample followed by explanatory blocks, or a callout with a heading. In the demo below, we use the block's text as a callout title:
+
+<Example name="custom-schema/callout-block" />
+
+Set `content` to `"inline"` for rich text or `"plain"` for unstyled text, and add `children: { allow: "blocks" }`. Use `render` for the block's own text and `renderFrame` to style that content and its child blocks together:
+
+```tsx
+import { createReactBlockSpec } from "@blocknote/react";
+
+export const createCallout = createReactBlockSpec(
+  {
+    type: "callout",
+    propSchema: {},
+    content: "inline",
+    children: { allow: "blocks" },
+  },
+  {
+    render: (props) => (
+      <div className="callout-title" ref={props.contentRef} />
+    ),
+    renderFrame: (props) => (
+      <div className="callout">
+        <div ref={props.contentRef} />
+      </div>
+    ),
+  },
+);
+```
+
+`render:` Attach `contentRef` to the block's own editable text. With `content: "inline"`, users can format it and add links, just like in a paragraph. In this example, we style it as a callout title.
+
+For plain text, set `content: "plain"` and use a `<pre>` element to display line breaks and spacing:
+
+```tsx
+render: (props) => <pre ref={props.contentRef} />,
+```
+
+The child blocks can still contain rich text, images, and other block types.
+
+`renderFrame:` An optional React component for styling the block and its children together, such as giving the callout a shared border or background. It receives `block`, `editor`, and `contentRef`, just like `render`. Attach `contentRef` where the block's content and children should appear. You can use the block's props to customize the frame, add interactive controls, or return `null` to show the block without a frame.
+
+You can also use `renderFrame` without the `children` option to style a block and its indented children together. For a container with `content: "none"`, like the panel above, add the surrounding styling directly in `render`.
+
+Add `callout: createCallout()` to your schema, then use `content` for the title and `children` for the body:
+
+```typescript
+{
+  type: "callout",
+  content: "Before you start",
+  children: [
+    { type: "paragraph", content: "Make sure you have an account." },
+  ],
+}
+```
+
+Pressing Enter at the end of the title starts a paragraph in the body. Moving the callout moves its title and body together.
+
+To add blocks to an existing container, see [Inserting Blocks](/docs/reference/editor/manipulating-content#inserting-blocks).
+
+## Restricting Children
+
+For structured layouts, you can limit a container to specific container types. For example, a column layout should only contain columns, while each column can contain any block.
+
+Use an array of container type names for `children.allow`, and `min` to set the minimum number of children:
+
+```typescript
+// Column layout config:
+children: { allow: ["column"], min: 2 },
+```
+
+On the column itself, set `placeable` to `"namedOnly"` so it can only be used inside a container that explicitly allows it:
+
+```typescript
+// Column config:
+children: { allow: "blocks" },
+placeable: "namedOnly",
+```
+
+`children.allow:` Accepts `"blocks"` or an array of container type names. You cannot list regular block types such as `"paragraph"` individually.
+
+`children.min:` The minimum number of children. Defaults to `1`.
+
+`placeable:` Set to `"namedOnly"` to restrict a container to parents that name it in `children.allow`. Defaults to `"anywhere"`.
+
+These options apply to containers with `content: "none"`. Blocks with `content: "inline"` or `"plain"` use `children: { allow: "blocks" }` and can have no child blocks.
+
+For built-in column blocks, see [Multi-Column Layouts](/docs/foundations/document-structure#column-blocks).
diff --git a/docs/content/docs/features/custom-schemas/custom-blocks.mdx b/docs/content/docs/features/custom-schemas/custom-blocks.mdx
index ff25cf838c..4146907f28 100644
--- a/docs/content/docs/features/custom-schemas/custom-blocks.mdx
+++ b/docs/content/docs/features/custom-schemas/custom-blocks.mdx
@@ -56,6 +56,11 @@ type BlockConfig = {
   type: string;
   content: "inline" | "plain" | "none";
   readonly propSchema: PropSchema;
+  children?: {
+    allow: "blocks" | string[];
+    min?: number;
+  };
+  placeable?: "anywhere" | "namedOnly";
 };
 ```
 
@@ -72,6 +77,14 @@ type BlockConfig = {
   alert, so we set `content` to `"inline"`._
 </Callout>
 
+<Callout type="info">
+  _Custom blocks can also contain child blocks by declaring the `children`
+  option, with or without editable content of their own. See [Container
+  Blocks](/docs/features/custom-schemas/container-blocks)._
+</Callout>
+
+`children?:` Defines which child blocks the block can contain. `placeable?:` Controls where a container block can be used. See [Container Blocks](/docs/features/custom-schemas/container-blocks) for the supported configurations.
+
 `propSchema:` The `PropSchema` specifies the props that the block supports. Block props (properties) are data stored with your Block in the document, and can be used to customize its appearance or behavior.
 
 ```typescript
diff --git a/docs/content/docs/features/export/typst.mdx b/docs/content/docs/features/export/typst.mdx
index 4a5e0ddaa3..39e908cba7 100644
--- a/docs/content/docs/features/export/typst.mdx
+++ b/docs/content/docs/features/export/typst.mdx
@@ -120,6 +120,22 @@ For a block with inline content, render it the way the default mappings do:
 `exporter.transformInlineContent(block.content).join("")` (inline results are
 markup strings, so plain concatenation composes them).
 
+### Container blocks
+
+A [container block](/docs/features/custom-schemas/container-blocks) holds
+child blocks, and its mapping decides where they go: the exporter renders the
+children first and passes them in as the mapping's last argument, rather than
+appending them after the container's own output. A container without a
+mapping is an error rather than a silent omission, since dropping it would
+drop its children too.
+
+```typescript
+myContainer: (block, exporter, nestingLevel, numberedListIndex, children) =>
+  `#rect(width: 100%)[${children.join("\n\n")}]`,
+```
+
+Separate the children with a blank line, as above, if each should stay its own
+block — a single `\n` is only a soft break in Typst markup.
 
 ### Math & diagram blocks
 
diff --git a/docs/content/docs/reference/editor/manipulating-content.mdx b/docs/content/docs/reference/editor/manipulating-content.mdx
index bcc3d57ceb..317879a072 100644
--- a/docs/content/docs/reference/editor/manipulating-content.mdx
+++ b/docs/content/docs/reference/editor/manipulating-content.mdx
@@ -165,14 +165,16 @@ editor.insertBlocks(
   "after",
 );
 
-// Insert a paragraph as the last child of an existing block
+// Insert a paragraph as the last child of a container block
 editor.insertBlocks(
   [{ type: "paragraph", content: "Nested paragraph" }],
-  "existing-block-id",
+  "container-block-id",
   "last-child",
 );
 ```
 
+For [container blocks](/docs/features/custom-schemas/container-blocks), `"first-child"` inserts at the beginning of the container and `"last-child"` inserts at the end. Use `"before"` or `"after"` to insert next to the container instead.
+
 ### Updating Blocks
 
 #### Modifying Existing Blocks
diff --git a/examples/01-basic/01-minimal/vite.config.ts b/examples/01-basic/01-minimal/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/01-minimal/vite.config.ts
+++ b/examples/01-basic/01-minimal/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/02-block-objects/vite.config.ts b/examples/01-basic/02-block-objects/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/02-block-objects/vite.config.ts
+++ b/examples/01-basic/02-block-objects/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/03-multi-column/vite.config.ts b/examples/01-basic/03-multi-column/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/03-multi-column/vite.config.ts
+++ b/examples/01-basic/03-multi-column/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/04-default-blocks/vite.config.ts b/examples/01-basic/04-default-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/04-default-blocks/vite.config.ts
+++ b/examples/01-basic/04-default-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/05-removing-default-blocks/vite.config.ts b/examples/01-basic/05-removing-default-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/05-removing-default-blocks/vite.config.ts
+++ b/examples/01-basic/05-removing-default-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/06-block-manipulation/vite.config.ts b/examples/01-basic/06-block-manipulation/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/06-block-manipulation/vite.config.ts
+++ b/examples/01-basic/06-block-manipulation/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/07-selection-blocks/vite.config.ts b/examples/01-basic/07-selection-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/07-selection-blocks/vite.config.ts
+++ b/examples/01-basic/07-selection-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/08-ariakit/vite.config.ts b/examples/01-basic/08-ariakit/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/08-ariakit/vite.config.ts
+++ b/examples/01-basic/08-ariakit/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/09-shadcn/vite.config.ts b/examples/01-basic/09-shadcn/vite.config.ts
index c990876056..6bfee196fb 100644
--- a/examples/01-basic/09-shadcn/vite.config.ts
+++ b/examples/01-basic/09-shadcn/vite.config.ts
@@ -14,7 +14,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -25,11 +25,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/10-localization/vite.config.ts b/examples/01-basic/10-localization/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/10-localization/vite.config.ts
+++ b/examples/01-basic/10-localization/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/11-custom-placeholder/vite.config.ts b/examples/01-basic/11-custom-placeholder/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/11-custom-placeholder/vite.config.ts
+++ b/examples/01-basic/11-custom-placeholder/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/12-multi-editor/vite.config.ts b/examples/01-basic/12-multi-editor/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/12-multi-editor/vite.config.ts
+++ b/examples/01-basic/12-multi-editor/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/13-custom-paste-handler/vite.config.ts b/examples/01-basic/13-custom-paste-handler/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/13-custom-paste-handler/vite.config.ts
+++ b/examples/01-basic/13-custom-paste-handler/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/14-editor-scrollable/vite.config.ts b/examples/01-basic/14-editor-scrollable/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/14-editor-scrollable/vite.config.ts
+++ b/examples/01-basic/14-editor-scrollable/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/15-shadowdom/vite.config.ts b/examples/01-basic/15-shadowdom/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/15-shadowdom/vite.config.ts
+++ b/examples/01-basic/15-shadowdom/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/16-read-only-editor/vite.config.ts b/examples/01-basic/16-read-only-editor/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/16-read-only-editor/vite.config.ts
+++ b/examples/01-basic/16-read-only-editor/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/17-no-trailing-block/vite.config.ts b/examples/01-basic/17-no-trailing-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/17-no-trailing-block/vite.config.ts
+++ b/examples/01-basic/17-no-trailing-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/01-basic/testing/vite.config.ts b/examples/01-basic/testing/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/01-basic/testing/vite.config.ts
+++ b/examples/01-basic/testing/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/02-backend/01-file-uploading/vite.config.ts b/examples/02-backend/01-file-uploading/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/02-backend/01-file-uploading/vite.config.ts
+++ b/examples/02-backend/01-file-uploading/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/02-backend/02-saving-loading/vite.config.ts b/examples/02-backend/02-saving-loading/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/02-backend/02-saving-loading/vite.config.ts
+++ b/examples/02-backend/02-saving-loading/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/02-backend/03-s3/vite.config.ts b/examples/02-backend/03-s3/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/02-backend/03-s3/vite.config.ts
+++ b/examples/02-backend/03-s3/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/02-backend/04-rendering-static-documents/vite.config.ts b/examples/02-backend/04-rendering-static-documents/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/02-backend/04-rendering-static-documents/vite.config.ts
+++ b/examples/02-backend/04-rendering-static-documents/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/01-ui-elements-remove/vite.config.ts b/examples/03-ui-components/01-ui-elements-remove/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/01-ui-elements-remove/vite.config.ts
+++ b/examples/03-ui-components/01-ui-elements-remove/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/02-formatting-toolbar-buttons/vite.config.ts b/examples/03-ui-components/02-formatting-toolbar-buttons/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/02-formatting-toolbar-buttons/vite.config.ts
+++ b/examples/03-ui-components/02-formatting-toolbar-buttons/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/03-formatting-toolbar-block-type-items/vite.config.ts b/examples/03-ui-components/03-formatting-toolbar-block-type-items/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/03-formatting-toolbar-block-type-items/vite.config.ts
+++ b/examples/03-ui-components/03-formatting-toolbar-block-type-items/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/04-side-menu-buttons/vite.config.ts b/examples/03-ui-components/04-side-menu-buttons/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/04-side-menu-buttons/vite.config.ts
+++ b/examples/03-ui-components/04-side-menu-buttons/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/05-side-menu-drag-handle-items/vite.config.ts b/examples/03-ui-components/05-side-menu-drag-handle-items/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/05-side-menu-drag-handle-items/vite.config.ts
+++ b/examples/03-ui-components/05-side-menu-drag-handle-items/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/06-suggestion-menus-slash-menu-items/vite.config.ts b/examples/03-ui-components/06-suggestion-menus-slash-menu-items/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/06-suggestion-menus-slash-menu-items/vite.config.ts
+++ b/examples/03-ui-components/06-suggestion-menus-slash-menu-items/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/07-suggestion-menus-slash-menu-component/vite.config.ts b/examples/03-ui-components/07-suggestion-menus-slash-menu-component/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/07-suggestion-menus-slash-menu-component/vite.config.ts
+++ b/examples/03-ui-components/07-suggestion-menus-slash-menu-component/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/08-suggestion-menus-emoji-picker-columns/vite.config.ts b/examples/03-ui-components/08-suggestion-menus-emoji-picker-columns/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/08-suggestion-menus-emoji-picker-columns/vite.config.ts
+++ b/examples/03-ui-components/08-suggestion-menus-emoji-picker-columns/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/09-suggestion-menus-emoji-picker-component/vite.config.ts b/examples/03-ui-components/09-suggestion-menus-emoji-picker-component/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/09-suggestion-menus-emoji-picker-component/vite.config.ts
+++ b/examples/03-ui-components/09-suggestion-menus-emoji-picker-component/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/10-suggestion-menus-grid-mentions/vite.config.ts b/examples/03-ui-components/10-suggestion-menus-grid-mentions/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/10-suggestion-menus-grid-mentions/vite.config.ts
+++ b/examples/03-ui-components/10-suggestion-menus-grid-mentions/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/11-uppy-file-panel/vite.config.ts b/examples/03-ui-components/11-uppy-file-panel/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/11-uppy-file-panel/vite.config.ts
+++ b/examples/03-ui-components/11-uppy-file-panel/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/12-static-formatting-toolbar/vite.config.ts b/examples/03-ui-components/12-static-formatting-toolbar/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/12-static-formatting-toolbar/vite.config.ts
+++ b/examples/03-ui-components/12-static-formatting-toolbar/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/13-custom-ui/vite.config.ts b/examples/03-ui-components/13-custom-ui/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/13-custom-ui/vite.config.ts
+++ b/examples/03-ui-components/13-custom-ui/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/14-experimental-mobile-formatting-toolbar/vite.config.ts b/examples/03-ui-components/14-experimental-mobile-formatting-toolbar/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/14-experimental-mobile-formatting-toolbar/vite.config.ts
+++ b/examples/03-ui-components/14-experimental-mobile-formatting-toolbar/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/15-advanced-tables/vite.config.ts b/examples/03-ui-components/15-advanced-tables/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/15-advanced-tables/vite.config.ts
+++ b/examples/03-ui-components/15-advanced-tables/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/16-link-toolbar-buttons/vite.config.ts b/examples/03-ui-components/16-link-toolbar-buttons/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/16-link-toolbar-buttons/vite.config.ts
+++ b/examples/03-ui-components/16-link-toolbar-buttons/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/17-advanced-tables-2/vite.config.ts b/examples/03-ui-components/17-advanced-tables-2/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/17-advanced-tables-2/vite.config.ts
+++ b/examples/03-ui-components/17-advanced-tables-2/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/18-drag-n-drop/vite.config.ts b/examples/03-ui-components/18-drag-n-drop/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/18-drag-n-drop/vite.config.ts
+++ b/examples/03-ui-components/18-drag-n-drop/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/19-suggestion-menus-grouping-ordering/vite.config.ts b/examples/03-ui-components/19-suggestion-menus-grouping-ordering/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/19-suggestion-menus-grouping-ordering/vite.config.ts
+++ b/examples/03-ui-components/19-suggestion-menus-grouping-ordering/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/03-ui-components/20-portal-elements/vite.config.ts b/examples/03-ui-components/20-portal-elements/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/03-ui-components/20-portal-elements/vite.config.ts
+++ b/examples/03-ui-components/20-portal-elements/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/01-theming-dom-attributes/vite.config.ts b/examples/04-theming/01-theming-dom-attributes/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/01-theming-dom-attributes/vite.config.ts
+++ b/examples/04-theming/01-theming-dom-attributes/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/02-changing-font/vite.config.ts b/examples/04-theming/02-changing-font/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/02-changing-font/vite.config.ts
+++ b/examples/04-theming/02-changing-font/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/03-theming-css/vite.config.ts b/examples/04-theming/03-theming-css/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/03-theming-css/vite.config.ts
+++ b/examples/04-theming/03-theming-css/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/04-theming-css-variables/vite.config.ts b/examples/04-theming/04-theming-css-variables/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/04-theming-css-variables/vite.config.ts
+++ b/examples/04-theming/04-theming-css-variables/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/05-theming-css-variables-code/vite.config.ts b/examples/04-theming/05-theming-css-variables-code/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/05-theming-css-variables-code/vite.config.ts
+++ b/examples/04-theming/05-theming-css-variables-code/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/06-code-block/vite.config.ts b/examples/04-theming/06-code-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/06-code-block/vite.config.ts
+++ b/examples/04-theming/06-code-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/04-theming/07-custom-code-block/vite.config.ts b/examples/04-theming/07-custom-code-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/04-theming/07-custom-code-block/vite.config.ts
+++ b/examples/04-theming/07-custom-code-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/01-converting-blocks-to-html/vite.config.ts b/examples/05-interoperability/01-converting-blocks-to-html/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/01-converting-blocks-to-html/vite.config.ts
+++ b/examples/05-interoperability/01-converting-blocks-to-html/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/02-converting-blocks-from-html/vite.config.ts b/examples/05-interoperability/02-converting-blocks-from-html/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/02-converting-blocks-from-html/vite.config.ts
+++ b/examples/05-interoperability/02-converting-blocks-from-html/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/03-converting-blocks-to-md/vite.config.ts b/examples/05-interoperability/03-converting-blocks-to-md/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/03-converting-blocks-to-md/vite.config.ts
+++ b/examples/05-interoperability/03-converting-blocks-to-md/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/04-converting-blocks-from-md/vite.config.ts b/examples/05-interoperability/04-converting-blocks-from-md/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/04-converting-blocks-from-md/vite.config.ts
+++ b/examples/05-interoperability/04-converting-blocks-from-md/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/05-converting-blocks-to-pdf/vite.config.ts b/examples/05-interoperability/05-converting-blocks-to-pdf/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/05-converting-blocks-to-pdf/vite.config.ts
+++ b/examples/05-interoperability/05-converting-blocks-to-pdf/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/06-converting-blocks-to-docx/vite.config.ts b/examples/05-interoperability/06-converting-blocks-to-docx/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/06-converting-blocks-to-docx/vite.config.ts
+++ b/examples/05-interoperability/06-converting-blocks-to-docx/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/07-converting-blocks-to-odt/vite.config.ts b/examples/05-interoperability/07-converting-blocks-to-odt/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/07-converting-blocks-to-odt/vite.config.ts
+++ b/examples/05-interoperability/07-converting-blocks-to-odt/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/08-converting-blocks-to-react-email/vite.config.ts b/examples/05-interoperability/08-converting-blocks-to-react-email/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/08-converting-blocks-to-react-email/vite.config.ts
+++ b/examples/05-interoperability/08-converting-blocks-to-react-email/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/09-blocks-to-html-static-render/vite.config.ts b/examples/05-interoperability/09-blocks-to-html-static-render/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/09-blocks-to-html-static-render/vite.config.ts
+++ b/examples/05-interoperability/09-blocks-to-html-static-render/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/10-static-html-render/vite.config.ts b/examples/05-interoperability/10-static-html-render/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/10-static-html-render/vite.config.ts
+++ b/examples/05-interoperability/10-static-html-render/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/05-interoperability/11-converting-blocks-to-pdf-react-pdf-deprecated/vite.config.ts b/examples/05-interoperability/11-converting-blocks-to-pdf-react-pdf-deprecated/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/05-interoperability/11-converting-blocks-to-pdf-react-pdf-deprecated/vite.config.ts
+++ b/examples/05-interoperability/11-converting-blocks-to-pdf-react-pdf-deprecated/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/01-alert-block/vite.config.ts b/examples/06-custom-schema/01-alert-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/01-alert-block/vite.config.ts
+++ b/examples/06-custom-schema/01-alert-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/02-suggestion-menus-mentions/vite.config.ts b/examples/06-custom-schema/02-suggestion-menus-mentions/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/02-suggestion-menus-mentions/vite.config.ts
+++ b/examples/06-custom-schema/02-suggestion-menus-mentions/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/03-font-style/vite.config.ts b/examples/06-custom-schema/03-font-style/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/03-font-style/vite.config.ts
+++ b/examples/06-custom-schema/03-font-style/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/04-pdf-file-block/vite.config.ts b/examples/06-custom-schema/04-pdf-file-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/04-pdf-file-block/vite.config.ts
+++ b/examples/06-custom-schema/04-pdf-file-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/05-alert-block-full-ux/vite.config.ts b/examples/06-custom-schema/05-alert-block-full-ux/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/05-alert-block-full-ux/vite.config.ts
+++ b/examples/06-custom-schema/05-alert-block-full-ux/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/06-toggleable-blocks/vite.config.ts b/examples/06-custom-schema/06-toggleable-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/06-toggleable-blocks/vite.config.ts
+++ b/examples/06-custom-schema/06-toggleable-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/07-configuring-blocks/vite.config.ts b/examples/06-custom-schema/07-configuring-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/07-configuring-blocks/vite.config.ts
+++ b/examples/06-custom-schema/07-configuring-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/08-non-editable-block/vite.config.ts b/examples/06-custom-schema/08-non-editable-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/08-non-editable-block/vite.config.ts
+++ b/examples/06-custom-schema/08-non-editable-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/09-container-block/.bnexample.json b/examples/06-custom-schema/09-container-block/.bnexample.json
new file mode 100644
index 0000000000..3de7330631
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/.bnexample.json
@@ -0,0 +1,15 @@
+{
+  "playground": true,
+  "docs": true,
+  "author": "nickthesick",
+  "tags": [
+    "Intermediate",
+    "Blocks",
+    "Custom Schemas",
+    "Suggestion Menus",
+    "Slash Menu"
+  ],
+  "dependencies": {
+    "react-icons": "^5.5.0"
+  }
+}
diff --git a/examples/06-custom-schema/09-container-block/README.md b/examples/06-custom-schema/09-container-block/README.md
new file mode 100644
index 0000000000..999bf62786
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/README.md
@@ -0,0 +1,18 @@
+# Container Block
+
+In this example, we create a custom `Panel` block that holds other blocks as its body, such as a panel containing headings and paragraphs.
+
+The block declares the `children` config on `BlockConfig`. `children: { allow: "blocks" }` makes it a container: its child blocks mount into the rendered content region (attached with `ref={contentRef}`), and live on `block.children` at runtime. A pure container like this draws its box in `render`, which re-renders live when props change.
+
+We also wire up a Slash Menu item to insert the panel.
+
+**Try it out:**
+
+- Press the "/" key inside the panel's body and add a code block, heading, or list.
+- Insert a new panel via the Slash Menu (search "panel").
+
+**Relevant Docs:**
+
+- [Container Blocks](/docs/features/custom-schemas/container-blocks)
+- [Custom Blocks](/docs/features/custom-schemas/custom-blocks)
+- [Editor Setup](/docs/getting-started/editor-setup)
diff --git a/examples/06-custom-schema/09-container-block/index.html b/examples/06-custom-schema/09-container-block/index.html
new file mode 100644
index 0000000000..19321f77b5
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/index.html
@@ -0,0 +1,14 @@
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Container Block</title>
+    <script>
+      <!-- AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY -->
+    </script>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="./main.tsx"></script>
+  </body>
+</html>
diff --git a/examples/06-custom-schema/09-container-block/main.tsx b/examples/06-custom-schema/09-container-block/main.tsx
new file mode 100644
index 0000000000..1260513388
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/main.tsx
@@ -0,0 +1,11 @@
+// AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY
+import React from "react";
+import { createRoot } from "react-dom/client";
+import App from "./src/App.jsx";
+
+const root = createRoot(document.getElementById("root")!);
+root.render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>,
+);
diff --git a/examples/06-custom-schema/09-container-block/package.json b/examples/06-custom-schema/09-container-block/package.json
new file mode 100644
index 0000000000..29778f9255
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/package.json
@@ -0,0 +1,31 @@
+{
+  "name": "@blocknote/example-custom-schema-container-block",
+  "description": "AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY",
+  "type": "module",
+  "private": true,
+  "version": "0.12.4",
+  "scripts": {
+    "start": "vite",
+    "dev": "vite",
+    "build:prod": "tsc && vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@blocknote/ariakit": "latest",
+    "@blocknote/core": "latest",
+    "@blocknote/mantine": "latest",
+    "@blocknote/react": "latest",
+    "@blocknote/shadcn": "latest",
+    "@mantine/core": "^9.0.2",
+    "@mantine/hooks": "^9.0.2",
+    "react": "^19.2.3",
+    "react-dom": "^19.2.3",
+    "react-icons": "^5.5.0"
+  },
+  "devDependencies": {
+    "@types/react": "^19.2.3",
+    "@types/react-dom": "^19.2.3",
+    "@vitejs/plugin-react": "^6.0.1",
+    "vite": "^8.0.0"
+  }
+}
diff --git a/examples/06-custom-schema/09-container-block/src/App.tsx b/examples/06-custom-schema/09-container-block/src/App.tsx
new file mode 100644
index 0000000000..c93bbe6f87
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/src/App.tsx
@@ -0,0 +1,92 @@
+import { BlockNoteSchema } from "@blocknote/core";
+import {
+  filterSuggestionItems,
+  insertOrUpdateBlockForSlashMenu,
+} from "@blocknote/core/extensions";
+import "@blocknote/core/fonts/inter.css";
+import { BlockNoteView } from "@blocknote/mantine";
+import "@blocknote/mantine/style.css";
+import {
+  SuggestionMenuController,
+  getDefaultReactSlashMenuItems,
+  useCreateBlockNote,
+} from "@blocknote/react";
+import { RiChatQuoteLine } from "react-icons/ri";
+
+import { createPanel } from "./Panel";
+import "./styles.css";
+
+// Schema with the default blocks plus our custom Panel container block.
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    panel: createPanel(),
+  },
+});
+
+// Slash menu item to insert a Panel. Inserting one with no children fills
+// it with an empty paragraph, as `min` defaults to 1.
+function insertPanel(editor: typeof schema.BlockNoteEditor) {
+  return {
+    title: "Panel",
+    subtext: "Container block that wraps other blocks",
+    onItemClick: () =>
+      insertOrUpdateBlockForSlashMenu(editor, {
+        type: "panel",
+      }),
+    aliases: ["panel", "container", "callout", "alert", "note", "tip", "info"],
+    group: "Basic blocks",
+    icon: <RiChatQuoteLine />,
+  };
+}
+
+export default function App() {
+  const editor = useCreateBlockNote({
+    schema,
+    initialContent: [
+      {
+        type: "paragraph",
+        content: "Welcome! This demo shows the new container block kind.",
+      },
+      {
+        type: "panel",
+        children: [
+          {
+            type: "heading",
+            props: { level: 3 },
+            content: "More than paragraphs",
+          },
+          {
+            type: "paragraph",
+            content: "Panels can hold any block as their body.",
+          },
+          {
+            type: "paragraph",
+            content:
+              "Try pressing '/' inside this panel to add a heading or code block.",
+          },
+        ],
+      },
+      {
+        type: "paragraph",
+        content: "Press '/' anywhere to insert a new Panel.",
+      },
+      {
+        type: "paragraph",
+      },
+    ],
+  });
+
+  return (
+    <BlockNoteView editor={editor} slashMenu={false}>
+      <SuggestionMenuController
+        triggerCharacter={"/"}
+        getItems={async (query) =>
+          filterSuggestionItems(
+            [...getDefaultReactSlashMenuItems(editor), insertPanel(editor)],
+            query,
+          )
+        }
+      />
+    </BlockNoteView>
+  );
+}
diff --git a/examples/06-custom-schema/09-container-block/src/Panel.tsx b/examples/06-custom-schema/09-container-block/src/Panel.tsx
new file mode 100644
index 0000000000..7af68eff48
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/src/Panel.tsx
@@ -0,0 +1,16 @@
+import { createReactBlockSpec } from "@blocknote/react";
+
+import "./styles.css";
+
+export const createPanel = createReactBlockSpec(
+  {
+    type: "panel",
+    propSchema: {},
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    // With no content of its own, contentRef receives the child blocks.
+    render: (props) => <div className="panel" ref={props.contentRef} />,
+  },
+);
diff --git a/examples/06-custom-schema/09-container-block/src/styles.css b/examples/06-custom-schema/09-container-block/src/styles.css
new file mode 100644
index 0000000000..ed2f1b8b6b
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/src/styles.css
@@ -0,0 +1,10 @@
+.panel {
+  border-left: 4px solid #507aff;
+  border-radius: 6px;
+  background-color: var(--panel-bg, #e6ebff);
+  padding: 12px 16px;
+}
+
+[data-color-scheme="dark"] .panel {
+  --panel-bg: #1e2a5c;
+}
diff --git a/examples/06-custom-schema/09-container-block/tsconfig.json b/examples/06-custom-schema/09-container-block/tsconfig.json
new file mode 100644
index 0000000000..2aa62c56e6
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/tsconfig.json
@@ -0,0 +1,32 @@
+{
+  "__comment": "AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY",
+  "compilerOptions": {
+    "target": "ESNext",
+    "useDefineForClassFields": true,
+    "lib": ["DOM", "DOM.Iterable", "ESNext"],
+    "allowJs": false,
+    "skipLibCheck": true,
+    "allowSyntheticDefaultImports": true,
+    "strict": true,
+    "forceConsistentCasingInFileNames": true,
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "composite": true,
+    "paths": {
+      "@shared/*": ["../../../shared/*"]
+    }
+  },
+  "include": ["."],
+  "__ADD_FOR_LOCAL_DEV_references": [
+    {
+      "path": "../../../packages/core/"
+    },
+    {
+      "path": "../../../packages/react/"
+    }
+  ]
+}
diff --git a/examples/06-custom-schema/09-container-block/vite-env.d.ts b/examples/06-custom-schema/09-container-block/vite-env.d.ts
new file mode 100644
index 0000000000..11f02fe2a0
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/vite-env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vite/client" />
diff --git a/examples/06-custom-schema/09-container-block/vite.config.ts b/examples/06-custom-schema/09-container-block/vite.config.ts
new file mode 100644
index 0000000000..cbf6ff2ffc
--- /dev/null
+++ b/examples/06-custom-schema/09-container-block/vite.config.ts
@@ -0,0 +1,35 @@
+// AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY
+import react from "@vitejs/plugin-react";
+import * as fs from "fs";
+import * as path from "path";
+import { defineConfig } from "vite";
+// https://vitejs.dev/config/
+export default defineConfig(((conf: { command: string }) => ({
+  plugins: [react()],
+  optimizeDeps: {},
+  build: {
+    sourcemap: true,
+  },
+  resolve: {
+    alias:
+      conf.command === "build" ||
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
+        ? {}
+        : ({
+            // The repo-wide alias for the shared test-utils directory (private,
+            // so it only resolves inside the monorepo). Harmless for examples
+            // that don't use it.
+            "@shared": path.resolve(__dirname, "../../../shared/"),
+            // Comment out the lines below to load a built version of blocknote
+            // or, keep as is to load live from sources with live reload working
+            "@blocknote/core": path.resolve(
+              __dirname,
+              "../../../packages/core/src/",
+            ),
+            "@blocknote/react": path.resolve(
+              __dirname,
+              "../../../packages/react/src/",
+            ),
+          } as any),
+  },
+})) as Parameters<typeof defineConfig>[0]);
diff --git a/examples/06-custom-schema/09-math-block/vite.config.ts b/examples/06-custom-schema/09-math-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/09-math-block/vite.config.ts
+++ b/examples/06-custom-schema/09-math-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/10-diagram-block/vite.config.ts b/examples/06-custom-schema/10-diagram-block/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/10-diagram-block/vite.config.ts
+++ b/examples/06-custom-schema/10-diagram-block/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/11-source-with-preview/vite.config.ts b/examples/06-custom-schema/11-source-with-preview/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/11-source-with-preview/vite.config.ts
+++ b/examples/06-custom-schema/11-source-with-preview/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/13-callout-block/.bnexample.json b/examples/06-custom-schema/13-callout-block/.bnexample.json
new file mode 100644
index 0000000000..3de7330631
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/.bnexample.json
@@ -0,0 +1,15 @@
+{
+  "playground": true,
+  "docs": true,
+  "author": "nickthesick",
+  "tags": [
+    "Intermediate",
+    "Blocks",
+    "Custom Schemas",
+    "Suggestion Menus",
+    "Slash Menu"
+  ],
+  "dependencies": {
+    "react-icons": "^5.5.0"
+  }
+}
diff --git a/examples/06-custom-schema/13-callout-block/README.md b/examples/06-custom-schema/13-callout-block/README.md
new file mode 100644
index 0000000000..20071bb974
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/README.md
@@ -0,0 +1,19 @@
+# Callout Block
+
+In this example, we create a custom `Callout` block with a real rich-text title and a body of child blocks (a titled block), like a Notion-style callout.
+
+The block combines `content: "inline"` with the `children` config on `BlockConfig`. The title is ordinary inline content — formatting, links, and multiplayer cursors all work — while `children: { allow: "blocks" }` hosts the body blocks, which live on `block.children` at runtime. `render` draws the title row and `renderFrame` draws the box around the title and body together.
+
+We also wire up a Slash Menu item to insert the callout.
+
+**Try it out:**
+
+- Press Enter at the end of the callout's title to jump into its body.
+- Press Backspace at the start of the first body block to merge it back into the title.
+- Press "/" inside the body and add a code block, heading, or list.
+
+**Relevant Docs:**
+
+- [Container Blocks](/docs/features/custom-schemas/container-blocks)
+- [Custom Blocks](/docs/features/custom-schemas/custom-blocks)
+- [Editor Setup](/docs/getting-started/editor-setup)
diff --git a/examples/06-custom-schema/13-callout-block/index.html b/examples/06-custom-schema/13-callout-block/index.html
new file mode 100644
index 0000000000..389f1cfc66
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/index.html
@@ -0,0 +1,14 @@
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Callout Block</title>
+    <script>
+      <!-- AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY -->
+    </script>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="./main.tsx"></script>
+  </body>
+</html>
diff --git a/examples/06-custom-schema/13-callout-block/main.tsx b/examples/06-custom-schema/13-callout-block/main.tsx
new file mode 100644
index 0000000000..1260513388
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/main.tsx
@@ -0,0 +1,11 @@
+// AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY
+import React from "react";
+import { createRoot } from "react-dom/client";
+import App from "./src/App.jsx";
+
+const root = createRoot(document.getElementById("root")!);
+root.render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>,
+);
diff --git a/examples/06-custom-schema/13-callout-block/package.json b/examples/06-custom-schema/13-callout-block/package.json
new file mode 100644
index 0000000000..9a61db5e93
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/package.json
@@ -0,0 +1,31 @@
+{
+  "name": "@blocknote/example-custom-schema-callout-block",
+  "description": "AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY",
+  "type": "module",
+  "private": true,
+  "version": "0.12.4",
+  "scripts": {
+    "start": "vite",
+    "dev": "vite",
+    "build:prod": "tsc && vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@blocknote/ariakit": "latest",
+    "@blocknote/core": "latest",
+    "@blocknote/mantine": "latest",
+    "@blocknote/react": "latest",
+    "@blocknote/shadcn": "latest",
+    "@mantine/core": "^9.0.2",
+    "@mantine/hooks": "^9.0.2",
+    "react": "^19.2.3",
+    "react-dom": "^19.2.3",
+    "react-icons": "^5.5.0"
+  },
+  "devDependencies": {
+    "@types/react": "^19.2.3",
+    "@types/react-dom": "^19.2.3",
+    "@vitejs/plugin-react": "^6.0.1",
+    "vite": "^8.0.0"
+  }
+}
diff --git a/examples/06-custom-schema/13-callout-block/src/App.tsx b/examples/06-custom-schema/13-callout-block/src/App.tsx
new file mode 100644
index 0000000000..bb199625b9
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/src/App.tsx
@@ -0,0 +1,89 @@
+import { BlockNoteSchema } from "@blocknote/core";
+import {
+  filterSuggestionItems,
+  insertOrUpdateBlockForSlashMenu,
+} from "@blocknote/core/extensions";
+import "@blocknote/core/fonts/inter.css";
+import { BlockNoteView } from "@blocknote/mantine";
+import "@blocknote/mantine/style.css";
+import {
+  SuggestionMenuController,
+  getDefaultReactSlashMenuItems,
+  useCreateBlockNote,
+} from "@blocknote/react";
+import { RiChatQuoteLine } from "react-icons/ri";
+
+import { createCallout } from "./Callout";
+import "./styles.css";
+
+// Schema with the default blocks plus our custom Callout titled block.
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    callout: createCallout(),
+  },
+});
+
+// Slash menu item to insert a Callout.
+function insertCallout(editor: typeof schema.BlockNoteEditor) {
+  return {
+    title: "Callout",
+    subtext: "Titled container block that wraps other blocks",
+    onItemClick: () =>
+      insertOrUpdateBlockForSlashMenu(editor, {
+        type: "callout",
+      }),
+    aliases: ["callout", "container", "alert", "note", "tip", "info"],
+    group: "Basic blocks",
+    icon: <RiChatQuoteLine />,
+  };
+}
+
+export default function App() {
+  const editor = useCreateBlockNote({
+    schema,
+    initialContent: [
+      {
+        type: "paragraph",
+        content:
+          "Welcome! This demo shows a titled block: a rich-text title with a body of child blocks.",
+      },
+      {
+        type: "callout",
+        content: "A callout with a real title",
+        children: [
+          {
+            type: "paragraph",
+            content:
+              "The title is ordinary inline content: formatting, links, and multiplayer cursors all work.",
+          },
+          {
+            type: "paragraph",
+            content:
+              "Press Enter at the end of the title to jump into the body, or Backspace at the start of the body to merge back.",
+          },
+        ],
+      },
+      {
+        type: "paragraph",
+        content: "Press '/' anywhere to insert a new Callout.",
+      },
+      {
+        type: "paragraph",
+      },
+    ],
+  });
+
+  return (
+    <BlockNoteView editor={editor} slashMenu={false}>
+      <SuggestionMenuController
+        triggerCharacter={"/"}
+        getItems={async (query) =>
+          filterSuggestionItems(
+            [...getDefaultReactSlashMenuItems(editor), insertCallout(editor)],
+            query,
+          )
+        }
+      />
+    </BlockNoteView>
+  );
+}
diff --git a/examples/06-custom-schema/13-callout-block/src/Callout.tsx b/examples/06-custom-schema/13-callout-block/src/Callout.tsx
new file mode 100644
index 0000000000..d26c7eb81a
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/src/Callout.tsx
@@ -0,0 +1,32 @@
+import { createReactBlockSpec } from "@blocknote/react";
+
+import "./styles.css";
+
+// The Callout block: a titled block. `content: "inline"` plus `children`
+// gives the block its own rich-text title with child blocks as its body.
+// `render` draws the title row (the title mounts into `contentRef`), while
+// `renderFrame` draws the box around the title and the body together.
+export const createCallout = createReactBlockSpec(
+  {
+    type: "callout",
+    propSchema: {},
+    content: "inline",
+    // The title is ordinary inline content; the children are the body.
+    children: { allow: "blocks" },
+  },
+  {
+    render: (props) => (
+      <div className={"callout-title-row"}>
+        <span className={"callout-badge"} contentEditable={false}>
+          !
+        </span>
+        <span className={"callout-title"} ref={props.contentRef} />
+      </div>
+    ),
+    renderFrame: (props) => (
+      <div className={"callout"}>
+        <div className={"callout-slot"} ref={props.contentRef} />
+      </div>
+    ),
+  },
+);
diff --git a/examples/06-custom-schema/13-callout-block/src/styles.css b/examples/06-custom-schema/13-callout-block/src/styles.css
new file mode 100644
index 0000000000..c4ca0071da
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/src/styles.css
@@ -0,0 +1,42 @@
+.callout {
+  border-radius: 6px;
+  padding: 12px 16px;
+  border-left: 4px solid var(--callout-accent, #507aff);
+  background-color: var(--callout-bg, #e6ebff);
+}
+
+[data-color-scheme="dark"] .callout {
+  --callout-bg: #1e2a5c;
+}
+
+.callout-title-row {
+  display: flex;
+  align-items: flex-start;
+  gap: 8px;
+  margin-bottom: 4px;
+}
+
+.callout-badge {
+  flex-shrink: 0;
+  width: 20px;
+  height: 20px;
+  border-radius: 9999px;
+  background-color: var(--callout-accent, #507aff);
+  color: #fff;
+  font-size: 12px;
+  font-weight: 700;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  margin-top: 2px;
+}
+
+.callout-title {
+  flex-grow: 1;
+  min-width: 0;
+  font-weight: 600;
+}
+
+.callout-slot {
+  min-width: 0;
+}
diff --git a/examples/06-custom-schema/13-callout-block/tsconfig.json b/examples/06-custom-schema/13-callout-block/tsconfig.json
new file mode 100644
index 0000000000..2aa62c56e6
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/tsconfig.json
@@ -0,0 +1,32 @@
+{
+  "__comment": "AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY",
+  "compilerOptions": {
+    "target": "ESNext",
+    "useDefineForClassFields": true,
+    "lib": ["DOM", "DOM.Iterable", "ESNext"],
+    "allowJs": false,
+    "skipLibCheck": true,
+    "allowSyntheticDefaultImports": true,
+    "strict": true,
+    "forceConsistentCasingInFileNames": true,
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "composite": true,
+    "paths": {
+      "@shared/*": ["../../../shared/*"]
+    }
+  },
+  "include": ["."],
+  "__ADD_FOR_LOCAL_DEV_references": [
+    {
+      "path": "../../../packages/core/"
+    },
+    {
+      "path": "../../../packages/react/"
+    }
+  ]
+}
diff --git a/examples/06-custom-schema/13-callout-block/vite-env.d.ts b/examples/06-custom-schema/13-callout-block/vite-env.d.ts
new file mode 100644
index 0000000000..11f02fe2a0
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/vite-env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vite/client" />
diff --git a/examples/06-custom-schema/13-callout-block/vite.config.ts b/examples/06-custom-schema/13-callout-block/vite.config.ts
new file mode 100644
index 0000000000..cbf6ff2ffc
--- /dev/null
+++ b/examples/06-custom-schema/13-callout-block/vite.config.ts
@@ -0,0 +1,35 @@
+// AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY
+import react from "@vitejs/plugin-react";
+import * as fs from "fs";
+import * as path from "path";
+import { defineConfig } from "vite";
+// https://vitejs.dev/config/
+export default defineConfig(((conf: { command: string }) => ({
+  plugins: [react()],
+  optimizeDeps: {},
+  build: {
+    sourcemap: true,
+  },
+  resolve: {
+    alias:
+      conf.command === "build" ||
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
+        ? {}
+        : ({
+            // The repo-wide alias for the shared test-utils directory (private,
+            // so it only resolves inside the monorepo). Harmless for examples
+            // that don't use it.
+            "@shared": path.resolve(__dirname, "../../../shared/"),
+            // Comment out the lines below to load a built version of blocknote
+            // or, keep as is to load live from sources with live reload working
+            "@blocknote/core": path.resolve(
+              __dirname,
+              "../../../packages/core/src/",
+            ),
+            "@blocknote/react": path.resolve(
+              __dirname,
+              "../../../packages/react/src/",
+            ),
+          } as any),
+  },
+})) as Parameters<typeof defineConfig>[0]);
diff --git a/examples/06-custom-schema/draggable-inline-content/vite.config.ts b/examples/06-custom-schema/draggable-inline-content/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/draggable-inline-content/vite.config.ts
+++ b/examples/06-custom-schema/draggable-inline-content/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/react-custom-blocks/vite.config.ts b/examples/06-custom-schema/react-custom-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/react-custom-blocks/vite.config.ts
+++ b/examples/06-custom-schema/react-custom-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/react-custom-inline-content/vite.config.ts b/examples/06-custom-schema/react-custom-inline-content/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/react-custom-inline-content/vite.config.ts
+++ b/examples/06-custom-schema/react-custom-inline-content/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/06-custom-schema/react-custom-styles/vite.config.ts b/examples/06-custom-schema/react-custom-styles/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/06-custom-schema/react-custom-styles/vite.config.ts
+++ b/examples/06-custom-schema/react-custom-styles/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/01-partykit/vite.config.ts b/examples/07-collaboration/01-partykit/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/01-partykit/vite.config.ts
+++ b/examples/07-collaboration/01-partykit/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/02-liveblocks/vite.config.ts b/examples/07-collaboration/02-liveblocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/02-liveblocks/vite.config.ts
+++ b/examples/07-collaboration/02-liveblocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/03-y-sweet/vite.config.ts b/examples/07-collaboration/03-y-sweet/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/03-y-sweet/vite.config.ts
+++ b/examples/07-collaboration/03-y-sweet/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/04-electric-sql/vite.config.ts b/examples/07-collaboration/04-electric-sql/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/04-electric-sql/vite.config.ts
+++ b/examples/07-collaboration/04-electric-sql/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/05-comments/vite.config.ts b/examples/07-collaboration/05-comments/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/05-comments/vite.config.ts
+++ b/examples/07-collaboration/05-comments/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/06-comments-with-sidebar/vite.config.ts b/examples/07-collaboration/06-comments-with-sidebar/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/06-comments-with-sidebar/vite.config.ts
+++ b/examples/07-collaboration/06-comments-with-sidebar/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/07-ghost-writer/vite.config.ts b/examples/07-collaboration/07-ghost-writer/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/07-ghost-writer/vite.config.ts
+++ b/examples/07-collaboration/07-ghost-writer/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/08-forking/vite.config.ts b/examples/07-collaboration/08-forking/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/08-forking/vite.config.ts
+++ b/examples/07-collaboration/08-forking/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/09-comments-testing/vite.config.ts b/examples/07-collaboration/09-comments-testing/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/09-comments-testing/vite.config.ts
+++ b/examples/07-collaboration/09-comments-testing/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/10-suggestion-multi-editor/vite.config.ts b/examples/07-collaboration/10-suggestion-multi-editor/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/10-suggestion-multi-editor/vite.config.ts
+++ b/examples/07-collaboration/10-suggestion-multi-editor/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/11-versioning-yjs13/vite.config.ts b/examples/07-collaboration/11-versioning-yjs13/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/11-versioning-yjs13/vite.config.ts
+++ b/examples/07-collaboration/11-versioning-yjs13/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/12-multi-doc-versioning/vite.config.ts b/examples/07-collaboration/12-multi-doc-versioning/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/12-multi-doc-versioning/vite.config.ts
+++ b/examples/07-collaboration/12-multi-doc-versioning/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/13-versioning-yjs14/vite.config.ts b/examples/07-collaboration/13-versioning-yjs14/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/13-versioning-yjs14/vite.config.ts
+++ b/examples/07-collaboration/13-versioning-yjs14/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/07-collaboration/14-suggestion-gallery/vite.config.ts b/examples/07-collaboration/14-suggestion-gallery/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/07-collaboration/14-suggestion-gallery/vite.config.ts
+++ b/examples/07-collaboration/14-suggestion-gallery/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/08-extensions/01-tiptap-arrow-conversion/vite.config.ts b/examples/08-extensions/01-tiptap-arrow-conversion/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/08-extensions/01-tiptap-arrow-conversion/vite.config.ts
+++ b/examples/08-extensions/01-tiptap-arrow-conversion/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/08-extensions/02-versioning/vite.config.ts b/examples/08-extensions/02-versioning/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/08-extensions/02-versioning/vite.config.ts
+++ b/examples/08-extensions/02-versioning/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/01-minimal/vite.config.ts b/examples/09-ai/01-minimal/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/01-minimal/vite.config.ts
+++ b/examples/09-ai/01-minimal/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/02-playground/vite.config.ts b/examples/09-ai/02-playground/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/02-playground/vite.config.ts
+++ b/examples/09-ai/02-playground/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/03-custom-ai-menu-items/vite.config.ts b/examples/09-ai/03-custom-ai-menu-items/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/03-custom-ai-menu-items/vite.config.ts
+++ b/examples/09-ai/03-custom-ai-menu-items/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/04-with-collaboration/vite.config.ts b/examples/09-ai/04-with-collaboration/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/04-with-collaboration/vite.config.ts
+++ b/examples/09-ai/04-with-collaboration/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/05-manual-execution/vite.config.ts b/examples/09-ai/05-manual-execution/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/05-manual-execution/vite.config.ts
+++ b/examples/09-ai/05-manual-execution/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/06-client-side-transport/vite.config.ts b/examples/09-ai/06-client-side-transport/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/06-client-side-transport/vite.config.ts
+++ b/examples/09-ai/06-client-side-transport/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/09-ai/07-server-persistence/vite.config.ts b/examples/09-ai/07-server-persistence/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/09-ai/07-server-persistence/vite.config.ts
+++ b/examples/09-ai/07-server-persistence/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/vanilla-js/react-vanilla-custom-blocks/vite.config.ts b/examples/vanilla-js/react-vanilla-custom-blocks/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/vanilla-js/react-vanilla-custom-blocks/vite.config.ts
+++ b/examples/vanilla-js/react-vanilla-custom-blocks/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/vanilla-js/react-vanilla-custom-inline-content/vite.config.ts b/examples/vanilla-js/react-vanilla-custom-inline-content/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/vanilla-js/react-vanilla-custom-inline-content/vite.config.ts
+++ b/examples/vanilla-js/react-vanilla-custom-inline-content/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/vanilla-js/react-vanilla-custom-styles/vite.config.ts b/examples/vanilla-js/react-vanilla-custom-styles/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/vanilla-js/react-vanilla-custom-styles/vite.config.ts
+++ b/examples/vanilla-js/react-vanilla-custom-styles/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/examples/vanilla-js/vanilla-custom-side-menu/vite.config.ts b/examples/vanilla-js/vanilla-custom-side-menu/vite.config.ts
index a96f1f04ff..cbf6ff2ffc 100644
--- a/examples/vanilla-js/vanilla-custom-side-menu/vite.config.ts
+++ b/examples/vanilla-js/vanilla-custom-side-menu/vite.config.ts
@@ -13,7 +13,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -24,11 +24,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/",
+              "../../../packages/core/src/",
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/",
+              "../../../packages/react/src/",
             ),
           } as any),
   },
diff --git a/packages/core/src/api/blockManipulation/commands/insertBlocks/insertBlocks.ts b/packages/core/src/api/blockManipulation/commands/insertBlocks/insertBlocks.ts
index 9d695e38b6..c2045121f4 100644
--- a/packages/core/src/api/blockManipulation/commands/insertBlocks/insertBlocks.ts
+++ b/packages/core/src/api/blockManipulation/commands/insertBlocks/insertBlocks.ts
@@ -59,9 +59,10 @@ export function insertBlocks<
   }
 
   // `getInsertionPos` can only answer for the first node's type: the fragment
-  // doesn't exist yet when it runs. The whole fragment still has to fit, so it
-  // is checked here, where the nodes are known, rather than left to `tr.step`
-  // to reject with a ProseMirror-level message.
+  // doesn't exist yet when it runs. The whole fragment still has to fit — a
+  // `blockGroup` takes a paragraph but not a `namedOnly` block — so it is
+  // checked here, where the nodes are known, rather than left to `tr.step` to
+  // reject with a ProseMirror-level message.
   if (
     target.wrapIn &&
     !target.wrapIn.validContent(Fragment.from(nodesToInsert))
diff --git a/packages/core/src/api/blockManipulation/commands/insertBlocks/insertPlacement.test.ts b/packages/core/src/api/blockManipulation/commands/insertBlocks/insertPlacement.test.ts
index 8da2132a40..d2d1022389 100644
--- a/packages/core/src/api/blockManipulation/commands/insertBlocks/insertPlacement.test.ts
+++ b/packages/core/src/api/blockManipulation/commands/insertBlocks/insertPlacement.test.ts
@@ -8,12 +8,48 @@ import {
   it,
 } from "vite-plus/test";
 
+import { BlockNoteSchema } from "../../../../blocks/BlockNoteSchema.js";
+import { defaultBlockSpecs } from "../../../../blocks/defaultBlocks.js";
 import { BlockNoteEditor } from "../../../../editor/BlockNoteEditor.js";
+import { createBlockSpec } from "../../../../schema/blocks/createSpec.js";
+
+// The editor stays headless, so these blocks are never rendered. `render`
+// only has to exist for `createBlockSpec` to accept the spec.
+const container = (type: string, config: Record<string, unknown>) =>
+  createBlockSpec({ type, propSchema: {}, ...config } as any, {
+    render: () => {
+      throw new Error("not rendered in this suite");
+    },
+  })();
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    // Why `"first-child"`/`"last-child"` exist: a container that may legally
+    // hold nothing has no child block to address, so `"before"`/`"after"`
+    // cannot reach inside it.
+    box: container("box", {
+      content: "none",
+      children: { allow: "blocks", min: 0 },
+    }),
+    // A container that only accepts other containers, so an insertion has to
+    // descend a level to find a place for a regular block.
+    grid: container("grid", {
+      content: "none",
+      children: { allow: ["cell"], min: 2 },
+    }),
+    cell: container("cell", {
+      content: "none",
+      children: { allow: "blocks" },
+      placeable: "namedOnly",
+    }),
+  } as const,
+});
 
 let editor: BlockNoteEditor<any, any, any>;
 
 beforeAll(() => {
-  editor = BlockNoteEditor.create() as any;
+  editor = BlockNoteEditor.create({ schema }) as any;
 });
 
 afterAll(() => {
@@ -28,21 +64,25 @@ beforeEach(() => {
 });
 
 describe('insertBlocks "first-child" / "last-child"', () => {
-  it("nests under a childless block, creating the blockGroup", () => {
-    expect(editor.getBlock("p-0")!.children).toHaveLength(0);
+  it("inserts into a childless container", () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "b-0", type: "box" },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+    expect(editor.getBlock("b-0")!.children).toHaveLength(0);
 
     editor.insertBlocks(
       [{ id: "first", type: "paragraph" }],
-      "p-0",
+      "b-0",
       "first-child",
     );
     editor.insertBlocks(
       [{ id: "last", type: "paragraph" }],
-      "p-0",
+      "b-0",
       "last-child",
     );
 
-    expect(editor.getBlock("p-0")!.children.map((child) => child.id)).toEqual([
+    expect(editor.getBlock("b-0")!.children.map((child) => child.id)).toEqual([
       "first",
       "last",
     ]);
@@ -51,63 +91,146 @@ describe('insertBlocks "first-child" / "last-child"', () => {
   it("prepends and appends around existing children", () => {
     editor.replaceBlocks(editor.document, [
       {
-        id: "p-0",
-        type: "paragraph",
-        content: "Paragraph 0",
+        id: "b-0",
+        type: "box",
         children: [{ id: "existing", type: "paragraph", content: "Existing" }],
       },
+      { id: "trailing", type: "paragraph", content: "" },
     ]);
 
     editor.insertBlocks(
       [{ id: "first", type: "paragraph" }],
-      "p-0",
+      "b-0",
       "first-child",
     );
     editor.insertBlocks(
       [{ id: "last", type: "paragraph" }],
-      "p-0",
+      "b-0",
       "last-child",
     );
 
-    expect(editor.getBlock("p-0")!.children.map((child) => child.id)).toEqual([
+    expect(editor.getBlock("b-0")!.children.map((child) => child.id)).toEqual([
       "first",
       "existing",
       "last",
     ]);
   });
 
-  it("still inserts siblings with the default and explicit placements", () => {
-    editor.insertBlocks([{ id: "after", type: "paragraph" }], "p-0");
-    editor.insertBlocks([{ id: "before", type: "paragraph" }], "p-0", "before");
-    editor.insertBlocks([{ id: "sibling", type: "paragraph" }], "p-0", "after");
+  it("descends into a nested container that accepts the block", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        id: "g-0",
+        type: "grid",
+        children: [
+          { id: "c-0", type: "cell" },
+          { id: "c-1", type: "cell" },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
 
-    expect(editor.document.map((block) => block.id)).toEqual([
-      "after",
-      "before",
+    // `grid` itself only accepts `cell`s, so both placements have to find the
+    // leading/trailing cell rather than giving up.
+    editor.insertBlocks(
+      [{ id: "first", type: "paragraph" }],
+      "g-0",
+      "first-child",
+    );
+    editor.insertBlocks(
+      [{ id: "last", type: "paragraph" }],
+      "g-0",
+      "last-child",
+    );
+
+    const grid = editor.getBlock("g-0")!;
+    expect(grid.children[0].children.map((child: any) => child.id)).toContain(
+      "first",
+    );
+    expect(grid.children[1].children.map((child: any) => child.id)).toContain(
+      "last",
+    );
+  });
+
+  it("nests under a regular block, with or without existing children", () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "p-0", type: "paragraph", content: "Paragraph 0" },
+    ]);
+
+    editor.insertBlocks(
+      [{ id: "existing", type: "paragraph" }],
       "p-0",
-      "sibling",
+      "last-child",
+    );
+    editor.insertBlocks(
+      [{ id: "first", type: "paragraph" }],
+      "p-0",
+      "first-child",
+    );
+
+    expect(editor.getBlock("p-0")!.children.map((child) => child.id)).toEqual([
+      "first",
+      "existing",
+    ]);
+  });
+
+  it("throws when a sibling placement isn't allowed either", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        id: "g-0",
+        type: "grid",
+        children: [
+          { id: "c-0", type: "cell" },
+          { id: "c-1", type: "cell" },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
     ]);
+
+    // `grid`'s children are `cell`s only, so a paragraph can't become one's
+    // sibling. Previously this threw a raw ProseMirror `ReplaceError`.
+    expect(() =>
+      editor.insertBlocks([{ type: "paragraph" }], "c-0", "after"),
+    ).toThrow(/at "after" of block "c-0": no valid position/);
+  });
+
+  it("throws when only the first of several blocks would fit", () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "p-0", type: "paragraph", content: "Paragraph 0" },
+    ]);
+
+    // Nesting under a childless regular block wraps the batch in a fresh
+    // `blockGroup`, which takes the paragraph but not the `namedOnly`
+    // cell. Validating only the first node used to let the batch through and
+    // fail later with a raw ProseMirror `ReplaceError`.
+    expect(() =>
+      editor.insertBlocks(
+        [{ type: "paragraph" }, { type: "cell" }],
+        "p-0",
+        "last-child",
+      ),
+    ).toThrow(/at "last-child" of block "p-0": .* doesn't accept them/);
+
+    expect(editor.getBlock("p-0")!.children).toEqual([]);
   });
 
   it("still inserts a batch that fits in full", () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "b-0", type: "box", children: [] },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
     editor.insertBlocks(
       [
         { id: "one", type: "paragraph" },
         { id: "two", type: "paragraph" },
       ],
-      "p-0",
+      "b-0",
       "last-child",
     );
 
-    expect(editor.getBlock("p-0")!.children.map((child) => child.id)).toEqual([
+    expect(editor.getBlock("b-0")!.children.map((child) => child.id)).toEqual([
       "one",
       "two",
     ]);
   });
-
-  it("throws when the reference block does not exist", () => {
-    expect(() =>
-      editor.insertBlocks([{ type: "paragraph" }], "missing-id", "last-child"),
-    ).toThrow(/Block with ID missing-id not found/);
-  });
 });
diff --git a/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.test.ts b/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.test.ts
index b339f66ec1..532da5aaef 100644
--- a/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.test.ts
+++ b/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.test.ts
@@ -3,6 +3,8 @@ import { describe, expect, it } from "vite-plus/test";
 import { getBlockInfoFromSelection } from "../../../getBlockInfoFromPos.js";
 import { setupTestEnv } from "../../setupTestEnv.js";
 import { getParentBlockInfo } from "../../../getBlockInfoFromPos.js";
+import { getNodeById } from "../../../nodeUtil.js";
+import { containerSchema } from "../../containers/containers.fixture.js";
 import { mergeBlocksCommand } from "./mergeBlocks.js";
 
 const getEditor = setupTestEnv();
@@ -146,3 +148,87 @@ describe("Test mergeBlocks", () => {
     expect(ret).toBeFalsy();
   });
 });
+
+describe("Test mergeBlocks at container boundaries", () => {
+  const getContainerEditor = setupTestEnv({
+    schema: containerSchema,
+    document: [
+      { id: "before-callout", type: "paragraph", content: "Before callout" },
+      {
+        id: "callout-0",
+        type: "callout",
+        children: [
+          {
+            id: "callout-child-0",
+            type: "paragraph",
+            content: "Callout child 0",
+          },
+          {
+            id: "callout-child-1",
+            type: "paragraph",
+            content: "Callout child 1",
+          },
+        ],
+      },
+      { id: "after-callout", type: "paragraph", content: "After callout" },
+    ],
+  });
+
+  function mergeContainerBlocks(posBetweenBlocks: number) {
+    return getContainerEditor()._tiptapEditor.commands.command(
+      mergeBlocksCommand(posBetweenBlocks),
+    );
+  }
+
+  function getPosBefore(id: string) {
+    return getContainerEditor().transact((tr) => {
+      const node = getNodeById(id, tr.doc);
+      if (!node) {
+        throw new Error(`No block with id "${id}" in the test document`);
+      }
+      return node.posBeforeNode;
+    });
+  }
+
+  // A container's first child has no previous sibling, so there is nothing to
+  // merge it into. The block above it on screen sits outside the container.
+  it("Does not merge a container's first child out of the container", () => {
+    const originalDocument = getContainerEditor().document;
+    const ret = mergeContainerBlocks(getPosBefore("callout-child-0"));
+
+    expect(ret).toBeFalsy();
+    expect(getContainerEditor().document).toEqual(originalDocument);
+  });
+
+  // A container has no content of its own, so there is nothing to merge.
+  it("Does not merge a container into the block above it", () => {
+    const originalDocument = getContainerEditor().document;
+    const ret = mergeContainerBlocks(getPosBefore("callout-0"));
+
+    expect(ret).toBeFalsy();
+    expect(getContainerEditor().document).toEqual(originalDocument);
+  });
+
+  // `mergeBlocksCommand` treats a container like any other block with children
+  // and merges into its last descendant, which puts the merged text inside the
+  // container. Backspace never produces this, because
+  // `KeyboardShortcutsExtension` bails out when the previous sibling has no
+  // inline content and moves the block into the container instead. So this is
+  // the command's behaviour on its own, not the editor's; it is pinned here
+  // because `mergeBlocks.ts` documents the opposite.
+  it("Merges a block into the last descendant of the container above it", () => {
+    const ret = mergeContainerBlocks(getPosBefore("after-callout"));
+
+    expect(ret).toBeTruthy();
+
+    const document = getContainerEditor().document;
+
+    expect(document.map((block) => block.id)).toEqual([
+      "before-callout",
+      "callout-0",
+    ]);
+    expect(document[1].children[1].content).toEqual([
+      { type: "text", text: "Callout child 1After callout", styles: {} },
+    ]);
+  });
+});
diff --git a/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.ts b/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.ts
index 7101698a39..e3817aa3a6 100644
--- a/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.ts
+++ b/packages/core/src/api/blockManipulation/commands/mergeBlocks/mergeBlocks.ts
@@ -1,11 +1,45 @@
-import { EditorState } from "prosemirror-state";
+import { Fragment, type Node } from "prosemirror-model";
+import { EditorState, TextSelection } from "prosemirror-state";
 
 import {
+  type BlockInfo,
   getBlockInfoAt,
   getLastDescendantBlockInfo,
   getPrevBlockInfo,
+  getParentBlockInfo,
 } from "../../../getBlockInfoFromPos.js";
 
+/** Returns compatible text to append, or undefined when the blocks cannot merge. */
+export function getMergeContent(
+  current: Extract<BlockInfo, { hasContent: true }>,
+  next: Extract<BlockInfo, { hasContent: true }>,
+): Fragment | undefined {
+  const inline =
+    current.contentKind === "inline" && next.contentKind === "inline";
+  const ownedText =
+    current.hasOwnedChildren &&
+    current.content.node.isTextblock &&
+    next.content.node.isTextblock;
+  if (!inline && !ownedText) {
+    return undefined;
+  }
+  if (current.contentKind === "plain") {
+    const type = current.content.node.type;
+    const children: Node[] = [];
+    next.content.node.forEach((child) => {
+      const text =
+        child.type === type.schema.linebreakReplacement
+          ? "\n"
+          : child.textContent;
+      if (text) {
+        children.push(type.schema.text(text, type.allowedMarks(child.marks)));
+      }
+    });
+    return Fragment.from(children);
+  }
+  return next.content.node.content;
+}
+
 /**
  * Merges the block starting at `posBetweenBlocks` into the block visually
  * above it, by deleting the boundary between the two.
@@ -15,9 +49,9 @@ import {
  * i.e. its `BlockInfo`'s `block.beforePos`. The block above is found by walking
  * back from there.
  * @returns A tiptap command that returns `false` (leaving the doc untouched)
- * when the two blocks can't merge: no block above, either side isn't an
- * inline-content block, or the block above is empty (deleting it is handled
- * elsewhere).
+ * when the two blocks can't merge: no compatible text block above, or the
+ * block above is empty (deleting it is handled elsewhere). An owning block
+ * can also merge plain text, dropping formatting that its schema disallows.
  */
 export const mergeBlocksCommand =
   (posBetweenBlocks: number) =>
@@ -30,42 +64,38 @@ export const mergeBlocksCommand =
   }) => {
     const nextBlockInfo = getBlockInfoAt(state.doc, posBetweenBlocks);
 
-    const prevBlockInfo = getPrevBlockInfo(
+    const prevSibling = getPrevBlockInfo(
       state.doc,
       nextBlockInfo.block.beforePos,
     );
-
+    const parent = prevSibling
+      ? undefined
+      : getParentBlockInfo(state.doc, nextBlockInfo.block.beforePos);
+    // An owned body's first block can merge into its title. Ordinary nested
+    // blocks still need a preceding sibling; lifting handles their boundary.
+    const prevBlockInfo = prevSibling
+      ? getLastDescendantBlockInfo(prevSibling)
+      : parent?.hasOwnedChildren
+        ? parent
+        : undefined;
     if (!prevBlockInfo) {
       return false;
     }
 
-    // The block we merge into is the last descendant of the previous block:
-    // visually, that's the block directly above the boundary.
-    const bottomNestedBlockInfo = getLastDescendantBlockInfo(prevBlockInfo);
-
-    // Only inline-content blocks can merge, and merging into an empty block
-    // is handled elsewhere (by deleting the empty block instead). Merging
-    // into or out of container blocks (columnLists, callouts, ...) is
-    // intentionally unsupported; the container-boundary Backspace/Delete
-    // branches in `KeyboardShortcutsExtension` handle those cases by moving
-    // blocks across the boundary instead of merging their content.
     if (
-      !bottomNestedBlockInfo.hasContent ||
-      bottomNestedBlockInfo.contentKind !== "inline" ||
-      bottomNestedBlockInfo.isContentEmpty ||
-      !nextBlockInfo.hasContent ||
-      nextBlockInfo.contentKind !== "inline"
+      !prevBlockInfo.hasContent ||
+      prevBlockInfo.isContentEmpty ||
+      !nextBlockInfo.hasContent
     ) {
       return false;
     }
+    const content = getMergeContent(prevBlockInfo, nextBlockInfo);
+    if (content === undefined) {
+      return false;
+    }
 
-    // Un-nests the next block's children by one level, so they survive as
-    // siblings of the merged block rather than as children of a block that no
-    // longer exists once the boundary below is deleted.
-    //
-    // Note `state.tr` is tiptap's chainable state, whose getter returns the one
-    // transaction shared by the command chain (not a fresh `Transaction` like
-    // `EditorState.tr`), so this lift carries over into the `dispatch` below.
+    // Lift children before removing their parent. Tiptap's chainable state
+    // returns the shared transaction, so the lift is included in dispatch.
     if (dispatch && nextBlockInfo.children) {
       const childBlocksRange = state.doc
         .resolve(nextBlockInfo.children.childrenStart)
@@ -86,16 +116,21 @@ export const mergeBlocksCommand =
       );
     }
 
-    // Deletes the boundary between the two blocks. Can be thought of as
-    // removing the closing tags of the first block and the opening tags of the
-    // second one to stitch them together.
     if (dispatch) {
-      dispatch(
-        state.tr.delete(
-          bottomNestedBlockInfo.contentEnd,
-          nextBlockInfo.contentStart,
-        ),
-      );
+      if (content !== nextBlockInfo.content.node.content) {
+        state.tr
+          .replaceWith(
+            prevBlockInfo.contentEnd,
+            nextBlockInfo.contentEnd,
+            content,
+          )
+          .setSelection(
+            TextSelection.create(state.tr.doc, prevBlockInfo.contentEnd),
+          );
+      } else {
+        state.tr.delete(prevBlockInfo.contentEnd, nextBlockInfo.contentStart);
+      }
+      dispatch(state.tr);
     }
 
     return true;
diff --git a/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.test.ts b/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.test.ts
index f9bba17c3f..2699217643 100644
--- a/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.test.ts
+++ b/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.test.ts
@@ -7,16 +7,25 @@ import {
   getBlockInfoFromSelection,
   getNodeId,
 } from "../../../getBlockInfoFromPos.js";
-import { setupTestEnv } from "../../setupTestEnv.js";
+import { getNodeById } from "../../../nodeUtil.js";
+import { containerSchema } from "../../containers/containers.fixture.js";
+import { setupTestEnv, testDocument } from "../../setupTestEnv.js";
 import {
   moveBlocksDown,
   moveBlocksUp,
   moveSelectedBlocksAndSelection,
 } from "./moveBlocks.js";
 
-const getEditor = setupTestEnv();
+const getEditor = setupTestEnv<
+  typeof containerSchema.blockSchema,
+  typeof containerSchema.inlineContentSchema,
+  typeof containerSchema.styleSchema
+>({
+  schema: containerSchema,
+  document: testDocument,
+});
 
-function makeSelectionSpanContent(selectionType: "text" | "node" | "cell") {
+function makeSelectionSpanContent(selectionType: "text" | "cell") {
   const blockInfo = getEditor().transact((tr) => getBlockInfoFromSelection(tr));
   if (!blockInfo.hasContent) {
     throw new Error(
@@ -36,10 +45,6 @@ function makeSelectionSpanContent(selectionType: "text" | "node" | "cell") {
         ),
       ),
     );
-  } else if (selectionType === "node") {
-    editor.transact((tr) =>
-      tr.setSelection(NodeSelection.create(tr.doc, content.beforePos)),
-    );
   } else {
     editor.transact((tr) =>
       tr.setSelection(
@@ -69,19 +74,30 @@ describe("Test moveSelectedBlockAndSelection", () => {
     ).toBeTruthy();
   });
 
-  it("Node selection", () => {
-    getEditor().setTextCursorPosition("image-0");
-    makeSelectionSpanContent("node");
-
-    moveSelectedBlocksAndSelection(getEditor(), "paragraph-0", "before");
-
-    const selection = getEditor().transact((tr) => tr.selection);
-    getEditor().setTextCursorPosition("image-0");
-    makeSelectionSpanContent("node");
-
-    expect(
-      selection.eq(getEditor().transact((tr) => tr.selection)),
-    ).toBeTruthy();
+  it.each([
+    { type: "image", offset: 1 },
+    { type: "callout", offset: 0 },
+  ] as const)("Node selection: $type", ({ type, offset }) => {
+    const editor = getEditor();
+    editor.insertBlocks([{ id: "selected", type }], "paragraph-1", "after");
+    editor.transact((tr) => {
+      const block = getNodeById("selected", tr.doc)!;
+      tr.setSelection(
+        NodeSelection.create(tr.doc, block.posBeforeNode + offset),
+      );
+    });
+
+    moveSelectedBlocksAndSelection(editor, "paragraph-0", "before");
+
+    expect(editor.document[0].id).toBe("selected");
+    editor.transact((tr) => {
+      const moved = getNodeById("selected", tr.doc)!;
+      expect(
+        tr.selection.eq(
+          NodeSelection.create(tr.doc, moved.posBeforeNode + offset),
+        ),
+      ).toBe(true);
+    });
   });
 
   it("Cell selection", () => {
diff --git a/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.ts b/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.ts
index 51ed7e6852..1cb6f2a53c 100644
--- a/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.ts
+++ b/packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.ts
@@ -1,4 +1,4 @@
-import type { NodeType } from "prosemirror-model";
+import type { NodeType, Schema } from "prosemirror-model";
 import {
   NodeSelection,
   Selection,
@@ -11,15 +11,38 @@ import { Block } from "../../../../blocks/defaultBlocks.js";
 import type { BlockNoteEditor } from "../../../../editor/BlockNoteEditor";
 import { BlockIdentifier } from "../../../../schema/index.js";
 import {
-  getBlockInfoNearPos,
-  getBlockInfoAt,
+  isContainerNode,
+  isNamedOnly,
+} from "../../../../schema/blocks/children.js";
+import {
   getInsertionPos,
+  getBlockInfoAt,
+  getBlockInfoNearPos,
   getNodeId,
 } from "../../../getBlockInfoFromPos.js";
 import { getNodeById } from "../../../nodeUtil.js";
 import { insertBlocks } from "../insertBlocks/insertBlocks.js";
 import { removeAndInsertBlocks } from "../replaceBlocks/replaceBlocks.js";
 
+/**
+ * Dissolves `placeable: "namedOnly"` blocks into their children.
+ *
+ * A `namedOnly` block (a `column`, say) is defined only in terms of the
+ * container that holds it, so it can't land anywhere a regular block goes —
+ * moving one out of its container moves its children instead. Every other
+ * block passes through as itself.
+ */
+function dissolveContainerOnlyBlocks(
+  blocks: Block<any, any, any>[],
+  pmSchema: Schema,
+): Block<any, any, any>[] {
+  return blocks.flatMap((block) =>
+    isNamedOnly(pmSchema.nodes[block.type])
+      ? dissolveContainerOnlyBlocks(block.children, pmSchema)
+      : [block],
+  );
+}
+
 type BlockSelectionData = (
   | {
       type: "text";
@@ -114,7 +137,11 @@ function updateBlockSelectionFromData(
       anchorBlockPos + data.headCellOffset,
     );
   } else if (data.type === "node") {
-    selection = NodeSelection.create(tr.doc, anchorBlockPos + 1);
+    const blockInfo = getBlockInfoAt(tr.doc, anchorBlockPos);
+    selection = NodeSelection.create(
+      tr.doc,
+      blockInfo.hasContent ? blockInfo.content.beforePos : anchorBlockPos,
+    );
   } else {
     const headBlockPos = getNodeById(data.headBlockId, tr.doc)?.posBeforeNode;
     if (headBlockPos === undefined) {
@@ -133,16 +160,6 @@ function updateBlockSelectionFromData(
   tr.setSelection(selection);
 }
 
-// Replaces top-level `column` blocks with their children, as a `column` is not
-// a valid block outside a `columnList`. Other blocks are returned as-is.
-function flattenColumns(
-  blocks: Block<any, any, any>[],
-): Block<any, any, any>[] {
-  return blocks.flatMap((block) =>
-    block.type === "column" ? block.children : [block],
-  );
-}
-
 /**
  * Removes the given blocks from the editor, then inserts them before/after a
  * reference block.
@@ -171,10 +188,10 @@ export function moveBlocks(
     // </column>
     // When the non-empty block is moved up, the column is seen as empty and
     // collapsed in the removal step, so the following insertion fails.
-    removeAndInsertBlocks(tr, blocks, [], { fixColumns: false });
+    removeAndInsertBlocks(tr, blocks, [], { fixContainers: false });
     insertBlocks<any, any, any>(
       tr,
-      flattenColumns(blocks),
+      dissolveContainerOnlyBlocks(blocks, editor.pmSchema),
       referenceBlock,
       placement,
     );
@@ -209,295 +226,125 @@ export function moveSelectedBlocksAndSelection(
   });
 }
 
-/**
- * All a placement check needs to know about the block being moved: where it
- * currently sits, and what would land at the destination. Neither changes as a
- * placement search walks the document, so both are resolved once up front.
- */
-type MovedBlock = {
-  /** The moved block's ID, to locate it in the doc. */
-  id: string;
-  /**
-   * The PM node type that would actually be inserted: a child-holding wrapper
-   * block (e.g. a `columnList`) goes in as its own node type; anything else
-   * as a generic `blockContainer` wrapper.
-   */
-  nodeType: NodeType;
-};
-
-function toMovedBlock(
+/** The first node type inserted after dissolving container-only blocks. */
+function getMovedNodeType(
   editor: BlockNoteEditor<any, any, any>,
   block: Block<any, any, any>,
-): MovedBlock {
-  const type = editor.pmSchema.nodes[block.type];
-
-  return {
-    id: block.id,
-    nodeType:
-      type && type.isInGroup("bnBlock") && type.isInGroup("childContainer")
-        ? type
-        : editor.pmSchema.nodes["blockContainer"],
-  };
-}
-
-// Checks if a block would be in a valid place after being moved
-// before/after `referenceBlock`. A regular block nests under any block (it
-// goes into that block's `blockGroup`), but a wrapper block (e.g. a
-// `columnList`) only accepts what its content expression allows.
-//
-// Deferred to `getInsertionPos` so that "can a block go here?" has exactly
-// one answer, shared with `insertBlocks`, and comes from the schema rather
-// than from a rule restated here.
-function checkPlacementIsValid(
-  editor: BlockNoteEditor<any, any, any>,
-  referenceBlock: Block<any, any, any>,
-  placement: "before" | "after",
-  movedBlock: MovedBlock,
-): boolean {
-  return editor.transact((tr) => {
-    const posInfo = getNodeById(referenceBlock.id, tr.doc);
-    const movedPosInfo = getNodeById(movedBlock.id, tr.doc);
-    if (!posInfo || !movedPosInfo) {
-      return false;
-    }
-
-    const target = getInsertionPos(
-      tr.doc,
-      getBlockInfoAt(tr.doc, posInfo.posBeforeNode),
-      placement,
-      movedBlock.nodeType,
-    );
-    return target !== null;
-  });
-}
-
-/**
- * Gets the placement for moving a block up. This has 3 cases:
- * 1. If the block has a previous sibling without children, the placement is
- * before it.
- * 2. If the block has a previous sibling with children, the placement is after
- * the last child.
- * 3. If the block has no previous sibling, but is nested, the placement is
- * before its parent.
- * If the placement is invalid, the function is called recursively until a valid
- * placement is found. Returns undefined if no valid placement is found, meaning
- * the block is already at the top of the document.
- *
- * @param movedBlock What is being moved (see {@link MovedBlock}). Carried
- * through the recursion because "is this placement valid?" depends on it: a
- * candidate destination has to accept the moved node's type. Only read by
- * `checkPlacementIsValid`.
- * @param prevBlock The candidate previous sibling, i.e. the block the
- * placement is measured against. Steps further back on each recursion.
- * @param parentBlock The parent of `prevBlock`'s level, used for case 3.
- */
-function getMoveUpPlacement(
-  editor: BlockNoteEditor<any, any, any>,
-  movedBlock: MovedBlock,
-  prevBlock?: Block<any, any, any>,
-  parentBlock?: Block<any, any, any>,
-):
-  | { referenceBlock: BlockIdentifier; placement: "before" | "after" }
-  | undefined {
-  let referenceBlock: Block<any, any, any> | undefined;
-  let placement: "before" | "after" | undefined;
-
-  if (!prevBlock) {
-    if (parentBlock) {
-      referenceBlock = parentBlock;
-      placement = "before";
-    }
-  } else if (prevBlock.children.length > 0) {
-    referenceBlock = prevBlock.children[prevBlock.children.length - 1];
-    placement = "after";
-  } else {
-    referenceBlock = prevBlock;
-    placement = "before";
-  }
-
-  // Case when the block is already at the top of the document.
-  if (!referenceBlock || !placement) {
-    return undefined;
-  }
-
-  if (!checkPlacementIsValid(editor, referenceBlock, placement, movedBlock)) {
-    const referenceBlockParent = editor.getParentBlock(referenceBlock);
-    return getMoveUpPlacement(
-      editor,
-      movedBlock,
-      placement === "after"
-        ? referenceBlock
-        : editor.getPrevBlock(referenceBlock),
-      referenceBlockParent,
-    );
-  }
-
-  return { referenceBlock, placement };
+): NodeType {
+  const first = dissolveContainerOnlyBlocks([block], editor.pmSchema)[0];
+  const type = first && editor.pmSchema.nodes[first.type];
+  return type && isContainerNode(type)
+    ? type
+    : editor.pmSchema.nodes["blockContainer"];
 }
 
 /**
- * Gets the placement for moving a block down. This has 3 cases:
- * 1. If the block has a next sibling without children, the placement is  after
- * it.
- * 2. If the block has a next sibling with children, the placement is before the
- * first child.
- * 3. If the block has no next sibling, but is nested, the placement is
- * after its parent.
- * If the placement is invalid, the function is called recursively until a valid
- * placement is found. Returns undefined if no valid placement is found, meaning
- * the block is already at the bottom of the document.
- *
- * @param movedBlock What is being moved; see `getMoveUpPlacement`.
- * @param nextBlock The candidate next sibling, i.e. the block the placement is
- * measured against. Steps further forward on each recursion.
- * @param parentBlock The parent of `nextBlock`'s level, used for case 3.
+ * Searches in document order for a placement accepted by the moved node's type.
+ * Moving past a sibling with children enters its nearest child; reaching the
+ * end of a sibling list moves outside its parent.
  */
-function getMoveDownPlacement(
+function getMovePlacement(
   editor: BlockNoteEditor<any, any, any>,
-  movedBlock: MovedBlock,
-  nextBlock?: Block<any, any, any>,
-  parentBlock?: Block<any, any, any>,
+  nodeType: NodeType,
+  direction: "up" | "down",
+  sibling?: Block<any, any, any>,
+  parent?: Block<any, any, any>,
 ):
   | { referenceBlock: BlockIdentifier; placement: "before" | "after" }
   | undefined {
-  let referenceBlock: Block<any, any, any> | undefined;
-  let placement: "before" | "after" | undefined;
-
-  if (!nextBlock) {
-    if (parentBlock) {
-      referenceBlock = parentBlock;
-      placement = "after";
+  const outside = direction === "up" ? "before" : "after";
+  const inside = direction === "up" ? "after" : "before";
+  while (sibling || parent) {
+    const hasChildren = sibling && sibling.children.length > 0;
+    const referenceBlock = sibling
+      ? hasChildren
+        ? sibling.children[direction === "up" ? sibling.children.length - 1 : 0]
+        : sibling
+      : parent!;
+    const placement = hasChildren ? inside : outside;
+    const valid = editor.transact((tr) => {
+      const target = getNodeById(referenceBlock.id, tr.doc);
+      return (
+        target !== undefined &&
+        getInsertionPos(
+          tr.doc,
+          getBlockInfoAt(tr.doc, target.posBeforeNode),
+          placement,
+          nodeType,
+        ) !== null
+      );
+    });
+    if (valid) {
+      return { referenceBlock, placement };
     }
-  } else if (nextBlock.children.length > 0) {
-    referenceBlock = nextBlock.children[0];
-    placement = "before";
-  } else {
-    referenceBlock = nextBlock;
-    placement = "after";
-  }
-
-  // Case when the block is already at the bottom of the document.
-  if (!referenceBlock || !placement) {
-    return undefined;
-  }
-
-  if (!checkPlacementIsValid(editor, referenceBlock, placement, movedBlock)) {
-    const referenceBlockParent = editor.getParentBlock(referenceBlock);
-    return getMoveDownPlacement(
-      editor,
-      movedBlock,
-      placement === "before"
+    parent = editor.getParentBlock(referenceBlock);
+    sibling =
+      placement === inside
         ? referenceBlock
-        : editor.getNextBlock(referenceBlock),
-      referenceBlockParent,
-    );
+        : direction === "up"
+          ? editor.getPrevBlock(referenceBlock)
+          : editor.getNextBlock(referenceBlock);
   }
-
-  return { referenceBlock, placement };
+  return undefined;
 }
 
-export function moveBlocksUp(
+function moveBlocksInDirection(
   editor: BlockNoteEditor<any, any, any>,
+  direction: "up" | "down",
   blockIdentifier?: BlockIdentifier,
 ) {
   editor.transact(() => {
-    let sourceBlock: Block<any, any, any> | undefined;
+    let blocks: Block<any, any, any>[];
     if (blockIdentifier) {
-      sourceBlock = editor.getBlock(blockIdentifier);
-      if (!sourceBlock) {
+      const block = editor.getBlock(blockIdentifier);
+      if (!block) {
         return;
       }
+      blocks = [block];
     } else {
-      const selection = editor.getSelection();
-      sourceBlock =
-        selection?.blocks[0] || editor.getTextCursorPosition().block;
+      blocks = editor.getSelection()?.blocks || [
+        editor.getTextCursorPosition().block,
+      ];
     }
 
-    const moveUpPlacement = getMoveUpPlacement(
+    // The last selected block anchors a downward move, but insertion always
+    // starts with the first selected block.
+    const sourceBlock = blocks[direction === "up" ? 0 : blocks.length - 1];
+    const target = getMovePlacement(
       editor,
-      // `moveBlocks` inserts the flattened selection (a `column` goes in as
-      // its children), so the placement is validated for the block that
-      // actually lands at the destination, not for the raw block.
-      toMovedBlock(editor, flattenColumns([sourceBlock])[0] ?? sourceBlock),
-      editor.getPrevBlock(sourceBlock),
+      getMovedNodeType(editor, blocks[0]),
+      direction,
+      direction === "up"
+        ? editor.getPrevBlock(sourceBlock)
+        : editor.getNextBlock(sourceBlock),
       editor.getParentBlock(sourceBlock),
     );
-
-    if (!moveUpPlacement) {
+    if (!target) {
       return;
     }
 
     if (blockIdentifier) {
-      moveBlocks(
-        editor,
-        [sourceBlock],
-        moveUpPlacement.referenceBlock,
-        moveUpPlacement.placement,
-      );
+      moveBlocks(editor, blocks, target.referenceBlock, target.placement);
     } else {
       moveSelectedBlocksAndSelection(
         editor,
-        moveUpPlacement.referenceBlock,
-        moveUpPlacement.placement,
+        target.referenceBlock,
+        target.placement,
       );
     }
   });
 }
 
-export function moveBlocksDown(
+export function moveBlocksUp(
   editor: BlockNoteEditor<any, any, any>,
   blockIdentifier?: BlockIdentifier,
 ) {
-  editor.transact(() => {
-    let sourceBlock: Block<any, any, any> | undefined;
-    // The block whose position anchors the move (the last of a selection when
-    // moving down) vs. the first block that gets inserted, which is what the
-    // placement check must validate against.
-    let firstMovedBlock: Block<any, any, any> | undefined;
-    if (blockIdentifier) {
-      sourceBlock = editor.getBlock(blockIdentifier);
-      if (!sourceBlock) {
-        return;
-      }
-      firstMovedBlock = sourceBlock;
-    } else {
-      const selection = editor.getSelection();
-      sourceBlock =
-        selection?.blocks[selection?.blocks.length - 1] ||
-        editor.getTextCursorPosition().block;
-      firstMovedBlock =
-        selection?.blocks[0] || editor.getTextCursorPosition().block;
-    }
-
-    const moveDownPlacement = getMoveDownPlacement(
-      editor,
-      // See `moveBlocksUp`: validate for the flattened block that actually
-      // lands at the destination.
-      toMovedBlock(
-        editor,
-        flattenColumns([firstMovedBlock])[0] ?? firstMovedBlock,
-      ),
-      editor.getNextBlock(sourceBlock),
-      editor.getParentBlock(sourceBlock),
-    );
-
-    if (!moveDownPlacement) {
-      return;
-    }
+  moveBlocksInDirection(editor, "up", blockIdentifier);
+}
 
-    if (blockIdentifier) {
-      moveBlocks(
-        editor,
-        [sourceBlock],
-        moveDownPlacement.referenceBlock,
-        moveDownPlacement.placement,
-      );
-    } else {
-      moveSelectedBlocksAndSelection(
-        editor,
-        moveDownPlacement.referenceBlock,
-        moveDownPlacement.placement,
-      );
-    }
-  });
+export function moveBlocksDown(
+  editor: BlockNoteEditor<any, any, any>,
+  blockIdentifier?: BlockIdentifier,
+) {
+  moveBlocksInDirection(editor, "down", blockIdentifier);
 }
diff --git a/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.test.ts b/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.test.ts
index 8247e9391c..cf24ec0556 100644
--- a/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.test.ts
+++ b/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.test.ts
@@ -3,6 +3,7 @@ import { describe, expect, it } from "vite-plus/test";
 import { afterAll, beforeAll } from "vite-plus/test";
 import { PartialBlock } from "../../../../blocks/defaultBlocks.js";
 import { BlockNoteEditor } from "../../../../editor/BlockNoteEditor.js";
+import { containerSchema } from "../../containers/containers.fixture.js";
 
 /**
  * Custom test setup with a document designed to reproduce nesting/unnesting bugs.
@@ -646,6 +647,223 @@ describe("unnestBlock / liftListItem", () => {
   });
 });
 
+// A second editor, on a schema that has container blocks. `setupNestTestEnv`
+// builds a default-schema editor, which can't express any of the cases below.
+function setupContainerNestTestEnv() {
+  let editor: BlockNoteEditor<any, any, any>;
+  const div = document.createElement("div");
+
+  beforeAll(() => {
+    editor = BlockNoteEditor.create({ schema: containerSchema });
+    editor.mount(div);
+  });
+
+  afterAll(() => {
+    editor._tiptapEditor.destroy();
+    editor = undefined as any;
+  });
+
+  return (doc: PartialBlock<any, any, any>[]) => {
+    editor.replaceBlocks(editor.document, doc);
+    return editor;
+  };
+}
+
+// `canNestBlock` and `canUnnestBlock` run the real command on a transaction
+// that is thrown away, rather than restating its preconditions. The cases here
+// are the ones where the old, restated preconditions gave the wrong answer:
+// they looked at a previous sibling's mere existence and at the block's depth,
+// neither of which knows anything about containers.
+describe("canNestBlock / canUnnestBlock around containers", () => {
+  const withContainerEditor = setupContainerNestTestEnv();
+
+  it("Reports that a block cannot be nested under a container sibling", () => {
+    const editor = withContainerEditor([
+      {
+        id: "callout-0",
+        type: "callout",
+        children: [
+          { id: "callout-child", type: "paragraph", content: "Callout child" },
+        ],
+      },
+      { id: "paragraph-0", type: "paragraph", content: "Paragraph 0" },
+    ]);
+
+    editor.setTextCursorPosition("paragraph-0", "start");
+
+    const before = editor.document;
+    expect(editor.canNestBlock()).toBe(false);
+
+    // And the answer matches what nesting actually does.
+    editor.nestBlock();
+    expect(editor.document).toEqual(before);
+  });
+
+  it("Reports that a container's child cannot be unnested out of it", () => {
+    const editor = withContainerEditor([
+      {
+        id: "callout-0",
+        type: "callout",
+        children: [
+          { id: "callout-child", type: "paragraph", content: "Callout child" },
+        ],
+      },
+    ]);
+
+    editor.setTextCursorPosition("callout-child", "start");
+
+    const before = editor.document;
+    expect(editor.canUnnestBlock()).toBe(false);
+
+    editor.unnestBlock();
+    expect(editor.document).toEqual(before);
+  });
+
+  it("Reports that a block with a plain previous sibling can be nested", () => {
+    const editor = withContainerEditor([
+      { id: "paragraph-0", type: "paragraph", content: "Paragraph 0" },
+      { id: "paragraph-1", type: "paragraph", content: "Paragraph 1" },
+    ]);
+
+    editor.setTextCursorPosition("paragraph-1", "start");
+
+    const before = editor.document;
+    expect(editor.canNestBlock()).toBe(true);
+    // The probe runs the command on a transaction it never dispatches, so
+    // answering must not change the document.
+    expect(editor.document).toEqual(before);
+
+    editor.nestBlock();
+    expect(editor.getBlock("paragraph-0")!.children.map((c) => c.id)).toEqual([
+      "paragraph-1",
+    ]);
+    expect(editor.canUnnestBlock()).toBe(true);
+  });
+
+  it("Nests and unnests a block inside a container's children", () => {
+    const editor = withContainerEditor([
+      {
+        id: "callout-0",
+        type: "callout",
+        children: [
+          { id: "child-0", type: "paragraph", content: "Child 0" },
+          { id: "child-1", type: "paragraph", content: "Child 1" },
+        ],
+      },
+    ]);
+
+    const before = editor.document;
+
+    editor.setTextCursorPosition("child-1", "start");
+    expect(editor.canNestBlock()).toBe(true);
+    editor.nestBlock();
+
+    expect(editor.getBlock("callout-0")!.children.map((c) => c.id)).toEqual([
+      "child-0",
+    ]);
+    expect(editor.getBlock("child-0")!.children.map((c) => c.id)).toEqual([
+      "child-1",
+    ]);
+
+    editor.setTextCursorPosition("child-1", "start");
+    expect(editor.canUnnestBlock()).toBe(true);
+    editor.unnestBlock();
+
+    expect(editor.document).toEqual(before);
+  });
+});
+
+// A `grid` holds only `gridCell`s, so a selection spanning two cells has no
+// nestable range inside the grid. The range has to resolve outside it, at the
+// `blockGroup` the grid sits in, so Tab moves the grid as a unit rather than
+// doing nothing. `columnList`/`column` in `@blocknote/xl-multi-column` are the
+// same shape, and the user-facing case this guards.
+describe("Nesting a selection that spans two of a container's children", () => {
+  const withContainerEditor = setupContainerNestTestEnv();
+
+  function gridWith(id: string) {
+    return {
+      id,
+      type: "grid" as const,
+      children: [
+        {
+          id: `${id}-cell-a`,
+          type: "gridCell" as const,
+          children: [
+            { id: `${id}-a`, type: "paragraph" as const, content: "A" },
+          ],
+        },
+        {
+          id: `${id}-cell-b`,
+          type: "gridCell" as const,
+          children: [
+            { id: `${id}-b`, type: "paragraph" as const, content: "B" },
+          ],
+        },
+      ],
+    };
+  }
+
+  it("Nests the whole grid under its previous sibling", () => {
+    const editor = withContainerEditor([
+      { id: "paragraph-0", type: "paragraph", content: "Paragraph 0" },
+      gridWith("grid-0"),
+    ]);
+
+    editor.setSelection("grid-0-a", "grid-0-b");
+
+    expect(editor.canNestBlock()).toBe(true);
+    editor.nestBlock();
+
+    expect(editor.document.map((block) => block.id)).toEqual(["paragraph-0"]);
+    expect(editor.getBlock("paragraph-0")!.children.map((c) => c.id)).toEqual([
+      "grid-0",
+    ]);
+    // The grid itself is untouched — only its position changed.
+    expect(editor.getBlock("grid-0")!.children.map((c) => c.id)).toEqual([
+      "grid-0-cell-a",
+      "grid-0-cell-b",
+    ]);
+  });
+
+  it("Unnests the whole grid out of its parent", () => {
+    const editor = withContainerEditor([
+      {
+        id: "paragraph-0",
+        type: "paragraph",
+        content: "Paragraph 0",
+        children: [gridWith("grid-0")],
+      },
+    ]);
+
+    editor.setSelection("grid-0-a", "grid-0-b");
+
+    expect(editor.canUnnestBlock()).toBe(true);
+    editor.unnestBlock();
+
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "paragraph-0",
+      "grid-0",
+    ]);
+    expect(editor.getBlock("paragraph-0")!.children).toEqual([]);
+    expect(editor.getBlock("grid-0")!.children.map((c) => c.id)).toEqual([
+      "grid-0-cell-a",
+      "grid-0-cell-b",
+    ]);
+  });
+
+  it("Reports no nesting when the grid has no previous sibling", () => {
+    const editor = withContainerEditor([gridWith("grid-0")]);
+
+    editor.setSelection("grid-0-a", "grid-0-b");
+
+    const before = editor.document;
+    expect(editor.canNestBlock()).toBe(false);
+    editor.nestBlock();
+    expect(editor.document).toEqual(before);
+  });
+});
+
 /** Recursively collects all block IDs from a document */
 function flattenBlockIds(blocks: any[]): string[] {
   const ids: string[] = [];
diff --git a/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.ts b/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.ts
index 55f7200f3f..7dc8fa9aa7 100644
--- a/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.ts
+++ b/packages/core/src/api/blockManipulation/commands/nestBlock/nestBlock.ts
@@ -3,6 +3,11 @@ import { Transaction } from "prosemirror-state";
 import { canJoin, liftTarget, ReplaceAroundStep } from "prosemirror-transform";
 
 import { BlockNoteEditor } from "../../../../editor/BlockNoteEditor.js";
+import {
+  CHILD_CONTAINER_GROUP,
+  hasOwnedChildren,
+} from "../../../../schema/blocks/children.js";
+
 /**
  * Whether `node` is the sibling list that nesting and unnesting operate on: a
  * node that holds child blocks, and can hold the kind of node being moved.
@@ -18,7 +23,7 @@ import { BlockNoteEditor } from "../../../../editor/BlockNoteEditor.js";
 function holdsItems(node: Node, itemType: NodeType) {
   return (
     node.childCount > 0 &&
-    node.type.isInGroup("childContainer") &&
+    node.type.isInGroup(CHILD_CONTAINER_GROUP) &&
     node.type.contentMatch.matchType(itemType) !== null
   );
 }
@@ -182,7 +187,14 @@ export function liftItem(
     return false;
   }
 
-  if ($from.node(range.depth - 1).type === itemType) {
+  const parent = $from.node(range.depth - 1);
+  // A titled block's body belongs to the block that owns it, so unnesting
+  // stops at its edge rather than lifting the block out of it.
+  if (parent.type === itemType && hasOwnedChildren(parent)) {
+    return false;
+  }
+
+  if (parent.type === itemType) {
     // Inside a parent node
     return liftToOuterList(tr, itemType, groupType, range); // change 2
   }
@@ -208,8 +220,8 @@ export function unnestBlock(editor: BlockNoteEditor<any, any, any>) {
 // `canExec` hands the command a transaction it never dispatches, so "can I
 // nest?" is answered by nesting and throwing the result away. A second
 // statement of the preconditions would drift from the command it describes —
-// and did: it read a previous sibling's mere existence, so a block before the
-// cursor enabled the button while `nestBlock` did nothing.
+// and did: it read a previous sibling's mere existence, so a container block
+// before the cursor enabled the button while `nestBlock` did nothing.
 export function canNestBlock(editor: BlockNoteEditor<any, any, any>) {
   return editor.canExec((state) => nestCommand(editor)(state.tr));
 }
diff --git a/packages/core/src/api/blockManipulation/commands/replaceBlocks/replaceBlocks.ts b/packages/core/src/api/blockManipulation/commands/replaceBlocks/replaceBlocks.ts
index d9e1e72981..5d693850ee 100644
--- a/packages/core/src/api/blockManipulation/commands/replaceBlocks/replaceBlocks.ts
+++ b/packages/core/src/api/blockManipulation/commands/replaceBlocks/replaceBlocks.ts
@@ -1,7 +1,10 @@
 import { type Node } from "prosemirror-model";
 import { type Transaction } from "prosemirror-state";
 import type { Block, PartialBlock } from "../../../../blocks/defaultBlocks.js";
-import { getNodeId } from "../../../getBlockInfoFromPos.js";
+import {
+  getNodeId,
+  getAncestorContainers,
+} from "../../../getBlockInfoFromPos.js";
 import type {
   BlockIdentifier,
   BlockSchema,
@@ -11,7 +14,7 @@ import type {
 import { blockToNode } from "../../../nodeConversions/blockToNode.js";
 import { nodeToBlock } from "../../../nodeConversions/nodeToBlock.js";
 import { getPmSchema } from "../../../pmUtil.js";
-import { fixColumnList } from "./util/fixColumnList.js";
+import { fixContainersById } from "../../containers/fixContainer.js";
 
 export function removeAndInsertBlocks<
   BSchema extends BlockSchema,
@@ -22,7 +25,7 @@ export function removeAndInsertBlocks<
   blocksToRemove: BlockIdentifier[],
   blocksToInsert: PartialBlock<BSchema, I, S>[],
   options: {
-    fixColumns?: boolean;
+    fixContainers?: boolean;
   } = {},
 ): {
   insertedBlocks: Block<BSchema, I, S>[];
@@ -43,13 +46,21 @@ export function removeAndInsertBlocks<
     ),
   );
   const removedBlocks: Block<BSchema, I, S>[] = [];
-  const columnListPositions = new Set<number>();
+  // Ancestor containers of removed blocks, to repair afterwards. Tracked by
+  // node id (not position) since the removals and earlier repairs shift
+  // positions; recorded with their depth so repairs run deepest-first.
+  const containersToFix: { id: string; depth: number }[] = [];
 
   const idOfFirstBlock =
     typeof blocksToRemove[0] === "string"
       ? blocksToRemove[0]
       : blocksToRemove[0].id;
-  let removedSize = 0;
+
+  // The walk below reads the document as it is now, but mutates it as it
+  // goes, so its positions go stale. `tr.mapping` already tracks exactly
+  // that; sliced from here so it ignores steps the caller added earlier.
+  const stepsBefore = tr.steps.length;
+  const mapPos = (pos: number) => tr.mapping.slice(stepsBefore).map(pos);
 
   tr.doc.descendants((node, pos) => {
     // Skips traversing nodes after all target blocks have been removed.
@@ -73,39 +84,35 @@ export function removeAndInsertBlocks<
     idsOfBlocksToRemove.delete(nodeId);
 
     if (blocksToInsert.length > 0 && nodeId === idOfFirstBlock) {
-      const oldDocSize = tr.doc.nodeSize;
-      tr.insert(pos, nodesToInsert);
-      const newDocSize = tr.doc.nodeSize;
-
-      removedSize += oldDocSize - newDocSize;
+      tr.insert(mapPos(pos), nodesToInsert);
     }
 
-    const oldDocSize = tr.doc.nodeSize;
+    const $pos = tr.doc.resolve(mapPos(pos));
 
-    const $pos = tr.doc.resolve(pos - removedSize);
-
-    if ($pos.node().type.name === "column") {
-      columnListPositions.add($pos.before(-1));
-    } else if ($pos.node().type.name === "columnList") {
-      columnListPositions.add($pos.before());
+    for (const container of getAncestorContainers($pos.doc, $pos.pos)) {
+      if (!containersToFix.some((c) => c.id === container.id)) {
+        containersToFix.push(container);
+      }
     }
 
+    // When the block is the only child of a nested `blockGroup`, delete the
+    // group with it (`blockGroup` acting as a `min: 1` container that unwraps
+    // when emptied). This can't route through `fixContainer`: repair runs after
+    // the delete, and by then ProseMirror's replace-fitting has padded the
+    // `blockGroupChild+` group with a fresh empty `blockContainer`
+    // indistinguishable from an intentional one. Only here, before the
+    // delete, is "this was the group's last child" still knowable.
+    const parent = $pos.node();
     if (
-      $pos.node().type.name === "blockGroup" &&
+      parent.type.name === "blockGroup" &&
       $pos.node($pos.depth - 1).type.name !== "doc" &&
-      $pos.node().childCount === 1
+      parent.childCount === 1
     ) {
-      // Checks if the block is the only child of a parent `blockGroup` node.
-      // In this case, we need to delete the parent `blockGroup` node instead
-      // of just the `blockContainer`.
       tr.delete($pos.before(), $pos.after());
     } else {
-      tr.delete(pos - removedSize, pos - removedSize + node.nodeSize);
+      tr.delete($pos.pos, $pos.pos + node.nodeSize);
     }
 
-    const newDocSize = tr.doc.nodeSize;
-    removedSize += oldDocSize - newDocSize;
-
     return false;
   });
 
@@ -119,11 +126,12 @@ export function removeAndInsertBlocks<
     );
   }
 
-  // Collapses empty columns/columnLists. Callers where the removal isn't a
-  // deletion can opt out - e.g. `moveBlocks` re-inserts the blocks elsewhere
-  // and deliberately leaves emptied columns as-is.
-  if (options.fixColumns !== false) {
-    columnListPositions.forEach((pos) => fixColumnList(tr, pos));
+  // Repairs the containers the removed blocks lived in (e.g. collapses
+  // emptied columns/columnLists), deepest-first. Callers where the removal
+  // isn't a deletion can opt out, e.g. `moveBlocks` re-inserts the blocks
+  // elsewhere and deliberately leaves emptied containers as-is.
+  if (options.fixContainers !== false) {
+    fixContainersById(tr, containersToFix);
   }
 
   // Converts the nodes created from `blocksToInsert` into full `Block`s.
diff --git a/packages/core/src/api/blockManipulation/commands/replaceBlocks/util/fixColumnList.ts b/packages/core/src/api/blockManipulation/commands/replaceBlocks/util/fixColumnList.ts
deleted file mode 100644
index 3097851f47..0000000000
--- a/packages/core/src/api/blockManipulation/commands/replaceBlocks/util/fixColumnList.ts
+++ /dev/null
@@ -1,173 +0,0 @@
-import { Slice, type Node } from "prosemirror-model";
-import { type Transaction } from "prosemirror-state";
-import { ReplaceAroundStep } from "prosemirror-transform";
-
-/**
- * Checks if a `column` node is empty, i.e. if it has only a single empty
- * paragraph.
- * @param column The column to check.
- * @returns Whether the column is empty.
- */
-export function isEmptyColumn(column: Node) {
-  if (!column || column.type.name !== "column") {
-    throw new Error("Invalid columnPos: does not point to column node.");
-  }
-
-  const blockContainer = column.firstChild;
-  if (!blockContainer) {
-    throw new Error("Invalid column: does not have child node.");
-  }
-
-  const blockContent = blockContainer.firstChild;
-  if (!blockContent) {
-    throw new Error("Invalid blockContainer: does not have child node.");
-  }
-
-  return (
-    column.childCount === 1 &&
-    blockContainer.childCount === 1 &&
-    blockContent.type.name === "paragraph" &&
-    blockContent.content.content.length === 0
-  );
-}
-
-/**
- * Removes all empty `column` nodes in a `columnList`. A `column` node is empty
- * if it has only a single empty block. If, however, removing the `column`s
- * leaves the `columnList` that has fewer than two, ProseMirror will re-add
- * empty columns.
- * @param tr The `Transaction` to add the changes to.
- * @param columnListPos The position just before the `columnList` node.
- */
-export function removeEmptyColumns(tr: Transaction, columnListPos: number) {
-  const $columnListPos = tr.doc.resolve(columnListPos);
-  const columnList = $columnListPos.nodeAfter;
-  if (!columnList || columnList.type.name !== "columnList") {
-    throw new Error(
-      "Invalid columnListPos: does not point to columnList node.",
-    );
-  }
-
-  for (
-    let columnIndex = columnList.childCount - 1;
-    columnIndex >= 0;
-    columnIndex--
-  ) {
-    const columnPos = tr.doc
-      .resolve($columnListPos.pos + 1)
-      .posAtIndex(columnIndex);
-    const $columnPos = tr.doc.resolve(columnPos);
-    const column = $columnPos.nodeAfter;
-    if (!column || column.type.name !== "column") {
-      throw new Error("Invalid columnPos: does not point to column node.");
-    }
-
-    if (isEmptyColumn(column)) {
-      tr.delete(columnPos, columnPos + column.nodeSize);
-    }
-  }
-}
-
-/**
- * Fixes potential issues in a `columnList` node after a
- * `blockContainer`/`column` node is (re)moved from it:
- *
- * - Removes all empty `column` nodes. A `column` node is empty if it has only
- * a single empty block.
- * - If all but one `column` nodes are empty, replaces the `columnList` with
- * the content of the non-empty `column`.
- * - If all `column` nodes are empty, removes the `columnList` entirely.
- * @param tr The `Transaction` to add the changes to.
- * @param columnListPos
- * @returns The position just before the `columnList` node.
- */
-export function fixColumnList(tr: Transaction, columnListPos: number) {
-  removeEmptyColumns(tr, columnListPos);
-
-  const $columnListPos = tr.doc.resolve(columnListPos);
-  const columnList = $columnListPos.nodeAfter;
-  if (!columnList || columnList.type.name !== "columnList") {
-    throw new Error(
-      "Invalid columnListPos: does not point to columnList node.",
-    );
-  }
-
-  if (columnList.childCount > 2) {
-    // Do nothing if the `columnList` has more than two non-empty `column`s. In
-    // the case that the `columnList` has exactly two columns, we may need to
-    // still remove it, as it's possible that one or both columns are empty.
-    // This is because after `removeEmptyColumns` is called, if the
-    // `columnList` has fewer than two `column`s, ProseMirror will re-add empty
-    // `column`s until there are two total, in order to fit the schema.
-    return;
-  }
-
-  if (columnList.childCount < 2) {
-    // Throw an error if the `columnList` has fewer than two columns. After
-    // `removeEmptyColumns` is called, if the `columnList` has fewer than two
-    // `column`s, ProseMirror will re-add empty `column`s until there are two
-    // total, in order to fit the schema. So if there are fewer than two here,
-    // either the schema, or ProseMirror's internals, must have changed.
-    throw new Error("Invalid columnList: contains fewer than two children.");
-  }
-
-  const firstColumnBeforePos = columnListPos + 1;
-  const $firstColumnBeforePos = tr.doc.resolve(firstColumnBeforePos);
-  const firstColumn = $firstColumnBeforePos.nodeAfter;
-
-  const lastColumnAfterPos = columnListPos + columnList.nodeSize - 1;
-  const $lastColumnAfterPos = tr.doc.resolve(lastColumnAfterPos);
-  const lastColumn = $lastColumnAfterPos.nodeBefore;
-
-  if (!firstColumn || !lastColumn) {
-    throw new Error("Invalid columnList: does not contain children.");
-  }
-
-  const firstColumnEmpty = isEmptyColumn(firstColumn);
-  const lastColumnEmpty = isEmptyColumn(lastColumn);
-
-  if (firstColumnEmpty && lastColumnEmpty) {
-    // Removes `columnList`
-    tr.delete(columnListPos, columnListPos + columnList.nodeSize);
-
-    return;
-  }
-
-  if (firstColumnEmpty) {
-    tr.step(
-      new ReplaceAroundStep(
-        // Replaces `columnList`.
-        columnListPos,
-        columnListPos + columnList.nodeSize,
-        // Replaces with content of last `column`.
-        lastColumnAfterPos - lastColumn.nodeSize + 1,
-        lastColumnAfterPos - 1,
-        // Doesn't append anything.
-        Slice.empty,
-        0,
-        false,
-      ),
-    );
-
-    return;
-  }
-
-  if (lastColumnEmpty) {
-    tr.step(
-      new ReplaceAroundStep(
-        // Replaces `columnList`.
-        columnListPos,
-        columnListPos + columnList.nodeSize,
-        // Replaces with content of first `column`.
-        firstColumnBeforePos + 1,
-        firstColumnBeforePos + firstColumn.nodeSize - 1,
-        // Doesn't append anything.
-        Slice.empty,
-        0,
-        false,
-      ),
-    );
-
-    return;
-  }
-}
diff --git a/packages/core/src/api/blockManipulation/commands/splitBlock/__snapshots__/splitBlock.test.ts.snap b/packages/core/src/api/blockManipulation/commands/splitBlock/__snapshots__/splitBlock.test.ts.snap
index 8cd297eaee..f76031684d 100644
--- a/packages/core/src/api/blockManipulation/commands/splitBlock/__snapshots__/splitBlock.test.ts.snap
+++ b/packages/core/src/api/blockManipulation/commands/splitBlock/__snapshots__/splitBlock.test.ts.snap
@@ -621,23 +621,6 @@ exports[`Test splitBlocks > Block has children 1`] = `
     },
     "type": "paragraph",
   },
-  {
-    "children": [],
-    "content": [
-      {
-        "styles": {},
-        "text": "Para",
-        "type": "text",
-      },
-    ],
-    "id": "paragraph-with-children",
-    "props": {
-      "backgroundColor": "default",
-      "textAlignment": "left",
-      "textColor": "default",
-    },
-    "type": "paragraph",
-  },
   {
     "children": [
       {
@@ -676,6 +659,23 @@ exports[`Test splitBlocks > Block has children 1`] = `
         "type": "paragraph",
       },
     ],
+    "content": [
+      {
+        "styles": {},
+        "text": "Para",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-with-children",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [],
     "content": [
       {
         "styles": {},
diff --git a/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.test.ts b/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.test.ts
index b403aec535..670839a66a 100644
--- a/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.test.ts
+++ b/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.test.ts
@@ -8,6 +8,7 @@ import {
   getNodeId,
 } from "../../../getBlockInfoFromPos.js";
 import { getNodeById } from "../../../nodeUtil.js";
+import { containerSchema } from "../../containers/containers.fixture.js";
 import { setupTestEnv } from "../../setupTestEnv.js";
 import { splitBlockCommand } from "./splitBlock.js";
 
@@ -147,3 +148,185 @@ describe("Test splitBlocks", () => {
     expect(anchorIsAtStartOfNewBlock).toBeTruthy();
   });
 });
+
+// `splitBlockTr` splits two levels deep (`blockContent` and its
+// `blockContainer`), which assumes the block's parent is a children holder that
+// accepts another `blockContainer`. A container's children holder is a
+// different node type than `blockGroup`, so these pin that the split lands
+// inside the container rather than tearing it open.
+describe("Test splitBlocks inside containers", () => {
+  const getContainerEditor = setupTestEnv({
+    schema: containerSchema,
+    document: [
+      { id: "before", type: "paragraph", content: "Before" },
+      {
+        id: "callout-0",
+        type: "callout",
+        children: [
+          {
+            id: "callout-child-0",
+            type: "paragraph",
+            content: "Callout child",
+          },
+          {
+            id: "callout-child-1",
+            type: "heading",
+            content: "Callout heading",
+            children: [
+              {
+                id: "nested-child",
+                type: "paragraph",
+                content: "Nested child",
+              },
+            ],
+          },
+        ],
+      },
+      {
+        id: "grid-0",
+        type: "grid",
+        children: [
+          {
+            id: "cell-0",
+            type: "gridCell",
+            children: [
+              { id: "cell-0-p", type: "paragraph", content: "Cell zero" },
+            ],
+          },
+          {
+            id: "cell-1",
+            type: "gridCell",
+            children: [
+              { id: "cell-1-p", type: "paragraph", content: "Cell one" },
+            ],
+          },
+        ],
+      },
+    ],
+  });
+
+  function splitContainerBlock(blockId: string, offset: number) {
+    const editor = getContainerEditor();
+
+    const posInBlock = editor.transact((tr) => {
+      const posInfo = getNodeById(blockId, tr.doc);
+      if (!posInfo) {
+        throw new Error(`Block with ID ${blockId} not found`);
+      }
+
+      const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
+
+      // A container has no content to offset into, so we aim at the node
+      // itself, which is where a `NodeSelection` on it would put the anchor.
+      return info.hasContent
+        ? info.content.beforePos + offset + 1
+        : info.block.beforePos;
+    });
+
+    return editor._tiptapEditor.commands.command(
+      splitBlockCommand(posInBlock, true),
+    );
+  }
+
+  function textOf(block: { content?: any }) {
+    return (block.content as { text: string }[]).map((c) => c.text).join("");
+  }
+
+  it("Splits a block inside a container in place", () => {
+    expect(splitContainerBlock("callout-child-0", 7)).toBe(true);
+
+    const document = getContainerEditor().document;
+
+    expect(document.map((block) => block.id)).toEqual([
+      "before",
+      "callout-0",
+      "grid-0",
+    ]);
+
+    const callout = document[1];
+    expect(callout.type).toBe("callout");
+    expect(callout.children.map(textOf)).toEqual([
+      "Callout",
+      " child",
+      "Callout heading",
+    ]);
+
+    expect(() =>
+      getContainerEditor().prosemirrorState.doc.check(),
+    ).not.toThrow();
+  });
+
+  it("Keeps the block's children on the first half of the split", () => {
+    expect(splitContainerBlock("callout-child-1", 7)).toBe(true);
+
+    const callout = getContainerEditor().document[1];
+
+    expect(callout.children.map(textOf)).toEqual([
+      "Callout child",
+      "Callout",
+      " heading",
+    ]);
+    // The children stay with the first half, as they do at the top level.
+    expect(callout.children[2].children).toEqual([]);
+    expect(callout.children[1].children.map((child) => child.id)).toEqual([
+      "nested-child",
+    ]);
+
+    expect(() =>
+      getContainerEditor().prosemirrorState.doc.check(),
+    ).not.toThrow();
+  });
+
+  it("Splits a block inside a nested container", () => {
+    expect(splitContainerBlock("cell-0-p", 4)).toBe(true);
+
+    const grid = getContainerEditor().document[2];
+
+    expect(grid.type).toBe("grid");
+    expect(grid.children.map((cell) => cell.id)).toEqual(["cell-0", "cell-1"]);
+    expect(grid.children[0].children.map(textOf)).toEqual(["Cell", " zero"]);
+    expect(grid.children[1].children.map(textOf)).toEqual(["Cell one"]);
+
+    expect(() =>
+      getContainerEditor().prosemirrorState.doc.check(),
+    ).not.toThrow();
+  });
+
+  it("Does not split a container block itself", () => {
+    const before = getContainerEditor().document;
+
+    expect(splitContainerBlock("callout-0", 0)).toBe(false);
+
+    expect(getContainerEditor().document).toEqual(before);
+  });
+});
+
+describe("split child ownership", () => {
+  it.each(["start", "middle", "end"] as const)(
+    "keeps children with the intended half when splitting at the %s",
+    (where) => {
+      const editor = getEditor();
+      const id = "paragraph-with-children";
+      const children = editor.getBlock(id)!.children;
+      const target = getNodeById(id, editor.prosemirrorState.doc)!;
+      const info = getBlockInfoFromNode(target.node, target.posBeforeNode);
+      if (!info.hasContent) {
+        throw new Error("Expected content block");
+      }
+      const offset =
+        where === "start"
+          ? 0
+          : where === "end"
+            ? info.contentEnd - info.contentStart
+            : 4;
+      setSelectionWithOffset(editor.prosemirrorState.doc, id, offset);
+      splitBlock(editor.prosemirrorState.selection.from);
+      const index = editor.document.findIndex((block) => block.id === id);
+      const [first, second] = editor.document.slice(index, index + 2);
+      expect((where === "start" ? second : first).children).toEqual(children);
+      expect((where === "start" ? first : second).children).toEqual([]);
+      expect(editor.getTextCursorPosition().block.id).toBe(second.id);
+      expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+    },
+  );
+});
diff --git a/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.ts b/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.ts
index d5229da6bf..74ffcd7067 100644
--- a/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.ts
+++ b/packages/core/src/api/blockManipulation/commands/splitBlock/splitBlock.ts
@@ -55,7 +55,23 @@ export const splitBlockTr = (
     },
   ];
 
+  // At the start, children follow the entire title to the second block.
+  // Otherwise they belong to the first half, all within the same undo step.
+  const children = posInBlock === info.contentStart ? undefined : info.children;
+  if (children) {
+    tr.delete(children.beforePos, children.afterPos);
+  }
   tr.split(posInBlock, 2, types);
+  if (children) {
+    const original = tr.doc.nodeAt(info.block.beforePos);
+    if (!original?.firstChild) {
+      throw new Error("Split lost its original block");
+    }
+    tr.insert(
+      info.block.beforePos + 1 + original.firstChild.nodeSize,
+      children.node,
+    );
+  }
 
   return true;
 };
diff --git a/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.test.ts b/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.test.ts
index 77d2cad826..40a2537cd9 100644
--- a/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.test.ts
+++ b/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.test.ts
@@ -2,13 +2,8 @@ import { describe, expect, it } from "vite-plus/test";
 
 import type { PartialBlock } from "../../../../blocks/defaultBlocks.js";
 import { getBlockInfoFromNode } from "../../../getBlockInfoFromPos.js";
-
-// Adapter over the renamed producer: `getNodeById` already returns the
-// `{ node, posBeforeNode }` pair it takes.
-function getBlockInfo(posInfo: { node: any; posBeforeNode: number }) {
-  return getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
-}
 import { getNodeById } from "../../../nodeUtil.js";
+import { containerSchema } from "../../containers/containers.fixture.js";
 import { setupTestEnv } from "../../setupTestEnv.js";
 import { updateBlock } from "./updateBlock.js";
 
@@ -183,9 +178,11 @@ describe("Test updateBlock", () => {
   });
 
   it("Update partial (offset start)", () => {
-    const info = getBlockInfo(
-      getNodeById("heading-with-everything", getEditor().prosemirrorState.doc)!,
-    );
+    const posInfo = getNodeById(
+      "heading-with-everything",
+      getEditor().prosemirrorState.doc,
+    )!;
+    const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
 
     if (!info.hasContent) {
       throw new Error("heading-with-everything is not a block container");
@@ -212,9 +209,11 @@ describe("Test updateBlock", () => {
   });
 
   it("Update partial (offset start + end)", () => {
-    const info = getBlockInfo(
-      getNodeById("heading-with-everything", getEditor().prosemirrorState.doc)!,
-    );
+    const posInfo = getNodeById(
+      "heading-with-everything",
+      getEditor().prosemirrorState.doc,
+    )!;
+    const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
 
     if (!info.hasContent) {
       throw new Error("heading-with-everything is not a block container");
@@ -242,9 +241,11 @@ describe("Test updateBlock", () => {
   });
 
   it("Update partial (props + offset end)", () => {
-    const info = getBlockInfo(
-      getNodeById("heading-with-everything", getEditor().prosemirrorState.doc)!,
-    );
+    const posInfo = getNodeById(
+      "heading-with-everything",
+      getEditor().prosemirrorState.doc,
+    )!;
+    const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
 
     if (!info.hasContent) {
       throw new Error("heading-with-everything is not a block container");
@@ -275,9 +276,8 @@ describe("Test updateBlock", () => {
   });
 
   it("Update partial (table cell)", () => {
-    const info = getBlockInfo(
-      getNodeById("table-0", getEditor().prosemirrorState.doc)!,
-    );
+    const posInfo = getNodeById("table-0", getEditor().prosemirrorState.doc)!;
+    const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
 
     if (!info.hasContent) {
       throw new Error("table-0 is not a block container");
@@ -305,9 +305,8 @@ describe("Test updateBlock", () => {
   });
 
   it("Update partial (table row)", () => {
-    const info = getBlockInfo(
-      getNodeById("table-0", getEditor().prosemirrorState.doc)!,
-    );
+    const posInfo = getNodeById("table-0", getEditor().prosemirrorState.doc)!;
+    const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
 
     if (!info.hasContent) {
       throw new Error("table-0 is not a block container");
@@ -940,12 +939,11 @@ describe("Test updateBlock minimal steps", () => {
 
   it("Type change with offset content replace stays minimal and valid", () => {
     const editor = getEditor();
-    const info = getBlockInfo(
-      getNodeById(
-        "paragraph-with-styled-content",
-        editor.prosemirrorState.doc,
-      )!,
-    );
+    const posInfo = getNodeById(
+      "paragraph-with-styled-content",
+      editor.prosemirrorState.doc,
+    )!;
+    const info = getBlockInfoFromNode(posInfo.node, posInfo.posBeforeNode);
     if (!info.hasContent) {
       throw new Error("paragraph-with-styled-content is not a block container");
     }
@@ -982,3 +980,257 @@ describe("Test updateBlock minimal steps", () => {
     expect(() => editor._tiptapEditor.state.doc.check()).not.toThrow();
   });
 });
+
+// Changing a block's type across the content/container divide can't happen in
+// place, so `updateBlock` rebuilds the node and has to decide what to do with
+// the content the old shape held and the new one can't. These tests pin that
+// decision. Assertions are explicit rather than snapshotted because the point
+// is *where* the carried content ends up.
+describe("Test updateBlock content carry-over", () => {
+  const getContainerEditor = setupTestEnv({
+    schema: containerSchema,
+    document: [
+      {
+        id: "paragraph-with-text",
+        type: "paragraph",
+        content: "Paragraph with text",
+      },
+      {
+        id: "empty-paragraph",
+        type: "paragraph",
+      },
+      {
+        id: "paragraph-with-text-and-children",
+        type: "paragraph",
+        content: "Parent text",
+        children: [
+          {
+            id: "existing-child",
+            type: "paragraph",
+            content: "Existing child",
+          },
+        ],
+      },
+      {
+        id: "table-0",
+        type: "table",
+        content: {
+          type: "tableContent",
+          rows: [{ cells: ["Cell 1", "Cell 2"] }],
+        },
+      },
+      {
+        id: "callout-0",
+        type: "callout",
+        children: [
+          {
+            id: "callout-child",
+            type: "paragraph",
+            content: "Callout child",
+          },
+        ],
+      },
+    ],
+  });
+
+  // A block that changes shape is rebuilt rather than updated in place, and the
+  // rebuilt node is minted a fresh ID. That is long-standing behaviour, not
+  // something the container work introduced, but converting a paragraph into a
+  // container is a far more ordinary action than the paragraph/column
+  // conversions that used to be the only way to reach this path. These tests
+  // therefore address blocks by position, and the first one pins the ID loss so
+  // that fixing it shows up as a deliberate change.
+  it("Moves inline content into a child paragraph when becoming a container", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "paragraph-with-text", { type: "callout" }),
+    );
+
+    const block = editor.document[0] as any;
+    expect(block.type).toBe("callout");
+    expect(block.id).not.toBe("paragraph-with-text");
+    expect(block.children).toHaveLength(1);
+    expect(block.children[0].type).toBe("paragraph");
+    expect(block.children[0].content).toEqual([
+      { type: "text", text: "Paragraph with text", styles: {} },
+    ]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Fills a container's children when there is no content to carry", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "empty-paragraph", { type: "pair" }),
+    );
+
+    // An empty paragraph carries nothing, so the rebuilt node holds just the
+    // empty fill its content expression requires — two paragraphs for the
+    // pair's `min: 2`.
+    const block = editor.document[1] as any;
+    expect(block.type).toBe("pair");
+    expect(block.children).toHaveLength(2);
+    expect(block.children.map((child: any) => child.content)).toEqual([[], []]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Puts carried content before existing children", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "paragraph-with-text-and-children", { type: "callout" }),
+    );
+
+    // The paragraph holding the carried text takes the place the text used to
+    // occupy, i.e. above the children that were already nested under it.
+    const block = editor.document[2] as any;
+    expect(block.type).toBe("callout");
+    expect(block.children.map((child: any) => child.content[0].text)).toEqual([
+      "Parent text",
+      "Existing child",
+    ]);
+    expect(block.children[1].id).toBe("existing-child");
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Drops table content when becoming a container", () => {
+    const editor = getContainerEditor();
+    // Table content isn't an inline array, so there is no sensible paragraph to
+    // wrap it in. It's dropped, and the container seeds as if the block had
+    // been empty.
+    expect(() =>
+      editor.transact((tr) => updateBlock(tr, "table-0", { type: "callout" })),
+    ).not.toThrow();
+
+    const block = editor.document[3] as any;
+    expect(block.type).toBe("callout");
+    expect(block.content).toBeUndefined();
+    expect(block.children).toHaveLength(1);
+    expect(block.children[0].type).toBe("paragraph");
+    expect(block.children[0].content).toEqual([]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it.each(["paragraph-with-text", "callout-0"])(
+    "Rejects conversion of %s rather than dropping incompatible children",
+    (id) => {
+      const editor = getContainerEditor();
+      const before = editor.prosemirrorState.doc;
+      expect(() =>
+        editor.transact((tr) => updateBlock(tr, id, { type: "grid" })),
+      ).toThrow();
+      expect(editor.prosemirrorState.doc.eq(before)).toBe(true);
+    },
+  );
+
+  it("Allows explicit replacement children when converting to a restricted container", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "callout-0", {
+        type: "grid",
+        children: [
+          {
+            type: "gridCell",
+            children: [{ type: "paragraph", content: "Replacement" }],
+          },
+          { type: "gridCell", children: [{ type: "paragraph" }] },
+        ],
+      }),
+    );
+    expect(editor.document[4].type).toBe("grid");
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Keeps existing children when a container drops the content", () => {
+    const editor = getContainerEditor();
+    // The carried content has nowhere to go, but the block's own children are
+    // regular blocks the pair can still hold.
+    expect(() =>
+      editor.transact((tr) =>
+        updateBlock(tr, "paragraph-with-text-and-children", {
+          type: "pair",
+        }),
+      ),
+    ).not.toThrow();
+
+    const block = editor.document[2] as any;
+    expect(block.type).toBe("pair");
+    // The kept child survives; the pair's `min: 2` is met by an empty fill.
+    expect(block.children.map((child: any) => child.id)).toContain(
+      "existing-child",
+    );
+    expect(block.children).toHaveLength(2);
+    expect(
+      block.children.find((child: any) => child.id === "existing-child")
+        .content,
+    ).toEqual([{ type: "text", text: "Existing child", styles: {} }]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Keeps a container's children when changing between container types", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) => updateBlock(tr, "callout-0", { type: "pair" }));
+
+    // Neither container holds content of its own, so the children move across
+    // untouched rather than being re-seeded; the pair's `min: 2` is met by an
+    // empty fill.
+    const block = editor.document[4] as any;
+    expect(block.type).toBe("pair");
+    expect(block.children.map((child: any) => child.id)).toContain(
+      "callout-child",
+    );
+    expect(block.children).toHaveLength(2);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Keeps a container's children alongside the content it gains", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "callout-0", {
+        type: "heading",
+        content: "Now a heading",
+      }),
+    );
+
+    // The container had nowhere to put inline content; the heading does, so
+    // the given content lands there and the children stay nested under it.
+    const block = editor.document[4] as any;
+    expect(block.type).toBe("heading");
+    expect(block.content).toEqual([
+      { type: "text", text: "Now a heading", styles: {} },
+    ]);
+    expect(block.children.map((child: any) => child.id)).toEqual([
+      "callout-child",
+    ]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Updates a container's props without rebuilding it", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "callout-0", { props: { flavor: "warning" } }),
+    );
+
+    // No shape change, so this is an in-place attribute update: the container
+    // keeps its ID (unlike the type changes above) and its children.
+    const block = editor.document[4] as any;
+    expect(block.id).toBe("callout-0");
+    expect(block.props.flavor).toBe("warning");
+    expect(block.children.map((child: any) => child.id)).toEqual([
+      "callout-child",
+    ]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("Keeps a container's children and invents no content when becoming a block", () => {
+    const editor = getContainerEditor();
+    editor.transact((tr) =>
+      updateBlock(tr, "callout-0", { type: "paragraph" }),
+    );
+
+    const block = editor.document[4] as any;
+    expect(block.type).toBe("paragraph");
+    expect(block.content).toEqual([]);
+    expect(block.children).toHaveLength(1);
+    expect(block.children[0].id).toBe("callout-child");
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+});
diff --git a/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.ts b/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.ts
index e487f99fd4..15caf1dca1 100644
--- a/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.ts
+++ b/packages/core/src/api/blockManipulation/commands/updateBlock/updateBlock.ts
@@ -27,7 +27,8 @@ import {
 } from "../../../nodeConversions/blockToNode.js";
 import { nodeToBlock } from "../../../nodeConversions/nodeToBlock.js";
 import { getNodeById } from "../../../nodeUtil.js";
-import { getPmSchema } from "../../../pmUtil.js";
+import { getBlockSchema, getPmSchema } from "../../../pmUtil.js";
+import { createBlockGroup } from "../../../../schema/blocks/children.js";
 
 // for compatibility with tiptap. TODO: remove as we want to remove dependency on tiptap command interface
 export const updateBlockCommand = <
@@ -70,10 +71,10 @@ export function updateBlockTr<
   const stepsBefore = tr.mapping.maps.length;
   const blockInfo = getBlockInfoAt(tr.doc, posBeforeBlock);
 
-  let cellAnchor: CellAnchor | null = null;
-  if (blockInfo.blockNoteType === "table") {
-    cellAnchor = captureCellAnchor(tr);
-  }
+  const cellAnchor =
+    blockInfo.hasContent && blockInfo.blockNoteType === "table"
+      ? captureCellAnchor(tr)
+      : null;
 
   const pmSchema = getPmSchema(tr);
 
@@ -85,8 +86,6 @@ export function updateBlockTr<
     throw new Error("Invalid replaceFromPos or replaceToPos");
   }
 
-  // Adds blockGroup node with child blocks if necessary.
-
   const newBlockType = block.type || blockInfo.blockNoteType;
   const newNodeType = pmSchema.nodes[newBlockType];
   const newBnBlockNodeType = newNodeType.isInGroup("bnBlock")
@@ -109,27 +108,56 @@ export function updateBlockTr<
       ? replaceToPos - blockInfo.contentStart
       : undefined;
 
-  // `hasContent` is exactly `blockContainer`-ness, and a block type resolves
-  // to either a `blockContent` node (a regular block) or a `bnBlock` one (a
-  // wrapper), so the two together say whether the update keeps the block's
-  // shape. Only a same-shape update can happen in place.
-  if (blockInfo.hasContent !== newNodeType.isInGroup("blockContent")) {
-    // switching from blockContainer to non-blockContainer or v.v.
-    // currently breaking for column slash menu items converting empty block
-    // to column.
-
-    // currently, we calculate the new node and replace the entire node with the desired new node.
-    // for this, we do a nodeToBlock on the existing block to get the children.
-    // it would be cleaner to use a ReplaceAroundStep, but this is a bit simpler and it's quite an edge case
-    const existingBlock = nodeToBlock(blockInfo.block.node, tr.doc);
+  // Rebuild when the block's shape changes or a container's existing children
+  // cannot satisfy the new type (e.g. changing to a pair requiring two children).
+  if (
+    blockInfo.hasContent !== newNodeType.isInGroup("blockContent") ||
+    (!blockInfo.hasContent &&
+      !newNodeType.validContent(blockInfo.block.node.content))
+  ) {
+    const existingBlock: Block<any, any, any> = nodeToBlock(
+      blockInfo.block.node,
+      tr.doc,
+    );
+    const targetConfig = getBlockSchema(pmSchema)[newBlockType];
+    let content: PartialBlock<any, any, any>["content"];
+    const children: PartialBlock<any, any, any>[] = [...existingBlock.children];
+    if (Array.isArray(existingBlock.content) && existingBlock.content.length) {
+      if (
+        targetConfig.content === "inline" ||
+        targetConfig.content === "plain"
+      ) {
+        content = existingBlock.content;
+      } else if (targetConfig.children !== undefined) {
+        children.unshift({ type: "paragraph", content: existingBlock.content });
+      }
+    }
+
     const replacementNode = blockToNode(
       {
-        children: existingBlock.children, // if no children are passed in, use existing children
+        ...(content ? { content } : {}),
+        // Omit empty children so a new container can seed its required children.
+        ...(children.length > 0 ? { children } : {}),
         ...block,
       },
       pmSchema,
     );
     replacementNode.check(); // `blockToNode` is lenient; validate before mutating the doc
+
+    // Validate the parent too: a valid column still cannot replace a root block.
+    const $oldPos = tr.doc.resolve(blockInfo.block.beforePos);
+    if (
+      !$oldPos.parent.canReplace(
+        $oldPos.index(),
+        $oldPos.index(),
+        Fragment.from(replacementNode),
+      )
+    ) {
+      throw new Error(
+        `Cannot update block to "${newBlockType}": a "${$oldPos.parent.type.name}" doesn't accept it`,
+      );
+    }
+
     tr.replaceWith(
       blockInfo.block.beforePos,
       blockInfo.block.afterPos,
@@ -163,8 +191,12 @@ export function updateBlockTr<
     ...block.props,
   });
 
-  if (cellAnchor) {
-    restoreCellAnchor(tr, blockInfo, cellAnchor, stepsBefore);
+  if (cellAnchor && blockInfo.hasContent) {
+    restoreCellAnchor(
+      tr,
+      tr.mapping.slice(stepsBefore).map(blockInfo.content.beforePos),
+      cellAnchor,
+    );
   }
 }
 
@@ -177,12 +209,7 @@ function updateBlockContentNode<
   tr: Transform,
   oldNodeType: NodeType,
   newNodeType: NodeType,
-  blockInfo: {
-    children?:
-      | { node: PMNode; beforePos: number; afterPos: number }
-      | undefined;
-    content: { node: PMNode; beforePos: number; afterPos: number };
-  },
+  blockInfo: Extract<BlockInfo, { hasContent: true }>,
   replaceFromOffset?: number,
   replaceToOffset?: number,
 ) {
@@ -211,7 +238,7 @@ function updateBlockContentNode<
     // no custom content has been provided, use existing content IF possible
     // Since some block types contain inline content and others don't,
     // we either need to call setNodeMarkup to just update type &
-    // attributes, or replaceWith to replace the whole blockContent.
+    // attributes, or replaceWith to replace the whole content.
     const oldContent = blockInfo.content.node.content;
     if (oldNodeType.spec.content === "") {
       // keep old content, because it's empty anyway and should be compatible with
@@ -235,7 +262,7 @@ function updateBlockContentNode<
     }
   }
 
-  // Now, changes the blockContent node type and adds the provided props
+  // Now, changes the content node type and adds the provided props
   // as attributes. Also preserves all existing attributes that are
   // compatible with the new type.
   //
@@ -520,11 +547,10 @@ function updateChildren<
       return node;
     });
 
-    // Checks if a blockGroup node already exists.
     if (blockInfo.children) {
-      // Replaces the child nodes in the existing blockGroup, only touching the
-      // range that actually changed (keeping unchanged leading/trailing
-      // children untouched).
+      // Replaces the child nodes in the existing children holder, only
+      // touching the range that actually changed (keeping unchanged
+      // leading/trailing children untouched).
       replaceContentMinimal(
         tr,
         blockInfo.children.beforePos,
@@ -532,11 +558,12 @@ function updateChildren<
       );
     } else if (blockInfo.hasContent) {
       // A `blockContainer` with no children yet: its `blockGroup` is lazy
-      // (`blockContent blockGroup?`), so insert a new one after the content
-      // node.
+      // (`blockContent blockGroup?`), so create it around the child nodes and
+      // insert it after the content node. (Containers always have a children
+      // holder, so no holder implies a `blockContainer`.)
       tr.insert(
         blockInfo.content.afterPos,
-        pmSchema.nodes["blockGroup"].createChecked({}, childNodes),
+        createBlockGroup(pmSchema, childNodes),
       );
     }
   }
@@ -639,34 +666,10 @@ export function captureCellAnchor(tr: Transform): CellAnchor | null {
 
 function restoreCellAnchor(
   tr: Transform | Transaction,
-  blockInfo: BlockInfo,
+  tablePos: number,
   a: CellAnchor,
-  stepsBefore: number,
 ): boolean {
-  if (blockInfo.blockNoteType !== "table") {
-    return false;
-  }
-
-  // 1) Resolve the table node in the current document
-  let tablePos = -1;
-
-  if (blockInfo.hasContent) {
-    // Prefer the content position when available (points directly at the PM table node)
-    tablePos = tr.mapping.slice(stepsBefore).map(blockInfo.content.beforePos);
-  } else {
-    // Fallback: scan within the mapped block range to find the inner table node
-    const start = tr.mapping.slice(stepsBefore).map(blockInfo.block.beforePos);
-    const end = start + (tr.doc.nodeAt(start)?.nodeSize || 0);
-    tr.doc.nodesBetween(start, end, (node, pos) => {
-      if (node.type.name === "table") {
-        tablePos = pos;
-        return false;
-      }
-      return true;
-    });
-  }
-
-  const table = tablePos >= 0 ? tr.doc.nodeAt(tablePos) : null;
+  const table = tr.doc.nodeAt(tablePos);
   if (!table || table.type.name !== "table") {
     return false;
   }
diff --git a/packages/core/src/api/blockManipulation/containers/containers.browser.test.ts b/packages/core/src/api/blockManipulation/containers/containers.browser.test.ts
new file mode 100644
index 0000000000..9d96276b73
--- /dev/null
+++ b/packages/core/src/api/blockManipulation/containers/containers.browser.test.ts
@@ -0,0 +1,264 @@
+import {
+  afterAll,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+} from "vite-plus/test";
+import { userEvent } from "vite-plus/test/browser";
+
+import { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
+import { containerSchema } from "./containers.fixture.js";
+
+// Keymap tests for container blocks, split off from the node-environment
+// `containers.test.ts`. tiptap can only reach `handleKeyDown` through a
+// mounted view, so the editor is mounted and focused here and the keys are
+// pressed for real.
+
+const schema = containerSchema;
+
+let editor: BlockNoteEditor<
+  typeof schema.blockSchema,
+  typeof schema.inlineContentSchema,
+  typeof schema.styleSchema
+>;
+let div: HTMLElement;
+
+beforeAll(() => {
+  div = document.createElement("div");
+  document.body.appendChild(div);
+  editor = BlockNoteEditor.create({ schema });
+  editor.mount(div);
+});
+
+afterAll(() => {
+  editor._tiptapEditor.destroy();
+  div.remove();
+  editor = undefined as any;
+});
+
+beforeEach(() => {
+  editor.replaceBlocks(editor.document, [
+    { id: "p-0", type: "paragraph", content: "Paragraph 0" },
+    { id: "p-1", type: "paragraph", content: "Paragraph 1" },
+  ]);
+});
+
+/** Puts the caret at the given position and presses the key. */
+async function pressKey(
+  key: string,
+  at: { block: string; placement: "start" | "end" },
+) {
+  editor.setTextCursorPosition(at.block, at.placement);
+  editor.focus();
+  await userEvent.keyboard(`{${key}}`);
+}
+
+describe("children keyboard handling", () => {
+  it("Enter on an empty last child escapes the container", async () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-p-0", type: "paragraph", content: "Hello" },
+          { id: "c-p-1", type: "paragraph", content: "" },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    await pressKey("Enter", { block: "c-p-1", placement: "end" });
+
+    const callout = editor.getBlock("c-0")!;
+    expect(callout.children.map((child) => child.id)).toEqual(["c-p-0"]);
+    expect(editor.document.map((block) => block.type)).toEqual([
+      "callout",
+      "paragraph",
+      "paragraph",
+    ]);
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "c-0",
+      "c-p-1",
+      "trailing",
+    ]);
+    // The caret moves out with the block.
+    expect(editor.getTextCursorPosition().block.id).toBe("c-p-1");
+  });
+
+  it("Enter escape ascends past levels that can't hold the block", async () => {
+    // A grid holds only cells, so a block escaping the last cell can't stop
+    // at the grid level. It lands below the grid itself.
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "grid",
+        id: "g-0",
+        children: [
+          {
+            type: "gridCell",
+            id: "g-c-0",
+            children: [{ id: "g-p-0", type: "paragraph", content: "A" }],
+          },
+          {
+            type: "gridCell",
+            id: "g-c-1",
+            children: [
+              { id: "g-p-1", type: "paragraph", content: "B" },
+              { id: "g-p-2", type: "paragraph", content: "" },
+            ],
+          },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    await pressKey("Enter", { block: "g-p-2", placement: "end" });
+
+    expect(editor.getBlock("g-c-1")!.children.map((child) => child.id)).toEqual(
+      ["g-p-1"],
+    );
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "g-0",
+      "g-p-2",
+      "trailing",
+    ]);
+    expect(editor.getTextCursorPosition().block.id).toBe("g-p-2");
+  });
+
+  it("Enter on an empty block mid-container stays inside", async () => {
+    // The escape only fires at the end of the container. An empty block with
+    // siblings after it never ejects.
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-p-0", type: "paragraph", content: "Hello" },
+          { id: "c-p-1", type: "paragraph", content: "" },
+          { id: "c-p-2", type: "paragraph", content: "World" },
+        ],
+      },
+    ]);
+
+    await pressKey("Enter", { block: "c-p-1", placement: "end" });
+
+    expect(editor.document.map((block) => block.id)).toEqual(["c-0"]);
+    expect(editor.getBlock("c-0")!.children).toHaveLength(4);
+  });
+
+  it("Backspace at the start of a container's first child moves it out", async () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "before", type: "paragraph", content: "Before" },
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-p-0", type: "paragraph", content: "First" },
+          { id: "c-p-1", type: "paragraph", content: "Second" },
+        ],
+      },
+    ]);
+
+    await pressKey("Backspace", { block: "c-p-0", placement: "start" });
+
+    expect(editor.getBlock("c-0")!.children.map((child) => child.id)).toEqual([
+      "c-p-1",
+    ]);
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "before",
+      "c-p-0",
+      "c-0",
+    ]);
+    expect(editor.getBlock("c-p-0")!.content).toEqual([
+      { type: "text", text: "First", styles: {} },
+    ]);
+  });
+
+  it("Backspace at the start of a block after a container moves it inside", async () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [{ id: "c-p-0", type: "paragraph", content: "In callout" }],
+      },
+      { id: "after", type: "paragraph", content: "After" },
+    ]);
+
+    await pressKey("Backspace", { block: "after", placement: "start" });
+
+    expect(editor.getBlock("c-0")!.children.map((child) => child.id)).toEqual([
+      "c-p-0",
+      "after",
+    ]);
+    expect(editor.document.map((block) => block.id)).toEqual(["c-0"]);
+    expect(editor.getBlock("after")!.content).toEqual([
+      { type: "text", text: "After", styles: {} },
+    ]);
+  });
+
+  it("Delete at the end of a block before a container pulls its first child out", async () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "before", type: "paragraph", content: "Before" },
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-p-0", type: "paragraph", content: "First" },
+          { id: "c-p-1", type: "paragraph", content: "Second" },
+        ],
+      },
+    ]);
+
+    await pressKey("Delete", { block: "before", placement: "end" });
+
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "before",
+      "c-p-0",
+      "c-0",
+    ]);
+    expect(editor.getBlock("c-0")!.children.map((child) => child.id)).toEqual([
+      "c-p-1",
+    ]);
+  });
+
+  it("Delete at the end of a container's last child pulls the next block in", async () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [{ id: "c-p-0", type: "paragraph", content: "In callout" }],
+      },
+      { id: "after", type: "paragraph", content: "After" },
+    ]);
+
+    await pressKey("Delete", { block: "c-p-0", placement: "end" });
+
+    expect(editor.getBlock("c-0")!.children.map((child) => child.id)).toEqual([
+      "c-p-0",
+      "after",
+    ]);
+    expect(editor.document.map((block) => block.id)).toEqual(["c-0"]);
+  });
+});
+
+// HTML round-trips (full, external, clipboard) live with the parse rules in
+// `schema/blocks/containerParse.browser.test.ts`.
+describe("children conversion", () => {
+  it("flattens containers to their children in markdown export", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-p-0", type: "paragraph", content: "In callout" },
+          { id: "c-p-1", type: "heading", content: "Heading in callout" },
+        ],
+      },
+    ]);
+
+    const markdown = editor.blocksToMarkdownLossy(editor.document);
+    expect(markdown).toContain("In callout");
+    expect(markdown).toContain("# Heading in callout");
+  });
+});
diff --git a/packages/core/src/api/blockManipulation/containers/containers.fixture.ts b/packages/core/src/api/blockManipulation/containers/containers.fixture.ts
new file mode 100644
index 0000000000..a32488ad5b
--- /dev/null
+++ b/packages/core/src/api/blockManipulation/containers/containers.fixture.ts
@@ -0,0 +1,96 @@
+import { BlockNoteSchema } from "../../../blocks/BlockNoteSchema.js";
+import { defaultBlockSpecs } from "../../../blocks/defaultBlocks.js";
+import { createBlockSpec } from "../../../schema/blocks/createSpec.js";
+
+const renderDiv = () => {
+  const dom = document.createElement("div");
+  return { dom, contentDOM: dom };
+};
+
+const Callout = createBlockSpec(
+  {
+    type: "callout" as const,
+    propSchema: {
+      flavor: {
+        default: "tip",
+        values: ["tip", "info", "warning", "success"],
+      },
+    },
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  { render: renderDiv },
+)();
+
+const Grid = createBlockSpec(
+  {
+    type: "grid" as const,
+    propSchema: {},
+    content: "none",
+    children: {
+      allow: ["gridCell"],
+      min: 2,
+    },
+  },
+  { render: renderDiv },
+)();
+
+const GridCell = createBlockSpec(
+  {
+    type: "gridCell" as const,
+    propSchema: {},
+    content: "none",
+    children: { allow: "blocks" },
+    placeable: "namedOnly",
+  },
+  { render: renderDiv },
+)();
+
+// A container that requires two children, so dropping below `min` dissolves
+// it into the survivors.
+const Pair = createBlockSpec(
+  {
+    type: "pair" as const,
+    propSchema: {},
+    content: "none",
+    children: {
+      allow: "blocks",
+      min: 2,
+    },
+  },
+  { render: renderDiv },
+)();
+
+// A titled block: an ordinary block with inline content (the title) whose
+// `children` are a body that belongs to it. The frame draws the box around
+// title and body together.
+const Alert = createBlockSpec(
+  {
+    type: "alert" as const,
+    propSchema: {},
+    content: "inline",
+    children: { allow: "blocks" },
+  },
+  {
+    render: renderDiv,
+    renderFrame: () => {
+      const dom = document.createElement("div");
+      dom.className = "alert-frame";
+      const slot = document.createElement("div");
+      slot.className = "alert-slot";
+      dom.append(slot);
+      return { dom, slot };
+    },
+  },
+)();
+
+export const containerSchema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    callout: Callout,
+    alert: Alert,
+    grid: Grid,
+    gridCell: GridCell,
+    pair: Pair,
+  } as const,
+});
diff --git a/packages/core/src/api/blockManipulation/containers/containers.test.ts b/packages/core/src/api/blockManipulation/containers/containers.test.ts
new file mode 100644
index 0000000000..db5606501c
--- /dev/null
+++ b/packages/core/src/api/blockManipulation/containers/containers.test.ts
@@ -0,0 +1,598 @@
+// @vitest-environment node
+import { TextSelection } from "prosemirror-state";
+import {
+  afterAll,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+} from "vite-plus/test";
+
+import { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
+import { createBlockSpec } from "../../../schema/blocks/createSpec.js";
+import { containerSchema } from "./containers.fixture.js";
+
+type PartialBlock = (typeof containerSchema)["PartialBlock"];
+
+// Document-model behaviour of container blocks: filling, schema enforcement,
+// repair and selection. Everything is `Block` JSON in and out, so the editor
+// runs headless with no DOM.
+//
+// The keymap (tiptap can only reach it through a mounted view) and
+// HTML/markdown serialization (builds real DOM) are tested in
+// `containers.browser.test.ts`.
+
+const schema = containerSchema;
+
+let editor: BlockNoteEditor<
+  typeof schema.blockSchema,
+  typeof schema.inlineContentSchema,
+  typeof schema.styleSchema
+>;
+
+beforeAll(() => {
+  editor = BlockNoteEditor.create({ schema });
+});
+
+afterAll(() => {
+  editor._tiptapEditor.destroy();
+  editor = undefined as any;
+});
+
+beforeEach(() => {
+  editor.replaceBlocks(editor.document, [
+    { id: "p-0", type: "paragraph", content: "Paragraph 0" },
+    { id: "p-1", type: "paragraph", content: "Paragraph 1" },
+  ]);
+});
+
+describe("children insertion & filling", () => {
+  it.each([
+    { block: { type: "callout" }, childType: "paragraph", min: 1 },
+    {
+      block: { type: "callout", children: [] },
+      childType: "paragraph",
+      min: 1,
+    },
+    { block: { type: "pair" }, childType: "paragraph", min: 2 },
+    { block: { type: "grid" }, childType: "gridCell", min: 2 },
+  ] satisfies { block: PartialBlock; childType: string; min: number }[])(
+    "fills $block to its minimum with identifiable $childType children",
+    ({ block, childType, min }) => {
+      editor.insertBlocks([{ ...block, id: "container" }], "p-1", "after");
+      const children = editor.getBlock("container")!.children;
+      expect(children.map((child) => child.type)).toEqual(
+        Array(min).fill(childType),
+      );
+      for (const child of children) {
+        expect(child.id).toBeTruthy();
+        expect(editor.getBlock(child.id)).toBeDefined();
+      }
+    },
+  );
+
+  it("does not re-fill a container round-tripped through the document", () => {
+    editor.insertBlocks([{ type: "callout", id: "c-0" }], "p-1", "after");
+    const inserted = editor.getBlock("c-0")!;
+
+    // `nodeToBlock` always emits an array, so a round-trip must not read an
+    // empty one as "unspecified" and fill on top of it.
+    editor.replaceBlocks([inserted], [inserted]);
+
+    expect(editor.getBlock("c-0")!.children).toHaveLength(
+      inserted.children.length,
+    );
+  });
+
+  it("accepts arbitrary block children, including nested containers", () => {
+    editor.insertBlocks(
+      [
+        {
+          type: "callout",
+          id: "c-0",
+          children: [
+            { type: "heading", content: "In callout" },
+            {
+              type: "callout",
+              id: "c-1",
+              children: [{ type: "paragraph", content: "Nested" }],
+            },
+          ],
+        },
+      ],
+      "p-1",
+      "after",
+    );
+
+    const callout = editor.getBlock("c-0")!;
+    expect(callout.children.map((child) => child.type)).toEqual([
+      "heading",
+      "callout",
+    ]);
+    expect(editor.getBlock("c-1")!.children[0].type).toBe("paragraph");
+  });
+
+  it("enforces a restricted container's allow list", () => {
+    editor.insertBlocks(
+      [
+        {
+          type: "grid",
+          id: "g-0",
+          children: [{ type: "gridCell" }, { type: "gridCell" }],
+        },
+      ],
+      "p-1",
+      "after",
+    );
+    expect(editor.getBlock("g-0")!.children.map((child) => child.type)).toEqual(
+      ["gridCell", "gridCell"],
+    );
+
+    expect(() =>
+      editor.insertBlocks(
+        [
+          {
+            type: "grid",
+            children: [
+              { type: "paragraph", content: "not a cell" },
+              { type: "paragraph", content: "not a cell" },
+            ],
+          },
+        ],
+        "p-1",
+        "after",
+      ),
+    ).toThrow();
+  });
+
+  // The `allow: "blocks"` wildcard compiles to the regular blocks plus the
+  // containers placeable anywhere, so a namedOnly block only fits where a
+  // parent names it explicitly: not at the root, and not under a wildcard
+  // container.
+  it("rejects a namedOnly block outside a parent that names it", () => {
+    expect(() =>
+      editor.insertBlocks(
+        [{ type: "gridCell", children: [{ type: "paragraph" }] }],
+        "p-1",
+        "after",
+      ),
+    ).toThrow();
+
+    expect(() =>
+      editor.insertBlocks(
+        [
+          {
+            type: "callout",
+            children: [{ type: "gridCell", children: [{ type: "paragraph" }] }],
+          },
+        ],
+        "p-1",
+        "after",
+      ),
+    ).toThrow();
+  });
+});
+
+describe("container nodes", () => {
+  // No container is `isolating`. PM only honours that flag while no selection
+  // spans the edge, and nothing prevents one: given a spanning slice, `Fitter`
+  // refuses to open into the container and wraps the content in a spurious
+  // `blockGroup`, corrupting the document.
+  it("leaves every container non-isolating", () => {
+    const nodes = editor.pmSchema.nodes;
+    for (const type of ["callout", "pair", "grid", "gridCell"]) {
+      expect(nodes[type].spec.isolating).toBeFalsy();
+    }
+  });
+
+  // The corruption the line above avoids, pinned end to end: copy a selection
+  // running from inside a container to after it, paste it back over itself,
+  // and the document must come back unchanged. Marking the container
+  // `isolating` instead re-nests the whole fragment a level too deep.
+  it.each(["callout", "pair"])(
+    "round-trips a paste across a %s's edge",
+    (type) => {
+      editor.replaceBlocks(editor.document, [
+        {
+          id: "c",
+          type,
+          children: [
+            { id: "c1", type: "paragraph", content: "Inner one" },
+            { id: "c2", type: "paragraph", content: "Inner two" },
+          ],
+        },
+        { id: "a", type: "paragraph", content: "After" },
+      ] as PartialBlock[]);
+
+      const before = JSON.stringify(editor.document);
+
+      editor.transact((tr) => {
+        let from = 0;
+        let to = 0;
+        tr.doc.descendants((node, pos) => {
+          if (node.isText && node.text === "Inner two") {
+            from = pos;
+          }
+          if (node.isText && node.text === "After") {
+            to = pos + node.nodeSize;
+          }
+        });
+
+        const selection = TextSelection.create(tr.doc, from, to);
+        tr.setSelection(selection).replace(from, to, selection.content());
+      });
+
+      expect(JSON.stringify(editor.document)).toBe(before);
+    },
+  );
+});
+
+// `initialContent` is the only path that builds a document without validating
+// it, since `blockToNode` is deliberately lenient and `createDocument` builds
+// from JSON. Regression: blocks that `insertBlocks` rejects loaded without
+// error, and a container below its `min` stayed there for the life of the
+// document.
+describe("initialContent enforcement", () => {
+  const createWith = (initialContent: PartialBlock[]) => {
+    return BlockNoteEditor.create({ schema, initialContent });
+  };
+
+  it("fills an explicitly empty `children` array up to `min`", () => {
+    const loaded = createWith([{ type: "callout", id: "c-0", children: [] }]);
+
+    const callout = loaded.getBlock("c-0")!;
+    expect(callout.children).toHaveLength(1);
+    expect(callout.children[0].type).toBe("paragraph");
+
+    loaded._tiptapEditor.destroy();
+  });
+
+  it("fills a container below `min` and rejects one it can never fill", () => {
+    // One cell under `min: 2` is padded up to it.
+    const loaded = createWith([
+      { type: "grid", id: "g-0", children: [{ type: "gridCell" }] },
+    ] as any);
+    expect(loaded.getBlock("g-0")!.children).toHaveLength(2);
+    loaded._tiptapEditor.destroy();
+
+    // A grid given paragraphs can never be filled: no amount of padding
+    // turns them into cells.
+    expect(() =>
+      createWith([
+        {
+          type: "grid",
+          id: "g-0",
+          children: [{ type: "paragraph" }, { type: "paragraph" }],
+        },
+      ] as any),
+    ).toThrow();
+  });
+});
+
+describe("children repair", () => {
+  it("dissolves a container that can stand anywhere when it drops below `min`", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [{ id: "c-p-0", type: "paragraph", content: "Only child" }],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    editor.removeBlocks(["c-p-0"]);
+
+    // A callout the user emptied gets out of the way: it is replaced by what
+    // its children held, which is nothing.
+    expect(editor.getBlock("c-0")).toBeUndefined();
+    expect(editor.document.map((block) => block.id)).toEqual(["trailing"]);
+  });
+
+  it("unwraps a container whose single survivor cannot stand alone", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "grid",
+        id: "g-0",
+        children: [
+          {
+            type: "gridCell",
+            id: "cell-a",
+            children: [{ id: "cell-a-p", type: "paragraph", content: "A" }],
+          },
+          {
+            type: "gridCell",
+            id: "cell-b",
+            children: [{ id: "cell-b-p", type: "paragraph", content: "B" }],
+          },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    editor.removeBlocks(["cell-a-p"]);
+
+    expect(editor.getBlock("g-0")).toBeUndefined();
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "cell-b-p",
+      "trailing",
+    ]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  // An emptied child of the container is dropped even when the container
+  // stays at or above `min`: an emptied column disappears rather than
+  // lingering. The multicolumn e2e snapshots pin the same behavior from the
+  // keyboard side.
+  it("drops emptied container children even at or above `min`", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "grid",
+        id: "g-0",
+        children: [
+          {
+            type: "gridCell",
+            id: "cell-a",
+            children: [
+              { id: "cell-a-p", type: "paragraph", content: "A" },
+              { id: "cell-a-extra", type: "paragraph", content: "A2" },
+            ],
+          },
+          {
+            type: "gridCell",
+            id: "cell-b",
+            children: [{ id: "cell-b-p", type: "paragraph", content: "B" }],
+          },
+          {
+            type: "gridCell",
+            id: "cell-c",
+            children: [{ id: "cell-c-p", type: "paragraph", content: "" }],
+          },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    // Removing a block inside cell A runs repair on the grid; the emptied
+    // cell C is dropped, and with cells A and B still meeting `min: 2` the
+    // grid itself survives.
+    editor.removeBlocks(["cell-a-extra"]);
+
+    const grid = editor.getBlock("g-0")!;
+    expect(grid.children.map((cell) => cell.id)).toEqual(["cell-a", "cell-b"]);
+  });
+});
+
+describe("repair edge cases", () => {
+  // A container that explicitly allows being empty. `min: 0` compiles to a
+  // `*` content expression, so ProseMirror never pads it and repair leaves
+  // it alone.
+  const Tray = createBlockSpec(
+    {
+      type: "tray" as const,
+      propSchema: {},
+      content: "none" as const,
+      children: { allow: "blocks", min: 0 },
+    },
+    {
+      render: () => {
+        const dom = document.createElement("div");
+        return { dom, contentDOM: dom };
+      },
+    },
+  )();
+
+  it("keeps a `min: 0` container with zero children", () => {
+    const trayEditor = BlockNoteEditor.create({
+      schema: containerSchema.extend({
+        blockSpecs: { tray: Tray },
+      }),
+    });
+    try {
+      trayEditor.replaceBlocks(trayEditor.document, [
+        {
+          type: "tray",
+          id: "t-0",
+          children: [{ id: "t-p-0", type: "paragraph", content: "" }],
+        },
+        { id: "trailing", type: "paragraph", content: "" },
+      ]);
+
+      // Removing its only (empty) child leaves zero children, which `min: 0`
+      // allows: the tray stays instead of dissolving, and nothing is padded
+      // back.
+      trayEditor.removeBlocks(["t-p-0"]);
+
+      expect(trayEditor.getBlock("t-0")).toBeDefined();
+      expect(trayEditor.getBlock("t-0")!.children).toHaveLength(0);
+      expect(() => trayEditor.prosemirrorState.doc.check()).not.toThrow();
+    } finally {
+      trayEditor._tiptapEditor.destroy();
+    }
+  });
+
+  it("keeps emptied regular blocks when the container survives", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-a", type: "paragraph", content: "A" },
+          { id: "c-b", type: "paragraph", content: "B" },
+          { id: "c-empty", type: "paragraph", content: "" },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    editor.removeBlocks(["c-a"]);
+
+    // Only emptied *container* children are dropped. The empty paragraph is
+    // content the user typed into, not structure, so it stays.
+    expect(editor.getBlock("c-0")!.children.map((child) => child.id)).toEqual([
+      "c-b",
+      "c-empty",
+    ]);
+  });
+
+  it("dissolves a `min: 2` container left with one surviving child", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "pair",
+        id: "s-0",
+        children: [
+          { id: "s-a", type: "paragraph", content: "A" },
+          { id: "s-b", type: "paragraph", content: "B" },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    editor.removeBlocks(["s-b"]);
+
+    // One survivor is below `min: 2`, so the pair dissolves into it. The
+    // padded empty ProseMirror filled back does not count as a survivor.
+    expect(editor.getBlock("s-0")).toBeUndefined();
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "s-a",
+      "trailing",
+    ]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+
+  it("leaves a titled block intact when its last body block is removed", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "alert",
+        id: "w",
+        content: "Title",
+        children: [{ id: "b1", type: "paragraph", content: "" }],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    editor.removeBlocks(["b1"]);
+
+    // Titled blocks never enter `fixContainer`: the alert keeps its title
+    // with an empty body rather than dissolving.
+    const alert = editor.getBlock("w")! as any;
+    expect(alert.type).toBe("alert");
+    expect(alert.content[0].text).toBe("Title");
+    expect(alert.children).toHaveLength(0);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+});
+
+describe("children selection", () => {
+  it("getSelectionCutBlocks handles selections reaching into a container", () => {
+    editor.replaceBlocks(editor.document, [
+      { id: "before", type: "paragraph", content: "Before" },
+      {
+        type: "callout",
+        id: "c-0",
+        children: [
+          { id: "c-p-0", type: "paragraph", content: "First" },
+          { id: "c-p-1", type: "paragraph", content: "Second" },
+        ],
+      },
+    ]);
+    editor.setSelection("before", "c-p-0");
+
+    // Previously threw "unexpected" for any partial selection touching a
+    // container (breaking comments/AI selection handling).
+    const result = editor.getSelectionCutBlocks();
+    expect(result.blocks.length).toBeGreaterThanOrEqual(1);
+    expect(result.blocks.map((block) => block.id)).toContain("before");
+  });
+});
+
+// Every mutation that can empty a container records its ancestors with
+// `getAncestorContainers` and hands them to `fixContainersById`, which repairs
+// them deepest-first. Removing a block therefore repairs the whole chain it
+// sat in, not just the container directly holding it.
+describe("ancestor container repair", () => {
+  it("repairs every container a single removal emptied", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "callout",
+        id: "c-0",
+        children: [{ id: "c-p-0", type: "paragraph", content: "Only child" }],
+      },
+      {
+        type: "pair",
+        id: "s-0",
+        children: [
+          { id: "s-p-0", type: "paragraph", content: "Kept" },
+          { id: "s-p-1", type: "paragraph", content: "Removed" },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    // Blocks from two different containers in one call: each container is
+    // recorded once and repaired on its own terms.
+    editor.removeBlocks(["c-p-0", "s-p-1"]);
+
+    // Both containers dissolve: the callout held nothing else, and the pair
+    // is replaced by the one child that still carried content.
+    expect(editor.getBlock("c-0")).toBeUndefined();
+    expect(editor.getBlock("s-0")).toBeUndefined();
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "s-p-0",
+      "trailing",
+    ]);
+  });
+
+  it("cascades a repair outwards from the deepest container", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "grid",
+        id: "g-outer",
+        children: [
+          {
+            type: "gridCell",
+            id: "outer-cell-a",
+            children: [
+              {
+                type: "grid",
+                id: "g-inner",
+                children: [
+                  {
+                    type: "gridCell",
+                    id: "inner-cell-a",
+                    children: [
+                      { id: "inner-p", type: "paragraph", content: "X" },
+                    ],
+                  },
+                  {
+                    type: "gridCell",
+                    id: "inner-cell-b",
+                    children: [{ type: "paragraph", content: "" }],
+                  },
+                ],
+              },
+            ],
+          },
+          {
+            type: "gridCell",
+            id: "outer-cell-b",
+            children: [{ type: "paragraph", content: "" }],
+          },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    // The only real content, three containers deep. Removing it empties the
+    // inner cell, and the emptiness has to travel all the way out: the inner
+    // grid loses both its cells, the outer cell loses the inner grid, and the
+    // outer grid loses both of its cells. Recording only the innermost
+    // container would leave a stack of empty grids behind.
+    editor.removeBlocks(["inner-p"]);
+
+    expect(editor.getBlock("g-inner")).toBeUndefined();
+    expect(editor.getBlock("g-outer")).toBeUndefined();
+    expect(editor.document.map((block) => block.id)).toEqual(["trailing"]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+});
diff --git a/packages/core/src/api/blockManipulation/containers/fixContainer.ts b/packages/core/src/api/blockManipulation/containers/fixContainer.ts
new file mode 100644
index 0000000000..ea467db1e1
--- /dev/null
+++ b/packages/core/src/api/blockManipulation/containers/fixContainer.ts
@@ -0,0 +1,131 @@
+import { Fragment, type Node } from "prosemirror-model";
+import { type Transaction } from "prosemirror-state";
+
+import {
+  isContainerNode,
+  isNamedOnly,
+} from "../../../schema/blocks/children.js";
+import { getNodeById } from "../../nodeUtil.js";
+
+/**
+ * Whether `node` is a container child the user has emptied out: a container
+ * (a column, a cell) holding nothing but one empty paragraph, or one holding
+ * nothing at all that its content expression requires children.
+ * @internal
+ */
+export function isEmptyContainerChild(node: Node): boolean {
+  if (node.type.name === "blockContainer") {
+    const content = node.firstChild;
+    return (
+      node.childCount === 1 &&
+      !!content &&
+      content.type.name === "paragraph" &&
+      content.childCount === 0
+    );
+  }
+  if (isContainerNode(node.type)) {
+    if (node.childCount === 1) {
+      return isEmptyContainerChild(node.firstChild!);
+    }
+    // A container left with no children at all — its last child was removed
+    // and no fill happened on the way. A `min: 0` container in this state is
+    // valid and stays; any other is broken structure.
+    if (node.childCount === 0) {
+      const children = node.type.spec.blockConfig?.children;
+      return !!children && (children.min ?? 1) >= 1;
+    }
+    return false;
+  }
+  return false;
+}
+
+/**
+ * Repairs the container at `containerPos` after children were (re)moved from
+ * it: drops the ones the user emptied, and dissolves the container when too
+ * few are left for it to mean anything (a column list with one column is just
+ * that column's blocks).
+ *
+ * A container that only exists inside another container (a column) is left to
+ * its parent, which is the thing that decides whether it still belongs.
+ *
+ * @param containerPos The position just before the container node.
+ * @internal
+ */
+export function fixContainer(tr: Transaction, containerPos: number) {
+  const container = tr.doc.resolve(containerPos).nodeAfter;
+  if (!container || !isContainerNode(container.type)) {
+    throw new Error(
+      "Invalid containerPos: does not point to a container node.",
+    );
+  }
+
+  // A `namedOnly` container (a column) keeps existing: it is its parent's
+  // decision whether the container still belongs, and ProseMirror pads it
+  // back up to its minimum when children are removed.
+  if (isNamedOnly(container.type)) {
+    return;
+  }
+
+  const childrenConfig = container.type.spec.blockConfig?.children;
+  const min = childrenConfig ? (childrenConfig.min ?? 1) : 1;
+  const survivors: Node[] = [];
+  const emptied: { from: number; to: number }[] = [];
+  container.forEach((child, offset) => {
+    if (!isEmptyContainerChild(child)) {
+      survivors.push(child);
+    } else if (isContainerNode(child.type)) {
+      const from = containerPos + 1 + offset;
+      emptied.push({ from, to: from + child.nodeSize });
+    }
+  });
+
+  if (survivors.length >= min) {
+    // Keep intentional empty paragraphs. Only remove empty structural children,
+    // back to front so positions (and selections in surviving children) stay valid.
+    for (const { from, to } of emptied.reverse()) {
+      tr.delete(from, to);
+    }
+    return;
+  }
+
+  // Too few children left for the container to mean anything, so it is
+  // replaced by its surviving children.
+  const replacement: Node[] = [];
+  for (const survivor of survivors) {
+    if (isNamedOnly(survivor.type)) {
+      // The survivor can't stand on its own either (a column only exists
+      // inside a column list), so what it holds is what's left.
+      survivor.forEach((grandChild) => replacement.push(grandChild));
+    } else {
+      replacement.push(survivor);
+    }
+  }
+
+  tr.replaceWith(
+    containerPos,
+    containerPos + container.nodeSize,
+    Fragment.from(replacement),
+  );
+}
+
+/**
+ * Runs {@link fixContainer} on each of the given containers, looked up by ID
+ * in `tr`'s current doc. Containers are repaired deepest-first so that an
+ * inner repair (e.g. a column emptying out) is observed by the outer
+ * container's repair (e.g. its columnList unwrapping) in the same pass.
+ * Containers that no longer exist by the time their turn comes are skipped —
+ * an earlier repair may have removed them.
+ */
+export function fixContainersById(
+  tr: Transaction,
+  containers: { id: string; depth: number }[],
+) {
+  [...containers]
+    .sort((a, b) => b.depth - a.depth)
+    .forEach(({ id }) => {
+      const target = getNodeById(id, tr.doc);
+      if (target && isContainerNode(target.node.type)) {
+        fixContainer(tr, target.posBeforeNode);
+      }
+    });
+}
diff --git a/packages/core/src/api/blockManipulation/containers/plainBlocks.test.ts b/packages/core/src/api/blockManipulation/containers/plainBlocks.test.ts
new file mode 100644
index 0000000000..7fd3b4dc58
--- /dev/null
+++ b/packages/core/src/api/blockManipulation/containers/plainBlocks.test.ts
@@ -0,0 +1,197 @@
+import { TextSelection } from "prosemirror-state";
+import { afterEach, describe, expect, it } from "vite-plus/test";
+
+import { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
+import { createBlockSpec } from "../../../schema/blocks/createSpec.js";
+import { containerSchema } from "./containers.fixture.js";
+
+const plainNote = createBlockSpec(
+  {
+    type: "plainNote",
+    propSchema: {},
+    content: "plain",
+    children: { allow: "blocks" },
+  },
+  {
+    render() {
+      const dom = document.createElement("pre");
+      return { dom, contentDOM: dom };
+    },
+    renderFrame() {
+      const dom = document.createElement("section");
+      dom.className = "plain-frame";
+      const slot = document.createElement("div");
+      dom.append(slot);
+      return { dom, slot };
+    },
+  },
+)();
+const schema = containerSchema.extend({ blockSpecs: { plainNote } });
+const editors = new Set<ReturnType<typeof editorWith>>();
+
+function editorWith(
+  content = "Source",
+  children: (typeof schema.PartialBlock)[] = [
+    { id: "body", type: "paragraph", content: "Explanation" },
+  ],
+) {
+  const editor = BlockNoteEditor.create({
+    schema,
+    initialContent: [
+      { id: "note", type: "plainNote", content, children },
+      { id: "after", type: "paragraph", content: "After" },
+    ],
+  });
+  editors.add(editor);
+  editor.mount(document.createElement("div"));
+  return editor;
+}
+
+afterEach(() => {
+  for (const editor of editors) {
+    editor._tiptapEditor.destroy();
+  }
+  editors.clear();
+});
+
+function press(
+  editor: ReturnType<typeof editorWith>,
+  key: "Enter" | "Backspace" | "Delete" | "Tab",
+  shiftKey = false,
+) {
+  const view = editor.prosemirrorView;
+  return view.someProp("handleKeyDown", (handler) =>
+    handler(
+      view,
+      new KeyboardEvent("keydown", {
+        key,
+        code: key,
+        keyCode: { Enter: 13, Backspace: 8, Delete: 46, Tab: 9 }[key],
+        shiftKey,
+      }),
+    ),
+  );
+}
+function text(editor: ReturnType<typeof editorWith>, id: string) {
+  const block = editor.getBlock(id)!;
+  if (block.type !== "plainNote" && block.type !== "paragraph") {
+    throw new Error("Expected a text block");
+  }
+  return block.content
+    .map((part) => (part.type === "text" ? part.text : ""))
+    .join("");
+}
+
+describe("plain blocks with owned children", () => {
+  it.each(["", "Source"])(
+    "Enter starts the body and preserves children for %j",
+    (content) => {
+      const editor = editorWith(content);
+      editor.setTextCursorPosition("note", "end");
+      press(editor, "Enter");
+      expect(editor.document.map((block) => block.id)).toEqual([
+        "note",
+        "after",
+      ]);
+      expect(
+        editor.getBlock("note")!.children.map((block) => block.id),
+      ).toEqual([expect.any(String), "body"]);
+      expect(text(editor, "body")).toBe("Explanation");
+      expect(editor.getTextCursorPosition().block.id).toBe(
+        editor.getBlock("note")!.children[0].id,
+      );
+      editor.prosemirrorState.doc.check();
+    },
+  );
+
+  it("Enter moves the remaining plain text into the body", () => {
+    const editor = editorWith("Source");
+    editor.setTextCursorPosition("note", "start");
+    editor.transact((tr) =>
+      tr.setSelection(TextSelection.create(tr.doc, tr.selection.from + 3)),
+    );
+    press(editor, "Enter");
+    expect(text(editor, "note")).toBe("Sou");
+    expect(text(editor, editor.getBlock("note")!.children[0].id)).toBe("rce");
+    expect(text(editor, "body")).toBe("Explanation");
+  });
+
+  it("Shift-Enter inserts a newline without moving children", () => {
+    const editor = editorWith();
+    editor.setTextCursorPosition("note", "end");
+    press(editor, "Enter", true);
+    expect(text(editor, "note")).toBe("Source\n");
+    expect(editor.getBlock("note")!.children.map((block) => block.id)).toEqual([
+      "body",
+    ]);
+    editor.prosemirrorState.doc.check();
+  });
+
+  it.each(["Backspace", "Delete"] as const)(
+    "%s preserves child text when merging into plain content",
+    (key) => {
+      const editor = editorWith("Source", [
+        {
+          id: "body",
+          type: "paragraph",
+          content: [
+            { type: "text", text: "Bold", styles: { bold: true } },
+            "\nNext",
+          ],
+          children: [{ id: "nested", type: "paragraph", content: "Nested" }],
+        },
+      ]);
+      editor.setTextCursorPosition("note", "end");
+      const joinPosition = editor.prosemirrorState.selection.from;
+      editor.setTextCursorPosition(
+        key === "Backspace" ? "body" : "note",
+        key === "Backspace" ? "start" : "end",
+      );
+      press(editor, key);
+      expect(editor.prosemirrorState.selection.from).toBe(joinPosition);
+      expect(text(editor, "note")).toBe("SourceBold\nNext");
+      expect(editor.getBlock("note")!.content).toEqual([
+        { type: "text", text: "SourceBold\nNext", styles: {} },
+      ]);
+      expect(
+        editor.getBlock("note")!.children.map((block) => block.id),
+      ).toEqual(["nested"]);
+      expect(editor.getBlock("body")).toBeUndefined();
+      editor.prosemirrorState.doc.check();
+    },
+  );
+
+  it("keeps owned children when Shift-Tab is pressed", () => {
+    const editor = editorWith();
+    editor.setTextCursorPosition("body", "start");
+    press(editor, "Tab", true);
+    expect(editor.getBlock("note")!.children.map((block) => block.id)).toEqual([
+      "body",
+    ]);
+  });
+
+  it("renders and round-trips multiline content with its children", () => {
+    const editor = editorWith("First\nSecond");
+    expect(editor.domElement?.querySelector(".plain-frame")?.textContent).toBe(
+      "First\nSecondExplanation",
+    );
+    const parsed = editor.tryParseHTMLToBlocks(
+      editor.blocksToFullHTML(editor.document),
+    );
+    expect(parsed).toEqual(editor.document);
+    expect(editor.blocksToHTMLLossy(editor.document)).toContain("Explanation");
+  });
+
+  it("preserves text and children when converting between plain, inline, and container blocks", () => {
+    const editor = editorWith("First\nSecond");
+    editor.updateBlock("note", { type: "alert" });
+    expect(editor.getBlock("note")!.children[0].id).toBe("body");
+    editor.updateBlock("note", { type: "plainNote" });
+    expect(text(editor, "note")).toBe("First\nSecond");
+    editor.updateBlock("note", { type: "callout" });
+    const container = editor.document[0];
+    expect(text(editor, container.children[0].id)).toBe("First\nSecond");
+    expect(container.children[1].id).toBe("body");
+    editor.prosemirrorState.doc.check();
+  });
+});
diff --git a/packages/core/src/api/blockManipulation/containers/titledBlocks.test.ts b/packages/core/src/api/blockManipulation/containers/titledBlocks.test.ts
new file mode 100644
index 0000000000..af683b567d
--- /dev/null
+++ b/packages/core/src/api/blockManipulation/containers/titledBlocks.test.ts
@@ -0,0 +1,352 @@
+import { NodeSelection, TextSelection } from "prosemirror-state";
+import { afterEach, describe, expect, it } from "vite-plus/test";
+
+import { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
+import {
+  hasOwnedChildren,
+  isContainerNode,
+} from "../../../schema/blocks/children.js";
+import { getBlockInfoAt } from "../../getBlockInfoFromPos.js";
+import { getNodeById } from "../../nodeUtil.js";
+import { containerSchema } from "./containers.fixture.js";
+
+// Behaviour of titled blocks: an ordinary block with inline content
+// (the title) whose `children` are a body that belongs to it. The `alert`
+// fixture block is the specimen; `callout` (a pure container) is the control.
+
+const schema = containerSchema;
+const editors = new Set<ReturnType<typeof editorWith>>();
+
+afterEach(() => {
+  for (const editor of editors) {
+    editor._tiptapEditor.destroy();
+  }
+  editors.clear();
+});
+
+function editorWith(initialContent: any[]) {
+  const editor = BlockNoteEditor.create({ schema, initialContent } as any);
+  editors.add(editor);
+  editor.mount(document.createElement("div"));
+  return editor;
+}
+
+function press(editor: any, key: string, mods: string[] = []) {
+  const view = editor._tiptapEditor.view;
+  const codes: Record<string, number> = {
+    Enter: 13,
+    Backspace: 8,
+    Tab: 9,
+    Delete: 46,
+  };
+  const event = new KeyboardEvent("keydown", {
+    key,
+    code: key,
+    keyCode: codes[key],
+    bubbles: true,
+    shiftKey: mods.includes("Shift"),
+  } as any);
+  return !!view.someProp("handleKeyDown", (f: any) => f(view, event));
+}
+
+function shape(blocks: any[]): string {
+  return blocks
+    .map((block) => {
+      const text = Array.isArray(block.content)
+        ? block.content.map((c: any) => c.text ?? "").join("")
+        : "";
+      const children = block.children?.length
+        ? `[${shape(block.children)}]`
+        : "";
+      return `${block.type}"${text}"${children}`;
+    })
+    .join(", ");
+}
+
+const before = { id: "pre", type: "paragraph" as const, content: "Before" };
+const after = { id: "post", type: "paragraph" as const, content: "After" };
+const body = [
+  { id: "b1", type: "paragraph" as const, content: "One" },
+  { id: "b2", type: "paragraph" as const, content: "Two" },
+];
+
+const withAlert = (children: any[] = body) => [
+  before,
+  { id: "w", type: "alert" as const, content: "Title", children },
+  after,
+];
+
+describe("titled-block schema shape", () => {
+  it("recognizes declared ownership on ordinary blocks", () => {
+    const editor = editorWith(withAlert());
+
+    editor.transact((tr) => {
+      const alert = getNodeById("w", tr.doc)!;
+      // An ordinary blockContainer: its node holds content, not children.
+      expect(alert.node.type.name).toBe("blockContainer");
+      expect(isContainerNode(alert.node.type)).toBe(false);
+      expect(hasOwnedChildren(alert.node)).toBe(true);
+      expect(alert.node.attrs.id).toBe("w");
+      expect(alert.node.firstChild!.attrs).not.toHaveProperty("id");
+
+      expect(hasOwnedChildren(getNodeById("pre", tr.doc)!.node)).toBe(false);
+
+      // The body is the blockGroup the alert nests, resolved with positions.
+      const info = getBlockInfoAt(tr.doc, alert.posBeforeNode);
+      expect(info.children?.node.type.name).toBe("blockGroup");
+      expect(info.children?.beforePos).toBe(info.content?.afterPos);
+    });
+  });
+
+  it("frames the title and the body together in the live DOM", () => {
+    const editor = editorWith(withAlert());
+
+    const frame = editor.domElement!.querySelector(".alert-frame");
+    expect(frame).not.toBeNull();
+    const slot = frame!.querySelector(".alert-slot");
+    expect(slot).not.toBeNull();
+    // The title's text and both body blocks render inside the slot.
+    expect(slot!.textContent).toContain("Title");
+    expect(slot!.textContent).toContain("One");
+    expect(slot!.textContent).toContain("Two");
+  });
+});
+
+describe("a titled block's keyboard behaviour", () => {
+  it.each([{ children: [] }, { children: body }])(
+    "Enter in an empty title preserves its body (%j)",
+    ({ children }) => {
+      const editor = editorWith([
+        before,
+        { id: "w", type: "alert", content: "", children },
+        after,
+      ]);
+      editor.setTextCursorPosition("w", "start");
+      expect(press(editor, "Enter")).toBe(true);
+      expect(editor.document.map((block) => block.id)).toEqual([
+        "pre",
+        "w",
+        "post",
+      ]);
+      expect(shape(editor.document[1].children)).toBe(
+        [
+          'paragraph""',
+          ...children.map((block) => `paragraph"${block.content}"`),
+        ].join(", "),
+      );
+      expect(
+        editor.document[1].children.slice(1).map((block) => block.id),
+      ).toEqual(children.map((block) => block.id));
+      expect(editor.getTextCursorPosition().block.id).toBe(
+        editor.document[1].children[0].id,
+      );
+    },
+  );
+
+  it("Enter at the end of the title starts the body, keeping it", () => {
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("w", "end");
+    press(editor, "Enter");
+
+    // The new block belongs to the alert, and the body is still the
+    // alert's — not carried off by a new sibling.
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Title"[paragraph"", paragraph"One", paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("Enter in the middle of the title keeps the body on the alert", () => {
+    // The bug behind the toggle-block reports: splitting a block handed its
+    // children to the new block, so a callout's body ended up under whatever
+    // the split created.
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("w", "start");
+    editor.transact((tr) =>
+      tr.setSelection(TextSelection.create(tr.doc, tr.selection.from + 2)),
+    );
+    press(editor, "Enter");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Ti"[paragraph"tle", paragraph"One", paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("Enter in an empty last body block leaves the alert", () => {
+    const editor = editorWith(
+      withAlert([body[0], { id: "b2", type: "paragraph", content: "" }]),
+    );
+    editor.setTextCursorPosition("b2", "start");
+    press(editor, "Enter");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Title"[paragraph"One"], paragraph"", paragraph"After"',
+    );
+  });
+
+  it("Enter in an empty body block that is the only one stays put", () => {
+    // Nothing to escape from yet: the block is where a new alert's body
+    // starts, and leaving would dissolve the alert the user just made.
+    const editor = editorWith(
+      withAlert([{ id: "b1", type: "paragraph", content: "" }]),
+    );
+    editor.setTextCursorPosition("b1", "start");
+    press(editor, "Enter");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Title"[paragraph"", paragraph""], paragraph"After"',
+    );
+  });
+
+  it("Backspace at the start of the first body block merges into the title", () => {
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("b1", "start");
+    press(editor, "Backspace");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"TitleOne"[paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("Shift-Tab in the body does not escape the alert", () => {
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("b1", "start");
+    press(editor, "Tab", ["Shift"]);
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Title"[paragraph"One", paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("Backspace in the block after moves it into the body, whole", () => {
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("post", "start");
+    press(editor, "Backspace");
+
+    // Moved in as its own block: text never merges across the edge.
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Title"[paragraph"One", paragraph"Two", paragraph"After"]',
+    );
+  });
+
+  it("Tab still nests inside the body", () => {
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("b2", "start");
+    press(editor, "Tab");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"Title"[paragraph"One"[paragraph"Two"]], paragraph"After"',
+    );
+  });
+
+  it("Delete at the end of the title merges the first body block into it", () => {
+    // The mirror of Backspace at the start of the first body block: the
+    // body's first block is consumed and its text joins the title.
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("w", "end");
+    press(editor, "Delete");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"TitleOne"[paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("Enter with a non-collapsed selection in the title takes the generic split path", () => {
+    // The titled block's Enter handler only fires for a collapsed selection,
+    // so a range selection falls through to the generic split: the selected
+    // text is deleted and the title splits, keeping the body on the alert.
+    const editor = editorWith(withAlert());
+    editor.setTextCursorPosition("w", "start");
+    editor.transact((tr) =>
+      tr.setSelection(
+        TextSelection.create(
+          tr.doc,
+          tr.selection.from + 1,
+          tr.selection.from + 3,
+        ),
+      ),
+    );
+    press(editor, "Enter");
+
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert"T"[paragraph"One", paragraph"Two"], paragraph"le", paragraph"After"',
+    );
+  });
+});
+
+describe("converting between a titled block and a pure container", () => {
+  it("carries the title into the body when an alert becomes a callout", () => {
+    const editor = editorWith(withAlert());
+    editor.updateBlock("w" as any, { type: "callout" } as any);
+
+    // A container holds no content of its own, so the title moves into the
+    // body as its first paragraph; the existing children stay after it, in
+    // order.
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", callout""[paragraph"Title", paragraph"One", paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("invents an empty title when a callout becomes an alert", () => {
+    const editor = editorWith([
+      before,
+      {
+        id: "w",
+        type: "callout" as const,
+        children: [
+          { id: "b1", type: "paragraph" as const, content: "One" },
+          { id: "b2", type: "paragraph" as const, content: "Two" },
+        ],
+      },
+      after,
+    ]);
+    editor.updateBlock("w" as any, { type: "alert" } as any);
+
+    // The container had no title to carry, so the alert starts empty; its
+    // children move across untouched.
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", alert""[paragraph"One", paragraph"Two"], paragraph"After"',
+    );
+  });
+});
+
+describe("blocks that declare no children are untouched", () => {
+  it("keeps ordinary nesting behaviour for a nested paragraph", () => {
+    const editor = editorWith([
+      before,
+      { id: "w", type: "paragraph", content: "Title", children: body },
+      after,
+    ]);
+    editor.setTextCursorPosition("b1", "start");
+    press(editor, "Tab", ["Shift"]);
+
+    // Shift-Tab lifts it out, as it always has.
+    expect(shape(editor.document)).toBe(
+      'paragraph"Before", paragraph"Title", paragraph"One"[paragraph"Two"], paragraph"After"',
+    );
+  });
+
+  it("survives the clipboard round-trip that copy and drag use", () => {
+    // Dragging a block inside the editor re-parses it from the HTML
+    // ProseMirror serializes the dragged slice to, so a titled block whose
+    // parse rules don't match that HTML comes back as a paragraph.
+    const editor = editorWith(withAlert());
+    const view = editor._tiptapEditor.view;
+
+    editor.transact((tr) => {
+      let pos = -1;
+      tr.doc.descendants((node: any, at: number) => {
+        if (pos < 0 && node.attrs?.id === "w") {
+          pos = at;
+        }
+        return pos < 0;
+      });
+      tr.setSelection(NodeSelection.create(tr.doc, pos));
+    });
+    const html = view.serializeForClipboard(view.state.selection.content()).dom
+      .innerHTML;
+
+    expect(shape(editor.tryParseHTMLToBlocks(html))).toBe(
+      'alert"Title"[paragraph"One", paragraph"Two"]',
+    );
+  });
+});
diff --git a/packages/core/src/api/blockManipulation/selections/selection.ts b/packages/core/src/api/blockManipulation/selections/selection.ts
index 34591c8c8d..ff60114b79 100644
--- a/packages/core/src/api/blockManipulation/selections/selection.ts
+++ b/packages/core/src/api/blockManipulation/selections/selection.ts
@@ -7,6 +7,7 @@ import {
   InlineContentSchema,
   StyleSchema,
 } from "../../../schema/index.js";
+import { CHILD_CONTAINER_GROUP } from "../../../schema/blocks/children.js";
 import { expandPMRangeToWords } from "../../../util/expandToWords.js";
 import {
   blockEdgePos,
@@ -100,7 +101,7 @@ export function getSelection<
     for (let depth = $startBlockBeforePos.depth; depth > sharedDepth; depth--) {
       const parentNode = $startBlockBeforePos.node(depth);
 
-      if (parentNode.type.isInGroup("childContainer")) {
+      if (parentNode.type.isInGroup(CHILD_CONTAINER_GROUP)) {
         const startIndexAtDepth = $startBlockBeforePos.index(depth) + 1;
         const childCountAtDepth = $startBlockBeforePos.node(depth).childCount;
 
diff --git a/packages/core/src/api/exporters/html/util/serializeBlocksExternalHTML.ts b/packages/core/src/api/exporters/html/util/serializeBlocksExternalHTML.ts
index e2274140f7..c381722789 100644
--- a/packages/core/src/api/exporters/html/util/serializeBlocksExternalHTML.ts
+++ b/packages/core/src/api/exporters/html/util/serializeBlocksExternalHTML.ts
@@ -8,6 +8,8 @@ import {
   InlineContentSchema,
   StyleSchema,
 } from "../../../../schema/index.js";
+import { isContainerNode } from "../../../../schema/blocks/children.js";
+import { containerRootDOM } from "../../../../schema/blocks/createSpec.js";
 import { UnreachableCaseError } from "../../../../util/typescript.js";
 import {
   inlineContentToNodes,
@@ -224,10 +226,11 @@ function serializeBlock<
 
   const blockImplementation = editor.blockImplementations[block.type as any]
     .implementation as BlockImplementation;
+  const blockWithDefaults = { ...block, props, children: block.children ?? [] };
   const ret =
     blockImplementation.toExternalHTML?.call(
       {},
-      { ...block, props } as any,
+      blockWithDefaults as any,
       editor as any,
       {
         nestingLevel,
@@ -235,16 +238,25 @@ function serializeBlock<
     ) ||
     blockImplementation.render.call(
       {},
-      { ...block, props } as any,
+      blockWithDefaults as any,
       editor as any,
     );
 
   const elementFragment = doc.createDocumentFragment();
 
-  if ((ret.dom as HTMLElement).classList.contains("bn-block-content")) {
+  // React renders can return a fragment around the root element.
+  const rootElement = containerRootDOM(ret);
+
+  const blockContentRoot = rootElement?.classList.contains("bn-block-content")
+    ? rootElement
+    : ret.contentDOM?.closest<HTMLElement>(".bn-block-content");
+
+  elementFragment.append(ret.dom);
+
+  if (blockContentRoot) {
     const blockContentDataAttributes = [
       ...attrs,
-      ...Array.from((ret.dom as HTMLElement).attributes),
+      ...Array.from(blockContentRoot.attributes),
     ].filter(
       (attr) =>
         attr.name.startsWith("data") &&
@@ -256,26 +268,32 @@ function serializeBlock<
         attr.name !== "data-editable",
     );
 
-    // ret.dom = ret.dom.firstChild! as any;
     for (const attr of blockContentDataAttributes) {
-      (ret.dom.firstChild! as HTMLElement).setAttribute(attr.name, attr.value);
+      (blockContentRoot.firstChild! as HTMLElement).setAttribute(
+        attr.name,
+        attr.value,
+      );
     }
 
-    addAttributesAndRemoveClasses(ret.dom.firstChild! as HTMLElement);
+    addAttributesAndRemoveClasses(blockContentRoot.firstChild! as HTMLElement);
     if (nestingLevel > 0) {
-      (ret.dom.firstChild! as HTMLElement).setAttribute(
+      (blockContentRoot.firstChild! as HTMLElement).setAttribute(
         "data-nesting-level",
         nestingLevel.toString(),
       );
     }
-    elementFragment.append(...Array.from(ret.dom.childNodes));
+    // Unwrap the content in place, preserving any surrounding frame.
+    blockContentRoot.replaceWith(...Array.from(blockContentRoot.childNodes));
   } else {
-    elementFragment.append(ret.dom);
+    if (isContainerNode(editor.pmSchema.nodes[block.type as any])) {
+      // Pasted external HTML gets fresh IDs; scope parsing to actual children.
+      rootElement?.removeAttribute("data-id");
+      const childrenDOM =
+        ("childrenDOM" in ret && ret.childrenDOM) || ret.contentDOM;
+      childrenDOM?.setAttribute("data-children-of", block.type!);
+    }
     if (nestingLevel > 0) {
-      (ret.dom as HTMLElement).setAttribute(
-        "data-nesting-level",
-        nestingLevel.toString(),
-      );
+      rootElement?.setAttribute("data-nesting-level", nestingLevel.toString());
     }
   }
 
@@ -301,11 +319,9 @@ function serializeBlock<
     // tables) fill their `contentDOM` with child blocks later on, and code
     // blocks would turn the placeholder into literal content.
     const blockNodeType = editor.pmSchema.nodes[block.type as any];
-    if (
-      blockNodeType?.inlineContent &&
-      !blockNodeType.spec.code &&
-      ret.contentDOM.childNodes.length === 0
-    ) {
+    const needsPlaceholder =
+      !!blockNodeType?.inlineContent && !blockNodeType.spec.code;
+    if (needsPlaceholder && ret.contentDOM.childNodes.length === 0) {
       ret.contentDOM.appendChild(doc.createTextNode(EMPTY_BLOCK_PLACEHOLDER));
     }
   }
diff --git a/packages/core/src/api/exporters/html/util/serializeBlocksInternalHTML.ts b/packages/core/src/api/exporters/html/util/serializeBlocksInternalHTML.ts
index 0f890b77ab..663a5c9689 100644
--- a/packages/core/src/api/exporters/html/util/serializeBlocksInternalHTML.ts
+++ b/packages/core/src/api/exporters/html/util/serializeBlocksInternalHTML.ts
@@ -7,6 +7,7 @@ import {
   InlineContentSchema,
   StyleSchema,
 } from "../../../../schema/index.js";
+import { isContainerNode } from "../../../../schema/blocks/children.js";
 import { UnreachableCaseError } from "../../../../util/typescript.js";
 import {
   inlineContentToNodes,
@@ -159,6 +160,8 @@ function serializeBlock<
     editor as any,
   );
 
+  const isContainer = isContainerNode(editor.pmSchema.nodes[block.type as any]);
+
   if (ret.contentDOM && block.content) {
     const ic = serializeInlineContentInternalHTML(
       editor,
@@ -170,9 +173,15 @@ function serializeBlock<
     ret.contentDOM.appendChild(ic);
   }
 
-  const pmType = editor.pmSchema.nodes[block.type as any];
-
-  if (pmType.isInGroup("bnBlock")) {
+  if (isContainer) {
+    // Mark where the children live so the container's round-trip parse rule
+    // can scope itself to this element (`contentElement` in `getParseRules`).
+    // A render is free to put non-content UI text elsewhere in its DOM
+    // (button labels, captions, ...), and without the marker that text would
+    // parse back as document content.
+    if (ret.contentDOM) {
+      ret.contentDOM.setAttribute("data-children-of", block.type!);
+    }
     if (block.children && block.children.length > 0) {
       const fragment = serializeBlocks(
         editor,
@@ -197,10 +206,30 @@ function serializeBlock<
     contentDOM?: HTMLElement;
   };
 
-  bc.contentDOM?.appendChild(ret.dom);
+  // Frames wrap the content and its child group in static HTML too. The DOM
+  // render context lets interactive frames export without browser view state.
+  const renderFrame = impl.renderFrame<I, S>;
+  const frame = renderFrame?.call(
+    {
+      renderType: "dom",
+      props: undefined,
+      blockContentDOMAttributes:
+        editor._tiptapEditor.extensionManager.extensions.find(
+          (extension) => extension.name === block.type,
+        )?.options.domAttributes?.blockContent || {},
+      propSchema: editor.schema.blockSchema[block.type!].propSchema,
+    },
+    { ...block, props, children },
+    editor,
+  );
+  if (frame) {
+    bc.contentDOM?.appendChild(frame.dom);
+  }
+  const contentDOM = frame?.slot ?? bc.contentDOM;
+  contentDOM?.appendChild(ret.dom);
 
   if (block.children && block.children.length > 0) {
-    bc.contentDOM?.appendChild(
+    contentDOM?.appendChild(
       serializeBlocksInternalHTML(editor, block.children, serializer, options),
     );
   }
diff --git a/packages/core/src/api/getBlockInfoFromPos.test.ts b/packages/core/src/api/getBlockInfoFromPos.test.ts
index 3e45c14330..5080902c0d 100644
--- a/packages/core/src/api/getBlockInfoFromPos.test.ts
+++ b/packages/core/src/api/getBlockInfoFromPos.test.ts
@@ -1,10 +1,13 @@
+import { containerSchema } from "./blockManipulation/containers/containers.fixture.js";
+import { getNodeById } from "./nodeUtil.js";
 import { Node, Schema } from "prosemirror-model";
-import { describe, expect, it } from "vite-plus/test";
+import { afterEach, beforeEach, describe, expect, it } from "vite-plus/test";
 
 import { BlockNoteEditor } from "../editor/BlockNoteEditor.js";
 import { blockToNode } from "./nodeConversions/blockToNode.js";
 import { docToBlocks } from "./nodeConversions/nodeToBlock.js";
 import {
+  getAncestorContainers,
   getBlockInfoFromNode,
   getLastDescendantBlockInfo,
   getNextBlockInfo,
@@ -281,21 +284,6 @@ describe("derived position and content fields", () => {
     expect(info.contentKind).toBe("plain");
   });
 
-  it("rejects malformed wrapper structure at the block-info boundary", () => {
-    const { blockContainer, paragraph, blockGroup } = getSchema().nodes;
-    const content = paragraph.create();
-    for (const children of [
-      [],
-      [blockGroup.create()],
-      [content, content],
-      [content, blockGroup.create(), blockGroup.create()],
-    ]) {
-      // Deliberately bypass schema checking, as transaction intermediates can.
-      const node = blockContainer.create(null, children);
-      expect(() => getBlockInfoFromNode(node, 0)).toThrow(/blockContainer/);
-    }
-  });
-
   it("rejects a content node that was not built from a block spec", () => {
     // A node dropped straight into the `blockContent` group of a ProseMirror
     // schema, with no block spec behind it: nothing declares what its content
@@ -522,3 +510,140 @@ describe("docToBlocks round trip with suggested deletions", () => {
     expect(new Set(ids).size).toBe(ids.length);
   });
 });
+
+describe("block info for containers", () => {
+  let editor: BlockNoteEditor<
+    typeof containerSchema.blockSchema,
+    typeof containerSchema.inlineContentSchema,
+    typeof containerSchema.styleSchema
+  >;
+  beforeEach(() => {
+    editor = BlockNoteEditor.create({ schema: containerSchema });
+  });
+  afterEach(() => {
+    editor._tiptapEditor.destroy();
+  });
+  it.each(["paragraph", "alert", "callout"] as const)(
+    "distinguishes %s ownership from the presence of children",
+    (type) => {
+      for (const children of [
+        [],
+        [{ type: "paragraph" as const, content: "Body" }],
+      ]) {
+        const node = blockToNode({ type, children }, editor.pmSchema);
+        const info = getBlockInfoFromNode(node, 10);
+        expect(info.hasOwnedChildren).toBe(type !== "paragraph");
+        expect(info.hasContent).toBe(type !== "callout");
+        if (children.length) {
+          expect(info.children?.node.childCount).toBe(1);
+        }
+      }
+    },
+  );
+
+  it("rejects malformed wrapper structure at the block-info boundary", () => {
+    const { blockContainer, paragraph, blockGroup } = editor.pmSchema.nodes;
+    const content = paragraph.create();
+    for (const children of [
+      [],
+      [blockGroup.create()],
+      [content, content],
+      [content, blockGroup.create(), blockGroup.create()],
+    ]) {
+      // Deliberately bypass schema checking, as transaction intermediates can.
+      const node = blockContainer.create(null, children);
+      expect(() => getBlockInfoFromNode(node, 0)).toThrow(/blockContainer/);
+    }
+  });
+
+  describe("parent lookups for container children", () => {
+    // Regression: `getParentBlockInfo` used to skip the container level for
+    // container children (returning the grid for a block inside a gridCell).
+    // The parent of a block is the block whose `children` contains it: the
+    // cell.
+    it("returns the container as the parent of its direct children", () => {
+      editor.replaceBlocks(editor.document, [
+        {
+          type: "grid",
+          id: "g-0",
+          children: [
+            {
+              type: "gridCell",
+              id: "cell-a",
+              children: [{ id: "cell-a-p", type: "paragraph", content: "A" }],
+            },
+            {
+              type: "gridCell",
+              id: "cell-b",
+              children: [{ id: "cell-b-p", type: "paragraph", content: "B" }],
+            },
+          ],
+        },
+        { id: "trailing", type: "paragraph", content: "" },
+      ]);
+
+      editor.transact((tr) => {
+        // The block directly containing a cell's paragraph is the cell.
+        const cellChild = getNodeById("cell-a-p", tr.doc)!;
+        expect(
+          getParentBlockInfo(tr.doc, cellChild.posBeforeNode)?.blockNoteType,
+        ).toBe("gridCell");
+
+        // The parent of a cell is the grid; the parent of the grid (a
+        // top-level block) is undefined.
+        const cell = getNodeById("cell-a", tr.doc)!;
+        expect(
+          getParentBlockInfo(tr.doc, cell.posBeforeNode)?.blockNoteType,
+        ).toBe("grid");
+
+        const grid = getNodeById("g-0", tr.doc)!;
+        expect(getParentBlockInfo(tr.doc, grid.posBeforeNode)).toBeUndefined();
+      });
+    });
+  });
+
+  it("lists the container ancestors of a position, innermost first", () => {
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "grid",
+        id: "g-0",
+        children: [
+          {
+            type: "gridCell",
+            id: "cell-a",
+            children: [
+              {
+                type: "callout",
+                id: "c-0",
+                children: [{ id: "deep-p", type: "paragraph", content: "X" }],
+              },
+            ],
+          },
+          {
+            type: "gridCell",
+            id: "cell-b",
+            children: [{ id: "cell-b-p", type: "paragraph", content: "B" }],
+          },
+        ],
+      },
+      { id: "trailing", type: "paragraph", content: "" },
+    ]);
+
+    editor.transact((tr) => {
+      const deep = getNodeById("deep-p", tr.doc)!;
+      const ancestors = getAncestorContainers(tr.doc, deep.posBeforeNode);
+
+      // Only the container nodes: the `blockGroup`/`blockContainer` levels
+      // between them are not containers and must not be repaired.
+      expect(ancestors.map(({ id }) => id)).toEqual(["c-0", "cell-a", "g-0"]);
+      // Depths shrink outwards, which is what `fixContainersById` sorts on.
+      expect(ancestors.map(({ depth }) => depth)).toEqual(
+        [...ancestors.map(({ depth }) => depth)].sort((a, b) => b - a),
+      );
+
+      // A top-level block has no container ancestors at all.
+      const trailing = getNodeById("trailing", tr.doc)!;
+      expect(getAncestorContainers(tr.doc, trailing.posBeforeNode)).toEqual([]);
+    });
+  });
+});
diff --git a/packages/core/src/api/getBlockInfoFromPos.ts b/packages/core/src/api/getBlockInfoFromPos.ts
index a9512f0f6a..e9712d1b4c 100644
--- a/packages/core/src/api/getBlockInfoFromPos.ts
+++ b/packages/core/src/api/getBlockInfoFromPos.ts
@@ -7,6 +7,11 @@ import {
   Transaction,
 } from "prosemirror-state";
 
+import {
+  CHILD_CONTAINER_GROUP,
+  isContainerNode,
+  hasOwnedChildren,
+} from "../schema/blocks/children.js";
 import type { BlockConfig } from "../schema/blocks/types.js";
 
 /**
@@ -69,6 +74,7 @@ export type BlockInfo = {
       children: ChildrenInfo;
       content?: undefined;
       hasContent: false;
+      hasOwnedChildren: true;
       contentStart?: undefined;
       contentEnd?: undefined;
       contentKind?: undefined;
@@ -105,6 +111,8 @@ export type BlockInfo = {
        * `hasContent: false`.
        */
       hasContent: true;
+      /** Whether children belong to this block, even before a body exists. */
+      hasOwnedChildren: boolean;
     }
 );
 
@@ -319,9 +327,10 @@ export function getBlockInfoFromNode(node: Node, beforePos: number): BlockInfo {
     afterPos: beforePos + node.nodeSize,
   };
 
-  if (node.type.isInGroup("bnBlock") && node.type.isInGroup("childContainer")) {
+  if (isContainerNode(node.type)) {
     return {
       hasContent: false,
+      hasOwnedChildren: true,
       block,
       children: {
         ...block,
@@ -375,6 +384,7 @@ export function getBlockInfoFromNode(node: Node, beforePos: number): BlockInfo {
 
     return {
       hasContent: true,
+      hasOwnedChildren: hasOwnedChildren(node),
       block,
       content,
       children,
@@ -452,7 +462,7 @@ export function getParentBlockInfo(
   }
   // A `blockGroup`: its own parent block is the real parent, unless it's the
   // document root group.
-  if (parent.type.isInGroup("childContainer") && $pos.depth > 1) {
+  if (parent.type.isInGroup(CHILD_CONTAINER_GROUP) && $pos.depth > 1) {
     return getBlockInfoAt(doc, $pos.before($pos.depth - 1));
   }
   return undefined;
@@ -583,13 +593,7 @@ export function getInsertionPos(
     // A restricted container can route insertion into its edge container,
     // e.g. inserting a paragraph into the last column of a column list.
     const child = last ? children.node.lastChild : children.node.firstChild;
-    if (
-      !child ||
-      !(
-        child.type.isInGroup("bnBlock") &&
-        child.type.isInGroup("childContainer")
-      )
-    ) {
+    if (!child || !isContainerNode(child.type)) {
       break;
     }
     info = getBlockInfoFromNode(
@@ -599,3 +603,71 @@ export function getInsertionPos(
   }
   return null;
 }
+
+/**
+ * Resolves a block to its first leaf block: the block itself when it is not a
+ * container, otherwise the first leaf of its first child. Returns `null` for
+ * an empty container.
+ */
+export function getFirstLeafBlock(info: BlockInfo): BlockInfo | null {
+  while (!info.hasContent) {
+    const { node, childrenStart } = info.children;
+    if (!node.firstChild) {
+      return null;
+    }
+    info = getBlockInfoFromNode(node.firstChild, childrenStart);
+  }
+  return info;
+}
+
+/**
+ * Climbs out of containers until it reaches a position where `nodeType` fits.
+ * `side` picks which edge of each climbed container to land on: `"before"` for
+ * moves that put a block above the containers it leaves (Backspace move-out),
+ * `"after"` for moves that put it below them (Enter-exit).
+ *
+ * Position-based rather than `BlockInfo`-based (unlike the descend/leaf
+ * helpers above) because its input is an arbitrary gap position — a point
+ * between blocks, not a block.
+ */
+export function ascendToInsertablePos(
+  doc: Node,
+  pos: number,
+  nodeType: NodeType,
+  side: "before" | "after" = "before",
+): number | undefined {
+  for (;;) {
+    const $pos = doc.resolve(pos);
+    const parent = $pos.node();
+    if (parent.canReplaceWith($pos.index(), $pos.index(), nodeType)) {
+      return pos;
+    }
+    if ($pos.depth > 0 && isContainerNode(parent.type)) {
+      pos = side === "before" ? $pos.before() : $pos.after();
+      continue;
+    }
+    return undefined;
+  }
+}
+
+/**
+ * The container ancestors of a position, outermost last, each with its block
+ * id and resolution depth. Used to re-run container repair (`fixContainersById`)
+ * on every container a mutation may have emptied. Position-based for the same
+ * reason as `ascendToInsertablePos`: selections and mapped positions are the
+ * natural inputs.
+ */
+export function getAncestorContainers(
+  doc: Node,
+  pos: number,
+): { id: string; depth: number }[] {
+  const $pos = doc.resolve(pos);
+  const containers: { id: string; depth: number }[] = [];
+  for (let depth = $pos.depth; depth > 0; depth--) {
+    const ancestor = $pos.node(depth);
+    if (isContainerNode(ancestor.type) && ancestor.attrs.id) {
+      containers.push({ id: ancestor.attrs.id, depth });
+    }
+  }
+  return containers;
+}
diff --git a/packages/core/src/api/nodeConversions/blockToNode.ts b/packages/core/src/api/nodeConversions/blockToNode.ts
index af5c0ba1b7..5f46f4b418 100644
--- a/packages/core/src/api/nodeConversions/blockToNode.ts
+++ b/packages/core/src/api/nodeConversions/blockToNode.ts
@@ -16,6 +16,10 @@ import {
   isPartialLinkInlineContent,
   isStyledTextInlineContent,
 } from "../../schema/inlineContent/types.js";
+import {
+  createBlockGroup,
+  isContainerNode,
+} from "../../schema/blocks/children.js";
 import { getColspan, isPartialTableCell } from "../../util/table.js";
 import { UnreachableCaseError } from "../../util/typescript.js";
 import { getAbsoluteTableCells } from "../blockManipulation/tables/tables.js";
@@ -288,13 +292,17 @@ export function tableContentToNodes<
   return rowNodes;
 }
 
+/**
+ * Converts a block's (or custom inline content element's) `content` field to a
+ * `blockContent` (or custom inline content) prosemirror node.
+ */
 function blockOrInlineContentToContentNode(
   block:
     | PartialBlock<any, any, any>
     | PartialCustomInlineContentFromConfig<any, any>,
   schema: Schema,
   styleSchema: StyleSchema,
-) {
+): Node {
   let contentNode: Node;
   let type = block.type;
 
@@ -334,6 +342,25 @@ function blockOrInlineContentToContentNode(
   return contentNode;
 }
 
+// `createAndFill` fills with schema defaults, which leaves `id: null`. Always
+// rebuilds: the only inputs are freshly created nodes, so there is no shared
+// structure worth preserving.
+function withGeneratedIds(node: Node): Node {
+  if (node.isText) {
+    return node;
+  }
+
+  const children: Node[] = [];
+  node.forEach((child) => children.push(withGeneratedIds(child)));
+
+  const needsId = node.type.isInGroup("bnBlock") && node.attrs.id === null;
+  return node.type.create(
+    needsId ? { ...node.attrs, id: UniqueID.options.generateID() } : node.attrs,
+    Fragment.from(children),
+    node.marks,
+  );
+}
+
 /**
  * Converts a BlockNote block to a Prosemirror node.
  */
@@ -361,8 +388,6 @@ export function blockToNode(
     schema.nodes[block.type].isInGroup("blockContent");
 
   if (isBlockContent) {
-    // Blocks with a type that matches "blockContent" group always need to be wrapped in a blockContainer
-
     const contentNode = blockOrInlineContentToContentNode(
       block,
       schema,
@@ -370,9 +395,7 @@ export function blockToNode(
     );
 
     const groupNode =
-      children.length > 0
-        ? schema.nodes["blockGroup"].createChecked({}, children)
-        : undefined;
+      children.length > 0 ? createBlockGroup(schema, children) : undefined;
 
     return schema.nodes["blockContainer"].createChecked(
       {
@@ -381,16 +404,21 @@ export function blockToNode(
       },
       groupNode ? [contentNode, groupNode] : contentNode,
     );
-  } else if (schema.nodes[block.type].isInGroup("bnBlock")) {
-    // `create` (not `createChecked`) so partial container blocks pass through;
-    // callers that mutate the doc validate via `node.check()` before inserting.
-    return schema.nodes[block.type].create(
-      {
-        id: id,
-        ...block.props,
-      },
-      children,
-    );
+  } else if (isContainerNode(schema.nodes[block.type])) {
+    const type = schema.nodes[block.type];
+    const attrs = { id: id, ...block.props };
+
+    // Fill missing children up to the configured minimum, including for an
+    // explicit empty array. Generated descendants need block IDs as well.
+    const node = type.createAndFill(attrs, children);
+    if (!node) {
+      throw new Error(
+        `Cannot create block "${block.type}": its children don't fit its \`children\` config ` +
+          `(it accepts \`${type.spec.content}\`).`,
+      );
+    }
+
+    return withGeneratedIds(node);
   } else {
     throw new Error(
       `block type ${block.type} doesn't match blockContent or bnBlock group`,
diff --git a/packages/core/src/api/nodeConversions/fragmentToBlocks.ts b/packages/core/src/api/nodeConversions/fragmentToBlocks.ts
index 19f063d8bb..101c87020a 100644
--- a/packages/core/src/api/nodeConversions/fragmentToBlocks.ts
+++ b/packages/core/src/api/nodeConversions/fragmentToBlocks.ts
@@ -1,63 +1,44 @@
-import { Fragment } from "@tiptap/pm/model";
+import { Fragment, Node } from "@tiptap/pm/model";
 import {
   BlockNoDefaults,
   BlockSchema,
   InlineContentSchema,
   StyleSchema,
 } from "../../schema/index.js";
+import { isContainerNode, isNamedOnly } from "../../schema/blocks/children.js";
 import { nodeToBlock } from "./nodeToBlock.js";
 
-/**
- * Converts all Blocks within a fragment to BlockNote blocks.
- */
 export function fragmentToBlocks<
   B extends BlockSchema,
   I extends InlineContentSchema,
   S extends StyleSchema,
 >(fragment: Fragment) {
-  // first convert selection to blocknote-style blocks, and then
-  // pass these to the exporter
   const blocks: BlockNoDefaults<B, I, S>[] = [];
-  fragment.descendants((node) => {
-    if (node.type.name === "blockContainer") {
-      if (node.firstChild?.type.name === "blockGroup") {
-        // selection started within a block group
-        // in this case the fragment starts with:
-        // <blockContainer>
-        //   <blockGroup>
-        //     <blockContainer ... />
-        //     <blockContainer ... />
-        //   </blockGroup>
-        // </blockContainer>
-        //
-        // instead of:
-        // <blockContainer>
-        //   <blockContent ... />
-        //   <blockGroup>
-        //     <blockContainer ... />
-        //     <blockContainer ... />
-        //   </blockGroup>
-        // </blockContainer>
-        //
-        // so we don't need to serialize this block, just descend into the children of the blockGroup
-        return true;
-      }
-    }
 
-    if (node.type.name === "columnList" && node.childCount === 1) {
-      // column lists with a single column should be flattened (not the entire column list has been selected)
-      node.firstChild?.forEach((child) => {
-        blocks.push(nodeToBlock(child, node));
-      });
-      return false;
-    }
+  function visit(node: Node, root: Node) {
+    const childrenConfig = node.type.spec.blockConfig?.children;
+    const incompleteBlock =
+      node.type.name === "blockContainer" &&
+      node.firstChild?.type.name === "blockGroup";
+    const flattenContainer =
+      isContainerNode(node.type) &&
+      (!childrenConfig ||
+        isNamedOnly(node.type) ||
+        node.childCount < (childrenConfig.min ?? 1));
 
-    if (node.type.isInGroup("bnBlock")) {
-      blocks.push(nodeToBlock(node, node));
-      // don't descend into children, as they're already included in the block returned by nodeToBlock
-      return false;
+    // Open selections and containers that cannot stand alone contribute
+    // their children. Complete blocks already include their descendants.
+    if (
+      incompleteBlock ||
+      flattenContainer ||
+      !node.type.isInGroup("bnBlock")
+    ) {
+      node.forEach((child) => visit(child, flattenContainer ? root : child));
+    } else {
+      blocks.push(nodeToBlock(node, root));
     }
-    return true;
-  });
+  }
+
+  fragment.forEach((node) => visit(node, node));
   return blocks;
 }
diff --git a/packages/core/src/api/nodeConversions/nodeToBlock.ts b/packages/core/src/api/nodeConversions/nodeToBlock.ts
index 004b7fd44b..ff890c09ac 100644
--- a/packages/core/src/api/nodeConversions/nodeToBlock.ts
+++ b/packages/core/src/api/nodeConversions/nodeToBlock.ts
@@ -1,5 +1,6 @@
 import { Mark, Node, Slice } from "@tiptap/pm/model";
 import type { Block } from "../../blocks/defaultBlocks.js";
+import { isContainerNode } from "../../schema/blocks/children.js";
 import UniqueID from "../../extensions/tiptap-extensions/UniqueID/UniqueID.js";
 import type {
   BlockSchema,
@@ -399,7 +400,7 @@ export function nodeToBlock<
   const styleSchema = getStyleSchema(schema) as S;
   const blockCache = getBlockCache(schema);
   if (!node.type.isInGroup("bnBlock")) {
-    throw Error("Node should be a bnBlock, but is instead: " + node.type.name);
+    throw Error("Node should be a block, but is instead: " + node.type.name);
   }
 
   const cachedBlock = blockCache?.get(node);
@@ -418,9 +419,9 @@ export function nodeToBlock<
     id = UniqueID.options.generateID();
   }
 
-  const blockSpec = blockSchema[blockInfo.blockNoteType];
+  const blockConfig = blockSchema[blockInfo.blockNoteType];
 
-  if (!blockSpec) {
+  if (!blockConfig) {
     throw Error("Block is of an unrecognized type: " + blockInfo.blockNoteType);
   }
 
@@ -429,7 +430,7 @@ export function nodeToBlock<
     ...node.attrs,
     ...(blockInfo.hasContent ? blockInfo.content.node.attrs : {}),
   })) {
-    const propSchema = blockSpec.propSchema;
+    const propSchema = blockConfig.propSchema;
 
     if (
       attr in propSchema &&
@@ -439,8 +440,6 @@ export function nodeToBlock<
     }
   }
 
-  const blockConfig = blockSchema[blockInfo.blockNoteType];
-
   const children: Block<BSchema, I, S>[] = [];
   blockInfo.children?.node.forEach((child) => {
     children.push(nodeToBlock(child, doc));
@@ -560,7 +559,9 @@ export function prosemirrorSliceToSlicedBlocks<
     blockCutAtStart: string | undefined;
     blockCutAtEnd: string | undefined;
   } {
-    if (node.type.name !== "blockGroup") {
+    // Both `blockGroup` and container nodes (columnList, column, callout,
+    // ...) hold block children directly, so both can be processed here.
+    if (node.type.name !== "blockGroup" && !isContainerNode(node.type)) {
       throw new Error("unexpected");
     }
     const blocks: Block<BSchema, I, S>[] = [];
@@ -568,37 +569,46 @@ export function prosemirrorSliceToSlicedBlocks<
     let blockCutAtEnd: string | undefined;
 
     node.forEach((blockContainer, _offset, index) => {
-      if (blockContainer.type.name !== "blockContainer") {
-        throw new Error("unexpected");
-      }
-      if (blockContainer.childCount === 0) {
-        return;
-      }
-      if (blockContainer.childCount === 0 || blockContainer.childCount > 2) {
-        throw new Error(
-          "unexpected, blockContainer.childCount: " + blockContainer.childCount,
-        );
-      }
-
       const isFirstBlock = index === 0;
       const isLastBlock = index === node.childCount - 1;
 
-      if (blockContainer.firstChild!.type.name === "blockGroup") {
-        // this is the parent where a selection starts within one of its children,
-        // e.g.:
-        // A
-        // ├── B
-        // selection starts within B, then this blockContainer is A, but we don't care about A
-        // so let's descend into B and continue processing
-        if (!isFirstBlock) {
+      const isContainer = isContainerNode(blockContainer.type);
+      if (!isContainer) {
+        if (blockContainer.type.name !== "blockContainer") {
           throw new Error("unexpected");
         }
+        if (blockContainer.childCount === 0) {
+          return;
+        }
+        if (blockContainer.childCount > 2) {
+          throw new Error(
+            "unexpected, blockContainer.childCount: " +
+              blockContainer.childCount,
+          );
+        }
+      }
+
+      const omittedParent =
+        !isContainer && blockContainer.firstChild!.type.name === "blockGroup";
+      if (omittedParent && !isFirstBlock) {
+        throw new Error("unexpected");
+      }
+
+      // Open containers and regular parents whose content was cut away both
+      // contribute their selected children, without their own wrapper.
+      if (
+        omittedParent ||
+        (isContainer &&
+          ((isFirstBlock && openStart > 0) || (isLastBlock && openEnd > 0)))
+      ) {
         const ret = processNode(
-          blockContainer.firstChild!,
-          Math.max(0, openStart - 1),
+          isContainer ? blockContainer : blockContainer.firstChild!,
+          isFirstBlock ? Math.max(0, openStart - 1) : 0,
           isLastBlock ? Math.max(0, openEnd - 1) : 0,
         );
-        blockCutAtStart = ret.blockCutAtStart;
+        if (isFirstBlock) {
+          blockCutAtStart = ret.blockCutAtStart;
+        }
         if (isLastBlock) {
           blockCutAtEnd = ret.blockCutAtEnd;
         }
@@ -606,6 +616,13 @@ export function prosemirrorSliceToSlicedBlocks<
         return;
       }
 
+      if (isContainer) {
+        blocks.push(
+          nodeToBlock<BSchema, I, S>(blockContainer, slice.content.firstChild!),
+        );
+        return;
+      }
+
       const block = nodeToBlock(blockContainer, slice.content.firstChild!);
       const childGroup =
         blockContainer.childCount > 1 ? blockContainer.child(1) : undefined;
diff --git a/packages/core/src/blocks/ListItem/CheckListItem/block.test.ts b/packages/core/src/blocks/ListItem/CheckListItem/block.test.ts
index b1da899571..9715bc503e 100644
--- a/packages/core/src/blocks/ListItem/CheckListItem/block.test.ts
+++ b/packages/core/src/blocks/ListItem/CheckListItem/block.test.ts
@@ -34,7 +34,7 @@ it("renders checkbox as enabled when editor is editable", () => {
     children: [],
   };
   const spec = editor.schema.blockSpecs.checkListItem;
-  const view = spec.implementation.render(block, editor);
+  const view = spec.implementation.render!(block, editor);
   const checkbox = getCheckboxFromView(view);
   expect(checkbox.disabled).toBe(false);
 });
@@ -55,7 +55,7 @@ it("renders checkbox as disabled when editor is not editable", () => {
     children: [],
   };
   const spec = editor.schema.blockSpecs.checkListItem;
-  const view = spec.implementation.render(block, editor);
+  const view = spec.implementation.render!(block, editor);
   const checkbox = getCheckboxFromView(view);
   expect(checkbox.disabled).toBe(true);
 });
diff --git a/packages/core/src/editor/managers/BlockManager.ts b/packages/core/src/editor/managers/BlockManager.ts
index 5b16ec0fcc..dbae8b1281 100644
--- a/packages/core/src/editor/managers/BlockManager.ts
+++ b/packages/core/src/editor/managers/BlockManager.ts
@@ -1,5 +1,5 @@
+import type { BlockPlacement } from "../../api/getBlockInfoFromPos.js";
 import { insertBlocks } from "../../api/blockManipulation/commands/insertBlocks/insertBlocks.js";
-import { BlockPlacement } from "../../api/getBlockInfoFromPos.js";
 import {
   moveBlocksDown,
   moveBlocksUp,
diff --git a/packages/core/src/editor/managers/ExtensionManager/extensions.ts b/packages/core/src/editor/managers/ExtensionManager/extensions.ts
index 853cca2493..c1626636b4 100644
--- a/packages/core/src/editor/managers/ExtensionManager/extensions.ts
+++ b/packages/core/src/editor/managers/ExtensionManager/extensions.ts
@@ -39,6 +39,7 @@ import {
   UniqueID,
 } from "../../../extensions/tiptap-extensions/index.js";
 import { BlockContainer, BlockGroup, Doc } from "../../../pm-nodes/index.js";
+import { isContainerConfig } from "../../../schema/blocks/children.js";
 import type {
   BlockNoteEditor,
   BlockNoteEditorOptions,
@@ -62,7 +63,13 @@ export function getDefaultTiptapExtensions(
 
     UniqueID.configure({
       // everything from bnBlock group (nodes that represent a BlockNote block should have an id)
-      types: ["blockContainer", "columnList", "column"],
+      types: [
+        "blockContainer",
+        // Only pure containers own their ID; titled blocks use blockContainer.
+        ...Object.values(editor.schema.blockSpecs)
+          .filter((spec) => isContainerConfig(spec.config))
+          .map((spec) => spec.config.type),
+      ],
       setIdAttribute: options.setIdAttribute,
       isWithinEditor: editor.isWithinEditor,
     }),
diff --git a/packages/core/src/exporter/Exporter.test.ts b/packages/core/src/exporter/Exporter.test.ts
index 98e7b34f1c..39f49f2ed7 100644
--- a/packages/core/src/exporter/Exporter.test.ts
+++ b/packages/core/src/exporter/Exporter.test.ts
@@ -83,7 +83,12 @@ describe("Exporter mapping typing", () => {
         ...defaultBlockSpecs,
         extraBlock: createBlockSpec(
           { content: "none", type: "extraBlock", propSchema: {} },
-          {} as any,
+          {
+            render: () => {
+              const dom = document.createElement("div");
+              return { dom, contentDOM: dom };
+            },
+          } as any,
         )(),
       },
     });
@@ -184,3 +189,31 @@ describe("Exporter missing mappings", () => {
     ).toThrow('missing a style mapping for style "bold"');
   });
 });
+
+describe("Exporter block types outside its schema", () => {
+  it("treats a childless block of an unknown type as a regular block", () => {
+    // Block packages (math, diagram, ...) commonly supply only a mapping,
+    // which reads the block's JSON - their specs need not be in the schema.
+    expect(
+      new EmptyMappingsExporter().isContainerBlock({
+        type: "mathBlock",
+        children: [],
+      }),
+    ).toBe(false);
+  });
+
+  it("throws when a block of an unknown type has children", () => {
+    // Ambiguous: without the spec there is no way to tell whether the
+    // mapping places these children itself (container) or the exporter
+    // appends them (regular block), and guessing puts them in the wrong
+    // place silently.
+    expect(() =>
+      new EmptyMappingsExporter().isContainerBlock({
+        type: "columnList",
+        children: [{ type: "column" }],
+      }),
+    ).toThrow(
+      'Exporter has no block spec for block type "columnList", and blocks of that type in this document have children',
+    );
+  });
+});
diff --git a/packages/core/src/exporter/Exporter.ts b/packages/core/src/exporter/Exporter.ts
index 6ca0efa222..babd4b1cc6 100644
--- a/packages/core/src/exporter/Exporter.ts
+++ b/packages/core/src/exporter/Exporter.ts
@@ -3,7 +3,7 @@ import { COLORS_DEFAULT } from "../editor/defaultColors.js";
 import type { Dictionary } from "../i18n/dictionary.js";
 import { en } from "../i18n/locales/index.js";
 import {
-  BlockFromConfig,
+  BlockNoDefaults,
   BlockSchema,
   InlineContent,
   InlineContentSchema,
@@ -61,7 +61,7 @@ export abstract class Exporter<
   TS,
 > {
   public constructor(
-    _schema: BlockNoteSchema<B, I, S>, // only used for type inference
+    protected readonly schema: BlockNoteSchema<B, I, S>,
     protected readonly mappings: {
       blockMapping: BlockMapping<B, I, S, RB, RI>;
       inlineContentMapping: InlineContentMapping<I, S, RI, TS>;
@@ -70,6 +70,20 @@ export abstract class Exporter<
     public readonly options: ExporterOptions,
   ) {}
 
+  /** Container mappings place their own children; regular mappings do not. */
+  public isContainerBlock(block: {
+    type: string;
+    children?: unknown[];
+  }): boolean {
+    const spec = this.schema.blockSpecs[block.type];
+    if (!spec && block.children?.length) {
+      throw new Error(
+        `Exporter has no block spec for block type "${block.type}", and blocks of that type in this document have children. Add its spec to the exporter schema so it can determine who renders the children.`,
+      );
+    }
+    return spec?.config.children !== undefined;
+  }
+
   /**
    * The strings this exporter renders into the produced document - the
    * `exporter` section of the configured dictionary (the `dictionary`
@@ -139,7 +153,7 @@ export abstract class Exporter<
   public abstract transformStyledText(styledText: StyledText<S>): TS;
 
   public async mapBlock(
-    block: BlockFromConfig<B[keyof B], I, S>,
+    block: BlockNoDefaults<B, I, S>,
     nestingLevel: number,
     numberedListIndex: number,
     children?: Array<Awaited<RB>>,
@@ -147,7 +161,9 @@ export abstract class Exporter<
     const mapping = this.mappings.blockMapping[block.type];
     if (!mapping) {
       throw new Error(
-        `Exporter is missing a block mapping for block type "${block.type}". If this block comes from a separate package, spread that package's exporter mappings into your blockMapping.`,
+        this.isContainerBlock(block)
+          ? `No mapping found for container block type "${block.type}". Container blocks require an explicit block mapping that places their children.`
+          : `Exporter is missing a block mapping for block type "${block.type}". If this block comes from a separate package, spread that package's exporter mappings into your blockMapping.`,
       );
     }
     return mapping(block, this, nestingLevel, numberedListIndex, children);
diff --git a/packages/core/src/extensions/SideMenu/SideMenu.ts b/packages/core/src/extensions/SideMenu/SideMenu.ts
index fddd2712e9..1300fa2112 100644
--- a/packages/core/src/extensions/SideMenu/SideMenu.ts
+++ b/packages/core/src/extensions/SideMenu/SideMenu.ts
@@ -20,8 +20,16 @@ import {
   InlineContentSchema,
   StyleSchema,
 } from "../../schema/index.js";
-import { getDraggableBlockFromElement } from "../getDraggableBlockFromElement.js";
+import {
+  CONTAINER_SELECTOR,
+  getBlockFromElement,
+  getDraggableBlockFromElement,
+} from "../blockDOM.js";
 import { dragStart, unsetDragImage } from "./dragging.js";
+import {
+  getNestedBlockAtCursor,
+  getDirectChildBlocks,
+} from "./sideMenuContainerGeometry.js";
 
 export type SideMenuState<
   BSchema extends BlockSchema,
@@ -37,7 +45,6 @@ const DISTANCE_TO_CONSIDER_EDITOR_BOUNDS = 250;
 function getBlockFromCoords(
   view: EditorView,
   coords: { left: number; top: number },
-  adjustForColumns = true,
 ) {
   const elements = view.root.elementsFromPoint(coords.left, coords.top);
 
@@ -46,21 +53,15 @@ function getBlockFromCoords(
       // probably a ui overlay like formatting toolbar etc
       continue;
     }
-    if (adjustForColumns) {
-      const column = element.closest("[data-node-type=columnList]");
-      if (column) {
-        return getBlockFromCoords(
-          view,
-          {
-            // TODO can we do better than this?
-            left: coords.left + 50, // bit hacky, but if we're inside a column, offset x position to right to account for the width of sidemenu itself
-            top: coords.top,
-          },
-          false,
-        );
-      }
-    }
-    return getDraggableBlockFromElement(element, view);
+    const block = getBlockFromElement(element, view);
+    return block
+      ? {
+          ...block,
+          // Controls in a container's chrome belong to that container, even
+          // when they share a row with one of its child blocks.
+          isControl: !!element.closest('[contenteditable="false"]'),
+        }
+      : undefined;
   }
   return undefined;
 }
@@ -71,6 +72,7 @@ function getBlockFromMousePos(
     y: number;
   },
   view: EditorView,
+  isDraggable: (type: string) => boolean,
 ): { node: HTMLElement; id: string } | undefined {
   // Editor itself may have padding or other styling which affects
   // size/position, so we get the boundingRect of the first child (i.e. the
@@ -101,6 +103,10 @@ function getBlockFromMousePos(
     return undefined;
   }
 
+  if (referenceBlock.isControl) {
+    return getDraggableBlockFromElement(referenceBlock.node, view, isDraggable);
+  }
+
   /**
    * Because blocks may be nested, we need to check the right edge of the parent block:
    * ```
@@ -109,17 +115,26 @@ function getBlockFromMousePos(
    * ```
    * Hovering at position x (left edge of BlockB) would return BlockA.
    * Instead, we check at position y (right edge of BlockA) to correctly identify BlockB.
+   * `elementsFromPoint` returns the deepest element at a point, so this single
+   * probe descends through any depth of regular nesting.
+   *
+   * For a container block, the probe is
+   * aimed at the innermost child under the cursor instead of the container
+   * itself. The container's own padding can exceed the probe inset, which
+   * would keep resolving the container even though the cursor is aligned with
+   * one of its children (making the child's menu jump away as the cursor
+   * moves towards it).
    */
-  const referenceBlocksBoundingBox =
-    referenceBlock.node.getBoundingClientRect();
-  return getBlockFromCoords(
-    view,
-    {
-      left: referenceBlocksBoundingBox.right - 10,
-      top: mousePos.y,
-    },
-    false,
-  );
+  const probeTarget = getNestedBlockAtCursor(referenceBlock.node, mousePos);
+  const target = getBlockFromCoords(view, {
+    left: probeTarget.getBoundingClientRect().right - 10,
+    top: mousePos.y,
+  });
+  // Resolve layout before applying drag policy: columns have no handle, but
+  // their children do, and their gutter still needs to resolve those children.
+  return target
+    ? getDraggableBlockFromElement(target.node, view, isDraggable)
+    : undefined;
 }
 
 /**
@@ -135,8 +150,6 @@ export class SideMenuView<
 
   private mousePos: { x: number; y: number } | undefined;
 
-  private hoveredBlock: HTMLElement | undefined;
-
   public menuFrozen = false;
 
   public isDragOrigin = false;
@@ -214,7 +227,11 @@ export class SideMenuView<
       return;
     }
 
-    const block = getBlockFromMousePos(this.mousePos, this.pmView);
+    const blockSpecs = this.editor.schema.blockSpecs;
+    function isDraggable(type: string) {
+      return blockSpecs[type].implementation.meta?.draggable !== false;
+    }
+    const block = getBlockFromMousePos(this.mousePos, this.pmView, isDraggable);
 
     // Closes the menu if the mouse cursor is beyond the editor vertically.
     if (!block || !this.editor.isEditable) {
@@ -227,51 +244,48 @@ export class SideMenuView<
     }
 
     // Doesn't update if the menu is already open and the mouse cursor is still hovering the same block.
-    if (
-      this.state?.show &&
-      this.hoveredBlock?.hasAttribute("data-id") &&
-      this.hoveredBlock?.getAttribute("data-id") === block.id
-    ) {
+    if (this.state?.show && this.state.block.id === block.id) {
       return;
     }
 
-    this.hoveredBlock = block.node;
-
-    // Shows or updates elements.
-    if (this.editor.isEditable) {
-      const blockContentBoundingBox = block.node.getBoundingClientRect();
-      const column = block.node.closest("[data-node-type=column]");
-      const sideMenuBlock = this.editor.getBlock(
-        this.hoveredBlock!.getAttribute("data-id")!,
-      );
-      if (!sideMenuBlock) {
-        if (this.state?.show) {
-          this.state.show = false;
-          this.hoveredBlock = undefined;
-          this.emitUpdate(this.state);
-        }
-        return;
+    const blockContentBoundingBox = block.node.getBoundingClientRect();
+    // The closest container ancestor (a column, callout, ...), excluding
+    // the hovered block itself, which may be a draggable container. Blocks
+    // inside a container anchor the side menu to the container's block
+    // area rather than the editor's left edge, which would put the menu
+    // over unrelated content (or off-screen inside columns).
+    const container = block.node.parentElement?.closest(CONTAINER_SELECTOR);
+    const sideMenuBlock = this.editor.getBlock(block.id);
+    if (!sideMenuBlock) {
+      if (this.state?.show) {
+        this.state.show = false;
+        this.emitUpdate(this.state);
       }
-      this.state = {
-        show: true,
-        referencePos: new DOMRect(
-          column
-            ? // We take the first child as column elements have some default
-              // padding. This is a little weird since this child element will
-              // be the first block, but since it's always non-nested and we
-              // only take the x coordinate, it's ok.
-              column.firstElementChild!.getBoundingClientRect().x
-            : (
-                this.pmView.dom.firstChild as HTMLElement
-              ).getBoundingClientRect().x,
-          blockContentBoundingBox.y,
-          blockContentBoundingBox.width,
-          blockContentBoundingBox.height,
-        ),
-        block: sideMenuBlock,
-      };
-      this.updateState(this.state);
+      return;
     }
+    this.state = {
+      show: true,
+      referencePos: new DOMRect(
+        container
+          ? // We anchor to the container's first child block (rather than
+            // the container itself, which may have padding or its own
+            // chrome around the block area). This is a little weird since
+            // this element is the first block, but since it's always
+            // non-nested and we only take the x coordinate, it's ok.
+            (
+              getDirectChildBlocks(container)[0] ??
+              container.firstElementChild ??
+              container
+            ).getBoundingClientRect().x
+          : (this.pmView.dom.firstChild as HTMLElement).getBoundingClientRect()
+              .x,
+        blockContentBoundingBox.y,
+        blockContentBoundingBox.width,
+        blockContentBoundingBox.height,
+      ),
+      block: sideMenuBlock,
+    };
+    this.updateState(this.state);
   };
 
   /**
diff --git a/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.browser.test.ts b/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.browser.test.ts
new file mode 100644
index 0000000000..7d7ab91d09
--- /dev/null
+++ b/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.browser.test.ts
@@ -0,0 +1,169 @@
+import { afterEach, describe, expect, it } from "vite-plus/test";
+
+import {
+  getNestedBlockAtCursor,
+  getDirectChildBlocks,
+} from "./sideMenuContainerGeometry.js";
+
+// Exercise container hit testing with real layout, including nested columns.
+
+/** Attaches a tree to the document so the browser actually lays it out. */
+function mount<T extends HTMLElement>(el: T): T {
+  document.body.appendChild(el);
+  mounted.push(el);
+  return el;
+}
+
+let mounted: HTMLElement[] = [];
+
+afterEach(() => {
+  mounted.forEach((el) => el.remove());
+  mounted = [];
+});
+
+function el(nodeType: string): HTMLElement {
+  const node = document.createElement("div");
+  node.setAttribute("data-node-type", nodeType);
+  node.setAttribute("data-id", crypto.randomUUID());
+  return node;
+}
+
+/** The `blockOuter > blockContainer` chrome BlockNote renders around every
+ * regular block, with real text in it so it has a real height. */
+function regularChild(text = "block"): {
+  outer: HTMLElement;
+  blockContainer: HTMLElement;
+} {
+  const outer = el("blockOuter");
+  const blockContainer = el("blockContainer");
+  blockContainer.textContent = text;
+  outer.append(blockContainer);
+  return { outer, blockContainer };
+}
+
+/**
+ * A column list laid out the way the real one is: a flex row of two columns,
+ * each holding one block. Nothing declares "horizontal". The browser puts the
+ * columns side by side and the module has to notice.
+ */
+function buildColumnList() {
+  const columnList = el("columnList");
+  columnList.style.display = "flex";
+  columnList.style.width = "400px";
+
+  const columnA = el("column");
+  const columnB = el("column");
+  for (const column of [columnA, columnB]) {
+    column.style.flex = "1";
+  }
+
+  const childA = regularChild("A");
+  const childB = regularChild("B");
+  columnA.append(childA.outer);
+  columnB.append(childB.outer);
+  columnList.append(columnA, columnB);
+  mount(columnList);
+
+  return { columnList, columnA, columnB, childA, childB };
+}
+
+/** A callout: an ordinary block-flow container, so its children stack. */
+function buildVerticalContainer() {
+  const callout = el("callout");
+  callout.style.width = "400px";
+  const first = regularChild("first");
+  const second = regularChild("second");
+  callout.append(first.outer, second.outer);
+  mount(callout);
+
+  return { callout, first, second };
+}
+
+describe("getDirectChildBlocks", () => {
+  it("returns direct child blocks, skipping nested grandchildren", () => {
+    const { columnList, columnA, columnB } = buildColumnList();
+
+    // The blocks inside each column must not come back as the list's own
+    // children. The `closest` check stops the walk one level down.
+    expect(getDirectChildBlocks(columnList)).toEqual([columnA, columnB]);
+  });
+
+  it("sees through blockOuter wrappers to the blockContainer child", () => {
+    const { columnA, childA } = buildColumnList();
+
+    // The column's own direct child is the wrapped blockContainer, not the
+    // blockOuter chrome (which isn't a block in the selector's sense).
+    expect(getDirectChildBlocks(columnA)).toEqual([childA.blockContainer]);
+  });
+});
+
+describe("getNestedBlockAtCursor", () => {
+  it("keeps a regular block as the probe target", () => {
+    const { childA } = buildColumnList();
+    expect(
+      getNestedBlockAtCursor(childA.blockContainer, { x: 10, y: 10 }),
+    ).toBe(childA.blockContainer);
+  });
+
+  it("descends into the hovered column's block", () => {
+    const { columnList, childA, childB } = buildColumnList();
+    for (const child of [childA, childB]) {
+      const rect = child.blockContainer.getBoundingClientRect();
+      expect(
+        getNestedBlockAtCursor(columnList, {
+          x: rect.left + rect.width / 2,
+          y: rect.top + rect.height / 2,
+        }),
+      ).toBe(child.blockContainer);
+    }
+  });
+
+  it("finds a stacked child from the container gutter", () => {
+    const { callout, second } = buildVerticalContainer();
+    const rect = second.blockContainer.getBoundingClientRect();
+    expect(
+      getNestedBlockAtCursor(callout, {
+        x: rect.left - 20,
+        y: rect.top + rect.height / 2,
+      }),
+    ).toBe(second.blockContainer);
+  });
+
+  it("finds a framed block's child when moving into the side-menu gutter", () => {
+    const parent = regularChild("");
+    const frame = document.createElement("div");
+    frame.style.padding = "12px 16px";
+    const title = document.createElement("div");
+    title.textContent = "Callout title";
+    const child = regularChild("Callout body");
+    frame.append(title, child.outer);
+    parent.blockContainer.append(frame);
+    parent.outer.style.width = "400px";
+    mount(parent.outer);
+
+    const rect = child.blockContainer.getBoundingClientRect();
+    for (const x of [rect.left + 20, rect.left - 12, rect.left - 40]) {
+      expect(
+        getNestedBlockAtCursor(parent.blockContainer, {
+          x,
+          y: rect.top + rect.height / 2,
+        }),
+      ).toBe(child.blockContainer);
+    }
+    const titleRect = title.getBoundingClientRect();
+    expect(
+      getNestedBlockAtCursor(parent.blockContainer, {
+        x: titleRect.left,
+        y: titleRect.top + titleRect.height / 2,
+      }),
+    ).toBe(parent.blockContainer);
+  });
+
+  it("keeps the container when the cursor misses its children", () => {
+    const { callout } = buildVerticalContainer();
+    const rect = callout.getBoundingClientRect();
+    expect(
+      getNestedBlockAtCursor(callout, { x: rect.left, y: rect.bottom + 10 }),
+    ).toBe(callout);
+  });
+});
diff --git a/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.test.ts b/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.test.ts
new file mode 100644
index 0000000000..926271b5a1
--- /dev/null
+++ b/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import {
+  rectIndexAtCursor,
+  type BlockRect,
+} from "./sideMenuContainerGeometry.js";
+
+// Hit testing works for both side-by-side and stacked children.
+
+const rect = (
+  top: number,
+  bottom: number,
+  left: number,
+  right: number,
+): BlockRect => ({ top, bottom, left, right });
+
+// Two columns of a column list: same vertical band, adjacent horizontally.
+const SIDE_BY_SIDE = [rect(0, 100, 0, 100), rect(0, 100, 100, 200)];
+// Two blocks of a callout: same horizontal band, stacked vertically.
+const STACKED = [rect(0, 40, 0, 200), rect(50, 90, 0, 200)];
+
+describe("rectIndexAtCursor", () => {
+  it("returns the rect whose x range contains the cursor (side-by-side)", () => {
+    // Both rects share the y range, so only x distinguishes them. The
+    // vertical-only fallback recorded for the first must not win over an x
+    // match found later in the list; otherwise hovering the second column of
+    // a row would resolve to its neighbour.
+    expect(rectIndexAtCursor(SIDE_BY_SIDE, { x: 150, y: 50 })).toBe(1);
+    expect(rectIndexAtCursor(SIDE_BY_SIDE, { x: 10, y: 50 })).toBe(0);
+  });
+
+  it("falls back to the first vertical match when x is in the gutter", () => {
+    // The cursor's y is in the first block's band but its x is left of it (the
+    // side-menu gutter). The first vertical match wins.
+    expect(rectIndexAtCursor(STACKED, { x: -20, y: 20 })).toBe(0);
+  });
+
+  it("returns undefined when the cursor misses every rect vertically", () => {
+    expect(rectIndexAtCursor(STACKED, { x: 10, y: 999 })).toBeUndefined();
+    expect(rectIndexAtCursor(STACKED, { x: 10, y: -999 })).toBeUndefined();
+    expect(rectIndexAtCursor([], { x: 10, y: 10 })).toBeUndefined();
+  });
+
+  it("includes the rect edges", () => {
+    const single = [rect(0, 40, 0, 200)];
+    expect(rectIndexAtCursor(single, { x: 0, y: 0 })).toBe(0);
+    expect(rectIndexAtCursor(single, { x: 200, y: 40 })).toBe(0);
+  });
+});
diff --git a/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.ts b/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.ts
new file mode 100644
index 0000000000..dc4ae46c40
--- /dev/null
+++ b/packages/core/src/extensions/SideMenu/sideMenuContainerGeometry.ts
@@ -0,0 +1,56 @@
+import { BLOCK_SELECTOR } from "../blockDOM.js";
+
+export function getDirectChildBlocks(container: Element): Element[] {
+  const children: Element[] = [];
+  for (const child of container.querySelectorAll(BLOCK_SELECTOR)) {
+    if (child.parentElement?.closest(BLOCK_SELECTOR) === container) {
+      children.push(child);
+    }
+  }
+  return children;
+}
+
+export type BlockRect = {
+  top: number;
+  bottom: number;
+  left: number;
+  right: number;
+};
+
+// X-match wins over y-only match (disambiguates side-by-side children).
+export function rectIndexAtCursor(
+  rects: BlockRect[],
+  mousePos: { x: number; y: number },
+): number | undefined {
+  let verticalMatch: number | undefined = undefined;
+  for (let i = 0; i < rects.length; i++) {
+    const rect = rects[i];
+    if (mousePos.y < rect.top || mousePos.y > rect.bottom) {
+      continue;
+    }
+    if (mousePos.x >= rect.left && mousePos.x <= rect.right) {
+      return i;
+    }
+    verticalMatch = verticalMatch ?? i;
+  }
+  return verticalMatch;
+}
+
+// Descend through child blocks, including regular blocks with padded frames.
+export function getNestedBlockAtCursor(
+  element: Element,
+  mousePos: { x: number; y: number },
+): Element {
+  while (element.matches(BLOCK_SELECTOR)) {
+    const children = getDirectChildBlocks(element);
+    const index = rectIndexAtCursor(
+      children.map((child) => child.getBoundingClientRect()),
+      mousePos,
+    );
+    if (index === undefined) {
+      break;
+    }
+    element = children[index];
+  }
+  return element;
+}
diff --git a/packages/core/src/extensions/TableHandles/TableHandles.ts b/packages/core/src/extensions/TableHandles/TableHandles.ts
index bb396fbdd7..5abdbfab8d 100644
--- a/packages/core/src/extensions/TableHandles/TableHandles.ts
+++ b/packages/core/src/extensions/TableHandles/TableHandles.ts
@@ -42,7 +42,7 @@ import {
   BlockFromConfigNoChildren,
   BlockSchemaWithBlock,
 } from "../../schema/index.js";
-import { getDraggableBlockFromElement } from "../getDraggableBlockFromElement.js";
+import { getBlockFromElement } from "../blockDOM.js";
 
 let dragImageElement: HTMLElement | undefined;
 
@@ -246,8 +246,9 @@ export class TableHandlesView implements PluginView {
 
     const tableRect = target.tbodyNode.getBoundingClientRect();
 
-    const blockEl = getDraggableBlockFromElement(target.domNode, this.pmView);
+    const blockEl = getBlockFromElement(target.domNode, this.pmView);
     if (!blockEl) {
+      this.hideHandles();
       return;
     }
 
@@ -256,10 +257,7 @@ export class TableHandlesView implements PluginView {
       doc: tr.doc,
     }));
 
-    // The hovered cell may belong to a document other than this editor's, as a
-    // custom block can embed a nested editor which itself contains a table. The
-    // nested editor's DOM is inside this view's DOM, so its cells still reach
-    // this handler, but its block IDs are unknown here.
+    // The DOM target must still correspond to a block in this document.
     if (!pmNodeInfo) {
       this.hideHandles();
       return;
diff --git a/packages/core/src/extensions/blockDOM.test.ts b/packages/core/src/extensions/blockDOM.test.ts
new file mode 100644
index 0000000000..27f6fa1de6
--- /dev/null
+++ b/packages/core/src/extensions/blockDOM.test.ts
@@ -0,0 +1,139 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import {
+  getBlockFromElement,
+  getDraggableBlockFromElement,
+} from "./blockDOM.js";
+
+function isDraggable(type: string) {
+  return type !== "lockedBlock" && type !== "column";
+}
+
+// Identity and ownership need detached DOM trees, not browser layout.
+
+/** Builds the `blockOuter > blockContainer > blockContent` chrome BlockNote
+ * renders around every regular block. */
+function regularBlock(
+  id: string,
+  contentType: string,
+): { outer: HTMLElement; blockContainer: HTMLElement; content: HTMLElement } {
+  const outer = document.createElement("div");
+  outer.setAttribute("data-node-type", "blockOuter");
+  outer.setAttribute("data-id", id);
+
+  const blockContainer = document.createElement("div");
+  blockContainer.setAttribute("data-node-type", "blockContainer");
+  blockContainer.setAttribute("data-id", id);
+
+  const content = document.createElement("div");
+  content.setAttribute("data-content-type", contentType);
+
+  blockContainer.append(content);
+  outer.append(blockContainer);
+  return { outer, blockContainer, content };
+}
+
+/** Nests `child` under `parent` in a `blockGroup`, as list nesting does. */
+function nest(parent: HTMLElement, child: HTMLElement) {
+  const group = document.createElement("div");
+  group.setAttribute("data-node-type", "blockGroup");
+  group.append(child);
+  parent.append(group);
+}
+
+function viewWith(root: HTMLElement) {
+  const dom = document.createElement("div");
+  dom.append(root);
+  return { dom };
+}
+
+describe("getDraggableBlockFromElement", () => {
+  it("returns the block container for a regular block", () => {
+    const { outer, blockContainer, content } = regularBlock("a", "paragraph");
+
+    expect(
+      getDraggableBlockFromElement(content, viewWith(outer), isDraggable),
+    ).toEqual({
+      node: blockContainer,
+      id: "a",
+      type: "paragraph",
+    });
+  });
+
+  it("resolves a locked block's identity but gives it no drag handle", () => {
+    const { outer, content, blockContainer } = regularBlock("a", "lockedBlock");
+
+    expect(getBlockFromElement(content, viewWith(outer))).toEqual({
+      node: blockContainer,
+      id: "a",
+      type: "lockedBlock",
+    });
+
+    expect(
+      getDraggableBlockFromElement(content, viewWith(outer), isDraggable),
+    ).toBeUndefined();
+  });
+
+  it("falls through to the nearest draggable ancestor", () => {
+    const parent = regularBlock("parent", "paragraph");
+    const child = regularBlock("child", "lockedBlock");
+    nest(parent.blockContainer, child.outer);
+
+    // Dragging from inside the locked child should hand back the parent's
+    // handle rather than no handle at all.
+    expect(
+      getDraggableBlockFromElement(
+        child.content,
+        viewWith(parent.outer),
+        isDraggable,
+      ),
+    ).toEqual({ node: parent.blockContainer, id: "parent", type: "paragraph" });
+  });
+
+  it("reads the block's own content type, not a nested block's", () => {
+    const parent = regularBlock("parent", "lockedBlock");
+    const child = regularBlock("child", "paragraph");
+    nest(parent.blockContainer, child.outer);
+
+    // `parent`'s own content element precedes the nested `blockGroup`, so the
+    // first `[data-content-type]` match inside it must be "lockedBlock".
+    expect(
+      getDraggableBlockFromElement(
+        parent.content,
+        viewWith(parent.outer),
+        isDraggable,
+      ),
+    ).toBeUndefined();
+  });
+
+  it("returns a container block only when its type is draggable", () => {
+    const column = document.createElement("div");
+    column.setAttribute("data-node-type", "column");
+    column.setAttribute("data-id", "col");
+
+    expect(
+      getDraggableBlockFromElement(column, viewWith(column), isDraggable),
+    ).toBeUndefined();
+
+    expect(
+      getDraggableBlockFromElement(column, viewWith(column), () => true),
+    ).toEqual({ node: column, id: "col", type: "column" });
+  });
+});
+
+it("does not resolve blocks outside this editor", () => {
+  const { content } = regularBlock("outside", "paragraph");
+  expect(
+    getBlockFromElement(content, viewWith(document.createElement("div"))),
+  ).toBeUndefined();
+});
+
+it("does not resolve a block owned by an embedded editor", () => {
+  const nested = regularBlock("nested", "paragraph");
+  const nestedView = viewWith(nested.outer);
+  nestedView.dom.className = "bn-editor";
+  const outerView = viewWith(nestedView.dom);
+  outerView.dom.className = "bn-editor";
+  expect(getBlockFromElement(nested.content, outerView)).toBeUndefined();
+  expect(getBlockFromElement(nested.content, nestedView)?.id).toBe("nested");
+});
diff --git a/packages/core/src/extensions/blockDOM.ts b/packages/core/src/extensions/blockDOM.ts
new file mode 100644
index 0000000000..bef930bda1
--- /dev/null
+++ b/packages/core/src/extensions/blockDOM.ts
@@ -0,0 +1,69 @@
+import type { EditorView } from "prosemirror-view";
+
+// UniqueID and the block renderers put data-id on every block root.
+// Ordinary blocks also copy it to blockOuter, which is only rendering chrome.
+export const BLOCK_SELECTOR =
+  '[data-node-type][data-id]:not([data-node-type="blockOuter"])';
+export const CONTAINER_SELECTOR = `${BLOCK_SELECTOR}:not([data-node-type="blockContainer"])`;
+
+/** Resolves block identity independently of whether it gets a drag handle. */
+export function getBlockFromElement(
+  element: Element,
+  view: Pick<EditorView, "dom">,
+): { node: HTMLElement; id: string; type: string } | undefined {
+  if (!view.dom.contains(element)) {
+    return undefined;
+  }
+  const node = element.closest(BLOCK_SELECTOR);
+  if (!node || node === view.dom || !view.dom.contains(node)) {
+    return undefined;
+  }
+
+  // Embedded editors own their blocks, even though their DOM is inside ours.
+  const owner = element.closest(".bn-editor");
+  if (owner && owner !== view.dom) {
+    return undefined;
+  }
+
+  const id = node.getAttribute("data-id");
+  const nodeType = node.getAttribute("data-node-type");
+  // The regular block's own content precedes its nested blockGroup, even
+  // when a renderFrame adds chrome around it.
+  const type =
+    nodeType === "blockContainer"
+      ? node
+          .querySelector("[data-content-type]")
+          ?.getAttribute("data-content-type")
+      : nodeType;
+  // A matched block root must expose its own identity. Validate this at the
+  // DOM boundary so callers never need casts or non-null assertions.
+  const HTMLElementClass = node.ownerDocument.defaultView?.HTMLElement;
+  if (
+    !HTMLElementClass ||
+    !(node instanceof HTMLElementClass) ||
+    !id ||
+    !type
+  ) {
+    throw new Error(
+      "Block root is missing its HTML element, ID, or block type.",
+    );
+  }
+  return { node, id, type };
+}
+
+/** A block that opts out hands its drag handle to the nearest eligible ancestor. */
+export function getDraggableBlockFromElement(
+  element: Element,
+  view: Pick<EditorView, "dom">,
+  isDraggable: (type: string) => boolean,
+) {
+  let block = getBlockFromElement(element, view);
+  while (block) {
+    if (isDraggable(block.type)) {
+      return block;
+    }
+    const parent = block.node.parentElement;
+    block = parent ? getBlockFromElement(parent, view) : undefined;
+  }
+  return undefined;
+}
diff --git a/packages/core/src/extensions/getDraggableBlockFromElement.ts b/packages/core/src/extensions/getDraggableBlockFromElement.ts
deleted file mode 100644
index abc6bd2906..0000000000
--- a/packages/core/src/extensions/getDraggableBlockFromElement.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-import { EditorView } from "prosemirror-view";
-
-export function getDraggableBlockFromElement(
-  element: Element,
-  view: EditorView,
-) {
-  while (
-    element &&
-    element.parentElement &&
-    element.parentElement !== view.dom &&
-    element.getAttribute?.("data-node-type") !== "blockContainer"
-  ) {
-    element = element.parentElement;
-  }
-  if (element.getAttribute?.("data-node-type") !== "blockContainer") {
-    return undefined;
-  }
-  return { node: element as HTMLElement, id: element.getAttribute("data-id")! };
-}
diff --git a/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.test.ts b/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.test.ts
index 2f3464a2db..5e4723c847 100644
--- a/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.test.ts
+++ b/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.test.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it } from "vite-plus/test";
 
 import { BlockNoteSchema } from "../../../blocks/BlockNoteSchema.js";
-import { defaultBlockSpecs } from "../../../blocks/defaultBlocks.js";
+import {
+  type PartialBlock,
+  defaultBlockSpecs,
+} from "../../../blocks/defaultBlocks.js";
 import { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
 import { createBlockSpec } from "../../../schema/index.js";
 
@@ -548,3 +551,42 @@ describe("KeyboardShortcutsExtension hardBreakShortcut", () => {
     editor._tiptapEditor.destroy();
   });
 });
+
+describe("Delete preserves the caret before appended text", () => {
+  function paragraph(id: string, children: PartialBlock[] = []): PartialBlock {
+    return { id, type: "paragraph", content: id, children };
+  }
+
+  it.each([
+    {
+      name: "sole child",
+      initialContent: [paragraph("selected", [paragraph("removed")])],
+    },
+    {
+      name: "following shallower block",
+      initialContent: [
+        paragraph("parent", [paragraph("selected")]),
+        paragraph("removed"),
+      ],
+    },
+  ])("$name", ({ initialContent }) => {
+    const editor = BlockNoteEditor.create({ initialContent });
+    editor.mount(document.createElement("div"));
+    editor.setTextCursorPosition("selected", "end");
+
+    const view = editor.prosemirrorView;
+    const event = new KeyboardEvent("keydown", {
+      key: "Delete",
+      code: "Delete",
+      keyCode: 46,
+    });
+    view.someProp("handleKeyDown", (handler) => handler(view, event));
+
+    expect(editor.getBlock("removed")).toBeUndefined();
+    expect(editor.getTextCursorPosition().block.id).toBe("selected");
+    expect(editor.prosemirrorState.selection.$from.parentOffset).toBe(
+      "selected".length,
+    );
+    editor._tiptapEditor.destroy();
+  });
+});
diff --git a/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.ts b/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.ts
index 20e5941fb6..56f2c043bd 100644
--- a/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.ts
+++ b/packages/core/src/extensions/tiptap-extensions/KeyboardShortcuts/KeyboardShortcutsExtension.ts
@@ -1,29 +1,79 @@
-import { Extension } from "@tiptap/core";
-import { Fragment, Node } from "prosemirror-model";
-import { TextSelection } from "prosemirror-state";
+import { type ChainedCommands, Extension } from "@tiptap/core";
+import { Fragment } from "prosemirror-model";
+import { TextSelection, Transaction } from "prosemirror-state";
 
-import { mergeBlocksCommand } from "../../../api/blockManipulation/commands/mergeBlocks/mergeBlocks.js";
+import {
+  mergeBlocksCommand,
+  getMergeContent,
+} from "../../../api/blockManipulation/commands/mergeBlocks/mergeBlocks.js";
 import {
   liftItem,
   nestBlock,
   unnestBlock,
 } from "../../../api/blockManipulation/commands/nestBlock/nestBlock.js";
-import { fixColumnList } from "../../../api/blockManipulation/commands/replaceBlocks/util/fixColumnList.js";
+import { fixContainersById } from "../../../api/blockManipulation/containers/fixContainer.js";
+import { isContainerNode } from "../../../schema/blocks/children.js";
 import { splitBlockCommand } from "../../../api/blockManipulation/commands/splitBlock/splitBlock.js";
 import { updateBlockCommand } from "../../../api/blockManipulation/commands/updateBlock/updateBlock.js";
 import {
+  type BlockInfo,
+  ascendToInsertablePos,
+  getInsertionPos,
+  getAncestorContainers,
+  getFirstLeafBlock,
   getBlockInfoAt,
+  getBlockInfoFromNode,
   getBlockInfoFromSelection,
   getLastDescendantBlockInfo,
   getNextBlockInfo,
   getParentBlockInfo,
   getPrevBlockInfo,
-  tableContentCaretPos,
+  blockEdgeSelection,
 } from "../../../api/getBlockInfoFromPos.js";
 import { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
 import { FilePanelExtension } from "../../FilePanel/FilePanel.js";
 import { FormattingToolbarExtension } from "../../FormattingToolbar/FormattingToolbar.js";
 
+// Move a block across a container boundary, repair its former ancestors, and
+// map the caret through any repairs that change the insertion position.
+function moveBlockOutAndPlaceCaret(
+  tr: Transaction,
+  block: BlockInfo["block"],
+  insertAt: number,
+) {
+  const containersToFix = getAncestorContainers(tr.doc, block.beforePos);
+  tr.delete(block.beforePos, block.afterPos);
+  const insertionPos = tr.mapping.map(insertAt);
+  tr.insert(insertionPos, block.node);
+  const stepsBeforeFix = tr.steps.length;
+  fixContainersById(tr, containersToFix);
+  tr.setSelection(
+    TextSelection.near(
+      tr.doc.resolve(tr.mapping.slice(stepsBeforeFix).map(insertionPos) + 1),
+    ),
+  );
+}
+
+// Delete a following block, retaining its children and any compatible text.
+// A sole child also removes its child group instead of leaving an empty body.
+function deleteBlockAndAppendContent(
+  chain: ChainedCommands,
+  current: Extract<BlockInfo, { hasContent: true }>,
+  next: Extract<BlockInfo, { hasContent: true }>,
+  remove: Pick<BlockInfo["block"], "beforePos" | "afterPos"> = next.block,
+) {
+  return chain
+    .insertContentAt(
+      next.block.afterPos,
+      next.children?.node.content || Fragment.empty,
+    )
+    .deleteRange({ from: remove.beforePos, to: remove.afterPos })
+    .insertContentAt(current.contentEnd, getMergeContent(current, next) ?? null)
+    .setTextSelection(current.contentEnd)
+    .scrollIntoView()
+    .run();
+}
+
 export const KeyboardShortcutsExtension = Extension.create<{
   editor: BlockNoteEditor<any, any, any>;
   tabBehavior: "prefer-navigate-ui" | "prefer-indent";
@@ -49,7 +99,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
             }
 
             const selectionAtBlockStart =
-              state.selection.from === blockInfo.content.beforePos + 1;
+              state.selection.from === blockInfo.contentStart;
             const isParagraph =
               blockInfo.content.node.type.name === "paragraph";
 
@@ -71,10 +121,9 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { content } = blockInfo;
 
             const selectionAtBlockStart =
-              state.selection.from === content.beforePos + 1;
+              state.selection.from === blockInfo.contentStart;
 
             if (selectionAtBlockStart) {
               return liftItem(
@@ -94,28 +143,28 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { block, content } = blockInfo;
+            const { block: blockContainer } = blockInfo;
 
-            const prevBlockInfo = getPrevBlockInfo(
+            const prevSibling = getPrevBlockInfo(
               state.doc,
               blockInfo.block.beforePos,
             );
-            // If the previous block has no inline content, it can't be merged.
-            // It's instead deleted, which is done later in the chan, so we
-            // return early here.
+            // A preceding container or owned body takes the move branch below.
+            // With no sibling, mergeBlocksCommand checks for an owning title.
             if (
-              !prevBlockInfo ||
-              !prevBlockInfo.hasContent ||
-              prevBlockInfo.contentKind !== "inline"
+              prevSibling &&
+              (!prevSibling.hasContent ||
+                prevSibling.contentKind !== "inline" ||
+                (prevSibling.children && prevSibling.hasOwnedChildren))
             ) {
               return false;
             }
 
             const selectionAtBlockStart =
-              state.selection.from === content.beforePos + 1;
+              state.selection.from === blockInfo.contentStart;
             const selectionEmpty = state.selection.empty;
 
-            const posBetweenBlocks = block.beforePos;
+            const posBetweenBlocks = blockContainer.beforePos;
 
             if (selectionAtBlockStart && selectionEmpty) {
               return chain()
@@ -126,93 +175,68 @@ export const KeyboardShortcutsExtension = Extension.create<{
 
             return false;
           }),
-        // If the previous block is a columnList, moves the current block to
-        // the end of the last column in it.
-        () =>
-          commands.command(({ state, tr, dispatch }) => {
-            const blockInfo = getBlockInfoFromSelection(state);
-            if (!blockInfo.hasContent) {
-              return false;
-            }
-
-            const selectionAtBlockStart =
-              state.selection.from === blockInfo.content.beforePos + 1;
-            if (!selectionAtBlockStart) {
-              return false;
-            }
-
-            const prevBlockInfo = getPrevBlockInfo(
-              state.doc,
-              blockInfo.block.beforePos,
-            );
-            if (!prevBlockInfo || prevBlockInfo.hasContent) {
-              return false;
-            }
-
-            if (dispatch) {
-              const columnAfterPos = prevBlockInfo.block.afterPos - 1;
-              const $blockAfterPos = tr.doc.resolve(columnAfterPos - 1);
-
-              tr.delete(blockInfo.block.beforePos, blockInfo.block.afterPos);
-              tr.insert($blockAfterPos.pos, blockInfo.block.node);
-              tr.setSelection(
-                TextSelection.near(tr.doc.resolve($blockAfterPos.pos + 1)),
-              );
-
-              return true;
-            }
-
-            return false;
-          }),
-        // If the block is the first in a column, moves it to the end of the
-        // previous column. If there is no previous column, moves it above the
-        // columnList.
+        // Move into the preceding container's trailing slot, or out of the
+        // current container when this is its first block.
         () =>
           commands.command(({ state, tr, dispatch }) => {
             const blockInfo = getBlockInfoFromSelection(state);
-            if (!blockInfo.hasContent) {
+            if (
+              !blockInfo.hasContent ||
+              state.selection.from !== blockInfo.contentStart
+            ) {
               return false;
             }
 
-            const selectionAtBlockStart =
-              tr.selection.from === blockInfo.content.beforePos + 1;
-            if (!selectionAtBlockStart) {
-              return false;
+            const blockType = blockInfo.block.node.type;
+            let target = getPrevBlockInfo(tr.doc, blockInfo.block.beforePos);
+            let insertionPos: number | undefined;
+            if (target) {
+              if (
+                target.hasContent &&
+                !(target.children && target.hasOwnedChildren)
+              ) {
+                return false;
+              }
+            } else {
+              const $pos = tr.doc.resolve(blockInfo.block.beforePos);
+              if (!isContainerNode($pos.parent.type)) {
+                return false;
+              }
+              const $containerPos = tr.doc.resolve($pos.before());
+              // Between columns, move into the previous column. Outside a
+              // container, move above the closest boundary that accepts us.
+              const prevSibling = $containerPos.nodeBefore;
+              if (
+                isContainerNode($containerPos.parent.type) &&
+                prevSibling &&
+                isContainerNode(prevSibling.type)
+              ) {
+                target = getBlockInfoFromNode(
+                  prevSibling,
+                  $containerPos.pos - prevSibling.nodeSize,
+                );
+              } else {
+                insertionPos = ascendToInsertablePos(
+                  tr.doc,
+                  $containerPos.pos,
+                  blockType,
+                );
+              }
             }
-
-            const $pos = tr.doc.resolve(blockInfo.block.beforePos);
-
-            const prevBlock = $pos.nodeBefore;
-            if (prevBlock) {
-              return false;
+            if (target) {
+              insertionPos = getInsertionPos(
+                tr.doc,
+                target,
+                "last-child",
+                blockType,
+              )?.pos;
             }
-
-            const parentBlock = $pos.node();
-            if (parentBlock.type.name !== "column") {
+            if (insertionPos === undefined) {
               return false;
             }
-
-            const $blockPos = tr.doc.resolve(blockInfo.block.beforePos);
-            const $columnPos = tr.doc.resolve($blockPos.before());
-            const columnListPos = $columnPos.before();
-
             if (dispatch) {
-              tr.delete(blockInfo.block.beforePos, blockInfo.block.afterPos);
-              fixColumnList(tr, columnListPos);
-
-              if ($columnPos.pos === columnListPos + 1) {
-                tr.insert(columnListPos, blockInfo.block.node);
-                tr.setSelection(
-                  TextSelection.near(tr.doc.resolve(columnListPos)),
-                );
-              } else {
-                tr.insert($columnPos.pos - 1, blockInfo.block.node);
-                tr.setSelection(
-                  TextSelection.near(tr.doc.resolve($columnPos.pos)),
-                );
-              }
+              moveBlockOutAndPlaceCaret(tr, blockInfo.block, insertionPos);
             }
-
             return true;
           }),
         // Deletes the current block if it's an empty block with inline content,
@@ -225,8 +249,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
             }
 
             const blockEmpty =
-              blockInfo.content.node.childCount === 0 &&
-              blockInfo.contentKind === "inline";
+              blockInfo.isContentEmpty && blockInfo.contentKind === "inline";
 
             if (blockEmpty) {
               const prevBlockInfo = getPrevBlockInfo(
@@ -241,14 +264,8 @@ export const KeyboardShortcutsExtension = Extension.create<{
               if (!bottomNestedPrevBlockInfo.hasContent) {
                 return false;
               }
-              if (
-                !bottomNestedPrevBlockInfo ||
-                !bottomNestedPrevBlockInfo.hasContent
-              ) {
-                return false;
-              }
 
-              let chainedCommands = chain();
+              const chainedCommands = chain();
 
               // Moves the children the current block.
               if (blockInfo.children) {
@@ -258,24 +275,12 @@ export const KeyboardShortcutsExtension = Extension.create<{
                 );
               }
 
-              if (bottomNestedPrevBlockInfo.contentKind === "table") {
-                chainedCommands = chainedCommands.setTextSelection(
-                  tableContentCaretPos(
-                    bottomNestedPrevBlockInfo.content,
-                    "end",
-                  ),
-                );
-              } else if (bottomNestedPrevBlockInfo.contentKind === "none") {
-                chainedCommands = chainedCommands.setNodeSelection(
-                  bottomNestedPrevBlockInfo.content.beforePos,
+              chainedCommands.command(({ tr }) => {
+                tr.setSelection(
+                  blockEdgeSelection(tr.doc, bottomNestedPrevBlockInfo, "end"),
                 );
-              } else {
-                const contentEndPos =
-                  bottomNestedPrevBlockInfo.content.afterPos - 1;
-
-                chainedCommands =
-                  chainedCommands.setTextSelection(contentEndPos);
-              }
+                return true;
+              });
 
               return chainedCommands
                 .deleteRange({
@@ -300,7 +305,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
             }
 
             const selectionAtBlockStart =
-              state.selection.from === blockInfo.content.beforePos + 1;
+              state.selection.from === blockInfo.contentStart;
             const selectionEmpty = state.selection.empty;
 
             const prevBlockInfo = getPrevBlockInfo(
@@ -309,6 +314,9 @@ export const KeyboardShortcutsExtension = Extension.create<{
             );
 
             if (prevBlockInfo && selectionAtBlockStart && selectionEmpty) {
+              // An emptied container has no content to merge with, so the
+              // guard below rejects it — the merge branch above only fires
+              // for a previous block with content of its own.
               const bottomBlock = getLastDescendantBlockInfo(prevBlockInfo);
 
               if (!bottomBlock.hasContent) {
@@ -356,56 +364,34 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent || !blockInfo.children) {
               return false;
             }
-            const { content, children } = blockInfo;
+            const { children } = blockInfo;
+
+            // A container allowed to hold no children still has a child
+            // container node, but no first child to pull anything out of.
+            if (children.node.childCount === 0) {
+              return false;
+            }
 
             const selectionAtBlockEnd =
-              state.selection.from === content.afterPos - 1;
+              state.selection.from === blockInfo.contentEnd;
             const selectionEmpty = state.selection.empty;
 
             const firstChildBlockInfo = getBlockInfoAt(
               state.doc,
-              children.beforePos + 1,
+              children.childrenStart,
             );
             if (!firstChildBlockInfo.hasContent) {
               return false;
             }
 
             if (selectionAtBlockEnd && selectionEmpty) {
-              const firstChildBlockContent = firstChildBlockInfo.content.node;
-              const firstChildBlockHasInlineContent =
-                firstChildBlockInfo.contentKind === "inline";
-              const blockHasInlineContent = blockInfo.contentKind === "inline";
-
-              return (
-                chain()
-                  // Un-nests child block's children if necessary.
-                  .insertContentAt(
-                    firstChildBlockInfo.block.afterPos,
-                    firstChildBlockInfo.children?.node.content ||
-                      Fragment.empty,
-                  )
-                  .deleteRange(
-                    // Deletes whole child container if there's only one child.
-                    children.node.childCount === 1
-                      ? {
-                          from: children.beforePos,
-                          to: children.afterPos,
-                        }
-                      : {
-                          from: firstChildBlockInfo.block.beforePos,
-                          to: firstChildBlockInfo.block.afterPos,
-                        },
-                  )
-                  // Appends inline content from child block if possible.
-                  .insertContentAt(
-                    state.selection.from,
-                    firstChildBlockHasInlineContent && blockHasInlineContent
-                      ? firstChildBlockContent.content
-                      : null,
-                  )
-                  .setTextSelection(state.selection.from)
-                  .scrollIntoView()
-                  .run()
+              return deleteBlockAndAppendContent(
+                chain(),
+                blockInfo,
+                firstChildBlockInfo,
+                children.node.childCount === 1
+                  ? children
+                  : firstChildBlockInfo.block,
               );
             }
 
@@ -420,7 +406,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { block, content } = blockInfo;
+            const { block: blockContainer } = blockInfo;
 
             const nextBlockInfo = getNextBlockInfo(
               state.doc,
@@ -431,10 +417,10 @@ export const KeyboardShortcutsExtension = Extension.create<{
             }
 
             const selectionAtBlockEnd =
-              state.selection.from === content.afterPos - 1;
+              state.selection.from === blockInfo.contentEnd;
             const selectionEmpty = state.selection.empty;
 
-            const posBetweenBlocks = block.afterPos;
+            const posBetweenBlocks = blockContainer.afterPos;
 
             if (selectionAtBlockEnd && selectionEmpty) {
               return chain()
@@ -445,103 +431,49 @@ export const KeyboardShortcutsExtension = Extension.create<{
 
             return false;
           }),
-        // If the next block is a columnList, moves the first block from its
-        // first column to after the current block.
+        // Pull the next leaf across a container boundary. It may be inside
+        // the next sibling container, or follow the containers we're leaving.
         () =>
           commands.command(({ state, tr, dispatch }) => {
             const blockInfo = getBlockInfoFromSelection(state);
-            if (!blockInfo.hasContent) {
-              return false;
-            }
-
-            const selectionAtBlockEnd =
-              state.selection.from === blockInfo.content.afterPos - 1;
-            if (!selectionAtBlockEnd) {
-              return false;
-            }
-
-            const nextBlockInfo = getNextBlockInfo(
-              state.doc,
-              blockInfo.block.beforePos,
-            );
-            if (!nextBlockInfo || nextBlockInfo.hasContent) {
+            if (
+              !blockInfo.hasContent ||
+              state.selection.from !== blockInfo.contentEnd
+            ) {
               return false;
             }
 
-            if (dispatch) {
-              const columnBeforePos = nextBlockInfo.block.beforePos + 1;
-              const $blockBeforePos = tr.doc.resolve(columnBeforePos + 1);
-
-              tr.delete(
-                $blockBeforePos.pos,
-                $blockBeforePos.pos + $blockBeforePos.nodeAfter!.nodeSize,
-              );
-              fixColumnList(tr, nextBlockInfo.block.beforePos);
-              tr.insert(blockInfo.block.afterPos, $blockBeforePos.nodeAfter!);
-              tr.setSelection(
-                TextSelection.near(tr.doc.resolve($blockBeforePos.pos)),
-              );
-
-              return true;
-            }
-
-            return false;
-          }),
-        // If the block is the last in a column, moves it to the start of the
-        // next column. If there is no next column, moves it below the
-        // columnList.
-        () =>
-          commands.command(({ state, tr, dispatch }) => {
-            const blockInfo = getBlockInfoFromSelection(state);
-            if (!blockInfo.hasContent) {
-              return false;
+            let $boundary = tr.doc.resolve(blockInfo.block.afterPos);
+            while (
+              !$boundary.nodeAfter &&
+              $boundary.depth > 0 &&
+              isContainerNode($boundary.parent.type)
+            ) {
+              $boundary = tr.doc.resolve($boundary.after());
             }
-
-            const selectionAtBlockEnd =
-              tr.selection.from === blockInfo.content.afterPos - 1;
-            if (!selectionAtBlockEnd) {
+            const nextNode = $boundary.nodeAfter;
+            if (!nextNode) {
               return false;
             }
 
-            const $pos = tr.doc.resolve(blockInfo.block.afterPos);
-
-            const nextBlock = $pos.nodeAfter;
-            if (nextBlock) {
+            const crossedBoundary = $boundary.pos !== blockInfo.block.afterPos;
+            if (!crossedBoundary && !isContainerNode(nextNode.type)) {
               return false;
             }
-
-            const parentBlock = $pos.node();
-            if (parentBlock.type.name !== "column") {
+            const target = getFirstLeafBlock(
+              getBlockInfoFromNode(nextNode, $boundary.pos),
+            );
+            if (!target) {
               return false;
             }
 
-            const $blockEndPos = tr.doc.resolve(blockInfo.block.afterPos);
-            const $columnEndPos = tr.doc.resolve($blockEndPos.after());
-            const columnListEndPos = $columnEndPos.after();
-
             if (dispatch) {
-              // Position before first block in next column, or first block
-              // after columnList if there is no next column.
-              const nextBlockBeforePos =
-                $columnEndPos.pos === columnListEndPos - 1
-                  ? columnListEndPos
-                  : $columnEndPos.pos + 1;
-              const nextBlockInfo = getBlockInfoAt(tr.doc, nextBlockBeforePos);
-
-              tr.delete(
-                nextBlockInfo.block.beforePos,
-                nextBlockInfo.block.afterPos,
-              );
-              fixColumnList(
+              moveBlockOutAndPlaceCaret(
                 tr,
-                columnListEndPos - $columnEndPos.node().nodeSize,
-              );
-              tr.insert($blockEndPos.pos, nextBlockInfo.block.node);
-              tr.setSelection(
-                TextSelection.near(tr.doc.resolve(nextBlockBeforePos)),
+                target.block,
+                blockInfo.block.afterPos,
               );
             }
-
             return true;
           }),
         // Deletes the next block at either the same or lower nesting level, if
@@ -555,66 +487,35 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { content } = blockInfo;
 
             const selectionAtBlockEnd =
-              state.selection.from === content.afterPos - 1;
+              state.selection.from === blockInfo.contentEnd;
             const selectionEmpty = state.selection.empty;
 
             if (selectionAtBlockEnd && selectionEmpty) {
-              const getNextBlockInfoAtAnyLevel = (
-                doc: Node,
-                beforePos: number,
-              ) => {
-                const nextBlockInfo = getNextBlockInfo(doc, beforePos);
+              let nextBlockInfo: BlockInfo | undefined;
+              let ancestor: BlockInfo | undefined = blockInfo;
+              while (ancestor) {
+                nextBlockInfo = getNextBlockInfo(
+                  state.doc,
+                  ancestor.block.beforePos,
+                );
                 if (nextBlockInfo) {
-                  return nextBlockInfo;
-                }
-
-                const parentBlockInfo = getParentBlockInfo(doc, beforePos);
-                if (!parentBlockInfo) {
-                  return undefined;
+                  break;
                 }
-
-                return getNextBlockInfoAtAnyLevel(
-                  doc,
-                  parentBlockInfo.block.beforePos,
+                ancestor = getParentBlockInfo(
+                  state.doc,
+                  ancestor.block.beforePos,
                 );
-              };
-
-              const nextBlockInfo = getNextBlockInfoAtAnyLevel(
-                state.doc,
-                blockInfo.block.beforePos,
-              );
+              }
               if (!nextBlockInfo || !nextBlockInfo.hasContent) {
                 return false;
               }
 
-              const nextBlockHasInlineContent =
-                nextBlockInfo.contentKind === "inline";
-              const blockHasInlineContent = blockInfo.contentKind === "inline";
-
-              return (
-                chain()
-                  // Un-nests next block's children if necessary.
-                  .insertContentAt(
-                    nextBlockInfo.block.afterPos,
-                    nextBlockInfo.children?.node.content || Fragment.empty,
-                  )
-                  .deleteRange({
-                    from: nextBlockInfo.block.beforePos,
-                    to: nextBlockInfo.block.afterPos,
-                  })
-                  // Appends inline content from child block if possible.
-                  .insertContentAt(
-                    state.selection.from,
-                    nextBlockHasInlineContent && blockHasInlineContent
-                      ? nextBlockInfo.content.node.content
-                      : null,
-                  )
-                  .setTextSelection(state.selection.from)
-                  .scrollIntoView()
-                  .run()
+              return deleteBlockAndAppendContent(
+                chain(),
+                blockInfo,
+                nextBlockInfo,
               );
             }
 
@@ -630,8 +531,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
             }
 
             const blockEmpty =
-              blockInfo.content.node.childCount === 0 &&
-              blockInfo.contentKind === "inline";
+              blockInfo.isContentEmpty && blockInfo.contentKind === "inline";
 
             if (blockEmpty) {
               const nextBlockInfo = getNextBlockInfo(
@@ -642,21 +542,14 @@ export const KeyboardShortcutsExtension = Extension.create<{
                 return false;
               }
 
-              let chainedCommands = chain();
+              const chainedCommands = chain();
 
-              if (nextBlockInfo.contentKind === "table") {
-                chainedCommands = chainedCommands.setTextSelection(
-                  tableContentCaretPos(nextBlockInfo.content, "start"),
-                );
-              } else if (nextBlockInfo.contentKind === "none") {
-                chainedCommands = chainedCommands.setNodeSelection(
-                  nextBlockInfo.content.beforePos,
-                );
-              } else {
-                chainedCommands = chainedCommands.setTextSelection(
-                  nextBlockInfo.content.beforePos + 1,
+              chainedCommands.command(({ tr }) => {
+                tr.setSelection(
+                  blockEdgeSelection(tr.doc, nextBlockInfo, "start"),
                 );
-              }
+                return true;
+              });
 
               return chainedCommands
                 .deleteRange({
@@ -681,7 +574,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
             }
 
             const selectionAtBlockEnd =
-              state.selection.from === blockInfo.content.afterPos - 1;
+              state.selection.from === blockInfo.contentEnd;
             const selectionEmpty = state.selection.empty;
 
             const nextBlockInfo = getNextBlockInfo(
@@ -702,7 +595,6 @@ export const KeyboardShortcutsExtension = Extension.create<{
                   nextBlockInfo.isContentEmpty);
 
               if (nextBlockNotTableAndNoContent) {
-                const childBlocks = nextBlockInfo.block.node.lastChild!.content;
                 return chain()
                   .deleteRange({
                     from: nextBlockInfo.block.beforePos,
@@ -710,9 +602,7 @@ export const KeyboardShortcutsExtension = Extension.create<{
                   })
                   .insertContentAt(
                     blockInfo.block.afterPos,
-                    nextBlockInfo.block.node.childCount === 2
-                      ? childBlocks
-                      : null,
+                    nextBlockInfo.children?.node.content ?? null,
                   )
                   .run();
               }
@@ -732,15 +622,15 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { block, content } = blockInfo;
+            const { block: blockContainer } = blockInfo;
 
-            const { depth } = state.doc.resolve(block.beforePos);
+            const { depth } = state.doc.resolve(blockContainer.beforePos);
 
             const selectionAtBlockStart =
               state.selection.$anchor.parentOffset === 0;
             const selectionEmpty =
               state.selection.anchor === state.selection.head;
-            const blockEmpty = content.node.childCount === 0;
+            const blockEmpty = blockInfo.isContentEmpty;
             const blockIndented = depth > 1;
 
             if (
@@ -766,14 +656,6 @@ export const KeyboardShortcutsExtension = Extension.create<{
             const blockSpec =
               this.options.editor.schema.blockSpecs[blockInfo.blockNoteType];
 
-            // NOTE: This likely doesn't work as intended - `blockSchema[type]`
-            // holds the block *config* (type/propSchema/content), which carries
-            // no `meta`, so `meta?.hardBreakShortcut` is always `undefined` and
-            // this falls back to the default. It should read from the block
-            // spec's implementation instead (i.e.
-            // `editor.schema.blockSpecs[type].implementation.meta`), the way the
-            // syntax-highlighting extension reads `meta.highlight`. Left as-is
-            // for a follow-up pass.
             const blockHardBreakShortcut =
               blockSpec?.implementation?.meta?.hardBreakShortcut ??
               "shift+enter";
@@ -818,6 +700,63 @@ export const KeyboardShortcutsExtension = Extension.create<{
 
             return false;
           }),
+        // If the block is empty and the last child of a container or an
+        // owned-children body, moves the block out (double Enter exits the
+        // container). The block lands at the nearest enclosing position that
+        // accepts it. E.g. out of a column it skips the columnList, which
+        // holds only columns, and lands below it. Without this, Enter only
+        // ever creates new blocks within the container, so the cursor could
+        // never leave a trailing container. Shift+Enter still adds spacing
+        // inside a container. The first block of a body stays put: it is
+        // where the body begins, not a way out of it.
+        () =>
+          commands.command(({ state, tr, dispatch }) => {
+            const blockInfo = getBlockInfoFromSelection(state);
+            if (!blockInfo.hasContent) {
+              return false;
+            }
+
+            const selectionEmpty =
+              state.selection.anchor === state.selection.head;
+            const blockEmpty = blockInfo.isContentEmpty;
+            if (!selectionEmpty || !blockEmpty) {
+              return false;
+            }
+
+            const $pos = tr.doc.resolve(blockInfo.block.beforePos);
+            // Only fires on the container's last child.
+            if (tr.doc.resolve(blockInfo.block.afterPos).nodeAfter !== null) {
+              return false;
+            }
+
+            const owner = getParentBlockInfo(tr.doc, blockInfo.block.beforePos);
+            if (!owner || !owner.hasOwnedChildren) {
+              return false;
+            }
+            // The first block of a body stays put: it is where the body
+            // begins, not a way out of it. (A container's own first child has
+            // no such role, so it may still leave.)
+            if ($pos.index() === 0 && owner.hasContent) {
+              return false;
+            }
+
+            const ownerAfterPos = ascendToInsertablePos(
+              tr.doc,
+              owner.block.afterPos,
+              state.schema.nodes["blockContainer"],
+              "after",
+            );
+            if (ownerAfterPos === undefined) {
+              return false;
+            }
+
+            if (dispatch) {
+              moveBlockOutAndPlaceCaret(tr, blockInfo.block, ownerAfterPos);
+              tr.scrollIntoView();
+            }
+
+            return true;
+          }),
         // Creates a new block and moves the selection to it if the current one is empty, while the selection is also
         // empty & at the start of the block.
         () =>
@@ -826,16 +765,21 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { block, content } = blockInfo;
+            const { block: blockContainer } = blockInfo;
 
             const selectionAtBlockStart =
               state.selection.$anchor.parentOffset === 0;
             const selectionEmpty =
               state.selection.anchor === state.selection.head;
-            const blockEmpty = content.node.childCount === 0;
+            const blockEmpty = blockInfo.isContentEmpty;
 
-            if (selectionAtBlockStart && selectionEmpty && blockEmpty) {
-              const newBlockInsertionPos = block.afterPos;
+            if (
+              selectionAtBlockStart &&
+              selectionEmpty &&
+              blockEmpty &&
+              !blockInfo.hasOwnedChildren
+            ) {
+              const newBlockInsertionPos = blockContainer.afterPos;
               const newBlockContentPos = newBlockInsertionPos + 2;
 
               if (dispatch) {
@@ -874,6 +818,69 @@ export const KeyboardShortcutsExtension = Extension.create<{
 
             return false;
           }),
+        // Enter in a titled block's own content (a callout's title) starts its
+        // body rather than splitting the block in two: whatever follows the
+        // cursor becomes the body's first block, and the body the callout
+        // already had stays where it is.
+        () =>
+          commands.command(({ state, tr, dispatch }) => {
+            const blockInfo = getBlockInfoFromSelection(state);
+            if (!blockInfo.hasContent) {
+              return false;
+            }
+
+            if (!blockInfo.hasOwnedChildren) {
+              return false;
+            }
+            if (!state.selection.empty) {
+              return false;
+            }
+            if (
+              state.selection.from < blockInfo.contentStart ||
+              state.selection.from > blockInfo.contentEnd
+            ) {
+              return false;
+            }
+
+            if (dispatch) {
+              // Everything after the cursor moves into the new block, so
+              // splitting the title mid-way puts its tail at the top of the
+              // body instead of handing the body to a new sibling.
+              const tail = blockInfo.content.node.cut(
+                state.selection.from - blockInfo.contentStart,
+              );
+              const newBlock = state.schema.nodes["blockContainer"].create(
+                undefined,
+                state.schema.nodes["paragraph"].create(undefined, tail.content),
+              );
+
+              tr.delete(state.selection.from, blockInfo.contentEnd);
+
+              const body = getBlockInfoAt(
+                tr.doc,
+                blockInfo.block.beforePos,
+              ).children;
+              // Without a body yet, one is created around the new block.
+              const insertPos = body
+                ? body.childrenStart
+                : tr.mapping.map(blockInfo.content.afterPos);
+              tr.insert(
+                insertPos,
+                body
+                  ? newBlock
+                  : state.schema.nodes["blockGroup"].create(
+                      undefined,
+                      newBlock,
+                    ),
+              )
+                .setSelection(
+                  new TextSelection(tr.doc.resolve(insertPos + (body ? 2 : 3))),
+                )
+                .scrollIntoView();
+            }
+
+            return true;
+          }),
         // Splits the current block, moving content inside that's after the cursor to a new text block below. Also
         // deletes the selection beforehand, if it's not empty.
         () =>
@@ -882,11 +889,10 @@ export const KeyboardShortcutsExtension = Extension.create<{
             if (!blockInfo.hasContent) {
               return false;
             }
-            const { content } = blockInfo;
 
             const selectionAtBlockStart =
               state.selection.$anchor.parentOffset === 0;
-            const blockEmpty = content.node.childCount === 0;
+            const blockEmpty = blockInfo.isContentEmpty;
 
             if (!blockEmpty) {
               chain()
@@ -909,42 +915,27 @@ export const KeyboardShortcutsExtension = Extension.create<{
       ]);
     };
 
+    const options = this.options;
+    function handleTab(shift: boolean) {
+      const { editor, tabBehavior } = options;
+      if (
+        tabBehavior !== "prefer-indent" &&
+        (editor.getExtension(FormattingToolbarExtension)?.store.state ||
+          editor.getExtension(FilePanelExtension)?.store.state !== undefined)
+      ) {
+        // Let the browser navigate into and out of an open toolbar.
+        return false;
+      }
+      return shift ? unnestBlock(editor) : nestBlock(editor);
+    }
+
     return {
       Backspace: handleBackspace,
       Delete: handleDelete,
       Enter: () => handleEnter(),
       "Shift-Enter": () => handleEnter(true),
-      // Always returning true for tab key presses ensures they're not captured by the browser. Otherwise, they blur the
-      // editor since the browser will try to use tab for keyboard navigation.
-      Tab: () => {
-        if (
-          this.options.tabBehavior !== "prefer-indent" &&
-          (this.options.editor.getExtension(FormattingToolbarExtension)?.store
-            .state ||
-            this.options.editor.getExtension(FilePanelExtension)?.store
-              .state !== undefined)
-          // TODO need to check if the link toolbar is open or another alternative entirely
-        ) {
-          // don't handle tabs if a toolbar is shown, so we can tab into / out of it
-          return false;
-        }
-        return nestBlock(this.options.editor);
-      },
-      "Shift-Tab": () => {
-        if (
-          this.options.tabBehavior !== "prefer-indent" &&
-          (this.options.editor.getExtension(FormattingToolbarExtension)?.store
-            .state ||
-            this.options.editor.getExtension(FilePanelExtension)?.store
-              .state !== undefined)
-          // TODO need to check if the link toolbar is open or another alternative entirely
-          // other menu types?
-        ) {
-          // don't handle tabs if a toolbar is shown, so we can tab into / out of it
-          return false;
-        }
-        return unnestBlock(this.options.editor);
-      },
+      Tab: () => handleTab(false),
+      "Shift-Tab": () => handleTab(true),
       "Shift-Mod-ArrowUp": () => {
         this.options.editor.moveBlocksUp();
         return true;
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index b4f220e1e2..be0fac887b 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -1,6 +1,14 @@
 export * from "./api/blockManipulation/commands/insertBlocks/insertBlocks.js";
 export * from "./api/blockManipulation/commands/replaceBlocks/replaceBlocks.js";
-export * from "./api/blockManipulation/commands/replaceBlocks/util/fixColumnList.js";
+export {
+  isContainerNode,
+  isContainerConfig,
+} from "./schema/blocks/children.js";
+export { applyContainerAttributes } from "./schema/blocks/containerAttributes.js";
+export {
+  fixContainer,
+  isEmptyContainerChild,
+} from "./api/blockManipulation/containers/fixContainer.js";
 export * from "./api/blockManipulation/commands/updateBlock/updateBlock.js";
 export * from "./api/exporters/html/externalHTMLExporter.js";
 export * from "./api/exporters/html/internalHTMLSerializer.js";
diff --git a/packages/core/src/pm-nodes/BlockContainer.ts b/packages/core/src/pm-nodes/BlockContainer.ts
index 86bd2ccb15..87da0dffed 100644
--- a/packages/core/src/pm-nodes/BlockContainer.ts
+++ b/packages/core/src/pm-nodes/BlockContainer.ts
@@ -1,10 +1,67 @@
-import { Node } from "@tiptap/core";
+import {
+  Node,
+  type NodeViewRenderer,
+  type NodeViewRendererProps,
+} from "@tiptap/core";
 
+import type { NodeView } from "@tiptap/pm/view";
 import type { BlockNoteEditor } from "../editor/BlockNoteEditor.js";
+import { nodeToBlock } from "../api/nodeConversions/nodeToBlock.js";
+import { isDocumentFragment } from "../schema/blocks/internal.js";
 import { BlockNoteDOMAttributes } from "../schema/index.js";
+import { ignoreNonContentMutations } from "../schema/nodeViewMutations.js";
 import { mergeCSSClasses } from "../util/browser.js";
 import { suggestionMarks } from "./suggestionMarks.js";
 
+/** Adapts vanilla frames to the same lifecycle as framework node views. */
+function createFrameView(
+  props: NodeViewRendererProps,
+  editor: BlockNoteEditor,
+  fallback: HTMLElement,
+  blockContentDOMAttributes: Record<string, string>,
+): NodeView {
+  const type = props.node.firstChild!.type.name;
+  const implementation = editor.blockImplementations[type].implementation;
+  if (implementation.frameNodeView) {
+    return implementation.frameNodeView(props);
+  }
+
+  const renderFrame = implementation.renderFrame<
+    typeof editor.schema.inlineContentSchema,
+    typeof editor.schema.styleSchema
+  >;
+  const frame = renderFrame?.call(
+    {
+      renderType: "nodeView",
+      props,
+      blockContentDOMAttributes,
+      propSchema: editor.blockImplementations[type].config.propSchema,
+    },
+    nodeToBlock(props.node, props.view.state.doc),
+    editor,
+  );
+  let dom = frame?.dom ?? fallback;
+  if (isDocumentFragment(dom)) {
+    // Node views need a stable element even when the author returns siblings.
+    const wrapper = document.createElement("div");
+    wrapper.style.display = "contents";
+    wrapper.append(dom);
+    dom = wrapper;
+  }
+  return {
+    dom,
+    contentDOM: frame?.slot ?? fallback,
+    destroy: frame?.destroy?.bind(frame),
+    update(node) {
+      if (frame?.update) {
+        return frame.update(nodeToBlock(node, props.view.state.doc)) !== false;
+      }
+      // Declined frames must also be reconsidered when their block changes.
+      return !renderFrame || node.eq(props.node);
+    },
+  };
+}
+
 // Object containing all possible block attributes.
 const BlockAttributes: Record<string, string> = {
   blockColor: "data-block-color",
@@ -88,4 +145,57 @@ export const BlockContainer = Node.create<{
       contentDOM: block,
     };
   },
+
+  addNodeView() {
+    // Cast: this returns a plain ProseMirror node view, which tiptap's
+    // `NodeViewRenderer` type doesn't model.
+    return ((props: NodeViewRendererProps) => {
+      const editor = this.options.editor;
+      const { dom, contentDOM } = this.type.spec.toDOM!(props.node) as {
+        dom: HTMLElement;
+        contentDOM: HTMLElement;
+      };
+      const frameView = createFrameView(
+        props,
+        editor,
+        contentDOM,
+        this.options.domAttributes?.blockContent || {},
+      );
+      const framed = frameView.dom !== contentDOM;
+      if (framed) {
+        contentDOM.appendChild(frameView.dom);
+      }
+
+      const nodeView: NodeView = {
+        dom,
+        contentDOM: frameView.contentDOM ?? contentDOM,
+        update(node, decorations, innerDecorations) {
+          // Changing the wrapper or block type replaces the complete view.
+          return (
+            node.sameMarkup(props.node) &&
+            node.firstChild?.type === props.node.firstChild?.type &&
+            (frameView.update?.(node, decorations, innerDecorations) ?? false)
+          );
+        },
+        stopEvent(event) {
+          // Author chrome handles its own events; the slot remains editable.
+          const target = event.target;
+          return (
+            (target instanceof globalThis.Node &&
+              frameView.dom.contains(target) &&
+              !nodeView.contentDOM?.contains(target)) ||
+            (frameView.stopEvent?.(event) ?? false)
+          );
+        },
+        destroy: frameView.destroy?.bind(frameView),
+        selectNode: frameView.selectNode?.bind(frameView),
+        deselectNode: frameView.deselectNode?.bind(frameView),
+        ignoreMutation: frameView.ignoreMutation?.bind(frameView),
+      };
+      if (framed) {
+        ignoreNonContentMutations(nodeView);
+      }
+      return nodeView;
+    }) as unknown as NodeViewRenderer;
+  },
 });
diff --git a/packages/core/src/pm-nodes/BlockGroup.ts b/packages/core/src/pm-nodes/BlockGroup.ts
index 9fe644a5db..bba1d84f4d 100644
--- a/packages/core/src/pm-nodes/BlockGroup.ts
+++ b/packages/core/src/pm-nodes/BlockGroup.ts
@@ -1,4 +1,5 @@
 import { Node } from "@tiptap/core";
+import { CHILD_CONTAINER_GROUP } from "../schema/blocks/children.js";
 import { BlockNoteDOMAttributes } from "../schema/index.js";
 import { mergeCSSClasses } from "../util/browser.js";
 import { suggestionMarks } from "./suggestionMarks.js";
@@ -7,7 +8,7 @@ export const BlockGroup = Node.create<{
   domAttributes?: BlockNoteDOMAttributes;
 }>({
   name: "blockGroup",
-  group: "childContainer",
+  group: CHILD_CONTAINER_GROUP,
   content: "blockGroupChild+",
   marks() {
     return suggestionMarks(this.editor);
diff --git a/packages/core/src/schema/blocks/children.test.ts b/packages/core/src/schema/blocks/children.test.ts
new file mode 100644
index 0000000000..0945e577c0
--- /dev/null
+++ b/packages/core/src/schema/blocks/children.test.ts
@@ -0,0 +1,156 @@
+// @vitest-environment node
+import { describe, expect, it } from "vite-plus/test";
+
+import { childrenContentExpression } from "./children.js";
+import type { ChildrenConfig } from "./types.js";
+import { validateChildrenConfigs } from "./validateChildren.js";
+
+// All enforcement happens through the content expression. If this table is
+// right, `allow`/`min` are enforced by ProseMirror itself.
+const CASES: [string, ChildrenConfig, string][] = [
+  [
+    "any block or placeable container, at least one (the minimal config)",
+    { allow: "blocks" },
+    "blockGroupChild+",
+  ],
+  ["any block, possibly none", { allow: "blocks", min: 0 }, "blockGroupChild*"],
+  [
+    "any block, two or more",
+    { allow: "blocks", min: 2 },
+    "blockGroupChild{2,}",
+  ],
+  ["one container type only", { allow: ["column"], min: 2 }, "column{2,}"],
+  [
+    "several container types",
+    { allow: ["column", "card"] },
+    "(column | card)+",
+  ],
+];
+
+describe("childrenContentExpression", () => {
+  it.each(CASES)("%s", (_name, config, expected) => {
+    expect(childrenContentExpression(config)).toBe(expected);
+  });
+
+  // `validateChildrenConfigs` never builds the content expression — it only
+  // resolves `allow`/`min` — so an `allow` that permits nothing is caught
+  // here, at expression build, rather than by `validate` below.
+  it("throws for an allow array that permits nothing", () => {
+    expect(() => childrenContentExpression({ allow: [] })).toThrow(
+      /permits nothing/,
+    );
+  });
+});
+
+type ContainerFixture = {
+  children: ChildrenConfig;
+  content?: "none" | "inline" | "plain";
+  placeable?: "anywhere" | "namedOnly";
+};
+
+function specsWith(containers: Record<string, ContainerFixture>) {
+  return {
+    paragraph: { config: { content: "inline" as const } },
+    heading: { config: { content: "inline" as const } },
+    ...Object.fromEntries(
+      Object.entries(containers).map(
+        ([type, { children, content, placeable }]) => [
+          type,
+          {
+            config: {
+              content: content ?? ("none" as const),
+              children,
+              placeable,
+            },
+          },
+        ],
+      ),
+    ),
+  };
+}
+
+const validate = (containers: Record<string, ContainerFixture>) => () =>
+  validateChildrenConfigs(specsWith(containers));
+
+describe("validateChildrenConfigs", () => {
+  it("accepts recursive containers, named-only children, and titled blocks", () => {
+    expect(
+      validate({ callout: { children: { allow: "blocks" } } }),
+    ).not.toThrow();
+    expect(
+      validate({
+        // gridCell is a terminating alternative to the recursive grid.
+        grid: { children: { allow: ["gridCell", "grid"], min: 2 } },
+        gridCell: { children: { allow: "blocks" }, placeable: "namedOnly" },
+        alert: { children: { allow: "blocks" }, content: "inline" },
+        source: { children: { allow: "blocks" }, content: "plain" },
+      }),
+    ).not.toThrow();
+  });
+
+  it.each(["inline", "plain"] as const)(
+    "rejects %s child restrictions the shared blockGroup cannot enforce",
+    (content) => {
+      for (const children of [
+        { allow: "blocks", min: 2 },
+        { allow: ["cell"] },
+      ] as const) {
+        expect(
+          validate({
+            alert: { content, children },
+            cell: { children: { allow: "blocks" } },
+          }),
+        ).toThrow(/blocks with inline or plain content support/);
+      }
+    },
+  );
+
+  it("does not treat a titled block's content node as an allowed container", () => {
+    expect(
+      validate({
+        box: { children: { allow: ["alert"] } },
+        alert: { content: "inline", children: { allow: "blocks" } },
+      }),
+    ).toThrow(/regular block/);
+  });
+
+  it("rejects named-only placement on a shared regular block wrapper", () => {
+    expect(
+      validate({
+        alert: {
+          content: "inline",
+          children: { allow: "blocks" },
+          placeable: "namedOnly",
+        },
+      }),
+    ).toThrow(/requires a container node/);
+  });
+
+  // Tables do not support owned child blocks.
+  it("rejects children combined with table content", () => {
+    for (const content of ["table"] as const) {
+      expect(() =>
+        validateChildrenConfigs({
+          box: {
+            config: { content, children: { allow: "blocks" } },
+          },
+        }),
+      ).toThrow(/not supported on table blocks/);
+    }
+  });
+
+  it.each(["typo", "blockGroupChild", "toString"])(
+    "rejects an allow entry that is not a configured block: %s",
+    (allowed) => {
+      expect(validate({ box: { children: { allow: [allowed] } } })).toThrow(
+        /not a configured block type/,
+      );
+    },
+  );
+
+  it("rejects a regular block type in the allow array", () => {
+    expect(validate({ box: { children: { allow: ["heading"] } } })).toThrow(
+      /not yet supported/,
+    );
+  });
+});
diff --git a/packages/core/src/schema/blocks/children.ts b/packages/core/src/schema/blocks/children.ts
new file mode 100644
index 0000000000..7b4dd04071
--- /dev/null
+++ b/packages/core/src/schema/blocks/children.ts
@@ -0,0 +1,117 @@
+import type { Node, NodeType, Schema } from "prosemirror-model";
+
+import type { ChildrenConfig } from "./types.js";
+
+export const CHILD_CONTAINER_GROUP = "childContainer";
+
+export const BLOCK_GROUP_CHILD_GROUP = "blockGroupChild";
+
+/**
+ * Whether a block config declares a *container block*: one whose own node
+ * holds its children. A block that has content of its own keeps its ordinary
+ * shape, and its `children` declare owned children instead.
+ * @internal
+ */
+export function isContainerConfig(config: {
+  content: string;
+  children?: unknown;
+}): boolean {
+  return config.children !== undefined && config.content === "none";
+}
+
+// Whether `type` is a node that holds child blocks directly: a container
+// block's own node. A container is a child-holding node that is itself a
+// block; `blockGroup` also holds children but is not a block (it's regular
+// blocks' nesting machinery), so the `bnBlock` check excludes it.
+export function isContainerNode(type: NodeType): boolean {
+  return type.isInGroup(CHILD_CONTAINER_GROUP) && type.isInGroup("bnBlock");
+}
+
+/**
+ * Whether `node` is a block whose children are owned children: a container
+ * block, or a `blockContainer` whose content node declares `children`.
+ */
+export function hasOwnedChildren(node: Node): boolean {
+  return (
+    isContainerNode(node.type) ||
+    (node.type.name === "blockContainer" &&
+      node.firstChild?.type.spec.blockConfig?.children !== undefined)
+  );
+}
+
+// Builds the `blockGroup` node that holds a block's children when converting
+// blocks to nodes. Transaction-level nesting (`sinkItem`, `findWrapping` in the
+// keyboard shortcuts) wraps existing nodes in a `blockGroup` instead, and the
+// document's root `blockGroup` is created by the parsers and `y`/`yjs` utils.
+export function createBlockGroup(
+  schema: Schema,
+  children: readonly Node[],
+): Node {
+  return schema.nodes["blockGroup"].createChecked({}, children as Node[]);
+}
+
+/**
+ * Whether `type` is a container declared `placeable: "namedOnly"`: one
+ * defined only in terms of the container that holds it (a `column`), so it can
+ * never stand where a regular block goes.
+ *
+ * The schema encodes this by keeping such types out of
+ * `BLOCK_GROUP_CHILD_GROUP`, which is how ProseMirror enforces it while
+ * matching content. This answers the same question from the declaration
+ * itself, for code reasoning about the block rather than about what PM will
+ * match.
+ */
+export function isNamedOnly(type: NodeType): boolean {
+  return (
+    isContainerNode(type) && type.spec.blockConfig?.placeable === "namedOnly"
+  );
+}
+
+// Below `blockContainer`'s priority (50) so PM's `fillBefore` picks
+// `blockContainer` first, avoiding recursion through nested containers.
+export const CONTAINER_NODE_PRIORITY = 40;
+
+const CONTAINER_PRIORITY_BAND = { min: 30, max: 49 };
+const DEFAULT_SPEC_PRIORITY = 101;
+
+// Maps `sortByDependencies` priority into the container band (30–49).
+// Preserves relative order but keeps all containers below regular blocks.
+export function containerNodePriority(priority: number | undefined): number {
+  if (priority === undefined) {
+    return CONTAINER_NODE_PRIORITY;
+  }
+
+  const steps = Math.round((priority - DEFAULT_SPEC_PRIORITY) / 10);
+
+  return Math.min(
+    CONTAINER_PRIORITY_BAND.max,
+    Math.max(CONTAINER_PRIORITY_BAND.min, CONTAINER_NODE_PRIORITY + steps),
+  );
+}
+
+/**
+ * Compiles a container's `children` config into its node's ProseMirror content
+ * expression: which types may be its children (`allow`), followed by how few
+ * of them it takes (`min`).
+ */
+export function childrenContentExpression(children: ChildrenConfig): string {
+  const { allow, min = 1 } = children;
+
+  let allowed: string;
+  if (allow === "blocks") {
+    // "Anything" is already a group, so use it rather than spelling out a
+    // union that would need rebuilding whenever the schema gains a container
+    // type.
+    allowed = BLOCK_GROUP_CHILD_GROUP;
+  } else {
+    if (allow.length === 0) {
+      throw new Error(
+        "Container `allow` permits nothing. A container must accept at least one block or container type; drop `children` entirely for a block that holds none.",
+      );
+    }
+
+    allowed = allow.length === 1 ? allow[0] : `(${allow.join(" | ")})`;
+  }
+
+  return allowed + (min === 0 ? "*" : min === 1 ? "+" : `{${min},}`);
+}
diff --git a/packages/core/src/schema/blocks/containerAttributes.ts b/packages/core/src/schema/blocks/containerAttributes.ts
new file mode 100644
index 0000000000..c25677c8f2
--- /dev/null
+++ b/packages/core/src/schema/blocks/containerAttributes.ts
@@ -0,0 +1,37 @@
+import { camelToDataKebab } from "../../util/string.js";
+import { PropSchema, Props } from "../propTypes.js";
+
+/**
+ * Writes the attributes a container block's round-trip parse reads onto its
+ * root element: the `data-node-type` marker, the block's non-default props as
+ * `data-*` (the convention `propsToAttributes` and the generated parse rules
+ * use), and its id where there is one.
+ * Existing attributes follow the block props, including removing defaults.
+ * @internal
+ */
+export function applyContainerAttributes<PSchema extends PropSchema>(
+  element: HTMLElement | undefined | null,
+  blockType: string,
+  blockProps: Partial<Props<PSchema>>,
+  propSchema: PSchema,
+  id?: string,
+) {
+  if (!element) {
+    return;
+  }
+
+  for (const [prop, value] of Object.entries(blockProps)) {
+    const attribute = camelToDataKebab(prop);
+    if (value === undefined || value === propSchema[prop]?.default) {
+      element.removeAttribute(attribute);
+    } else {
+      element.setAttribute(attribute, String(value));
+    }
+  }
+
+  // Reserved markers win even when a prop maps to the same attribute.
+  element.setAttribute("data-node-type", blockType);
+  if (id) {
+    element.setAttribute("data-id", id);
+  }
+}
diff --git a/packages/core/src/schema/blocks/createSpec.browser.test.ts b/packages/core/src/schema/blocks/createSpec.browser.test.ts
new file mode 100644
index 0000000000..7505f47068
--- /dev/null
+++ b/packages/core/src/schema/blocks/createSpec.browser.test.ts
@@ -0,0 +1,176 @@
+import { Fragment } from "prosemirror-model";
+import {
+  afterAll,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+} from "vite-plus/test";
+
+import { BlockNoteSchema } from "../../blocks/BlockNoteSchema.js";
+import { defaultBlockSpecs } from "../../blocks/defaultBlocks.js";
+import { BlockNoteEditor } from "../../editor/BlockNoteEditor.js";
+import { createBlockSpec } from "./createSpec.js";
+
+// Every test here goes through `tryParseHTMLToBlocks`, which parses real HTML
+// into a real DOM (`document.implementation.createHTMLDocument` in
+// `api/parsers/html/util/nestedLists.ts`) before ProseMirror's parser ever
+// runs. Parsing HTML is the capability under test, so the whole suite runs
+// against a real browser engine rather than jsdom's.
+
+const renderDiv = () => {
+  const dom = document.createElement("div");
+  return { dom, contentDOM: dom };
+};
+
+// A pure container that recognizes its own external HTML. Before containers
+// went through `getParseRules`, `parse` was silently dropped for them and this
+// produced nothing at all.
+const Card = createBlockSpec(
+  {
+    type: "card" as const,
+    propSchema: { tone: { default: "neutral" } },
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    render: renderDiv,
+    parse: (el) =>
+      el.classList.contains("card")
+        ? { tone: el.getAttribute("data-tone") ?? undefined }
+        : undefined,
+  },
+)();
+
+// The same, but taking over the parsing of its own body.
+const Quote = createBlockSpec(
+  {
+    type: "quote" as const,
+    propSchema: {},
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    render: renderDiv,
+    parse: (el) => (el.tagName === "BLOCKQUOTE" ? {} : undefined),
+    // Returns inline nodes, the natural thing to build from an element, and
+    // relies on ProseMirror's parser to wrap them into child blocks.
+    parseContent: ({ el, schema }) =>
+      Fragment.from(schema.text(el.textContent?.trim() || "empty")),
+  },
+)();
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    card: Card,
+    quote: Quote,
+  } as const,
+});
+
+let editor: BlockNoteEditor<any, any, any>;
+const div = document.createElement("div");
+
+beforeAll(() => {
+  document.body.appendChild(div);
+  editor = BlockNoteEditor.create({ schema }) as any;
+  editor.mount(div);
+});
+
+afterAll(() => {
+  editor._tiptapEditor.destroy();
+  div.remove();
+  editor = undefined as any;
+});
+
+beforeEach(() => {
+  editor.replaceBlocks(editor.document, [
+    { id: "p-0", type: "paragraph", content: "Paragraph 0" },
+  ]);
+});
+
+describe("container `parse`", () => {
+  it("parses an external element into a container, children intact", () => {
+    const blocks = editor.tryParseHTMLToBlocks(
+      '<div class="card" data-tone="warning"><p>First</p><h1>Second</h1></div>',
+    );
+
+    expect(blocks).toHaveLength(1);
+    expect(blocks[0].type).toBe("card");
+    expect(blocks[0].props.tone).toBe("warning");
+    // No `getContent` is supplied, so ProseMirror parses the children with the
+    // normal block rules and `findWrapping` adds the `blockContainer`s.
+    expect(blocks[0].children.map((child: any) => child.type)).toEqual([
+      "paragraph",
+      "heading",
+    ]);
+    expect(blocks[0].children[0].content).toEqual([
+      { type: "text", text: "First", styles: {} },
+    ]);
+  });
+
+  it("places inline nodes returned by `parseContent` into a child block", () => {
+    const blocks = editor.tryParseHTMLToBlocks(
+      "<blockquote>Quoted text</blockquote>",
+    );
+
+    expect(blocks).toHaveLength(1);
+    expect(blocks[0].type).toBe("quote");
+    expect(blocks[0].children.map((child: any) => child.type)).toEqual([
+      "paragraph",
+    ]);
+    expect(blocks[0].children[0].content).toEqual([
+      { type: "text", text: "Quoted text", styles: {} },
+    ]);
+  });
+});
+
+describe("container `runsBefore`", () => {
+  const ambiguous = (type: string) =>
+    createBlockSpec(
+      {
+        type,
+        propSchema: {},
+        content: "none",
+        children: { allow: "blocks" },
+      } as any,
+      {
+        render: renderDiv,
+        parse: (el: HTMLElement) =>
+          el.classList.contains("shared") ? {} : undefined,
+      },
+    );
+
+  const makeEditor = (betaRunsBefore?: string[]) => {
+    const alpha = ambiguous("alpha")();
+    const beta = ambiguous("beta")();
+    if (betaRunsBefore) {
+      (beta.implementation as any).runsBefore = betaRunsBefore;
+    }
+
+    return BlockNoteEditor.create({
+      schema: BlockNoteSchema.create().extend({
+        blockSpecs: { ...defaultBlockSpecs, alpha, beta } as any,
+      }),
+    }) as BlockNoteEditor<any, any, any>;
+  };
+
+  it("orders a container's parse rules before another container's", () => {
+    // Declaration order wins by default; `runsBefore` overrides it.
+    for (const [runsBefore, winner] of [
+      [undefined, "alpha"],
+      [["alpha"], "beta"],
+    ] as const) {
+      const other = makeEditor(runsBefore ? [...runsBefore] : undefined);
+      try {
+        expect(
+          other.tryParseHTMLToBlocks('<div class="shared"><p>x</p></div>')[0]
+            .type,
+        ).toBe(winner);
+      } finally {
+        other._tiptapEditor.destroy();
+      }
+    }
+  });
+});
diff --git a/packages/core/src/schema/blocks/createSpec.test.ts b/packages/core/src/schema/blocks/createSpec.test.ts
index c42a9151ad..d8380e4f13 100644
--- a/packages/core/src/schema/blocks/createSpec.test.ts
+++ b/packages/core/src/schema/blocks/createSpec.test.ts
@@ -1,3 +1,4 @@
+import { Node as TiptapNode } from "@tiptap/core";
 import { describe, expect, it } from "vite-plus/test";
 
 import { BlockNoteSchema } from "../../blocks/BlockNoteSchema.js";
@@ -5,6 +6,8 @@ import { defaultBlockSpecs } from "../../blocks/defaultBlocks.js";
 import { BlockNoteEditor } from "../../editor/BlockNoteEditor.js";
 import { YAttributionMarksExtension } from "../../y/extensions/YAttributionMarks.js";
 import { createBlockConfig, createBlockSpec } from "../index.js";
+import { containerRootDOM } from "./createSpec.js";
+import { createBlockSpecFromTiptapNode } from "./internal.js";
 
 // A minimal "plain" content block WITHOUT a custom `parseContent`, so parsing
 // its HTML exercises the generic plain branch in `getParseRules`' `getContent`.
@@ -121,3 +124,259 @@ describe("plain content parsing", () => {
     editor._tiptapEditor.destroy();
   });
 });
+
+describe("block spec and node agreement", () => {
+  it("leaves a hand-written node's content expression authoritative", () => {
+    expect(() =>
+      BlockNoteSchema.create().extend({
+        blockSpecs: {
+          holder: createBlockSpecFromTiptapNode(
+            {
+              node: TiptapNode.create({
+                name: "holder",
+                group: "blockContent",
+                content: "paragraph+",
+              }),
+              type: "holder",
+              content: "none",
+            },
+            {},
+          ),
+        },
+      }),
+    ).not.toThrow();
+  });
+
+  it("rejects a hand-written node whose name contradicts its config", () => {
+    expect(() =>
+      BlockNoteSchema.create().extend({
+        blockSpecs: {
+          holder: createBlockSpecFromTiptapNode(
+            {
+              node: TiptapNode.create({
+                name: "notHolder",
+                group: "block",
+                content: "block+",
+              }),
+              type: "holder",
+              content: "none",
+              children: { allow: "blocks" },
+            },
+            {},
+          ),
+        },
+      }),
+    ).toThrow(/Node name does not match block type/);
+  });
+});
+
+describe("containerRootDOM", () => {
+  const element = () => document.createElement("div");
+
+  it("returns the dom itself when it is an element", () => {
+    const dom = element();
+    expect(containerRootDOM({ dom })).toBe(dom);
+  });
+
+  it("unwraps a fragment wrapping exactly one element", () => {
+    const root = element();
+    const fragment = document.createDocumentFragment();
+    fragment.append(root);
+    expect(containerRootDOM({ dom: fragment })).toBe(root);
+  });
+
+  it("returns null for a fragment with no single element root", () => {
+    const empty = document.createDocumentFragment();
+    expect(containerRootDOM({ dom: empty })).toBeNull();
+
+    const multi = document.createDocumentFragment();
+    multi.append(element(), element());
+    expect(containerRootDOM({ dom: multi })).toBeNull();
+
+    const textOnly = document.createDocumentFragment();
+    textOnly.append(document.createTextNode("text"));
+    expect(containerRootDOM({ dom: textOnly })).toBeNull();
+  });
+});
+
+describe("container children parsing", () => {
+  const renderDiv = () => {
+    const dom = document.createElement("div");
+    return { dom, contentDOM: dom };
+  };
+
+  const MixedBox = createBlockSpec(
+    {
+      type: "mixedBox" as const,
+      propSchema: {},
+      content: "none",
+      children: { allow: "blocks" },
+    },
+    { render: renderDiv },
+  )();
+
+  const createEditor = () =>
+    BlockNoteEditor.create({
+      schema: BlockNoteSchema.create({
+        blockSpecs: {
+          ...defaultBlockSpecs,
+          mixedBox: MixedBox,
+        },
+      }),
+    });
+
+  it("wraps loose text around blocks into child blocks without parseContent", () => {
+    const editor = createEditor();
+
+    const blocks = editor.tryParseHTMLToBlocks(
+      `<div data-node-type="mixedBox"><p>First</p>Loose text</div>`,
+    );
+
+    expect(blocks).toHaveLength(1);
+    expect(blocks[0].type).toBe("mixedBox");
+    expect(blocks[0].children.map((child: any) => child.type)).toEqual([
+      "paragraph",
+      "paragraph",
+    ]);
+    expect(
+      blocks[0].children.map((child: any) => child.content?.[0]?.text),
+    ).toEqual(["First", "Loose text"]);
+
+    editor._tiptapEditor.destroy();
+  });
+});
+
+describe("container render contract", () => {
+  const renderDiv = () => {
+    const dom = document.createElement("div");
+    return { dom, contentDOM: dom };
+  };
+
+  const createEditorWith = (spec: any) =>
+    BlockNoteEditor.create({
+      schema: BlockNoteSchema.create({
+        blockSpecs: { ...defaultBlockSpecs, probed: spec },
+      }),
+    });
+
+  it("rejects a container declaring neither render nor renderFrame", () => {
+    expect(() =>
+      createBlockSpec(
+        {
+          // @ts-expect-error render is required on every block.
+          type: "probed" as const,
+          propSchema: {},
+          content: "none" as const,
+          children: { allow: "blocks" },
+        },
+        {},
+      )(),
+    ).toThrow(/must declare `render`/);
+  });
+
+  it("rejects renderFrame alone on a block that is not a pure container", () => {
+    // A regular block always renders through `render`.
+    expect(() =>
+      createBlockSpec(
+        {
+          // @ts-expect-error render is required on every block.
+          type: "probed" as const,
+          propSchema: {},
+          content: "inline" as const,
+        },
+        {
+          renderFrame: () => {
+            const dom = document.createElement("div");
+            return { dom, slot: dom };
+          },
+        },
+      )(),
+    ).toThrow(/must declare `render`/);
+
+    // A titled block needs its title row: `renderFrame` alone is not enough.
+    expect(() =>
+      createBlockSpec(
+        {
+          // @ts-expect-error render is required on every block.
+          type: "probed" as const,
+          propSchema: {},
+          content: "inline" as const,
+          children: { allow: "blocks" },
+        },
+        {
+          renderFrame: () => {
+            const dom = document.createElement("div");
+            return { dom, slot: dom };
+          },
+        },
+      )(),
+    ).toThrow(/must declare `render`/);
+  });
+
+  it("rejects framing a pure container, whose render already owns its box", () => {
+    const framed = createBlockSpec(
+      {
+        type: "probed",
+        propSchema: {},
+        content: "none",
+        children: { allow: "blocks" },
+      },
+      {
+        render: renderDiv,
+        renderFrame: () => {
+          const dom = document.createElement("div");
+          return { dom, slot: dom };
+        },
+      },
+    )();
+    expect(() => createEditorWith(framed)).toThrow(
+      /requires a separate content node/,
+    );
+  });
+});
+
+it("scopes external container parsing to childrenDOM", () => {
+  const box = createBlockSpec(
+    {
+      type: "box",
+      propSchema: {},
+      content: "none",
+      children: { allow: "blocks" },
+    },
+    {
+      render() {
+        const dom = document.createElement("div");
+        return { dom, contentDOM: dom };
+      },
+      toExternalHTML() {
+        const dom = document.createElement("div");
+        const label = document.createElement("button");
+        label.textContent = "Control label";
+        const childrenDOM = document.createElement("div");
+        dom.append(label, childrenDOM);
+        return { dom, childrenDOM };
+      },
+    },
+  )();
+  const editor = BlockNoteEditor.create({
+    schema: BlockNoteSchema.create({
+      blockSpecs: { ...defaultBlockSpecs, box },
+    }),
+    initialContent: [
+      { type: "box", children: [{ type: "paragraph", content: "Body" }] },
+    ],
+  });
+  try {
+    const html = editor.blocksToHTMLLossy(editor.document);
+    expect(html).toContain('data-children-of="box"');
+    const parsed = editor.tryParseHTMLToBlocks(html);
+    expect(parsed).toHaveLength(1);
+    expect(parsed[0].type).toBe("box");
+    expect(parsed[0].children).toHaveLength(1);
+    expect(parsed[0].children[0].content).toEqual([
+      { type: "text", text: "Body", styles: {} },
+    ]);
+  } finally {
+    editor._tiptapEditor.destroy();
+  }
+});
diff --git a/packages/core/src/schema/blocks/createSpec.ts b/packages/core/src/schema/blocks/createSpec.ts
index 22fb91c321..02e1902aa3 100644
--- a/packages/core/src/schema/blocks/createSpec.ts
+++ b/packages/core/src/schema/blocks/createSpec.ts
@@ -1,4 +1,4 @@
-import { Editor, Node } from "@tiptap/core";
+import { Editor, Node, NodeViewRendererProps } from "@tiptap/core";
 import {
   DOMParser,
   Fragment,
@@ -6,6 +6,7 @@ import {
   TagParseRule,
 } from "@tiptap/pm/model";
 import { NodeView } from "@tiptap/pm/view";
+import { nodeToBlock } from "../../api/nodeConversions/nodeToBlock.js";
 import { mergeParagraphs } from "../../blocks/defaultBlockHelpers.js";
 import {
   Extension,
@@ -13,9 +14,20 @@ import {
 } from "../../editor/BlockNoteExtension.js";
 import { nonFormattingMarks } from "../markGroups.js";
 import { ignoreNonContentMutations } from "../nodeViewMutations.js";
+import { suggestionMarks } from "../../pm-nodes/suggestionMarks.js";
 import { PropSchema } from "../propTypes.js";
 import {
+  BLOCK_GROUP_CHILD_GROUP,
+  CHILD_CONTAINER_GROUP,
+  childrenContentExpression,
+  containerNodePriority,
+  isContainerConfig,
+} from "./children.js";
+import { applyContainerAttributes } from "./containerAttributes.js";
+import {
+  applyDOMAttributes,
   getBlockFromNodeView,
+  isDocumentFragment,
   propsToAttributes,
   wrapInBlockStructure,
 } from "./internal.js";
@@ -45,9 +57,115 @@ export function applyNonSelectableBlockFix(nodeView: NodeView, editor: Editor) {
   };
 }
 
-// Function that uses the 'parse' function of a blockConfig to create a
-// TipTap node's `parseHTML` property. This is only used for parsing content
-// from the clipboard.
+// Finds the element holding a serialized container block's children, marked
+// `data-children-of` by the internal HTML serializer. Returns undefined when
+// no marker belonging to *this* block (rather than a same-typed nested
+// container) is present.
+function findContainerContentElement(
+  el: HTMLElement,
+  config: { type: string },
+): HTMLElement | undefined {
+  const selector = `[data-children-of="${config.type}"]`;
+
+  // The block's root may itself be the children host (a render that passes
+  // its own root to `contentRef`). `querySelectorAll` only sees descendants.
+  if (el.matches(selector)) {
+    return el;
+  }
+
+  for (const host of el.querySelectorAll<HTMLElement>(selector)) {
+    // Skip hosts of same-typed *nested* containers: this block's own host is
+    // the one with no other container root between it and `el`.
+    if (host.parentElement?.closest("[data-node-type]") === el) {
+      return host;
+    }
+  }
+
+  return undefined;
+}
+
+// Custom parsing, followed by the default parser for the block's content kind.
+function blockContentParser<
+  TName extends string,
+  TProps extends PropSchema,
+  TContent extends "inline" | "none" | "table" | "plain",
+>(
+  config: BlockConfig<TName, TProps, TContent>,
+  implementation: BlockImplementation<TName, TProps, TContent>,
+): TagParseRule["getContent"] | undefined {
+  const isContainer = isContainerConfig(config);
+  if (
+    config.content === "table" ||
+    (isContainer && !implementation.parseContent)
+  ) {
+    // Tables use their own rules. Containers without parseContent use PM's
+    // normal child parsing, including wrapping inline runs as paragraphs.
+    return undefined;
+  }
+
+  return (node, schema) => {
+    if (implementation.parseContent) {
+      const result = implementation.parseContent({
+        el: node as HTMLElement,
+        schema,
+      });
+      // parseContent may return undefined to fall through to the default
+      // inline content parsing below.
+      if (result !== undefined) {
+        return result;
+      }
+    }
+
+    if (isContainer) {
+      return DOMParser.fromSchema(schema).parse(node as HTMLElement, {
+        topNode: schema.nodes["blockGroup"].create(),
+        preserveWhitespace: true,
+      }).content;
+    }
+
+    if (config.content === "none") {
+      return Fragment.empty;
+    }
+
+    // Cloned so merging doesn't modify the element being parsed.
+    const clone = (node as HTMLElement).cloneNode(true) as HTMLElement;
+    // Merge multiple paragraphs into one with line breaks
+    mergeParagraphs(
+      clone,
+      config.content === "plain" || implementation.meta?.code ? "\n" : "<br>",
+    );
+
+    // Parsed as a paragraph, to extract the inline content by itself.
+    const parsed = DOMParser.fromSchema(schema).parse(clone, {
+      topNode: schema.nodes.paragraph.create(),
+      preserveWhitespace: config.content === "plain" ? "full" : true,
+    });
+
+    if (config.content === "inline") {
+      return parsed.content;
+    }
+
+    // Plain blocks hold text only, so non-text inline nodes are flattened:
+    // line breaks become newline characters and other nodes (e.g. mentions)
+    // are kept as their text.
+    const textNodes: PMNode[] = [];
+    parsed.content.forEach((child) => {
+      if (child.isText) {
+        textNodes.push(child);
+        return;
+      }
+      const text =
+        child.type === schema.linebreakReplacement ? "\n" : child.textContent;
+      if (text) {
+        textNodes.push(schema.text(text, child.marks));
+      }
+    });
+
+    return Fragment.fromArray(textNodes);
+  };
+}
+
+// Creates `parseHTML` rules for clipboard parsing.
 export function getParseRules<
   TName extends string,
   TProps extends PropSchema,
@@ -56,11 +174,27 @@ export function getParseRules<
   config: BlockConfig<TName, TProps, TContent>,
   implementation: BlockImplementation<TName, TProps, TContent>,
 ) {
+  const isContainer = isContainerConfig(config);
+
   const rules: TagParseRule[] = [
-    {
-      tag: "[data-content-type=" + config.type + "]",
-      contentElement: ".bn-inline-content",
-    },
+    isContainer
+      ? {
+          tag: `[data-node-type=${config.type}]`,
+          // Scope the round-trip parse to the block's content region, so text
+          // the render puts elsewhere in its DOM (button labels, captions,
+          // ...) doesn't parse back as document content. The internal HTML
+          // serializer marks the region with `data-children-of`; HTML without
+          // the marker (older or hand-written) falls back to the whole
+          // element, the previous behavior.
+          contentElement: (el) =>
+            findContainerContentElement(el as HTMLElement, config) ??
+            (el as HTMLElement),
+        }
+      : {
+          tag: "[data-content-type=" + config.type + "]",
+          contentElement: ".bn-inline-content",
+          preserveWhitespace: config.content === "plain" ? "full" : undefined,
+        },
   ];
 
   if (implementation.parse) {
@@ -81,280 +215,241 @@ export function getParseRules<
       },
       // Because we do the parsing ourselves, we want to preserve whitespace for content we've parsed
       preserveWhitespace: true,
-      getContent:
-        config.content === "inline" ||
-        config.content === "none" ||
-        config.content === "plain"
-          ? (node, schema) => {
-              if (implementation.parseContent) {
-                const result = implementation.parseContent({
-                  el: node as HTMLElement,
-                  schema,
-                });
-                // parseContent may return undefined to fall through to
-                // the default inline content parsing below.
-                if (result !== undefined) {
-                  return result;
-                }
-              }
-
-              if (config.content === "inline" || config.content === "plain") {
-                // Parse the inline content if it exists
-                const element = node as HTMLElement;
-
-                // Clone to avoid modifying the original
-                const clone = element.cloneNode(true) as HTMLElement;
-
-                // Merge multiple paragraphs into one with line breaks
-                mergeParagraphs(
-                  clone,
-                  config.content === "plain" || implementation.meta?.code
-                    ? "\n"
-                    : "<br>",
-                );
-
-                // Parse the content directly as a paragraph to extract inline content
-                const parser = DOMParser.fromSchema(schema);
-                const parsed = parser.parse(clone, {
-                  topNode: schema.nodes.paragraph.create(),
-                  preserveWhitespace: true,
-                });
-
-                if (config.content === "plain") {
-                  // Plain blocks hold text only, so non-text inline nodes are
-                  // flattened: line breaks become newline characters and other
-                  // nodes (e.g. mentions) are kept as their text.
-                  const textNodes: PMNode[] = [];
-                  parsed.content.forEach((child) => {
-                    if (child.isText) {
-                      textNodes.push(child);
-                    } else {
-                      const text =
-                        child.type === schema.linebreakReplacement
-                          ? "\n"
-                          : child.textContent;
-                      if (text) {
-                        textNodes.push(schema.text(text, child.marks));
-                      }
-                    }
-                  });
-
-                  return Fragment.fromArray(textNodes);
-                }
-                return parsed.content;
-              }
-              return Fragment.empty;
-            }
-          : undefined,
+      getContent: blockContentParser(config, implementation),
     });
   }
-  //     getContent(node, schema) {
-  //       const block = blockConfig.parse?.(node as HTMLElement);
-  //
-  //       if (block !== undefined && block.content !== undefined) {
-  //         return Fragment.from(
-  //           typeof block.content === "string"
-  //             ? schema.text(block.content)
-  //             : inlineContentToNodes(block.content, schema)
-  //         );
-  //       }
-  //
-  //       return Fragment.empty;
-  //     },
-  //   });
-  // }
 
   return rules;
 }
 
-// What the generated node's content expression is for each `content` kind.
-const CONTENT_EXPRESSIONS: Record<BlockConfig["content"], string> = {
-  inline: "inline*",
-  plain: "text*",
-  none: "",
-  table: "tableRow+",
-};
-
-/**
- * Content expressions that are spelled differently can still mean the same
- * thing, e.g. `"(text)*"` and `"text*"`. Unwraps a parenthesized single
- * term, with or without a trailing quantifier, so equivalent spellings
- * compare equal. Anything with real structure (sequences, alternation) is
- * left as-is: unwrapping those would change the expression's meaning.
- */
-function normalizeContentExpression(expression: string): string {
-  const trimmed = expression.trim();
-  const match = trimmed.match(/^\(([A-Za-z_][A-Za-z0-9_]*)\)([*+?])?$/);
-  return match ? `${match[1]}${match[2] ?? ""}` : trimmed;
+export function containerRootDOM(output: {
+  dom: HTMLElement | DocumentFragment;
+}): HTMLElement | null {
+  if (isDocumentFragment(output.dom)) {
+    // A fragment can't hold attributes, so the round-trip markers
+    // (`data-node-type`, prop `data-*`) would be lost with it as the root.
+    // When it wraps a single element (the shape a React render produces),
+    // that element is the block's real root. A multi-element fragment has no
+    // root to mark, so its container HTML can't parse back.
+    return output.dom.children.length === 1
+      ? (output.dom.children[0] as HTMLElement)
+      : null;
+  }
+  return output.dom;
 }
 
-/**
- * Checks a hand-written node against its config: that the node name matches
- * the block type, and that the node's content expression matches the
- * `content` the spec declares — the one `getBlockInfoFromPos` reports as the
- * block's `contentKind`, without looking at the node. A generated node's name
- * and expression come from that same config, so this only bites on a
- * hand-written one (`createBlockSpecFromTiptapNode`).
- */
-function checkNodeMatchesConfig(node: Node, blockConfig: BlockConfig) {
-  if (node.name !== blockConfig.type) {
-    throw new Error(
-      "Node name does not match block type. This is a bug in BlockNote.",
-    );
-  }
+function blockNodeView<
+  TName extends string,
+  TProps extends PropSchema,
+  TContent extends "inline" | "none" | "table" | "plain",
+>(
+  blockConfig: BlockConfig<TName, TProps, TContent>,
+  blockImplementation: BlockImplementation<TName, TProps, TContent>,
+  props: NodeViewRendererProps,
+): NodeView {
+  const isContainer = isContainerConfig(blockConfig);
+  const block = isContainer
+    ? nodeToBlock(props.node, props.view.state.doc)
+    : getBlockFromNodeView(props.getPos, props.node, props.view.state.doc);
+  const nodeView = blockImplementation.render.call(
+    {
+      blockContentDOMAttributes:
+        props.extension.options.domAttributes?.blockContent || {},
+      props,
+      renderType: "nodeView",
+      propSchema: blockConfig.propSchema,
+    },
+    block as any,
+    props.extension.options.editor,
+  );
+
+  const typedNodeView = nodeView as unknown as NodeView;
 
-  // A wrapper node that holds child blocks directly (e.g. a hand-written
-  // `column`) has no block content expression to compare against.
-  const groups = typeof node.config.group === "string" ? node.config.group : "";
-  if (groups.split(" ").includes("bnBlock")) {
-    return;
+  if (blockImplementation.meta?.selectable === false) {
+    applyNonSelectableBlockFix(typedNodeView, props.editor);
   }
 
-  // tiptap allows the expression to be a function of the editor, in which case
-  // there is nothing to compare yet.
-  const content = node.config.content;
-  if (content !== undefined && typeof content !== "string") {
-    return;
+  ignoreNonContentMutations(typedNodeView);
+
+  if (!isContainer) {
+    return typedNodeView;
   }
 
-  const expected = CONTENT_EXPRESSIONS[blockConfig.content];
-  if (
-    normalizeContentExpression(content ?? "") !==
-    normalizeContentExpression(expected)
-  ) {
-    throw new Error(
-      `Block "${blockConfig.type}" declares \`content: "${blockConfig.content}"\`, ` +
-        `but its node holds "${content ?? ""}" rather than "${expected}".`,
+  applyContainerAttributes(
+    containerRootDOM(nodeView),
+    blockConfig.type,
+    block.props as any,
+    blockConfig.propSchema,
+    block.id,
+  );
+
+  // Mark the children host in the live DOM, mirroring what the internal HTML
+  // serializer emits, so the container's round-trip parse rule can scope
+  // itself to it (`contentElement` in `getParseRules`) when ProseMirror
+  // re-reads editor DOM.
+  if (typedNodeView.contentDOM) {
+    (typedNodeView.contentDOM as HTMLElement).setAttribute(
+      "data-children-of",
+      blockConfig.type,
     );
   }
+
+  const update = typedNodeView.update?.bind(typedNodeView);
+  if (update) {
+    typedNodeView.update = (node, decorations, innerDecorations) => {
+      if (node.type.name !== blockConfig.type) {
+        return false;
+      }
+      if (update(node, decorations, innerDecorations) === false) {
+        return false;
+      }
+      applyContainerAttributes(
+        containerRootDOM(nodeView),
+        blockConfig.type,
+        nodeToBlock(node, props.view.state.doc).props as any,
+        blockConfig.propSchema,
+        node.attrs.id,
+      );
+      return true;
+    };
+  }
+
+  return typedNodeView;
 }
 
-// A function to create custom block for API consumers
-// we want to hide the tiptap node from API consumers and provide a simpler API surface instead
-export function addNodeAndExtensionsToSpec<
+function buildNode<
   TName extends string,
   TProps extends PropSchema,
   TContent extends "inline" | "none" | "table" | "plain",
 >(
   blockConfig: BlockConfig<TName, TProps, TContent>,
   blockImplementation: BlockImplementation<TName, TProps, TContent>,
-  extensions?: (ExtensionFactoryInstance | Extension)[],
   priority?: number,
-): LooseBlockSpec<TName, TProps, TContent> {
-  const builtNode =
-    ((blockImplementation as any).node as Node) ||
-    Node.create({
-      name: blockConfig.type,
-      content: (blockConfig.content === "inline"
+) {
+  const isContainer = isContainerConfig(blockConfig);
+  return Node.create({
+    name: blockConfig.type,
+    content: isContainer
+      ? childrenContentExpression(blockConfig.children!)
+      : blockConfig.content === "inline"
         ? "inline*"
         : blockConfig.content === "plain"
           ? "text*"
           : blockConfig.content === "none"
             ? ""
-            : blockConfig.content) as TContent extends "inline"
-        ? "inline*"
-        : TContent extends "plain"
-          ? "text*"
-          : "",
-      // "plain" blocks hold unstyled text, so they disallow formatting marks.
-      // They still allow the non-formatting marks (comments and
-      // suggestions/diffs) — those annotate content without changing it and are
-      // ignored by the block model. `nonFormattingMarks` resolves the group only
-      // when at least one such mark is registered, so a plain block in an editor
-      // without any of them doesn't reference an empty (unknown) mark group.
-      marks() {
-        return blockConfig.content === "plain"
+            : blockConfig.content,
+    // "plain" blocks hold unstyled text, so they disallow formatting marks.
+    // They still allow the non-formatting marks (comments and
+    // suggestions/diffs), which annotate content without changing it and are
+    // ignored by the block model. `nonFormattingMarks` resolves the group only
+    // when at least one such mark is registered, so a plain block in an editor
+    // without any of them doesn't reference an empty (unknown) mark group.
+    marks() {
+      return isContainer
+        ? suggestionMarks(this.editor)
+        : blockConfig.content === "plain"
           ? nonFormattingMarks(this.editor)
           : undefined;
-      },
-      group: "blockContent",
-      selectable: blockImplementation.meta?.selectable ?? true,
-      isolating: blockImplementation.meta?.isolating ?? true,
-      code: blockImplementation.meta?.code ?? false,
-      defining: blockImplementation.meta?.defining ?? true,
-      priority,
-      addAttributes() {
-        return propsToAttributes(blockConfig.propSchema);
-      },
-
-      parseHTML() {
-        return getParseRules(blockConfig, blockImplementation);
-      },
-
-      renderHTML({ HTMLAttributes }) {
-        // renderHTML is used for copy/pasting content from the editor back into
-        // the editor, so we need to make sure the `blockContent` element is
-        // structured correctly as this is what's used for parsing blocks. We
-        // just render a placeholder div inside as the `blockContent` element
-        // already has all the information needed for proper parsing.
-        const div = document.createElement("div");
-        return wrapInBlockStructure(
-          {
-            dom: div,
-            contentDOM:
-              blockConfig.content === "inline" ||
-              blockConfig.content === "plain"
-                ? div
-                : undefined,
-          },
-          blockConfig.type,
-          {},
-          blockConfig.propSchema,
-          blockImplementation.meta?.fileBlockAccept !== undefined,
-          HTMLAttributes,
-        );
-      },
+    },
+    group: isContainer
+      ? [
+          "bnBlock",
+          CHILD_CONTAINER_GROUP,
+          ...(blockConfig.placeable === "namedOnly"
+            ? []
+            : [BLOCK_GROUP_CHILD_GROUP]),
+        ].join(" ")
+      : "blockContent",
+    selectable: blockImplementation.meta?.selectable ?? true,
+    // Containers must remain open to paste across their edges; isolating
+    // makes ProseMirror wrap spanning slices in a spurious blockGroup.
+    isolating: isContainer
+      ? false
+      : (blockImplementation.meta?.isolating ?? true),
+    code: isContainer ? false : (blockImplementation.meta?.code ?? false),
+    defining: isContainer ? true : (blockImplementation.meta?.defining ?? true),
+    priority: isContainer ? containerNodePriority(priority) : priority,
+    addAttributes() {
+      return propsToAttributes(blockConfig.propSchema);
+    },
 
-      addNodeView() {
-        return (props) => {
-          // Gets the BlockNote editor instance
-          const editor = this.options.editor;
-          // Gets the block. Resolving this can't rely on `getPos()` alone —
-          // node views are constructed part-way through ProseMirror's
-          // reconciliation, where positions don't always line up with
-          // `view.state.doc` yet (see `getBlockFromNodeView`).
-          const block = getBlockFromNodeView(
-            props.getPos,
-            props.node,
-            props.view.state.doc,
-          );
-          // Gets the custom HTML attributes for `blockContent` nodes
-          const blockContentDOMAttributes =
-            this.options.domAttributes?.blockContent || {};
+    parseHTML() {
+      return getParseRules(blockConfig, blockImplementation);
+    },
 
-          const nodeView = blockImplementation.render.call(
-            {
-              blockContentDOMAttributes,
-              props,
-              renderType: "nodeView",
-              propSchema: blockConfig.propSchema,
-            },
-            block as any,
-            editor as any,
-          );
+    renderHTML({ HTMLAttributes }) {
+      if (isContainer) {
+        const dom = document.createElement("div");
+        dom.setAttribute("data-node-type", blockConfig.type);
+        for (const [attribute, value] of Object.entries(HTMLAttributes)) {
+          dom.setAttribute(attribute, value as string);
+        }
+        return { dom, contentDOM: dom };
+      }
+
+      // renderHTML is used for copy/pasting content from the editor back into
+      // the editor, so we need to make sure the `blockContent` element is
+      // structured correctly as this is what's used for parsing blocks. We
+      // just render a placeholder div inside as the `blockContent` element
+      // already has all the information needed for proper parsing.
+      const div = document.createElement("div");
+      return wrapInBlockStructure(
+        {
+          dom: div,
+          contentDOM:
+            blockConfig.content === "inline" || blockConfig.content === "plain"
+              ? div
+              : undefined,
+        },
+        blockConfig.type,
+        {},
+        blockConfig.propSchema,
+        blockImplementation.meta?.fileBlockAccept !== undefined,
+        HTMLAttributes,
+      );
+    },
 
-          // Cast needed because render returns `dom: HTMLElement | DocumentFragment`
-          // but tiptap's NodeView expects `dom: HTMLElement`
-          const typedNodeView = nodeView as unknown as NodeView;
+    addNodeView() {
+      return (props) => blockNodeView(blockConfig, blockImplementation, props);
+    },
+  });
+}
 
-          if (blockImplementation.meta?.selectable === false) {
-            applyNonSelectableBlockFix(typedNodeView, this.editor);
-          }
+// A function to create custom block for API consumers
+// we want to hide the tiptap node from API consumers and provide a simpler API surface instead
+export function addNodeAndExtensionsToSpec<
+  TName extends string,
+  TProps extends PropSchema,
+  TContent extends "inline" | "none" | "table" | "plain",
+>(
+  blockConfig: BlockConfig<TName, TProps, TContent>,
+  blockImplementation: BlockImplementation<TName, TProps, TContent>,
+  extensions?: (ExtensionFactoryInstance | Extension)[],
+  priority?: number,
+): LooseBlockSpec<TName, TProps, TContent> {
+  // Only a contentless block builds a container node. A block with content of
+  // its own keeps its ordinary shape, and its `children` are owned children
+  // instead.
+  const isContainer = isContainerConfig(blockConfig);
 
-          // Ignores DOM mutations that don't affect the block's content, so
-          // that browser extensions which rewrite the DOM (e.g. Dark Reader)
-          // can't trigger an infinite re-render loop that freezes the tab.
-          ignoreNonContentMutations(typedNodeView);
+  const builtNode: Node =
+    (blockImplementation as any).node ??
+    buildNode(blockConfig, blockImplementation, priority);
 
-          // See explanation for why `update` is not implemented for NodeViews
-          // https://github.com/TypeCellOS/BlockNote/pull/1904#discussion_r2313461464
-          // https://github.com/TypeCellOS/BlockNote/issues/220
-          return typedNodeView;
-        };
-      },
-    });
+  if (builtNode.name !== blockConfig.type) {
+    throw new Error(
+      "Node name does not match block type. This is a bug in BlockNote.",
+    );
+  }
 
-  checkNodeMatchesConfig(builtNode, blockConfig as BlockConfig);
+  if (!blockImplementation.render) {
+    throw new Error(`Block "${blockConfig.type}" must declare \`render\`.`);
+  }
+  if (isContainer && blockImplementation.renderFrame) {
+    throw new Error(
+      `Container block "${blockConfig.type}" draws its box in \`render\`; \`renderFrame\` requires a separate content node.`,
+    );
+  }
 
   // The block's config is stored on its node's PM spec
   // (`NodeSpec.blockConfig`), so code holding a bare `Node` can consult it
@@ -366,51 +461,65 @@ export function addNodeAndExtensionsToSpec<
     },
   });
 
+  function serialize(
+    block: Parameters<LooseBlockSpec["implementation"]["render"]>[0],
+    editor: Parameters<LooseBlockSpec["implementation"]["render"]>[1],
+    context?: { nestingLevel: number },
+  ) {
+    const blockContentDOMAttributes =
+      node.options.domAttributes?.blockContent || {};
+    const external =
+      context &&
+      blockImplementation.toExternalHTML?.call(
+        { blockContentDOMAttributes, propSchema: blockConfig.propSchema },
+        block,
+        editor as any,
+        context,
+      );
+    const output =
+      external ??
+      blockImplementation.render.call(
+        {
+          blockContentDOMAttributes,
+          props: undefined,
+          renderType: "dom",
+          propSchema: blockConfig.propSchema,
+        },
+        block,
+        editor as any,
+      );
+
+    if (isContainer) {
+      applyContainerAttributes(
+        containerRootDOM(output),
+        blockConfig.type,
+        block.props,
+        blockConfig.propSchema,
+        block.id,
+      );
+    } else if (context && !external) {
+      // An explicit external renderer owns the complete export. Otherwise
+      // wrap the default content and children in the editor's frame.
+      const frame = blockImplementation.renderFrame?.call(
+        { renderType: "dom", props: undefined, blockContentDOMAttributes },
+        block,
+        editor as any,
+      );
+      if (frame) {
+        frame.slot.append(output.dom);
+        return { ...output, dom: frame.dom, childrenDOM: frame.slot };
+      }
+    }
+    return output;
+  }
+
   return {
     config: blockConfig,
     implementation: {
       ...blockImplementation,
       node,
-      render(block, editor) {
-        const blockContentDOMAttributes =
-          node.options.domAttributes?.blockContent || {};
-
-        return blockImplementation.render.call(
-          {
-            blockContentDOMAttributes,
-            props: undefined,
-            renderType: "dom",
-            propSchema: blockConfig.propSchema,
-          },
-          block as any,
-          editor as any,
-        );
-      },
-      // TODO: this should not have wrapInBlockStructure and generally be a lot simpler
-      // post-processing in externalHTMLExporter should not be necessary
-      toExternalHTML: (block, editor, context) => {
-        const blockContentDOMAttributes =
-          node.options.domAttributes?.blockContent || {};
-
-        return (
-          blockImplementation.toExternalHTML?.call(
-            { blockContentDOMAttributes, propSchema: blockConfig.propSchema },
-            block as any,
-            editor as any,
-            context,
-          ) ??
-          blockImplementation.render.call(
-            {
-              blockContentDOMAttributes,
-              renderType: "dom",
-              props: undefined,
-              propSchema: blockConfig.propSchema,
-            },
-            block as any,
-            editor as any,
-          )
-        );
-      },
+      render: serialize,
+      toExternalHTML: serialize,
     },
     extensions,
   };
@@ -520,6 +629,16 @@ export function createBlockSpec<
         : extensionsOrCreator
       : undefined;
 
+    // Only a contentless block is a container here. A block with content of
+    // its own keeps its ordinary shape, and its `children` are owned children
+    // instead.
+    const isContainer = isContainerConfig(blockConfig);
+
+    // Keep the existing render contract, including for JS callers.
+    if (!blockImplementation.render) {
+      throw new Error(`Block "${blockConfig.type}" must declare \`render\`.`);
+    }
+
     return {
       config: blockConfig,
       implementation: {
@@ -538,6 +657,11 @@ export function createBlockSpec<
             return undefined;
           }
 
+          if (isContainer) {
+            applyDOMAttributes(output.dom, this.blockContentDOMAttributes);
+            return output;
+          }
+
           return wrapInBlockStructure(
             output,
             block.type,
@@ -557,6 +681,11 @@ export function createBlockSpec<
             editor as any,
           );
 
+          if (isContainer) {
+            applyDOMAttributes(output.dom, this.blockContentDOMAttributes);
+            return output;
+          }
+
           const nodeView = wrapInBlockStructure(
             output,
             block.type,
diff --git a/packages/core/src/schema/blocks/internal.ts b/packages/core/src/schema/blocks/internal.ts
index cfd17b9d11..cc8970940e 100644
--- a/packages/core/src/schema/blocks/internal.ts
+++ b/packages/core/src/schema/blocks/internal.ts
@@ -6,7 +6,7 @@ import type { ExtensionFactoryInstance } from "../../editor/BlockNoteExtension.j
 import { mergeCSSClasses } from "../../util/browser.js";
 import { camelToDataKebab } from "../../util/string.js";
 import { PropSchema, Props } from "../propTypes.js";
-import { LooseBlockSpec } from "./types.js";
+import { BlockConfig, ChildrenConfig, LooseBlockSpec } from "./types.js";
 
 // Function that uses the 'propSchema' of a blockConfig to create a TipTap
 // node's `addAttributes` property.
@@ -157,6 +157,39 @@ export function getBlockFromNodeView(
   }
 }
 
+/**
+ * `Node.DOCUMENT_FRAGMENT_NODE`, inlined. Server-side rendering shims only
+ * `document` and `window` onto the global scope, so `Node` and
+ * `DocumentFragment` are undefined there and `instanceof` throws.
+ */
+const DOCUMENT_FRAGMENT_NODE = 11;
+
+export function isDocumentFragment(
+  node: HTMLElement | DocumentFragment,
+): node is DocumentFragment {
+  return node.nodeType === DOCUMENT_FRAGMENT_NODE;
+}
+
+/**
+ * Applies custom `blockContent` DOM attributes to an element, merging (rather
+ * than overwriting) its class list.
+ */
+export function applyDOMAttributes(
+  dom: HTMLElement | DocumentFragment,
+  domAttributes: Record<string, string> | undefined,
+) {
+  if (!domAttributes || isDocumentFragment(dom)) {
+    return;
+  }
+  for (const [attr, value] of Object.entries(domAttributes)) {
+    if (attr === "class") {
+      dom.className = mergeCSSClasses(dom.className, value);
+    } else {
+      dom.setAttribute(attr, value);
+    }
+  }
+}
+
 // Function that wraps the `dom` element returned from 'blockConfig.render' in a
 // `blockContent` div, which contains the block type and props as HTML
 // attributes. If `blockConfig.render` also returns a `contentDOM`, it also adds
@@ -232,6 +265,12 @@ export function createBlockSpecFromTiptapNode<
     node: Node;
     type: string;
     content: "inline" | "table" | "none" | "plain";
+    // Declares the block's container semantics (child counts/repair etc.)
+    // even though the node itself is hand-written. The node's own content
+    // expression stays authoritative for the PM schema, while BlockNote-level
+    // behavior (repair, seeding, validation) reads this config.
+    children?: ChildrenConfig;
+    placeable?: BlockConfig["placeable"];
   },
   P extends PropSchema,
 >(
@@ -244,6 +283,10 @@ export function createBlockSpecFromTiptapNode<
       type: config.type as T["type"],
       content: config.content,
       propSchema,
+      ...(config.children !== undefined ? { children: config.children } : {}),
+      ...(config.placeable !== undefined
+        ? { placeable: config.placeable }
+        : {}),
     },
     implementation: {
       node: config.node,
diff --git a/packages/core/src/schema/blocks/renderFrame.test.ts b/packages/core/src/schema/blocks/renderFrame.test.ts
new file mode 100644
index 0000000000..cb0419b699
--- /dev/null
+++ b/packages/core/src/schema/blocks/renderFrame.test.ts
@@ -0,0 +1,450 @@
+import { describe, expect, it, vi } from "vite-plus/test";
+
+import { BlockNoteSchema } from "../../blocks/BlockNoteSchema.js";
+import { defaultBlockSpecs } from "../../blocks/defaultBlocks.js";
+import { BlockNoteEditor } from "../../editor/BlockNoteEditor.js";
+import {
+  CONTAINER_SELECTOR,
+  getBlockFromElement,
+  getDraggableBlockFromElement,
+} from "../../extensions/blockDOM.js";
+import type { LooseBlockSpec } from "./types.js";
+import { createBlockSpec } from "./createSpec.js";
+
+// Behaviour of the vanilla `renderFrame` hook: a block draws the box around
+// its content and children, and may decline the frame by returning
+// `undefined` — the toggle pattern. A frame can be patched
+// in place through `update`.
+
+const renderDiv = () => {
+  const dom = document.createElement("div");
+  return { dom, contentDOM: dom };
+};
+
+// A titled block that is only framed when it says so: closed toggles draw
+// the box, open ones render as plain nesting.
+const Toggle = createBlockSpec(
+  {
+    type: "toggle" as const,
+    propSchema: {
+      mode: {
+        default: "plain",
+        values: ["plain", "framed"],
+      },
+    },
+    content: "inline",
+    children: { allow: "blocks" },
+  },
+  {
+    render: renderDiv,
+    renderFrame: (block) => {
+      if (block.props.mode !== "framed") {
+        return undefined;
+      }
+      const dom = document.createElement("div");
+      dom.className = "toggle";
+      const slot = document.createElement("div");
+      slot.className = "toggle-slot";
+      dom.append(slot);
+      return { dom, slot };
+    },
+  },
+)();
+
+// A titled block with an update hook that patches frame chrome in place.
+const FrameBox = createBlockSpec(
+  {
+    type: "frameBox" as const,
+    propSchema: {
+      flavor: {
+        default: "tip",
+        values: ["tip", "warning"],
+      },
+    },
+    content: "inline",
+    children: { allow: "blocks" },
+  },
+  {
+    render: renderDiv,
+    renderFrame: (block) => {
+      const dom = document.createElement("div");
+      dom.className = "frame-box";
+      dom.dataset.flavor = block.props.flavor;
+      const slot = document.createElement("div");
+      slot.className = "frame-slot";
+      dom.append(slot);
+      return {
+        dom,
+        slot,
+        update: (newBlock) => {
+          dom.dataset.flavor = (newBlock as any).props.flavor;
+        },
+      };
+    },
+  },
+)();
+
+const ContentFrame = createBlockSpec(
+  {
+    type: "contentFrame",
+    propSchema: {},
+    content: "inline",
+    children: { allow: "blocks" },
+  },
+  {
+    render: renderDiv,
+    meta: { draggable: false },
+    renderFrame(block) {
+      if (block.children.length === 0) {
+        return undefined;
+      }
+      const dom = document.createElement("section");
+      dom.className = "content-frame";
+      dom.dataset.title = JSON.stringify(block.content);
+      dom.dataset.count = String(block.children.length);
+      const slot = document.createElement("div");
+      dom.append(slot);
+      const fragment = document.createDocumentFragment();
+      fragment.append(dom);
+      return { dom: fragment, slot };
+    },
+  },
+)();
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    toggle: Toggle,
+    contentFrame: ContentFrame,
+    frameBox: FrameBox,
+  } as const,
+});
+
+function editorWith(initialContent: any[]) {
+  const editor = BlockNoteEditor.create({ schema, initialContent });
+  editor.mount(document.createElement("div"));
+  return editor;
+}
+
+describe("renderFrame decline", () => {
+  it("renders plain nesting when declined, frames when accepted, and flips back", () => {
+    const editor = editorWith([
+      {
+        id: "t1",
+        type: "toggle",
+        props: { mode: "plain" },
+        content: "Title",
+        children: [{ id: "c1", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    try {
+      const root = editor.domElement!;
+      // Declined: ordinary nesting, no box.
+      expect(root.querySelector(".toggle")).toBeNull();
+      expect(root.textContent).toContain("Title");
+      expect(root.textContent).toContain("Body");
+
+      editor.updateBlock("t1", {
+        props: { mode: "framed" },
+      } as any);
+
+      // Accepted: the box wraps the title and the body together, and the
+      // child block survives the rebuild.
+      const framed = root.querySelector<HTMLElement>(".toggle")!;
+      expect(framed).not.toBeNull();
+      const slot = framed.querySelector<HTMLElement>(".toggle-slot")!;
+      expect(slot.textContent).toContain("Title");
+      expect(slot.querySelector('[data-id="c1"]')).not.toBeNull();
+      expect(slot.textContent).toContain("Body");
+      expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+
+      editor.updateBlock("t1", {
+        props: { mode: "plain" },
+      } as any);
+
+      // Declined again: the box is gone, the content is intact.
+      expect(root.querySelector(".toggle")).toBeNull();
+      expect(root.textContent).toContain("Title");
+      expect(root.textContent).toContain("Body");
+      expect(root.querySelector('[data-id="c1"]')).not.toBeNull();
+      expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+    } finally {
+      editor._tiptapEditor.destroy();
+    }
+  });
+});
+
+describe("renderFrame updates", () => {
+  it("re-evaluates a declined frame when children appear and disappear", () => {
+    const editor = editorWith([
+      { id: "frame", type: "contentFrame", content: "Title" },
+    ]);
+    try {
+      expect(editor.domElement!.querySelector(".content-frame")).toBeNull();
+      editor.updateBlock("frame", {
+        children: [{ id: "child", type: "paragraph", content: "Body" }],
+      });
+      expect(
+        editor
+          .domElement!.querySelector(".content-frame")
+          ?.getAttribute("data-count"),
+      ).toBe("1");
+      editor.removeBlocks(["child"]);
+      expect(editor.domElement!.querySelector(".content-frame")).toBeNull();
+      expect(editor.domElement!.textContent).toContain("Title");
+    } finally {
+      editor._tiptapEditor.destroy();
+    }
+  });
+
+  it("refreshes vanilla frame chrome when title content changes", () => {
+    const editor = editorWith([
+      {
+        id: "frame",
+        type: "contentFrame",
+        content: "Title",
+        children: [{ id: "child", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    try {
+      editor.updateBlock("frame", { content: "Updated" });
+      expect(
+        editor
+          .domElement!.querySelector(".content-frame")
+          ?.getAttribute("data-title"),
+      ).toContain("Updated");
+      expect(
+        editor.domElement!.querySelector('[data-id="child"]')?.textContent,
+      ).toBe("Body");
+    } finally {
+      editor._tiptapEditor.destroy();
+    }
+  });
+
+  it("mounts children in the slot and patches chrome in place on prop change", () => {
+    const editor = editorWith([
+      {
+        id: "box-0",
+        type: "frameBox",
+        props: { flavor: "warning" },
+        children: [{ id: "box-child", type: "paragraph", content: "Child" }],
+      },
+    ]);
+    try {
+      const root = editor.domElement!;
+      const box = root.querySelector<HTMLElement>(".frame-box")!;
+      // Non-default props are stamped for the round-trip parse to read.
+      expect(box.getAttribute("data-flavor")).toBe("warning");
+      const slot = box.querySelector<HTMLElement>(".frame-slot")!;
+      expect(slot.querySelector('[data-id="box-child"]')).not.toBeNull();
+      expect(slot.textContent).toBe("Child");
+
+      editor.updateBlock("box-0", {
+        props: { flavor: "tip" },
+      } as any);
+
+      // The chrome follows the prop change, and the slot element itself is
+      // untouched: the frame patched in place instead of rebuilding. The
+      // author's frame also follows a prop returning to its default.
+      expect(
+        root.querySelector(".frame-box")!.getAttribute("data-flavor"),
+      ).toBe("tip");
+      expect(root.querySelector(".frame-slot")).toBe(slot);
+      expect(slot.querySelector('[data-id="box-child"]')).not.toBeNull();
+      expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+    } finally {
+      editor._tiptapEditor.destroy();
+    }
+  });
+});
+
+it("honors a titled block's draggable flag through its regular block wrapper", () => {
+  const editor = editorWith([
+    { id: "locked", type: "contentFrame", content: "Title" },
+  ]);
+  try {
+    const blockSpecs: Record<string, LooseBlockSpec> = editor.schema.blockSpecs;
+    const title = editor.domElement!.querySelector(
+      '[data-content-type="contentFrame"]',
+    )!;
+    expect(
+      getDraggableBlockFromElement(
+        title,
+        editor._tiptapEditor.view,
+        (type) => blockSpecs[type].implementation.meta?.draggable !== false,
+      ),
+    ).toBeUndefined();
+    const block = getBlockFromElement(title, editor._tiptapEditor.view);
+    expect(block).toMatchObject({ id: "locked", type: "contentFrame" });
+    expect(block?.node.matches(CONTAINER_SELECTOR)).toBe(false);
+  } finally {
+    editor._tiptapEditor.destroy();
+  }
+});
+
+it("supplies the node-view context to vanilla frames", () => {
+  const contextualFrame = createBlockSpec(
+    { type: "contextualFrame", propSchema: {}, content: "inline" },
+    {
+      render: renderDiv,
+      renderFrame() {
+        expect(this.renderType).toBe("nodeView");
+        expect(this.props?.node.firstChild?.type.name).toBe("contextualFrame");
+        expect(this.blockContentDOMAttributes).toEqual({
+          "data-test": "content",
+        });
+        expect(this.propSchema).toEqual({});
+        const dom = document.createElement("div");
+        dom.className = "contextual-frame";
+        return { dom, slot: dom };
+      },
+    },
+  )();
+  const editor = BlockNoteEditor.create({
+    schema: BlockNoteSchema.create({
+      blockSpecs: { ...defaultBlockSpecs, contextualFrame },
+    }),
+    domAttributes: { blockContent: { "data-test": "content" } },
+    initialContent: [{ type: "contextualFrame", content: "Title" }],
+  });
+  try {
+    editor.mount(document.createElement("div"));
+    expect(
+      editor.domElement?.querySelector(".contextual-frame")?.textContent,
+    ).toBe("Title");
+  } finally {
+    editor._tiptapEditor.destroy();
+  }
+});
+
+it("rebuilds or declines a frame when update returns false and cleans up each instance", () => {
+  const destroy = vi.fn();
+  const lifecycleFrame = createBlockSpec(
+    {
+      type: "lifecycleFrame",
+      propSchema: {
+        mode: { default: "first", values: ["first", "second", "plain"] },
+      },
+      content: "inline",
+    },
+    {
+      render: renderDiv,
+      renderFrame(block) {
+        if (block.props.mode === "plain") {
+          return undefined;
+        }
+        const dom = document.createElement("section");
+        dom.className = "lifecycle-frame";
+        return {
+          dom,
+          slot: dom,
+          destroy,
+          update(updated) {
+            return updated.props.mode === block.props.mode;
+          },
+        };
+      },
+    },
+  )();
+  const editor = BlockNoteEditor.create({
+    schema: BlockNoteSchema.create({
+      blockSpecs: { ...defaultBlockSpecs, lifecycleFrame },
+    }),
+    initialContent: [
+      {
+        id: "frame",
+        type: "lifecycleFrame",
+        content: "Title",
+        children: [{ id: "child", content: "Body" }],
+      },
+    ],
+  });
+  try {
+    editor.mount(document.createElement("div"));
+    const root = editor.domElement!;
+    const first = root.querySelector(".lifecycle-frame");
+    editor.updateBlock("frame", { content: "Updated" });
+    expect(root.querySelector(".lifecycle-frame")).toBe(first);
+    expect(destroy).not.toHaveBeenCalled();
+    editor.updateBlock("frame", { props: { mode: "second" } });
+    expect(root.querySelector(".lifecycle-frame")).not.toBe(first);
+    expect(destroy).toHaveBeenCalledTimes(1);
+    editor.updateBlock("frame", { props: { mode: "plain" } });
+    expect(root.querySelector(".lifecycle-frame")).toBeNull();
+    expect(destroy).toHaveBeenCalledTimes(2);
+    expect(editor.getBlock("frame")!.children[0].id).toBe("child");
+    expect(root.textContent).toContain("Updated");
+    expect(root.textContent).toContain("Body");
+    editor.updateBlock("frame", { props: { mode: "first" } });
+    expect(root.querySelector(".lifecycle-frame")).not.toBeNull();
+  } finally {
+    editor._tiptapEditor.destroy();
+  }
+  expect(destroy).toHaveBeenCalledTimes(3);
+});
+
+it("exports title and children inside the static frame slot with the DOM context", () => {
+  const staticFrame = createBlockSpec(
+    {
+      type: "staticFrame",
+      propSchema: { framed: { default: true } },
+      content: "inline",
+    },
+    {
+      render: renderDiv,
+      renderFrame(block) {
+        expect(this.renderType).toBe("dom");
+        expect(this.props).toBeUndefined();
+        expect(this.blockContentDOMAttributes).toEqual({
+          "data-test": "static",
+        });
+        expect(this.propSchema).toEqual({ framed: { default: true } });
+        if (!block.props.framed) {
+          return undefined;
+        }
+        const dom = document.createElement("section");
+        dom.className = "static-frame";
+        const slot = document.createElement("div");
+        slot.className = "static-slot";
+        dom.append(slot);
+        return { dom, slot };
+      },
+    },
+  )();
+  const editor = BlockNoteEditor.create({
+    schema: BlockNoteSchema.create({
+      blockSpecs: { ...defaultBlockSpecs, staticFrame },
+    }),
+    domAttributes: { blockContent: { "data-test": "static" } },
+    initialContent: [
+      {
+        id: "framed",
+        type: "staticFrame",
+        content: "Title",
+        children: [{ id: "body", content: "Body" }],
+      },
+      {
+        id: "plain",
+        type: "staticFrame",
+        props: { framed: false },
+        content: "Plain",
+      },
+    ],
+  });
+  try {
+    const dom = document.createElement("div");
+    dom.innerHTML = editor.blocksToFullHTML(editor.document);
+    expect(dom.querySelectorAll(".static-frame")).toHaveLength(1);
+    const slot = dom.querySelector(".static-slot")!;
+    expect(slot.querySelector(":scope > .bn-block-content")?.textContent).toBe(
+      "Title",
+    );
+    expect(slot.querySelector(":scope > .bn-block-group")?.textContent).toBe(
+      "Body",
+    );
+    expect(dom.textContent).toContain("Plain");
+    expect(editor.tryParseHTMLToBlocks(dom.innerHTML)).toEqual(editor.document);
+  } finally {
+    editor._tiptapEditor.destroy();
+  }
+});
diff --git a/packages/core/src/schema/blocks/types.ts b/packages/core/src/schema/blocks/types.ts
index d91ee10f89..f6a06eb73e 100644
--- a/packages/core/src/schema/blocks/types.ts
+++ b/packages/core/src/schema/blocks/types.ts
@@ -1,11 +1,11 @@
 /** Define the main block types **/
 // import { Extension, Node } from "@tiptap/core";
-import type { Node, NodeViewRendererProps } from "@tiptap/core";
 import type {
-  Fragment,
-  Node as ProsemirrorNode,
-  Schema,
-} from "prosemirror-model";
+  Node,
+  NodeViewRenderer,
+  NodeViewRendererProps,
+} from "@tiptap/core";
+import type { Fragment, Node as PMNode, Schema } from "prosemirror-model";
 import type { ViewMutationRecord } from "prosemirror-view";
 import type { BlockNoteEditor } from "../../editor/BlockNoteEditor.js";
 import type {
@@ -67,6 +67,16 @@ export interface BlockConfigMeta<
    */
   isolating?: boolean;
 
+  /**
+   * Whether this block type gets a side menu drag handle (and can be dragged
+   * by it). Applies to any block type, container or not: e.g. a
+   * "locked" block can opt out of dragging entirely. A block that opts out is
+   * skipped when looking for a drag handle, so the handle falls through to the
+   * nearest draggable ancestor.
+   * @default true
+   */
+  draggable?: boolean;
+
   /**
    * Enables syntax highlighting of the contents of the block with the result of this callback
    */
@@ -81,9 +91,49 @@ export interface BlockConfigMeta<
 }
 
 /**
- * BlockConfig contains the "schema" info about a Block type
- * i.e. what props it supports, what content it supports, etc.
+ * The type name of a container block, as used in {@link ChildrenConfig.allow}.
+ */
+export type AllowedChildType = string;
+
+/**
+ * What may appear as a child of a container block.
+ *
+ * - `"blocks"`: any regular block, or any container block placeable anywhere.
+ *   This cannot be narrowed to specific regular block types: every regular
+ *   block is the *same* ProseMirror node (`blockContainer`), so paragraphs,
+ *   headings and code blocks are indistinguishable at the node level.
+ * - `readonly AllowedChildType[]`: only these container types, enforced exactly
+ *   by the schema. Naming a regular block type is a startup error; per-type
+ *   regular-block filtering can be added to this same form later, with no API
+ *   change.
+ *
+ * Neither form includes `placeable: "namedOnly"` types. Those appear only
+ * where a parent names them explicitly in an array.
+ */
+export type ChildrenAllow = "blocks" | readonly AllowedChildType[];
+
+/**
+ * Marks a block as a *container*: a block whose body is other blocks, exposed
+ * as `block.children` at runtime.
+ *
+ * The config describes one uniform body, semantically a single implicit
+ * slot. Ordered multi-slot bodies (a `sequence` of slots) can be added later
+ * as a sibling form.
  */
+export type ChildrenConfig = {
+  /** What may appear as a child. See {@link ChildrenAllow}. */
+  allow: ChildrenAllow;
+  /**
+   * How few children the container may hold. When children drop below the
+   * minimum, a container that can stand anywhere dissolves into its
+   * surviving children (a one-column column list is just those blocks), and
+   * one that only exists inside another container is topped back up with
+   * empty children (a column keeps existing).
+   * @default 1
+   */
+  min?: number;
+};
+
 export interface BlockConfig<
   T extends string = string,
   PS extends PropSchema = PropSchema,
@@ -106,8 +156,28 @@ export interface BlockConfig<
    * The content that the block supports
    */
   content: C;
-  // TODO: how do you represent things that have nested content?
-  // e.g. tables, alerts (with title & content)
+  /**
+   * Declares owned child blocks, exposed on `block.children`.
+   * With `content: "none"`, the block is a pure container whose `render`
+   * mounts children through contentDOM (React: contentRef).
+   * With `content: "inline"` or `"plain"`, `children: { allow: "blocks" }`
+   * gives the block owned children below its own text. These children remain
+   * optional; their types and minimum count cannot be restricted.
+   * `renderFrame` independently styles the block's content and children.
+   */
+  children?: ChildrenConfig;
+  /**
+   * Where this block may be placed.
+   *
+   * - `"anywhere"` (default): anywhere a regular block goes, the document
+   *   root or nested under any other block.
+   * - `"namedOnly"`: only inside a container that names this type in its
+   *   `children.allow` array (e.g. a `column` inside a `columnList`).
+   *
+   * Only meaningful for container blocks; regular blocks are always placeable
+   * anywhere.
+   */
+  placeable?: "anywhere" | "namedOnly";
 }
 
 declare module "prosemirror-model" {
@@ -224,7 +294,7 @@ export type LooseBlockSpec<
   config: BlockConfig<T, PS, C>;
   implementation: Omit<
     BlockImplementation<T, PS, C>,
-    "render" | "toExternalHTML"
+    "render" | "renderFrame" | "toExternalHTML"
   > & {
     // purposefully stub the types for render and toExternalHTML since they reference the block
     render: (
@@ -240,9 +310,21 @@ export type LooseBlockSpec<
       dom: HTMLElement | DocumentFragment;
       contentDOM?: HTMLElement;
       ignoreMutation?: (mutation: ViewMutationRecord) => boolean;
-      update?: (node: ProsemirrorNode) => boolean;
       destroy?: () => void;
+      update?: (node: PMNode) => boolean | void;
     };
+    renderFrame?: <I extends InlineContentSchema, S extends StyleSchema>(
+      block: any,
+      editor: BlockNoteEditor<any, I, S>,
+    ) =>
+      | {
+          dom: HTMLElement | DocumentFragment;
+          slot: HTMLElement;
+          /** Releases resources when the live frame is replaced or destroyed. */
+          destroy?: () => void;
+          update?: (block: any) => boolean | void;
+        }
+      | undefined;
     toExternalHTML?: (
       block: any,
       editor: BlockNoteEditor<any>,
@@ -283,7 +365,7 @@ export type BlockSpecs = {
     config: BlockSpec<k>["config"];
     implementation: Omit<
       BlockSpec<k>["implementation"],
-      "render" | "toExternalHTML"
+      "render" | "renderFrame" | "toExternalHTML"
     > & {
       // purposefully stub the types for render and toExternalHTML since they reference the block
       render: (
@@ -299,9 +381,21 @@ export type BlockSpecs = {
         dom: HTMLElement | DocumentFragment;
         contentDOM?: HTMLElement;
         ignoreMutation?: (mutation: ViewMutationRecord) => boolean;
-        update?: (node: ProsemirrorNode) => boolean;
         destroy?: () => void;
+        update?: (node: PMNode) => boolean | void;
       };
+      renderFrame?: <I extends InlineContentSchema, S extends StyleSchema>(
+        block: any,
+        editor: BlockNoteEditor<any, I, S>,
+      ) =>
+        | {
+            dom: HTMLElement | DocumentFragment;
+            slot: HTMLElement;
+            /** Releases resources when the live frame is replaced or destroyed. */
+            destroy?: () => void;
+            update?: (block: any) => boolean | void;
+          }
+        | undefined;
       toExternalHTML?: (
         block: any,
         editor: BlockNoteEditor<any>,
@@ -566,12 +660,14 @@ export type BlockImplementation<
     | "table"
     | "plain",
 > = {
+  /** @internal Framework adapter for the outer blockContainer node view. */
+  frameNodeView?: NodeViewRenderer;
   /**
    * Metadata
    */
   meta?: BlockConfigMeta<TName, TProps>;
   /**
-   * A function that converts the block into a DOM element
+   * A function that converts the block into a DOM element.
    */
   render: (
     this:
@@ -603,20 +699,79 @@ export type BlockImplementation<
     dom: HTMLElement | DocumentFragment;
     contentDOM?: HTMLElement;
     ignoreMutation?: (mutation: ViewMutationRecord) => boolean;
+    destroy?: () => void;
     /**
-     * Called by ProseMirror when this block's node is updated (e.g. its content
-     * or props change). Return `true` to handle the update in place - keeping
-     * the existing DOM - or `false` to have the node view recreated via
-     * `render`. When omitted, ProseMirror keeps the node view and reconciles its
-     * `contentDOM` in place as long as the node type stays the same.
+     * Optional NodeView update hook. Called when the underlying ProseMirror
+     * node's attributes change (or its decorations change). Return `false` to
+     * tell ProseMirror to destroy and recreate the NodeView (i.e. re-run
+     * `render` from scratch). Return `true` (or `undefined`) when you have
+     * patched `dom` in-place and PM should keep the existing view.
      *
-     * Useful for blocks whose `render` builds custom DOM that needs to stay in
-     * sync with the node (e.g. a code block rendering a preview of its content).
+     * Only honored for container blocks (blocks with `children`), where
+     * recreating the node view would remount every child block: e.g. column
+     * resizing patches widths in place through this hook. Non-container
+     * blocks always recreate on attr changes (see
+     * https://github.com/TypeCellOS/BlockNote/pull/1904#discussion_r2313461464).
      */
-    update?: (node: ProsemirrorNode) => boolean;
-    destroy?: () => void;
+    update?: (node: PMNode) => boolean | void;
   };
 
+  /**
+   * Draws the chrome *around* a block's content and children: the author's
+   * markup wraps both, and the `slot` is where BlockNote mounts them.
+   *
+   * The slot holds the content first and the children after it. A pure
+   * container already owns its outer DOM through `render`.
+   *
+   * `render` stays the knob for the block's own content. A block may use
+   * both: `render` draws the title, `renderFrame` draws the box around title
+   * and body. Returning `undefined` declines — the block renders plain — so
+   * a block can decide from its props, content, or children whether it is framed.
+   *
+   * Chrome outside the slot is the author's: ProseMirror leaves its events
+   * alone. An `update` hook receives the current block on updates and patches
+   * the frame in place. Return `false` to rebuild (or decline) the frame.
+   * Without an update hook, block changes rebuild the frame.
+   */
+  renderFrame?: <I extends InlineContentSchema, S extends StyleSchema>(
+    this:
+      | Record<string, never>
+      | ({
+          blockContentDOMAttributes: Record<string, string>;
+          propSchema?: TProps;
+        } & (
+          | {
+              renderType: "nodeView";
+              props: NodeViewRendererProps;
+            }
+          | {
+              renderType: "dom";
+              props: undefined;
+            }
+        )),
+    block: BlockFromConfig<BlockConfig<TName, TProps, TContent>, any, any>,
+    editor: BlockNoteEditor<
+      Record<TName, BlockConfig<TName, TProps, TContent>>,
+      I,
+      S
+    >,
+  ) =>
+    | {
+        dom: HTMLElement | DocumentFragment;
+        /** Where BlockNote mounts the block's content and/or children. */
+        slot: HTMLElement;
+        /** Releases resources when the live frame is replaced or destroyed. */
+        destroy?: () => void;
+        update?: (
+          block: BlockFromConfig<
+            BlockConfig<TName, TProps, TContent>,
+            any,
+            any
+          >,
+        ) => boolean | void;
+      }
+    | undefined;
+
   /**
    * Exports block to external HTML. If not defined, the output will be the same
    * as `render(...).dom`.
@@ -711,4 +866,4 @@ export type CustomBlockImplementation<
   T extends string = string,
   PS extends PropSchema = PropSchema,
   C extends "inline" | "none" | "plain" = "inline" | "none" | "plain",
-> = BlockImplementation<T, PS, C>;
+> = Omit<BlockImplementation<T, PS, C>, "frameNodeView">;
diff --git a/packages/core/src/schema/blocks/validateChildren.ts b/packages/core/src/schema/blocks/validateChildren.ts
new file mode 100644
index 0000000000..5525dc8cc5
--- /dev/null
+++ b/packages/core/src/schema/blocks/validateChildren.ts
@@ -0,0 +1,66 @@
+import { isContainerConfig } from "./children.js";
+import type { BlockConfig } from "./types.js";
+
+/** Reject declarations ProseMirror would accept with different semantics. */
+export function validateChildrenConfigs(
+  blockSpecs: Record<
+    string,
+    { config: Pick<BlockConfig, "content" | "placeable" | "children"> }
+  >,
+) {
+  for (const [type, { config }] of Object.entries(blockSpecs)) {
+    if (config.placeable === "namedOnly" && !isContainerConfig(config)) {
+      fail(
+        type,
+        '`placeable: "namedOnly"` requires a container node; regular blocks share the same wrapper and cannot restrict their placement.',
+      );
+    }
+    if (!config.children) {
+      continue;
+    }
+
+    const { allow, min } = config.children;
+    if (config.content === "table") {
+      fail(type, "`children` is not supported on table blocks.");
+    }
+
+    // Text blocks share an optional child group, so only pure containers
+    // can restrict their children's types or minimum count.
+    if (
+      config.content !== "none" &&
+      (allow !== "blocks" || min !== undefined)
+    ) {
+      fail(
+        type,
+        'blocks with inline or plain content support `children: { allow: "blocks" }` only. Child-type and minimum-count restrictions require a pure container.',
+      );
+    }
+
+    // Every regular block is the same node (`blockContainer`), so naming one
+    // here compiles to a valid schema that restricts nothing.
+    if (allow !== "blocks") {
+      for (const allowed of allow) {
+        if (!Object.prototype.hasOwnProperty.call(blockSpecs, allowed)) {
+          fail(
+            type,
+            `\`allow\` contains "${allowed}", which is not a configured block type.`,
+          );
+        }
+        if (!isContainerConfig(blockSpecs[allowed].config)) {
+          fail(
+            type,
+            `\`allow\` contains "${allowed}", which is a regular block, not a container block. ` +
+              "Restricting which regular block types a container accepts is not yet supported, as every regular block is the same ProseMirror node. " +
+              'Use `allow: "blocks"` to accept all regular blocks, or name only container block types.',
+          );
+        }
+      }
+    }
+  }
+}
+
+function fail(type: string, message: string): never {
+  throw new Error(
+    `Invalid \`children\` config for block "${type}": ${message}`,
+  );
+}
diff --git a/packages/core/src/schema/schema.ts b/packages/core/src/schema/schema.ts
index a9c9f814d3..7b0ffde4bf 100644
--- a/packages/core/src/schema/schema.ts
+++ b/packages/core/src/schema/schema.ts
@@ -16,6 +16,7 @@ import {
   getInlineContentSchemaFromSpecs,
   getStyleSchemaFromSpecs,
 } from "./index.js";
+import { validateChildrenConfigs } from "./blocks/validateChildren.js";
 
 function removeUndefined<T extends Record<string, any> | undefined>(obj: T): T {
   if (!obj) {
@@ -91,6 +92,10 @@ export class CustomBlockNoteSchema<
       })),
     );
 
+    // Validation runs before the nodes are built, so the misconfigurations
+    // ProseMirror cannot report on its own surface as clear errors.
+    validateChildrenConfigs(this.opts.blockSpecs);
+
     const blockSpecs = Object.fromEntries(
       Object.entries(this.opts.blockSpecs).map(([key, blockSpec]) => {
         return [
diff --git a/packages/core/src/yjs/extensions/FixUpSchema.ts b/packages/core/src/yjs/extensions/FixUpSchema.ts
index 37fb1fd4e9..42234c9b45 100644
--- a/packages/core/src/yjs/extensions/FixUpSchema.ts
+++ b/packages/core/src/yjs/extensions/FixUpSchema.ts
@@ -25,6 +25,12 @@ export const FixUpSchemaExtension = createExtension(({ editor }) => {
 
       // create a copy that we can mutate (otherwise, assigning attrs is not safe and corrupts the pm state)
       const jsonNode = JSON.parse(JSON.stringify(ret.toJSON()));
+      // The first fill of the doc's blockGroup is always a `blockContainer`:
+      // container block nodes are clamped below its priority
+      // (`containerNodePriority`) precisely so auto-fill picks it first. If
+      // that ever stops holding, throwing here is better than silently
+      // leaving the id unset, which would let every peer generate its own
+      // initial block id.
       jsonNode.content[0].content[0].attrs.id = "initialBlockId";
 
       cache = Node.fromJSON(schema, jsonNode);
diff --git a/packages/dev-scripts/examples/template-react/vite.config.ts.template.tsx b/packages/dev-scripts/examples/template-react/vite.config.ts.template.tsx
index 7b6f0af639..c6aefb8117 100644
--- a/packages/dev-scripts/examples/template-react/vite.config.ts.template.tsx
+++ b/packages/dev-scripts/examples/template-react/vite.config.ts.template.tsx
@@ -1,6 +1,5 @@
 import type { Project } from "../util";
 
-// TODO: the ../../ paths are broken
 const template = (
   project: Project,
 ) => `// AUTO-GENERATED FILE, DO NOT EDIT DIRECTLY
@@ -23,7 +22,7 @@ export default defineConfig(((conf: { command: string }) => ({
   resolve: {
     alias:
       conf.command === "build" ||
-      !fs.existsSync(path.resolve(__dirname, "../../packages/core/src"))
+      !fs.existsSync(path.resolve(__dirname, "../../../packages/core/src"))
         ? {}
         : ({
             // The repo-wide alias for the shared test-utils directory (private,
@@ -34,11 +33,11 @@ export default defineConfig(((conf: { command: string }) => ({
             // or, keep as is to load live from sources with live reload working
             "@blocknote/core": path.resolve(
               __dirname,
-              "../../packages/core/src/"
+              "../../../packages/core/src/"
             ),
             "@blocknote/react": path.resolve(
               __dirname,
-              "../../packages/react/src/"
+              "../../../packages/react/src/"
             ),
           } as any),
   },
diff --git a/packages/react/src/components/Popovers/BlockPopover.tsx b/packages/react/src/components/Popovers/BlockPopover.tsx
index 2bf0e4fa57..a61d60c4ee 100644
--- a/packages/react/src/components/Popovers/BlockPopover.tsx
+++ b/packages/react/src/components/Popovers/BlockPopover.tsx
@@ -1,4 +1,4 @@
-import { getNodeById } from "@blocknote/core";
+import { getNodeById, isContainerNode } from "@blocknote/core";
 import { ReactNode, useMemo } from "react";
 
 import { useBlockNoteEditor } from "../../hooks/useBlockNoteEditor.js";
@@ -29,6 +29,34 @@ export const BlockPopover = (
           return undefined;
         }
 
+        // Containers anchor to their own root, not the child-block contentDOM.
+        if (isContainerNode(nodePosInfo.node.type)) {
+          const dom = editor.prosemirrorView.nodeDOM(nodePosInfo.posBeforeNode);
+          if (dom instanceof Element) {
+            // React adds two display:contents wrappers around the author root.
+            const root = dom.matches(".bn-container-node-view")
+              ? dom.querySelector(":scope > [data-node-view-wrapper]")
+                  ?.firstElementChild
+              : dom;
+            return { element: root ?? dom };
+          }
+        }
+
+        // A frame's editable slot may start after interactive chrome, such as
+        // a toggle button. Anchor outside the whole block so the side menu
+        // does not cover that chrome. The blockContainer node view owns a
+        // boxed outer element, even when the frame returns a fragment.
+        const contentType = nodePosInfo.node.firstChild?.type.name;
+        if (
+          contentType &&
+          editor.schema.blockSpecs[contentType]?.implementation.renderFrame
+        ) {
+          const dom = editor.prosemirrorView.nodeDOM(nodePosInfo.posBeforeNode);
+          if (dom instanceof Element) {
+            return { element: dom };
+          }
+        }
+
         const { node } = editor.prosemirrorView.domAtPos(
           nodePosInfo.posBeforeNode + 1,
         );
diff --git a/packages/react/src/editor/styles.css b/packages/react/src/editor/styles.css
index 507f2cd46f..c3a39005a5 100644
--- a/packages/react/src/editor/styles.css
+++ b/packages/react/src/editor/styles.css
@@ -111,6 +111,13 @@
   width: 100%;
 }
 
+/* Container blocks own their outer DOM: the block's root element is the one
+   its `render` returned, so the wrapper React needs around it must not be a
+   box of its own. */
+.bn-react-node-view-renderer.bn-container-node-view {
+  display: contents;
+}
+
 /* Indent line styling */
 .bn-block-group
   .bn-block:not(:has(.bn-toggle-wrapper))
diff --git a/packages/react/src/schema/@util/ReactRenderUtil.ts b/packages/react/src/schema/@util/ReactRenderUtil.ts
index dac1a68a86..5ecc4ca6f3 100644
--- a/packages/react/src/schema/@util/ReactRenderUtil.ts
+++ b/packages/react/src/schema/@util/ReactRenderUtil.ts
@@ -36,9 +36,9 @@ export function renderToDOMSpec(
   }
 
   if (!div.childElementCount) {
-    // TODO
-    // eslint-disable-next-line no-console
-    console.warn("ReactInlineContentSpec: renderHTML() failed");
+    // A conditional frame may render null. Dispose its effects even when
+    // there is no DOM to clone, just as on the non-empty path below.
+    root?.unmount();
     return {
       dom: document.createElement("span"),
     };
diff --git a/packages/react/src/schema/ReactBlockSpec.container.browser.test.tsx b/packages/react/src/schema/ReactBlockSpec.container.browser.test.tsx
new file mode 100644
index 0000000000..4c29c09a15
--- /dev/null
+++ b/packages/react/src/schema/ReactBlockSpec.container.browser.test.tsx
@@ -0,0 +1,228 @@
+import { BlockNoteEditor, BlockNoteSchema } from "@blocknote/core";
+import { useState } from "react";
+import { userEvent } from "vite-plus/test/browser";
+import { flushSync } from "react-dom";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, describe, expect, it } from "vite-plus/test";
+
+import { BlockPopover } from "../components/Popovers/BlockPopover.js";
+import { BlockNoteViewRaw } from "../editor/BlockNoteView.js";
+import { createReactBlockSpec } from "./ReactBlockSpec.js";
+
+/**
+ * Tests for React container blocks in a real browser.
+ *
+ * Everything here needs a real DOM: the external-HTML path renders the block
+ * through a temporary `createRoot` (see `@util/ReactRenderUtil`), and a React
+ * node view only runs once `contentComponent` is set, which happens when
+ * `BlockNoteViewRaw` mounts the editor. Document-model behaviour of
+ * containers in general is covered by the core suites in
+ * `api/blockManipulation/containers/`.
+ */
+
+// A container: its `contentRef` element holds its child blocks.
+const createCallout = createReactBlockSpec(
+  {
+    type: "callout",
+    propSchema: { flavor: { default: "tip" } },
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    render: function Callout(props) {
+      const [alternate, setAlternate] = useState(false);
+      const Tag = alternate ? "section" : "div";
+      return (
+        <Tag className="callout">
+          <button
+            contentEditable={false}
+            onClick={() => setAlternate(!alternate)}
+          >
+            Swap root
+          </button>
+          <div className="callout-body" ref={props.contentRef} />
+        </Tag>
+      );
+    },
+  },
+);
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    callout: createCallout(),
+  },
+});
+
+describe("React container block external HTML", () => {
+  it("serializes the author's own root element, unwrapped", () => {
+    const editor = BlockNoteEditor.create({ schema });
+
+    const html = editor.blocksToHTMLLossy([
+      {
+        type: "callout",
+        id: "c-0",
+        children: [{ id: "c-p-0", type: "paragraph", content: "Hello" }],
+      },
+    ] as any);
+
+    // Container blocks own their outer DOM entirely. Regression test for the
+    // React `toExternalHTML` path wrapping them in a spurious
+    // `bn-block-content` div (core's `createBlockSpec` passes them through).
+    // The root is the element `render` returned, with no React wrapper in
+    // between, so `.callout[data-*]` CSS matches it here exactly as in the
+    // live editor.
+    expect(html).not.toContain('data-content-type="callout"');
+    expect(html).not.toContain("data-node-view-wrapper");
+    expect(html).toContain('class="callout"');
+    expect(html).toContain('data-node-type="callout"');
+    expect(html).toContain("Hello");
+
+    editor._tiptapEditor.destroy();
+  });
+});
+
+let root: Root | undefined;
+let div: HTMLDivElement | undefined;
+let editor: BlockNoteEditor<any, any, any> | undefined;
+
+afterEach(() => {
+  root?.unmount();
+  root = undefined;
+  if (div) {
+    document.body.removeChild(div);
+    div = undefined;
+  }
+  editor?._tiptapEditor.destroy();
+  editor = undefined;
+});
+
+/** Lets TipTap's deferred node-view render and React's commit run. */
+const tick = () => new Promise((resolve) => setTimeout(resolve, 0));
+
+async function mountEditor(initialContent: any[]) {
+  div = document.createElement("div");
+  document.body.appendChild(div);
+
+  editor = BlockNoteEditor.create({
+    schema,
+    trailingBlock: false,
+    initialContent,
+  }) as BlockNoteEditor<any, any, any>;
+
+  root = createRoot(div);
+  flushSync(() => {
+    root!.render(<BlockNoteViewRaw editor={editor as any} />);
+  });
+  // TipTap only renders a node view synchronously when this is set; BlockNote
+  // mounts the editor itself and never does, so the first batch of node views
+  // takes the deferred path (see `tests/src/unit/react/staleNodeViewPos.test.tsx`).
+  (editor as any)._tiptapEditor.isEditorContentInitialized = true;
+  await tick();
+
+  return { editor: editor!, div: div! };
+}
+
+describe("React container block node view", () => {
+  it("anchors a container popover to the author's box", async () => {
+    const { editor, div } = await mountEditor([
+      {
+        id: "outer",
+        type: "callout",
+        children: [{ id: "inner", type: "callout" }],
+      },
+    ]);
+    const box = div.querySelector<HTMLElement>(".callout")!;
+    let anchor: Element | undefined;
+    flushSync(() => {
+      root!.render(
+        <BlockNoteViewRaw editor={editor}>
+          <BlockPopover
+            blockId="outer"
+            focusManagerProps={{ disabled: true }}
+            useFloatingOptions={{
+              open: true,
+              whileElementsMounted(reference) {
+                anchor =
+                  reference instanceof Element
+                    ? reference
+                    : reference.contextElement;
+                return () => {};
+              },
+            }}
+          >
+            Container menu
+          </BlockPopover>
+        </BlockNoteViewRaw>,
+      );
+    });
+    await expect.poll(() => anchor).toBe(box);
+    expect(box.getBoundingClientRect().height).toBeGreaterThan(0);
+  });
+
+  it("keeps attributes and native editing after a local state root swap", async () => {
+    const { editor, div } = await mountEditor([
+      {
+        id: "c-0",
+        type: "callout",
+        props: { flavor: "warning" },
+        children: [{ id: "child", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    const child = div.querySelector('[data-id="child"]');
+    await userEvent.click(div.querySelector(".callout button")!);
+    const box = div.querySelector("section.callout")!;
+    expect(box.getAttribute("data-id")).toBe("c-0");
+    expect(box.getAttribute("data-node-type")).toBe("callout");
+    expect(box.getAttribute("data-flavor")).toBe("warning");
+    expect(box.querySelector('[data-id="child"]')).toBe(child);
+    editor.focus();
+    editor.setTextCursorPosition("child", "end");
+    await userEvent.keyboard("!");
+    expect(child?.textContent).toBe("Body!");
+    expect(editor.getTextCursorPosition().block.id).toBe("child");
+  });
+
+  it("stamps only non-default props onto the block's own root, and keeps them in sync", async () => {
+    const mounted = await mountEditor([
+      { id: "c-0", type: "callout", children: [{ type: "paragraph" }] },
+    ]);
+
+    const calloutRoot = mounted.div.querySelector<HTMLElement>(".callout")!;
+    // The author's element, not `div.react-renderer` or the node view
+    // wrapper: exactly the class the author wrote, and nothing else.
+    expect(calloutRoot.className).toBe("callout");
+    expect(calloutRoot.getAttribute("data-id")).toBe("c-0");
+    // `flavor` is at its default, so no attribute is written for it.
+    expect(calloutRoot.hasAttribute("data-flavor")).toBe(false);
+
+    mounted.editor.updateBlock("c-0", { props: { flavor: "warning" } } as any);
+    await tick();
+
+    // Re-queried: a prop change must land on whatever element is now the
+    // block's root, so `.callout[data-flavor="warning"]` selects in the live
+    // editor exactly as it does in the serialized HTML above.
+    expect(
+      mounted.div
+        .querySelector<HTMLElement>(".callout")!
+        .getAttribute("data-flavor"),
+    ).toBe("warning");
+  });
+
+  it("mounts a pure container's children inside its `contentRef` element", async () => {
+    const mounted = await mountEditor([
+      {
+        id: "c-0",
+        type: "callout",
+        children: [{ id: "c-child", type: "paragraph", content: "Child" }],
+      },
+    ]);
+
+    const body = mounted.div.querySelector<HTMLElement>(".callout-body")!;
+    // A container with no content of its own puts its children where the
+    // author placed `contentRef`, not somewhere else in the node view. The
+    // child's own block element is a descendant, so this checks structure,
+    // not just text that happened to bubble up.
+    expect(body.querySelector('[data-id="c-child"]')).not.toBeNull();
+    expect(body.textContent).toBe("Child");
+  });
+});
diff --git a/packages/react/src/schema/ReactBlockSpec.frame.browser.test.tsx b/packages/react/src/schema/ReactBlockSpec.frame.browser.test.tsx
new file mode 100644
index 0000000000..09208b7915
--- /dev/null
+++ b/packages/react/src/schema/ReactBlockSpec.frame.browser.test.tsx
@@ -0,0 +1,173 @@
+import {
+  BlockNoteEditor,
+  BlockNoteSchema,
+  createBlockSpec,
+} from "@blocknote/core";
+import { userEvent } from "vite-plus/test/browser";
+import { useState } from "react";
+import { flushSync } from "react-dom";
+import { createRoot } from "react-dom/client";
+import { expect, it, vi } from "vite-plus/test";
+
+import { BlockNoteViewRaw } from "../editor/BlockNoteView.js";
+import { createReactBlockSpec } from "./ReactBlockSpec.js";
+
+function createFrameSchema(content: "inline" | "plain") {
+  return BlockNoteSchema.create().extend({
+    blockSpecs: {
+      vanilla: createBlockSpec(
+        { type: "vanilla", propSchema: {}, content },
+        {
+          render() {
+            const dom = document.createElement("div");
+            return { dom, contentDOM: dom };
+          },
+          renderFrame(block) {
+            const dom = document.createElement("section");
+            dom.className = "vanilla-frame";
+            dom.dataset.title = JSON.stringify(block.content);
+            const slot = document.createElement("div");
+            dom.append(slot);
+            return { dom, slot };
+          },
+        },
+      )(),
+      framed: createReactBlockSpec(
+        {
+          type: "framed",
+          propSchema: { framed: { default: true } },
+          content,
+          children: { allow: "blocks" },
+        },
+        {
+          render: (props) => (
+            <div className="frame-title" ref={props.contentRef} />
+          ),
+          renderFrame: function Frame(props) {
+            const [clicks, setClicks] = useState(0);
+            if (!props.block.props.framed) {
+              return null;
+            }
+            return (
+              <section className="frame">
+                <button
+                  contentEditable={false}
+                  onClick={() => setClicks(clicks + 1)}
+                >
+                  {clicks}
+                </button>
+                <div className="frame-body" ref={props.contentRef} />
+              </section>
+            );
+          },
+        },
+      )(),
+    },
+  });
+}
+
+it.each(["inline", "plain"] as const)(
+  "keeps native %s editing and selection working across frame changes",
+  async (content) => {
+    const host = document.createElement("div");
+    document.body.append(host);
+    const root = createRoot(host);
+    const editor = BlockNoteEditor.create({
+      schema: createFrameSchema(content),
+      trailingBlock: false,
+      initialContent: [
+        {
+          id: "frame",
+          type: "framed",
+          content: "Title",
+          children: [{ id: "body", type: "paragraph", content: "Body" }],
+        },
+      ],
+    });
+    try {
+      flushSync(() => root.render(<BlockNoteViewRaw editor={editor} />));
+      await vi.waitFor(() =>
+        expect(host.querySelector(".frame-body")?.textContent).toBe(
+          "TitleBody",
+        ),
+      );
+      const child = host.querySelector('[data-id="body"]');
+
+      editor.focus();
+      editor.setTextCursorPosition("frame", "end");
+      await userEvent.keyboard("!");
+      await vi.waitFor(() =>
+        expect(host.querySelector(".frame-title")?.textContent).toBe("Title!"),
+      );
+      await userEvent.click(host.querySelector("button")!);
+      await vi.waitFor(() =>
+        expect(host.querySelector("button")?.textContent).toBe("1"),
+      );
+
+      editor.focus();
+      editor.setTextCursorPosition("body", "end");
+      editor.updateBlock("frame", { props: { framed: false } });
+      await vi.waitFor(() => expect(host.querySelector(".frame")).toBeNull());
+      await userEvent.keyboard("?");
+      await vi.waitFor(() => expect(child?.textContent).toBe("Body?"));
+
+      editor.updateBlock("frame", { props: { framed: true } });
+      await vi.waitFor(() =>
+        expect(host.querySelector(".frame-body")?.textContent).toBe(
+          "Title!Body?",
+        ),
+      );
+      await userEvent.keyboard("!");
+      await vi.waitFor(() => expect(child?.textContent).toBe("Body?!"));
+      expect(host.querySelector('[data-id="body"]')).toBe(child);
+      expect(editor.getTextCursorPosition().block.id).toBe("body");
+    } finally {
+      root.unmount();
+      editor._tiptapEditor.destroy();
+      host.remove();
+    }
+  },
+);
+
+it.each(["inline", "plain"] as const)(
+  "keeps native %s typing and selection while vanilla frames refresh",
+  async (content) => {
+    const host = document.createElement("div");
+    document.body.append(host);
+    const editor = BlockNoteEditor.create({
+      schema: createFrameSchema(content),
+      trailingBlock: false,
+      initialContent: [
+        {
+          id: "frame",
+          type: "vanilla",
+          content: "Title",
+          children: [{ id: "body", type: "paragraph", content: "Body" }],
+        },
+      ],
+    });
+    try {
+      editor.mount(host);
+      editor.focus();
+      editor.setTextCursorPosition("frame", "end");
+      await userEvent.keyboard("abc");
+      await vi.waitFor(() =>
+        expect(
+          host.querySelector(".vanilla-frame")?.getAttribute("data-title"),
+        ).toContain("Titleabc"),
+      );
+      expect(editor.getTextCursorPosition().block.id).toBe("frame");
+      editor.setTextCursorPosition("body", "end");
+      await userEvent.keyboard("xyz");
+      await vi.waitFor(() =>
+        expect(host.querySelector('[data-id="body"]')?.textContent).toBe(
+          "Bodyxyz",
+        ),
+      );
+      expect(editor.getTextCursorPosition().block.id).toBe("body");
+    } finally {
+      editor._tiptapEditor.destroy();
+      host.remove();
+    }
+  },
+);
diff --git a/packages/react/src/schema/ReactBlockSpec.tsx b/packages/react/src/schema/ReactBlockSpec.tsx
index 5311d4e37d..dc10df47af 100644
--- a/packages/react/src/schema/ReactBlockSpec.tsx
+++ b/packages/react/src/schema/ReactBlockSpec.tsx
@@ -1,16 +1,21 @@
 import {
+  applyContainerAttributes,
+  isContainerConfig,
   BlockConfig,
+  BlockFromConfig,
   BlockConfigOrCreator,
   BlockImplementation,
   BlockNoDefaults,
   BlockNoteEditor,
   BlockSpec,
   camelToDataKebab,
+  ChildrenConfig,
   CustomBlockImplementation,
   Extension,
   ExtensionFactoryInstance,
   ExtractBlockConfigFromConfigOrCreator,
   mergeCSSClasses,
+  nodeToBlock,
   Props,
   PropSchema,
 } from "@blocknote/core";
@@ -20,12 +25,17 @@ import {
   ReactNodeViewRenderer,
   useReactNodeView,
 } from "@tiptap/react";
-import { FC, ReactNode } from "react";
+import { CSSProperties, FC, ReactNode, useCallback, useRef } from "react";
 import { renderToDOMSpec } from "./@util/ReactRenderUtil.js";
 import { useNodeViewBlock } from "./useNodeViewBlock.js";
 
 // this file is mostly analogoues to `customBlocks.ts`, but for React blocks
 
+// A container block's root element is the block's own element, so every
+// wrapper React puts above it has to contribute no box of its own. Module
+// scope so the style object is referentially stable across renders.
+const DISPLAY_CONTENTS: CSSProperties = { display: "contents" };
+
 export type ReactCustomBlockRenderProps<
   B extends BlockConfigOrCreator,
   Config extends ExtractBlockConfigFromConfigOrCreator<B> =
@@ -33,11 +43,31 @@ export type ReactCustomBlockRenderProps<
 > = {
   block: BlockNoDefaults<Record<Config["type"], Config>, any, any>;
   editor: BlockNoteEditor<Record<Config["type"], Config>, any, any>;
-} & (Config["content"] extends "inline" | "plain"
-  ? {
-      contentRef: (node: HTMLElement | null) => void;
-    }
-  : object);
+  // A block gets a `contentRef` for its `render` to mount its editable region:
+  // its inline content, or, for a container, its child blocks. Only a
+  // `content: "none"` block without `children` (and the table block, whose
+  // content is managed separately) has nothing to place.
+} & (Config extends { children: ChildrenConfig }
+  ? { contentRef: (node: HTMLElement | null) => void }
+  : Config["content"] extends "inline" | "plain"
+    ? { contentRef: (node: HTMLElement | null) => void }
+    : object);
+
+// extend BlockConfig but use a React render function
+export type ReactCustomBlockFrameProps<
+  B extends BlockConfigOrCreator,
+  Config extends ExtractBlockConfigFromConfigOrCreator<B> =
+    ExtractBlockConfigFromConfigOrCreator<B>,
+> = {
+  block: BlockFromConfig<Config, any, any>;
+  editor: BlockNoteEditor<Record<Config["type"], Config>, any, any>;
+  // A frame gets a `contentRef` for its slot: the mount for the block's
+  // children, or for its content and children together when the block is a
+  // titled block (content of its own plus `children`). Attach it with
+  // `ref={contentRef}` on the slot element, the same way `render` mounts
+  // its editable region.
+  contentRef: (node: HTMLElement | null) => void;
+};
 
 // extend BlockConfig but use a React render function
 export type ReactCustomBlockImplementation<
@@ -50,9 +80,13 @@ export type ReactCustomBlockImplementation<
     Config["propSchema"],
     Config["content"]
   >,
-  "render" | "toExternalHTML"
+  "render" | "renderFrame" | "toExternalHTML"
 > & {
   render: FC<ReactCustomBlockRenderProps<B>>;
+  // The outer block node view renders this component live. Its slot holds
+  // the existing content node followed by the child blockGroup, regardless
+  // of whether those children are owned or ordinary nesting.
+  renderFrame?: FC<ReactCustomBlockFrameProps<B>>;
   toExternalHTML?: FC<
     ReactCustomBlockRenderProps<B> & {
       context: {
@@ -131,20 +165,20 @@ export function createReactBlockSpec<
   const TName extends string,
   const TProps extends PropSchema,
   const TContent extends "inline" | "none" | "plain",
+  // Inferred from the config object itself rather than widened to
+  // `BlockConfig<...>`, so `children` survives into the render props and
+  // `contentRef` is offered exactly when the block has an editable region.
+  const BlockConf extends BlockConfig<TName, TProps, TContent>,
   const TOptions extends Record<string, any> | undefined = undefined,
 >(
-  blockConfigOrCreator: BlockConfig<TName, TProps, TContent>,
+  blockConfigOrCreator: BlockConf,
   blockImplementationOrCreator:
-    | ReactCustomBlockImplementation<BlockConfig<TName, TProps, TContent>>
+    | ReactCustomBlockImplementation<BlockConf>
     | (TOptions extends undefined
-        ? () => ReactCustomBlockImplementation<
-            BlockConfig<TName, TProps, TContent>
-          >
+        ? () => ReactCustomBlockImplementation<BlockConf>
         : (
             options: Partial<TOptions>,
-          ) => ReactCustomBlockImplementation<
-            BlockConfig<TName, TProps, TContent>
-          >),
+          ) => ReactCustomBlockImplementation<BlockConf>),
   extensionsOrCreator?:
     | (ExtensionFactoryInstance | Extension)[]
     | (TOptions extends undefined
@@ -152,7 +186,13 @@ export function createReactBlockSpec<
         : (
             options: Partial<TOptions>,
           ) => (ExtensionFactoryInstance | Extension)[]),
-): (options?: Partial<TOptions>) => BlockSpec<TName, TProps, TContent>;
+): (
+  options?: Partial<TOptions>,
+) => BlockSpec<
+  BlockConf["type"],
+  BlockConf["propSchema"],
+  BlockConf["content"]
+>;
 export function createReactBlockSpec<
   const TName extends string,
   const TProps extends PropSchema,
@@ -219,48 +259,148 @@ export function createReactBlockSpec<
         ? blockImplementationOrCreator(options as any)
         : blockImplementationOrCreator;
 
+    if (!blockImplementation.render) {
+      throw new Error(`Block "${blockConfig.type}" must declare \`render\`.`);
+    }
+
+    const { renderFrame: reactRenderFrame, ...coreImplementation } =
+      blockImplementation;
+
     const extensions = extensionsOrCreator
       ? typeof extensionsOrCreator === "function"
         ? extensionsOrCreator(options as any)
         : extensionsOrCreator
       : undefined;
 
+    // Container-ness is fixed per spec, so every render path can decide once.
+    // A titled block (content of its own plus `children`) keeps its ordinary
+    // shape: only a contentless block builds a container node, so only one
+    // takes the container node view. The titled block's content node renders
+    // through the regular node view; core installs its frame at the
+    // `blockContainer` level (see the `renderFrame` adapter below).
+    const isContainer = isContainerConfig(blockConfig);
+
+    // Shared by the two paths that render to plain DOM (`toExternalHTML` and
+    // `render` outside a node view). A container block's output is the
+    // block's root element, with no wrapper: the attributes core stamps
+    // afterwards then land on the author's own element, the same element they
+    // land on in the live editor.
+    function renderStatic(args: {
+      BlockContent: FC<any>;
+      block: any;
+      editor: any;
+      domAttributes?: Record<string, string>;
+      isFileBlock?: boolean;
+      context?: any;
+    }) {
+      const { BlockContent, block, editor } = args;
+
+      return renderToDOMSpec((refCB) => {
+        const content = (
+          <BlockContent
+            block={block as any}
+            editor={editor as any}
+            contentRef={(element: HTMLElement | null) => {
+              refCB(element);
+              if (element && !isContainer) {
+                element.className = mergeCSSClasses(
+                  "bn-inline-content",
+                  element.className,
+                );
+              }
+            }}
+            context={args.context}
+          />
+        );
+
+        return isContainer ? (
+          content
+        ) : (
+          <BlockContentWrapper
+            blockType={block.type}
+            blockProps={block.props}
+            propSchema={blockConfig.propSchema}
+            domAttributes={args.domAttributes}
+            isFileBlock={args.isFileBlock}
+          >
+            {content}
+          </BlockContentWrapper>
+        );
+      }, editor);
+    }
+
+    const Frame = reactRenderFrame;
+
+    function FrameNodeView(props: NodeViewProps) {
+      // This view belongs to blockContainer itself, so its node is the block.
+      const block = nodeToBlock(props.node, props.view.state.doc);
+      if (block.type !== blockConfig.type) {
+        throw new Error(
+          `Frame for "${blockConfig.type}" received block "${block.type}".`,
+        );
+      }
+      const mountContent = useReactNodeView().nodeViewContentRef;
+      const wrapper = useRef<HTMLDivElement | null>(null);
+      const slot = useRef<HTMLElement | null>(null);
+      if (!mountContent || !Frame) {
+        throw new Error("Frame node view requires a frame and content mount.");
+      }
+      const contentRef = useCallback(
+        (element: HTMLElement | null) => {
+          slot.current = element;
+          if (element) {
+            element.dataset.nodeViewContent = "";
+          }
+          // TipTap owns contentDOM and preserves it as a conditional frame
+          // switches between author markup and the default wrapper.
+          mountContent(element ?? wrapper.current);
+        },
+        [mountContent],
+      );
+      const wrapperRef = useCallback(
+        (element: HTMLDivElement | null) => {
+          wrapper.current = element;
+          if (!slot.current) {
+            mountContent(element);
+          }
+        },
+        [mountContent],
+      );
+
+      return (
+        <NodeViewWrapper ref={wrapperRef} style={DISPLAY_CONTENTS}>
+          <Frame
+            // The outer node view checks the content type before reusing this
+            // renderer; the schema supplies the corresponding props/content.
+            block={
+              block as unknown as ReactCustomBlockFrameProps<
+                typeof blockConfig
+              >["block"]
+            }
+            editor={props.extension.options.editor}
+            contentRef={contentRef}
+          />
+        </NodeViewWrapper>
+      );
+    }
+
     return {
       config: blockConfig,
       implementation: {
-        ...blockImplementation,
+        ...coreImplementation,
         toExternalHTML(block, editor, context) {
-          const BlockContent =
-            blockImplementation.toExternalHTML || blockImplementation.render;
-          const output = renderToDOMSpec((refCB) => {
-            return (
-              <BlockContentWrapper
-                blockType={block.type}
-                blockProps={block.props}
-                propSchema={blockConfig.propSchema}
-                domAttributes={this.blockContentDOMAttributes}
-                isFileBlock={
-                  blockImplementation.meta?.fileBlockAccept !== undefined
-                }
-              >
-                <BlockContent
-                  block={block as any}
-                  editor={editor as any}
-                  contentRef={(element) => {
-                    refCB(element);
-                    if (element) {
-                      element.className = mergeCSSClasses(
-                        "bn-inline-content",
-                        element.className,
-                      );
-                    }
-                  }}
-                  context={context}
-                />
-              </BlockContentWrapper>
-            );
-          }, editor);
-          return output;
+          if (!blockImplementation.toExternalHTML) {
+            return undefined;
+          }
+          return renderStatic({
+            BlockContent: blockImplementation.toExternalHTML,
+            block,
+            editor,
+            domAttributes: this.blockContentDOMAttributes,
+            isFileBlock:
+              blockImplementation.meta?.fileBlockAccept !== undefined,
+            context,
+          });
         },
         render(block, editor) {
           if (this.renderType === "nodeView") {
@@ -268,82 +408,128 @@ export function createReactBlockSpec<
             // constructed (itself guarded, via `getBlockFromNodeView`). Seeds
             // the fallback below so there is always something to render.
             const initialBlock = block;
+            const BlockContent = blockImplementation.render;
+            const blockContentDOMAttributes = this.blockContentDOMAttributes;
 
-            return ReactNodeViewRenderer(
-              (props: NodeViewProps) => {
-                // Vanilla JS node views are recreated on each update. However,
-                // using `ReactNodeViewRenderer` makes it so the node view is
-                // only created once, so the block we get in the node view will
-                // be outdated. Therefore, we have to get the block in the
-                // `ReactNodeViewRenderer` instead. That position can be stale,
-                // so resolving it is guarded (see `useNodeViewBlock`).
-                const block = useNodeViewBlock(props, initialBlock);
+            function BlockNodeView(props: NodeViewProps) {
+              const block = useNodeViewBlock(props, initialBlock);
+              const ref = useReactNodeView().nodeViewContentRef;
+              if (!ref) {
+                throw new Error("nodeViewContentRef is not set");
+              }
 
-                const ref = useReactNodeView().nodeViewContentRef;
+              const mountContent = ref;
+              function contentRef(element: HTMLElement | null) {
+                mountContent(element);
+                if (!element) {
+                  return;
+                }
+                element.dataset.nodeViewContent = "";
+                if (!isContainer) {
+                  element.className = mergeCSSClasses(
+                    "bn-inline-content",
+                    element.className,
+                  );
+                  return;
+                }
 
-                if (!ref) {
-                  throw new Error("nodeViewContentRef is not set");
+                // Refs also run when author state replaces the root or slot.
+                element.setAttribute("data-children-of", blockConfig.type);
+                const root = element.closest(
+                  "[data-node-view-wrapper]",
+                )?.firstElementChild;
+                if (!(root instanceof HTMLElement)) {
+                  throw new Error(
+                    "Container content must be inside its node view wrapper.",
+                  );
                 }
+                applyContainerAttributes(
+                  root,
+                  blockConfig.type,
+                  block.props,
+                  blockConfig.propSchema,
+                  block.id,
+                );
+                root.toggleAttribute("data-selected", props.selected);
+              }
 
-                const BlockContent = blockImplementation.render;
+              const content = (
+                <BlockContent
+                  block={block as any}
+                  editor={editor as any}
+                  contentRef={contentRef}
+                />
+              );
+              if (isContainer) {
                 return (
-                  <BlockContentWrapper
-                    blockType={block.type}
-                    blockProps={block.props}
-                    propSchema={blockConfig.propSchema}
-                    isFileBlock={!!blockImplementation.meta?.fileBlockAccept}
-                    domAttributes={this.blockContentDOMAttributes}
-                  >
-                    <BlockContent
-                      block={block as any}
-                      editor={editor as any}
-                      contentRef={(element) => {
-                        ref(element);
-                        if (element) {
-                          element.className = mergeCSSClasses(
-                            "bn-inline-content",
-                            element.className,
-                          );
-                          element.dataset.nodeViewContent = "";
-                        }
-                      }}
-                    />
-                  </BlockContentWrapper>
+                  <NodeViewWrapper style={DISPLAY_CONTENTS}>
+                    {content}
+                  </NodeViewWrapper>
                 );
-              },
-              {
-                className: "bn-react-node-view-renderer",
-              },
-            )(this.props!) as ReturnType<BlockImplementation["render"]>;
-          } else {
-            const BlockContent = blockImplementation.render;
-            const output = renderToDOMSpec((refCB) => {
+              }
               return (
                 <BlockContentWrapper
                   blockType={block.type}
                   blockProps={block.props}
                   propSchema={blockConfig.propSchema}
-                  domAttributes={this.blockContentDOMAttributes}
+                  isFileBlock={!!blockImplementation.meta?.fileBlockAccept}
+                  domAttributes={blockContentDOMAttributes}
                 >
-                  <BlockContent
-                    block={block as any}
-                    editor={editor as any}
-                    contentRef={(element) => {
-                      refCB(element);
-                      if (element) {
-                        element.className = mergeCSSClasses(
-                          "bn-inline-content",
-                          element.className,
-                        );
-                      }
-                    }}
-                  />
+                  {content}
                 </BlockContentWrapper>
               );
-            }, editor);
-            return output;
+            }
+
+            const nodeView = ReactNodeViewRenderer(BlockNodeView, {
+              // The container class is separate because it removes the
+              // box the regular class relies on (see `Block.css`).
+              className: isContainer
+                ? "bn-react-node-view-renderer bn-container-node-view"
+                : "bn-react-node-view-renderer",
+            })(this.props!) as ReturnType<
+              NonNullable<BlockImplementation["render"]>
+            >;
+
+            // The container's author slot determines layout, not TipTap's host.
+            if (isContainer && nodeView.contentDOM) {
+              nodeView.contentDOM.style.display = "contents";
+            }
+
+            return nodeView;
+          } else {
+            return renderStatic({
+              BlockContent: blockImplementation.render,
+              block,
+              editor,
+              domAttributes: this.blockContentDOMAttributes,
+            });
           }
         },
+        ...(Frame
+          ? ({
+              // Serialization uses the same component through the existing
+              // static renderer. Live rendering uses the outer node view below.
+              renderFrame(block, editor) {
+                const { dom, contentDOM } = renderToDOMSpec(
+                  (contentRef) => (
+                    <Frame
+                      block={block}
+                      editor={editor}
+                      contentRef={contentRef}
+                    />
+                  ),
+                  editor,
+                );
+                return contentDOM ? { dom, slot: contentDOM } : undefined;
+              },
+              frameNodeView: ReactNodeViewRenderer(FrameNodeView, {
+                className: "bn-react-node-view-renderer bn-container-node-view",
+              }),
+            } satisfies Pick<
+              BlockImplementation<TName, TProps, TContent>,
+              "renderFrame" | "frameNodeView"
+            >)
+          : {}),
       },
       extensions: extensions,
     };
diff --git a/packages/react/src/schema/useNodeViewBlock.ts b/packages/react/src/schema/useNodeViewBlock.ts
index 02393a2fd0..2b96af297f 100644
--- a/packages/react/src/schema/useNodeViewBlock.ts
+++ b/packages/react/src/schema/useNodeViewBlock.ts
@@ -1,4 +1,4 @@
-import { Block, getBlockFromPos } from "@blocknote/core";
+import { Block, getBlockFromPos, nodeToBlock } from "@blocknote/core";
 import type { NodeViewProps } from "@tiptap/react";
 import { useRef } from "react";
 
@@ -42,6 +42,11 @@ export function useNodeViewBlock(
   const lastBlockRef = useRef(initialBlock);
   const doc = props.view.state.doc;
 
+  // Container node views already receive the complete block node.
+  if (props.node.type.isInGroup("bnBlock")) {
+    return nodeToBlock(props.node, doc);
+  }
+
   try {
     // Deliberate render-phase write: a monotonic "last good value" cache, so a
     // repeated render (e.g. StrictMode's double invoke) recomputes the same
diff --git a/packages/react/vite.config.ts b/packages/react/vite.config.ts
index d4e59a60b4..1001b8cbe8 100644
--- a/packages/react/vite.config.ts
+++ b/packages/react/vite.config.ts
@@ -1,7 +1,7 @@
 import react from "@vitejs/plugin-react";
 import * as path from "path";
 import { webpackStats } from "rollup-plugin-webpack-stats";
-import { defineConfig, type UserConfig } from "vite-plus";
+import { configDefaults, defineConfig, type UserConfig } from "vite-plus";
 import pkg from "./package.json";
 // import eslintPlugin from "vite-plugin-eslint";
 
@@ -26,6 +26,9 @@ export default defineConfig(
       test: {
         environment: "jsdom",
         setupFiles: ["./vitestSetup.ts"],
+        // `.browser.test` files need a real browser; the tests package's
+        // browser suite runs them.
+        exclude: [...configDefaults.exclude, "**/*.browser.test.*"],
       },
       plugins: [react(), webpackStats()],
       // used so that vitest resolves the core package from the sources instead of the built version
diff --git a/packages/xl-docx-exporter/src/docx/docxExporter.test.ts b/packages/xl-docx-exporter/src/docx/docxExporter.test.ts
index 11367c90f2..c1ca3a244c 100644
--- a/packages/xl-docx-exporter/src/docx/docxExporter.test.ts
+++ b/packages/xl-docx-exporter/src/docx/docxExporter.test.ts
@@ -1,5 +1,6 @@
 import {
   BlockNoteSchema,
+  createBlockSpec,
   defaultBlockSpecs,
   createPageBreakBlockSpec,
   PartialBlock,
@@ -416,6 +417,163 @@ describe("exporter", () => {
   );
 });
 
+describe("custom container blocks", () => {
+  const Box = createBlockSpec(
+    {
+      type: "box" as const,
+      propSchema: {},
+      content: "none",
+      children: { allow: "blocks" },
+    },
+    {
+      render: (block: any) => {
+        const dom = document.createElement("div");
+        dom.setAttribute("data-node-type", "box");
+        dom.setAttribute("data-id", block.id);
+        return { dom, contentDOM: dom };
+      },
+    },
+  )();
+
+  const boxSchema = BlockNoteSchema.create({
+    blockSpecs: {
+      ...defaultBlockSpecs,
+      box: Box,
+    },
+  });
+
+  const boxDocument = partialBlocksToBlocksForTesting(boxSchema, [
+    {
+      type: "box",
+      children: [
+        { type: "paragraph", content: "First" },
+        { type: "paragraph", content: "Second" },
+      ],
+    },
+  ] as any);
+
+  // A titled block: inline content (the title) plus children (the body). The
+  // mapping renders the title into its own paragraph and places the children
+  // after it; because the block counts as a container, transformBlocks must
+  // not append them a second time.
+  const Alert = createBlockSpec(
+    {
+      type: "alert" as const,
+      propSchema: {},
+      content: "inline",
+      children: { allow: "blocks" },
+    },
+    {
+      render: (block: any) => {
+        const dom = document.createElement("div");
+        dom.setAttribute("data-node-type", "alert");
+        dom.setAttribute("data-id", block.id);
+        return { dom, contentDOM: dom };
+      },
+      renderFrame: (_block: any) => {
+        const dom = document.createElement("div");
+        dom.className = "alert-box";
+        return { dom, slot: dom };
+      },
+    },
+  )();
+
+  const alertSchema = BlockNoteSchema.create({
+    blockSpecs: {
+      ...defaultBlockSpecs,
+      alert: Alert,
+    },
+  });
+
+  const alertDocument = partialBlocksToBlocksForTesting(alertSchema, [
+    {
+      type: "alert",
+      content: "Heads up",
+      children: [
+        { type: "paragraph", content: "First" },
+        { type: "paragraph", content: "Second" },
+      ],
+    },
+  ] as any);
+  it("passes children to a custom container mapping", async () => {
+    const exporter = new DOCXExporter(
+      boxSchema,
+      {
+        ...docxDefaultSchemaMappings,
+        blockMapping: {
+          ...docxDefaultSchemaMappings.blockMapping,
+          box: (
+            _block: any,
+            _exporter: any,
+            _nesting: any,
+            _index: any,
+            children: any,
+          ) =>
+            new Paragraph({
+              children: [new TextRun(`BOX(${children?.length ?? 0})`)],
+            }),
+        },
+      } as any,
+      { resolveFileUrl: testResolveFileUrl },
+    );
+
+    const transformed = await exporter.transformBlocks(boxDocument as any);
+    expect(transformed).toHaveLength(1);
+    const xml = JSON.stringify(transformed[0]);
+    expect(xml).toContain("BOX(2)");
+  });
+
+  it("throws a clear error for an unmapped container block", async () => {
+    const exporter = new DOCXExporter(
+      boxSchema,
+      docxDefaultSchemaMappings as any,
+      { resolveFileUrl: testResolveFileUrl },
+    );
+
+    await expect(exporter.transformBlocks(boxDocument as any)).rejects.toThrow(
+      /container block type "box"/,
+    );
+  });
+
+  it("renders a titled block's title and places its children inside", async () => {
+    const exporter = new DOCXExporter(
+      alertSchema,
+      {
+        ...docxDefaultSchemaMappings,
+        blockMapping: {
+          ...docxDefaultSchemaMappings.blockMapping,
+          alert: (
+            block: any,
+            exporter: any,
+            _nesting: any,
+            _index: any,
+            children: any,
+          ) => [
+            new Paragraph({
+              children: [
+                new TextRun("ALERT:"),
+                ...exporter.transformInlineContent(block.content),
+              ],
+            }),
+            ...(children ?? []),
+          ],
+        },
+      } as any,
+      { resolveFileUrl: testResolveFileUrl },
+    );
+
+    const transformed = await exporter.transformBlocks(alertDocument as any);
+    // Title paragraph plus the two children - handed to the mapping once,
+    // not appended again after it.
+    expect(transformed).toHaveLength(3);
+    const xml = JSON.stringify(transformed);
+    expect(xml).toContain("ALERT:");
+    expect(xml.indexOf("Heads up")).toBeGreaterThan(xml.indexOf("ALERT:"));
+    expect(xml.indexOf("First")).toBeGreaterThan(xml.indexOf("Heads up"));
+    expect(xml).toContain("Second");
+  });
+});
+
 function prettify(sourceXml: string) {
   let ret = xmlFormat(sourceXml);
 
diff --git a/packages/xl-docx-exporter/src/docx/docxExporter.ts b/packages/xl-docx-exporter/src/docx/docxExporter.ts
index f27a4b6bcb..a78baec9cc 100644
--- a/packages/xl-docx-exporter/src/docx/docxExporter.ts
+++ b/packages/xl-docx-exporter/src/docx/docxExporter.ts
@@ -56,7 +56,7 @@ export class DOCXExporter<
     /**
      * The schema of your editor. The mappings are automatically typed checked against this schema.
      */
-    protected readonly schema: BlockNoteSchema<B, I, S>,
+    schema: BlockNoteSchema<B, I, S>,
     /**
      * The mappings that map the BlockNote schema to the docxjs content.
      * Pass {@link docxDefaultSchemaMappings} for the default schema.
@@ -158,7 +158,7 @@ export class DOCXExporter<
 
       let children = await this.transformBlocks(b.children, nestingLevel + 1);
 
-      if (!["columnList", "column"].includes(b.type)) {
+      if (!this.isContainerBlock(b)) {
         children = children.map((c, _i) => {
           // NOTE: nested tables not supported (we can't insert the new Tab before a table)
           if (
@@ -178,17 +178,16 @@ export class DOCXExporter<
       // The `numberedListIndex` slot carries the numbering instance for the docx
       // block mappings (bullet/numbered list items); other block types ignore it.
       const self = await this.mapBlock(
-        b as any,
+        b,
         nestingLevel,
         numberingInstance,
         children,
-      ); // TODO: any
-      if (["columnList", "column"].includes(b.type)) {
-        ret.push(self as Table);
-      } else if (Array.isArray(self)) {
-        ret.push(...self, ...children);
-      } else {
-        ret.push(self, ...children);
+      );
+      ret.push(...(Array.isArray(self) ? self : [self]));
+      // A container's mapping is handed its children and places them itself,
+      // so they must not be appended after it as well.
+      if (!this.isContainerBlock(b)) {
+        ret.push(...children);
       }
     }
     return ret;
diff --git a/packages/xl-email-exporter/src/react-email/defaultSchema/blocks.tsx b/packages/xl-email-exporter/src/react-email/defaultSchema/blocks.tsx
index a3ba8b653e..716dd41d8a 100644
--- a/packages/xl-email-exporter/src/react-email/defaultSchema/blocks.tsx
+++ b/packages/xl-email-exporter/src/react-email/defaultSchema/blocks.tsx
@@ -542,10 +542,19 @@ export const createReactEmailBlockMappingForDefaultSchema = (
     );
   },
   // Email clients handle side-by-side layout poorly, so columns are stacked:
-  // these wrappers render nothing themselves and the exporter's generic child
-  // rendering stacks the column contents vertically.
-  column: () => <></>,
-  columnList: () => <></>,
+  // these container mappings place their children (which the exporter passes
+  // in) one after another, with no wrapper of their own - so the column
+  // contents render flat, in document order.
+  column: (_block, _exporter, _nestingLevel, _numberedListIndex, children) => (
+    <>{children}</>
+  ),
+  columnList: (
+    _block,
+    _exporter,
+    _nestingLevel,
+    _numberedListIndex,
+    children,
+  ) => <>{children}</>,
 });
 
 // Export the original mapping for backward compatibility
diff --git a/packages/xl-email-exporter/src/react-email/reactEmailExporter.test.tsx b/packages/xl-email-exporter/src/react-email/reactEmailExporter.test.tsx
index 91ef40cf36..6fe9ab7b06 100644
--- a/packages/xl-email-exporter/src/react-email/reactEmailExporter.test.tsx
+++ b/packages/xl-email-exporter/src/react-email/reactEmailExporter.test.tsx
@@ -3,15 +3,31 @@ import { ReactEmailExporter } from "./reactEmailExporter.jsx";
 import { reactEmailDefaultSchemaMappings } from "./defaultSchema/index.js";
 import {
   BlockNoteSchema,
+  createBlockSpec,
   createPageBreakBlockSpec,
   defaultBlockSpecs,
 } from "@blocknote/core";
+import { ColumnBlock, ColumnListBlock } from "@blocknote/xl-multi-column";
+import { partialBlocksToBlocksForTesting } from "@shared/formatConversionTestUtil.js";
 import { testDocument } from "@shared/testDocument.js";
 
+// Schema including the multi-column blocks, matching the shared testDocument.
+// The columns are container blocks, so the exporter only recognizes them as
+// such (and lets their mappings place the children) when they're in the
+// schema it was constructed with.
+const fullSchema = BlockNoteSchema.create({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    pageBreak: createPageBreakBlockSpec(),
+    column: ColumnBlock,
+    columnList: ColumnListBlock,
+  },
+});
+
 describe("react email exporter", () => {
   it("should export a document (HTML snapshot)", async () => {
     const exporter = new ReactEmailExporter(
-      BlockNoteSchema.create(),
+      fullSchema,
       reactEmailDefaultSchemaMappings,
     );
 
@@ -21,12 +37,7 @@ describe("react email exporter", () => {
 
   it("should export a document with preview", async () => {
     const exporter = new ReactEmailExporter(
-      BlockNoteSchema.create({
-        blockSpecs: {
-          ...defaultBlockSpecs,
-          pageBreak: createPageBreakBlockSpec(),
-        },
-      }),
+      fullSchema,
       reactEmailDefaultSchemaMappings,
     );
 
@@ -38,12 +49,7 @@ describe("react email exporter", () => {
 
   it("should export a document with multiple preview lines", async () => {
     const exporter = new ReactEmailExporter(
-      BlockNoteSchema.create({
-        blockSpecs: {
-          ...defaultBlockSpecs,
-          pageBreak: createPageBreakBlockSpec(),
-        },
-      }),
+      fullSchema,
       reactEmailDefaultSchemaMappings,
     );
 
@@ -655,7 +661,7 @@ describe("react email exporter", () => {
 
   it("should handle document with custom body styles", async () => {
     const exporter = new ReactEmailExporter(
-      BlockNoteSchema.create(),
+      fullSchema,
       reactEmailDefaultSchemaMappings,
     );
 
@@ -668,3 +674,93 @@ describe("react email exporter", () => {
     );
   });
 });
+
+describe("titled blocks", () => {
+  // A titled block: inline content (the title) plus children (the body). The
+  // mapping renders the title and places the children inside its own box;
+  // because the block counts as a container, transformBlocks must not render
+  // them after it as an indented sibling list.
+  const Alert = createBlockSpec(
+    {
+      type: "alert" as const,
+      propSchema: {},
+      content: "inline",
+      children: { allow: "blocks" },
+    },
+    {
+      render: (block: any) => {
+        const dom = document.createElement("div");
+        dom.setAttribute("data-node-type", "alert");
+        dom.setAttribute("data-id", block.id);
+        return { dom, contentDOM: dom };
+      },
+      renderFrame: (_block: any) => {
+        const dom = document.createElement("div");
+        dom.className = "alert-box";
+        return { dom, slot: dom };
+      },
+    },
+  )();
+
+  const alertSchema = BlockNoteSchema.create({
+    blockSpecs: {
+      ...defaultBlockSpecs,
+      alert: Alert,
+    },
+  });
+
+  const alertDocument = partialBlocksToBlocksForTesting(alertSchema, [
+    {
+      type: "alert",
+      content: "Heads up",
+      children: [
+        { type: "paragraph", content: "First" },
+        { type: "paragraph", content: "Second" },
+      ],
+    },
+  ] as any);
+
+  it("throws a clear error for an unmapped container block", async () => {
+    const exporter = new ReactEmailExporter(
+      alertSchema,
+      reactEmailDefaultSchemaMappings as any,
+    );
+
+    await expect(
+      exporter.transformBlocks(alertDocument as any),
+    ).rejects.toThrow(/container block type "alert"/);
+  });
+
+  it("renders a titled block's title and places its children inside", async () => {
+    const exporter = new ReactEmailExporter(alertSchema, {
+      ...reactEmailDefaultSchemaMappings,
+      blockMapping: {
+        ...reactEmailDefaultSchemaMappings.blockMapping,
+        alert: (
+          block: any,
+          exporter: any,
+          _nestingLevel: any,
+          _numberedListIndex: any,
+          children: any,
+        ) => (
+          <div data-alert-box={true}>
+            <strong>{exporter.transformInlineContent(block.content)}</strong>
+            {children}
+          </div>
+        ),
+      },
+    } as any);
+
+    const html = await exporter.toReactEmailDocument(alertDocument as any);
+
+    // Title and children all sit inside the mapping's own box - placed by
+    // the mapping, not rendered after it in an indented sibling list.
+    const boxIdx = html.indexOf("data-alert-box");
+    expect(boxIdx).toBeGreaterThan(-1);
+    const titleIdx = html.indexOf("Heads up");
+    expect(titleIdx).toBeGreaterThan(boxIdx);
+    expect(html.indexOf("First")).toBeGreaterThan(titleIdx);
+    expect(html).toContain("Second");
+    expect(html).not.toContain("margin-left:24px");
+  });
+});
diff --git a/packages/xl-email-exporter/src/react-email/reactEmailExporter.tsx b/packages/xl-email-exporter/src/react-email/reactEmailExporter.tsx
index c0d19108ae..3a2c942730 100644
--- a/packages/xl-email-exporter/src/react-email/reactEmailExporter.tsx
+++ b/packages/xl-email-exporter/src/react-email/reactEmailExporter.tsx
@@ -87,11 +87,7 @@ export class ReactEmailExporter<
       j++, itemIndex++
     ) {
       const block = blocks[j];
-      const liContent = (await this.mapBlock(
-        block as any,
-        nestingLevel,
-        itemIndex,
-      )) as any;
+      const liContent = await this.mapBlock(block, nestingLevel, itemIndex);
       let nestedList: React.ReactElement<any>[] = [];
       if (block.children && block.children.length > 0) {
         nestedList = await this.renderNestedLists(
@@ -152,11 +148,11 @@ export class ReactEmailExporter<
           j++, itemIndex++
         ) {
           const listItem = children[j];
-          const liContent = (await this.mapBlock(
-            listItem as any,
+          const liContent = await this.mapBlock(
+            listItem,
             nestingLevel,
             itemIndex,
-          )) as any;
+          );
           const style = this.blocknoteDefaultPropsToReactEmailStyle(
             listItem.props as any,
           );
@@ -246,26 +242,17 @@ export class ReactEmailExporter<
         i = nextIndex;
         continue;
       }
-      // Multi-column blocks stack their content vertically in email (their
-      // mappings render nothing themselves). The columns' children are
-      // structural, not nested sub-content, so they render flat - no
-      // indentation wrapper, and at the *same* nesting level (a level bump
-      // per wrapper would report column content as deeply nested to
-      // level-sensitive mappings).
-      if (b.type === "columnList" || b.type === "column") {
-        ret.push(
-          <React.Fragment key={b.id}>
-            {await this.transformBlocks(b.children, nestingLevel)}
-          </React.Fragment>,
-        );
-        i++;
-        continue;
-      }
-
-      // Non-list blocks
+      const isContainer = this.isContainerBlock(b);
       const children = await this.transformBlocks(b.children, nestingLevel + 1);
-      const self = (await this.mapBlock(b as any, nestingLevel, 0)) as any;
-      const style = this.blocknoteDefaultPropsToReactEmailStyle(b.props as any);
+      const self = await this.mapBlock(
+        b,
+        nestingLevel,
+        0,
+        isContainer ? children : undefined,
+      );
+      const style = isContainer
+        ? {}
+        : this.blocknoteDefaultPropsToReactEmailStyle(b.props);
 
       ret.push(
         <React.Fragment key={b.id}>
@@ -274,7 +261,7 @@ export class ReactEmailExporter<
           ) : (
             self
           )}
-          {children.length > 0 && (
+          {!isContainer && children.length > 0 && (
             <div style={{ marginLeft: "24px" }}>{children}</div>
           )}
         </React.Fragment>,
diff --git a/packages/xl-multi-column/src/blocks/Columns/index.ts b/packages/xl-multi-column/src/blocks/Columns/index.ts
index 2e49261ec6..8be04b6d1f 100644
--- a/packages/xl-multi-column/src/blocks/Columns/index.ts
+++ b/packages/xl-multi-column/src/blocks/Columns/index.ts
@@ -1,28 +1,68 @@
+import { createBlockSpec } from "@blocknote/core";
+
+import { ColumnResizeExtension } from "../../extensions/ColumnResize/ColumnResizeExtension.js";
 import { MultiColumnDropHandlerExtension } from "../../extensions/DropCursor/multiColumnHandleDropPlugin.js";
-import { Column } from "../../pm-nodes/Column.js";
-import { ColumnList } from "../../pm-nodes/ColumnList.js";
 
-import { createBlockSpecFromTiptapNode } from "@blocknote/core";
+const COLUMN_WIDTH_DEFAULT = 1;
 
-export const ColumnBlock = createBlockSpecFromTiptapNode(
+export const ColumnBlock = createBlockSpec(
   {
-    node: Column,
-    type: "column",
+    type: "column" as const,
+    propSchema: {
+      width: {
+        default: COLUMN_WIDTH_DEFAULT,
+      },
+    },
     content: "none",
+    children: { allow: "blocks" },
+    placeable: "namedOnly",
   },
   {
-    width: {
-      default: 1,
+    meta: {
+      draggable: false,
+    },
+    render: (block) => {
+      const dom = document.createElement("div");
+      dom.className = "bn-block-column";
+      dom.style.flexGrow = String(block.props.width ?? COLUMN_WIDTH_DEFAULT);
+
+      return {
+        dom,
+        contentDOM: dom,
+        update: (newBlock) => {
+          dom.style.flexGrow = String(
+            newBlock.attrs.width ?? COLUMN_WIDTH_DEFAULT,
+          );
+        },
+      };
     },
   },
-  [MultiColumnDropHandlerExtension()],
-);
+  [MultiColumnDropHandlerExtension(), ColumnResizeExtension()],
+)();
 
-export const ColumnListBlock = createBlockSpecFromTiptapNode(
+export const ColumnListBlock = createBlockSpec(
   {
-    node: ColumnList,
-    type: "columnList",
+    type: "columnList" as const,
+    propSchema: {},
     content: "none",
+    children: {
+      allow: ["column"],
+      min: 2,
+    },
+  },
+  {
+    meta: {
+      draggable: false,
+    },
+    render: () => {
+      const dom = document.createElement("div");
+      dom.className = "bn-block-column-list";
+      dom.style.display = "flex";
+
+      return {
+        dom,
+        contentDOM: dom,
+      };
+    },
   },
-  {},
-);
+)();
diff --git a/packages/xl-multi-column/src/extensions/ColumnResize/ColumnResizeExtension.ts b/packages/xl-multi-column/src/extensions/ColumnResize/ColumnResizeExtension.ts
index 5713466a6d..44bcc255c7 100644
--- a/packages/xl-multi-column/src/extensions/ColumnResize/ColumnResizeExtension.ts
+++ b/packages/xl-multi-column/src/extensions/ColumnResize/ColumnResizeExtension.ts
@@ -1,6 +1,5 @@
-import { BlockNoteEditor, getNodeById } from "@blocknote/core";
+import { BlockNoteEditor, createExtension, getNodeById } from "@blocknote/core";
 import { SideMenuExtension } from "@blocknote/core/extensions";
-import { Extension } from "@tiptap/core";
 import { Node } from "prosemirror-model";
 import { Plugin, PluginKey, PluginView } from "prosemirror-state";
 import { Decoration, DecorationSet, EditorView } from "prosemirror-view";
@@ -41,13 +40,75 @@ type ColumnResizeState = {
   columnList: ColumnData;
 };
 
-type ColumnState =
+// Exported for tests only - not part of the package's public API.
+export type ColumnState =
   | ColumnDefaultState
   | ColumnHoverState
   | ColumnHoverColumnListState
   | ColumnResizeState;
 
-const columnResizePluginKey = new PluginKey<ColumnState>("ColumnResizePlugin");
+// Exported for tests only - not part of the package's public API.
+export const columnResizePluginKey = new PluginKey<ColumnState>(
+  "ColumnResizePlugin",
+);
+
+function isAdjacentColumnPair(
+  doc: Node,
+  columnList: Pick<ColumnData, "node">,
+  leftColumn: Pick<ColumnData, "node" | "posBeforeNode">,
+  rightColumn: Pick<ColumnData, "node" | "posBeforeNode">,
+): boolean {
+  const left = doc.resolve(leftColumn.posBeforeNode);
+  const right = doc.resolve(rightColumn.posBeforeNode);
+  return (
+    columnList.node.type.name === "columnList" &&
+    leftColumn.node.type.name === "column" &&
+    rightColumn.node.type.name === "column" &&
+    left.parent === columnList.node &&
+    right.parent === columnList.node &&
+    left.index() + 1 === right.index()
+  );
+}
+
+// Resolve stored positions after edits; removed or separated columns end the interaction.
+function refreshColumnState(state: ColumnState, doc: Node): ColumnState {
+  if (state.type === "default") {
+    return state;
+  }
+
+  const columnList = getNodeById(state.columnList.id, doc);
+  if (!columnList) {
+    return { type: "default" };
+  }
+  const refreshedList = { ...state.columnList, ...columnList };
+  if (state.type === "hover-column-list") {
+    return { ...state, columnList: refreshedList };
+  }
+
+  const left = getNodeById(state.leftColumn.id, doc);
+  const right = getNodeById(state.rightColumn.id, doc);
+  if (!left || !right || !isAdjacentColumnPair(doc, columnList, left, right)) {
+    return { type: "default" };
+  }
+
+  // Narrow before spreading so resize columns retain their starting widths.
+  switch (state.type) {
+    case "hover-column":
+      return {
+        ...state,
+        columnList: refreshedList,
+        leftColumn: { ...state.leftColumn, ...left },
+        rightColumn: { ...state.rightColumn, ...right },
+      };
+    case "resize":
+      return {
+        ...state,
+        columnList: refreshedList,
+        leftColumn: { ...state.leftColumn, ...left },
+        rightColumn: { ...state.rightColumn, ...right },
+      };
+  }
+}
 
 class ColumnResizePluginView implements PluginView {
   editor: BlockNoteEditor<any, any, any>;
@@ -428,22 +489,26 @@ const createColumnResizePlugin = (editor: BlockNoteEditor<any, any, any>) =>
     state: {
       init: () => ({ type: "default" }) as ColumnState,
       apply: (tr, oldPluginState) => {
-        const newPluginState = tr.getMeta(columnResizePluginKey) as
+        const metaPluginState = tr.getMeta(columnResizePluginKey) as
           | ColumnState
           | undefined;
 
-        return newPluginState === undefined ? oldPluginState : newPluginState;
+        const pluginState =
+          metaPluginState === undefined ? oldPluginState : metaPluginState;
+
+        // The stored column nodes & positions were resolved against an older
+        // doc, so when the doc changes they must be re-resolved against the
+        // new one - a backspace may have removed a hovered column or
+        // unwrapped the column list entirely.
+        return tr.docChanged
+          ? refreshColumnState(pluginState, tr.doc)
+          : pluginState;
       },
     },
     view: (view) => new ColumnResizePluginView(editor, view),
   });
 
-export const createColumnResizeExtension = (
-  editor: BlockNoteEditor<any, any, any>,
-) =>
-  Extension.create({
-    name: "columnResize",
-    addProseMirrorPlugins() {
-      return [createColumnResizePlugin(editor)];
-    },
-  });
+export const ColumnResizeExtension = createExtension(({ editor }) => ({
+  key: "columnResize",
+  prosemirrorPlugins: [createColumnResizePlugin(editor)],
+}));
diff --git a/packages/xl-multi-column/src/extensions/DropCursor/multiColumnHandleDropPlugin.ts b/packages/xl-multi-column/src/extensions/DropCursor/multiColumnHandleDropPlugin.ts
index 1c64a25d1b..4e135aa143 100644
--- a/packages/xl-multi-column/src/extensions/DropCursor/multiColumnHandleDropPlugin.ts
+++ b/packages/xl-multi-column/src/extensions/DropCursor/multiColumnHandleDropPlugin.ts
@@ -51,12 +51,15 @@ export function createMultiColumnHandleDropPlugin(
           // emptied target in the same position, so do nothing. This also
           // keeps the column's ID and width instead of resetting them.
           let allTargetChildrenDragged = true;
-          blockInfo.block.node.forEach((child: any) => {
+          blockInfo.block.node.forEach((child) => {
             if (!draggedBlockIds.has(child.attrs.id)) {
               allTargetChildrenDragged = false;
             }
           });
-          if (allTargetChildrenDragged) {
+          if (
+            allTargetChildrenDragged &&
+            draggedBlockIds.size === blockInfo.block.node.childCount
+          ) {
             return true;
           }
 
@@ -116,36 +119,30 @@ export function createMultiColumnHandleDropPlugin(
                 blocksAlreadyInColumnList.add(block.id);
                 return false;
               }),
-            }))
-            // Remove empty columns (can happen when dragged blocks are
-            // removed).
-            .filter((column) => column.children.length > 0);
-
-          // The insertion index is computed on the remaining columns, as
-          // removing an emptied column before the drop target shifts the
-          // target's position in the list.
-          const targetIndex = remainingColumns.findIndex(
+            }));
+
+          // Count surviving columns before the original drop boundary. This
+          // also works when the selection empties the target column itself.
+          const originalTargetIndex = columnList.children.findIndex(
             (column) => column.id === targetColumnId,
           );
-          if (targetIndex === -1) {
-            // The target column can only be missing if the drag emptied it,
-            // which is handled as a no-op above.
-            throw new Error(
-              "Drop target column not found in the remaining columns",
-            );
-          }
-          const insertionIndex =
-            edgePos.position === "left" ? targetIndex : targetIndex + 1;
+          const boundary =
+            originalTargetIndex + (edgePos.position === "right" ? 1 : 0);
+          const insertionIndex = remainingColumns
+            .slice(0, boundary)
+            .filter((column) => column.children.length > 0).length;
 
           // Insert the dragged blocks as a new column in the correct
           // position.
-          const newChildren = remainingColumns.toSpliced(insertionIndex, 0, {
-            type: "column",
-            children: draggedBlocks,
-            props: {},
-            content: undefined,
-            id: UniqueID.options.generateID(),
-          });
+          const newChildren = remainingColumns
+            .filter((column) => column.children.length > 0)
+            .toSpliced(insertionIndex, 0, {
+              type: "column",
+              children: draggedBlocks,
+              props: {},
+              content: undefined,
+              id: UniqueID.options.generateID(),
+            });
 
           const blocksToRemove = draggedBlocks.filter(
             (block) =>
@@ -156,9 +153,13 @@ export function createMultiColumnHandleDropPlugin(
             editor.removeBlocks(blocksToRemove);
           }
 
-          editor.updateBlock(columnList, {
-            children: newChildren,
-          });
+          if (newChildren.length === 1) {
+            editor.replaceBlocks([columnList], draggedBlocks);
+          } else {
+            editor.updateBlock(columnList, {
+              children: newChildren,
+            });
+          }
         } else {
           // Create new columnList with blocks as columns
           const block = nodeToBlock(blockInfo.block.node, view.state.doc);
diff --git a/packages/xl-multi-column/src/pm-nodes/Column.ts b/packages/xl-multi-column/src/pm-nodes/Column.ts
deleted file mode 100644
index dccf60c74b..0000000000
--- a/packages/xl-multi-column/src/pm-nodes/Column.ts
+++ /dev/null
@@ -1,91 +0,0 @@
-import { suggestionMarks } from "@blocknote/core";
-import { Node } from "@tiptap/core";
-
-import { createColumnResizeExtension } from "../extensions/ColumnResize/ColumnResizeExtension.js";
-
-export const Column = Node.create({
-  name: "column",
-  group: "bnBlock childContainer",
-  // A block always contains content, and optionally a blockGroup which contains nested blocks
-  content: "blockContainer+",
-  priority: 40,
-  defining: true,
-  marks() {
-    return suggestionMarks(this.editor);
-  },
-  addAttributes() {
-    return {
-      width: {
-        // Why does each column have a default width of 1, i.e. 100%? Because
-        // when creating a new column, we want to make sure that existing
-        // column widths are preserved, while the new one also has a sensible
-        // width. If we'd set it so all column widths must add up to 100%
-        // instead, then each time a new column is created, we'd have to assign
-        // it a width depending on the total number of columns and also adjust
-        // the widths of the other columns. The same can be said for using px
-        // instead of percent widths and making them add to the editor width. So
-        // using this method is both simpler and computationally cheaper. This
-        // is possible because we can set the `flex-grow` property to the width
-        // value, which handles all the resizing for us, instead of manually
-        // having to set the `width` property of each column.
-        default: 1,
-        parseHTML: (element) => {
-          const attr = element.getAttribute("data-width");
-          if (attr === null) {
-            return null;
-          }
-
-          const parsed = parseFloat(attr);
-          if (isFinite(parsed)) {
-            return parsed;
-          }
-
-          return null;
-        },
-        renderHTML: (attributes) => {
-          return {
-            "data-width": (attributes.width as number).toString(),
-            style: `flex-grow: ${attributes.width as number};`,
-          };
-        },
-      },
-    };
-  },
-
-  parseHTML() {
-    return [
-      {
-        tag: "div",
-        getAttrs: (element) => {
-          if (typeof element === "string") {
-            return false;
-          }
-
-          if (element.getAttribute("data-node-type") === this.name) {
-            return {};
-          }
-
-          return false;
-        },
-      },
-    ];
-  },
-
-  renderHTML({ HTMLAttributes }) {
-    const column = document.createElement("div");
-    column.className = "bn-block-column";
-    column.setAttribute("data-node-type", this.name);
-    for (const [attribute, value] of Object.entries(HTMLAttributes)) {
-      column.setAttribute(attribute, value as any); // TODO as any
-    }
-
-    return {
-      dom: column,
-      contentDOM: column,
-    };
-  },
-
-  addExtensions() {
-    return [createColumnResizeExtension(this.options.editor)];
-  },
-});
diff --git a/packages/xl-multi-column/src/pm-nodes/ColumnList.ts b/packages/xl-multi-column/src/pm-nodes/ColumnList.ts
deleted file mode 100644
index eeb06f4d4e..0000000000
--- a/packages/xl-multi-column/src/pm-nodes/ColumnList.ts
+++ /dev/null
@@ -1,47 +0,0 @@
-import { suggestionMarks } from "@blocknote/core";
-import { Node } from "@tiptap/core";
-
-export const ColumnList = Node.create({
-  name: "columnList",
-  group: "childContainer bnBlock blockGroupChild",
-  // A block always contains content, and optionally a blockGroup which contains nested blocks
-  content: "column column+", // min two columns
-  priority: 40, // should be below blockContainer
-  defining: true,
-  marks() {
-    return suggestionMarks(this.editor);
-  },
-  parseHTML() {
-    return [
-      {
-        tag: "div",
-        getAttrs: (element) => {
-          if (typeof element === "string") {
-            return false;
-          }
-
-          if (element.getAttribute("data-node-type") === this.name) {
-            return {};
-          }
-
-          return false;
-        },
-      },
-    ];
-  },
-
-  renderHTML({ HTMLAttributes }) {
-    const columnList = document.createElement("div");
-    columnList.className = "bn-block-column-list";
-    columnList.setAttribute("data-node-type", this.name);
-    for (const [attribute, value] of Object.entries(HTMLAttributes)) {
-      columnList.setAttribute(attribute, value as any); // TODO as any
-    }
-    columnList.style.display = "flex";
-
-    return {
-      dom: columnList,
-      contentDOM: columnList,
-    };
-  },
-});
diff --git a/packages/xl-multi-column/src/test/commands/__snapshots__/insertBlocks.test.ts.snap b/packages/xl-multi-column/src/test/commands/__snapshots__/insertBlocks.test.ts.snap
index 476357f363..c6019e4dd8 100644
--- a/packages/xl-multi-column/src/test/commands/__snapshots__/insertBlocks.test.ts.snap
+++ b/packages/xl-multi-column/src/test/commands/__snapshots__/insertBlocks.test.ts.snap
@@ -429,6 +429,226 @@ exports[`Test insertBlocks > Insert column with paragraph into column list 1`] =
 ]
 `;
 
+exports[`Test insertBlocks > Insert empty column list 1`] = `
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Nested Paragraph 0",
+            "type": "text",
+          },
+        ],
+        "id": "nested-paragraph-0",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+    ],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 0",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-0",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [],
+            "id": "1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "2",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [],
+            "id": "3",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "4",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+    ],
+    "content": undefined,
+    "id": "0",
+    "props": {},
+    "type": "columnList",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 1",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-1",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 0",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-0",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 1",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-0",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 2",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-2",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 3",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-3",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-1",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+    ],
+    "content": undefined,
+    "id": "column-list-0",
+    "props": {},
+    "type": "columnList",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 2",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-2",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+]
+`;
+
 exports[`Test insertBlocks > Insert paragraph into column 1`] = `
 [
   {
diff --git a/packages/xl-multi-column/src/test/commands/__snapshots__/moveBlocks.test.ts.snap b/packages/xl-multi-column/src/test/commands/__snapshots__/moveBlocks.test.ts.snap
index d9021ec0e0..7851a21e5d 100644
--- a/packages/xl-multi-column/src/test/commands/__snapshots__/moveBlocks.test.ts.snap
+++ b/packages/xl-multi-column/src/test/commands/__snapshots__/moveBlocks.test.ts.snap
@@ -1,5 +1,591 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
+exports[`Empty a column by moving out of it > Move the only block out of the first column 1`] = `
+[
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Before",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-before",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Only 0",
+        "type": "text",
+      },
+    ],
+    "id": "only-0",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [],
+            "id": "0",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-single-0",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Only 1",
+                "type": "text",
+              },
+            ],
+            "id": "only-1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-single-1",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+    ],
+    "content": undefined,
+    "id": "column-list-single",
+    "props": {},
+    "type": "columnList",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "After",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-after",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+]
+`;
+
+exports[`Empty a column by moving out of it > Move the only block out of the last column 1`] = `
+[
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Before",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-before",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Only 0",
+                "type": "text",
+              },
+            ],
+            "id": "only-0",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-single-0",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [],
+            "id": "0",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-single-1",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+    ],
+    "content": undefined,
+    "id": "column-list-single",
+    "props": {},
+    "type": "columnList",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Only 1",
+        "type": "text",
+      },
+    ],
+    "id": "only-1",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "After",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-after",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+]
+`;
+
+exports[`Move a column > Move column down 1`] = `
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Nested Paragraph 0",
+            "type": "text",
+          },
+        ],
+        "id": "nested-paragraph-0",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+    ],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 0",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-0",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 1",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-1",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [],
+            "id": "1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "0",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 0",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-0",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 1",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 2",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-2",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 3",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-3",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-1",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+    ],
+    "content": undefined,
+    "id": "column-list-0",
+    "props": {},
+    "type": "columnList",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 2",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-2",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+]
+`;
+
+exports[`Move a column > Move column up 1`] = `
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Nested Paragraph 0",
+            "type": "text",
+          },
+        ],
+        "id": "nested-paragraph-0",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+    ],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 0",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-0",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 1",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-1",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+  {
+    "children": [
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 0",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-0",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 1",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 2",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-2",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Column Paragraph 3",
+                "type": "text",
+              },
+            ],
+            "id": "column-paragraph-3",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "column-0",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [],
+            "id": "1",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "0",
+        "props": {
+          "width": 1,
+        },
+        "type": "column",
+      },
+    ],
+    "content": undefined,
+    "id": "column-list-0",
+    "props": {},
+    "type": "columnList",
+  },
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "Paragraph 2",
+        "type": "text",
+      },
+    ],
+    "id": "paragraph-2",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+]
+`;
+
 exports[`Move past empty sibling within a column > Move down below empty sibling 1`] = `
 [
   {
diff --git a/packages/xl-multi-column/src/test/commands/enter.test.ts b/packages/xl-multi-column/src/test/commands/enter.test.ts
new file mode 100644
index 0000000000..273b68508c
--- /dev/null
+++ b/packages/xl-multi-column/src/test/commands/enter.test.ts
@@ -0,0 +1,100 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { BlockNoteEditor } from "@blocknote/core";
+
+import { setupTestEnv } from "../setupTestEnv.js";
+
+const getEditor = setupTestEnv();
+
+function pressEnter(editor: BlockNoteEditor<any, any, any>) {
+  const view = editor._tiptapEditor.view;
+  const event = new KeyboardEvent("keydown", {
+    key: "Enter",
+    code: "Enter",
+    keyCode: 13,
+    bubbles: true,
+  });
+  view.someProp("handleKeyDown", (f: any) => f(view, event));
+}
+
+// Columns have no special Enter config: like any container, an
+// empty last block escapes on Enter. The generic mechanics (escape, ascent
+// past levels that can't hold the block, mid-container stays) are covered in
+// core's `containers.browser.test.ts`; these two tests use the real column
+// schema and its interaction with the column-list repair.
+describe("Enter exit from columns", () => {
+  it("typing then double-Enter escapes in two presses", () => {
+    const editor = getEditor();
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "columnList",
+        id: "cl-0",
+        children: [
+          {
+            type: "column",
+            id: "col-1",
+            children: [{ id: "col1-para", type: "paragraph", content: "col1" }],
+          },
+          {
+            type: "column",
+            id: "col-2",
+            children: [{ id: "col2-para", type: "paragraph", content: "col2" }],
+          },
+        ],
+      },
+    ]);
+
+    editor.setTextCursorPosition("col2-para", "end");
+    pressEnter(editor);
+
+    // First press: a new empty block inside the column.
+    expect(editor.document.map((block) => block.id)).toEqual(["cl-0"]);
+    const children = editor.getBlock("col-2")!.children;
+    expect(children).toHaveLength(2);
+    const created = children[1].id;
+    expect(editor.getTextCursorPosition().block.id).toBe(created);
+
+    pressEnter(editor);
+
+    // Second press: that block moves below the column list (a block can't sit
+    // between columns, so the escape lands below the whole list), caret along.
+    expect(editor.getBlock("col-2")!.children.map((child) => child.id)).toEqual(
+      ["col2-para"],
+    );
+    expect(editor.document.map((block) => block.id)).toEqual(["cl-0", created]);
+    expect(editor.getTextCursorPosition().block.id).toBe(created);
+  });
+
+  it("escaping a column's only block dissolves it and unwraps the list", () => {
+    // The exit empties the column, so the column list's `whenEmptied: "unwrap"`
+    // repair kicks in: the emptied column disappears, and the one-column
+    // list unwraps to the surviving column's blocks.
+    const editor = getEditor();
+    editor.replaceBlocks(editor.document, [
+      {
+        type: "columnList",
+        id: "cl-0",
+        children: [
+          {
+            type: "column",
+            id: "col-1",
+            children: [{ id: "col1-para", type: "paragraph", content: "col1" }],
+          },
+          {
+            type: "column",
+            id: "col-2",
+            children: [{ id: "col2-empty", type: "paragraph", content: "" }],
+          },
+        ],
+      },
+    ]);
+
+    editor.setTextCursorPosition("col2-empty", "end");
+    pressEnter(editor);
+
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "col1-para",
+      "col2-empty",
+    ]);
+  });
+});
diff --git a/packages/xl-multi-column/src/test/commands/insertBlocks.test.ts b/packages/xl-multi-column/src/test/commands/insertBlocks.test.ts
index 319ceda379..329ba7ad12 100644
--- a/packages/xl-multi-column/src/test/commands/insertBlocks.test.ts
+++ b/packages/xl-multi-column/src/test/commands/insertBlocks.test.ts
@@ -6,60 +6,69 @@ const getEditor = setupTestEnv();
 
 describe("Test insertBlocks", () => {
   it("Insert empty column list", () => {
-    // should throw an error as we don't allow empty column lists
-    expect(() => {
-      getEditor().insertBlocks(
-        [{ type: "columnList" }],
-        "paragraph-0",
-        "after",
-      );
-    }).toThrow();
+    // An empty column list is filled to a valid two-column list (each with an
+    // empty paragraph) instead of throwing.
+    getEditor().insertBlocks([{ type: "columnList" }], "paragraph-0", "after");
+
+    expect(getEditor().document).toMatchSnapshot();
   });
 
   it("Insert column list with empty column", () => {
-    // should throw an error as we don't allow empty columns
-    expect(() => {
-      getEditor().insertBlocks(
-        [
-          {
-            type: "columnList",
-            children: [
-              {
-                type: "column",
-              },
-            ],
-          },
-        ],
-        "paragraph-0",
-        "after",
-      );
-    }).toThrow();
+    // The empty column is padded with a paragraph, and the list is padded to
+    // its `min: 2` with a second column, instead of throwing.
+    getEditor().insertBlocks(
+      [
+        {
+          type: "columnList",
+          children: [
+            {
+              type: "column",
+            },
+          ],
+        },
+      ],
+      "paragraph-0",
+      "after",
+    );
+
+    const list = getEditor().document[1] as any;
+    expect(list.type).toBe("columnList");
+    expect(list.children).toHaveLength(2);
+    expect(list.children[0].children).toHaveLength(1);
+    expect(list.children[1].children).toHaveLength(1);
   });
 
   it("Insert column list with single column", () => {
-    // should throw an error as we don't allow column list with single column
-    expect(() => {
-      getEditor().insertBlocks(
-        [
-          {
-            type: "columnList",
-            children: [
-              {
-                type: "column",
-                children: [
-                  {
-                    type: "paragraph",
-                    content: "Inserted Column Paragraph",
-                  },
-                ],
-              },
-            ],
-          },
-        ],
-        "paragraph-0",
-        "after",
-      );
-    }).toThrow();
+    // A one-column list is padded up to `min: 2` with a second column,
+    // instead of throwing.
+    getEditor().insertBlocks(
+      [
+        {
+          type: "columnList",
+          children: [
+            {
+              type: "column",
+              children: [
+                {
+                  type: "paragraph",
+                  content: "Inserted Column Paragraph",
+                },
+              ],
+            },
+          ],
+        },
+      ],
+      "paragraph-0",
+      "after",
+    );
+
+    const list = getEditor().document[1] as any;
+    expect(list.type).toBe("columnList");
+    expect(list.children).toHaveLength(2);
+    expect(list.children[0].children[0].content[0].text).toBe(
+      "Inserted Column Paragraph",
+    );
+    expect(list.children[1].children[0].content).toEqual([]);
   });
 
   it("Insert valid column list with two columns", () => {
diff --git a/packages/xl-multi-column/src/test/commands/moveBlocks.test.ts b/packages/xl-multi-column/src/test/commands/moveBlocks.test.ts
index 6970c6c036..474428330b 100644
--- a/packages/xl-multi-column/src/test/commands/moveBlocks.test.ts
+++ b/packages/xl-multi-column/src/test/commands/moveBlocks.test.ts
@@ -196,3 +196,64 @@ describe("Move past empty sibling within a column", () => {
     expect(getEditor().document).toMatchSnapshot();
   });
 });
+
+// A `column` is `placeable: "namedOnly"`, so it can't be moved anywhere a
+// regular block goes: moving one dissolves it and moves its children instead.
+// The column list is left at its `min` of 2 by an empty replacement column,
+// rather than unwrapping - see the note on emptied columns below.
+describe("Move a column", () => {
+  it("Move column up", () => {
+    getEditor().moveBlocksUp("column-1");
+
+    expect(getEditor().document).toMatchSnapshot();
+  });
+
+  it("Move column down", () => {
+    getEditor().moveBlocksDown("column-0");
+
+    expect(getEditor().document).toMatchSnapshot();
+  });
+});
+
+// A move is a rearrangement rather than a deletion, so a column it empties out
+// is deliberately left standing instead of being collapsed (see `moveBlocks`).
+describe("Empty a column by moving out of it", () => {
+  beforeEach(() => {
+    getEditor().replaceBlocks(getEditor().document, [
+      { id: "paragraph-before", type: "paragraph", content: "Before" },
+      {
+        id: "column-list-single",
+        type: "columnList",
+        children: [
+          {
+            id: "column-single-0",
+            type: "column",
+            children: [{ id: "only-0", type: "paragraph", content: "Only 0" }],
+          },
+          {
+            id: "column-single-1",
+            type: "column",
+            children: [{ id: "only-1", type: "paragraph", content: "Only 1" }],
+          },
+        ],
+      },
+      { id: "paragraph-after", type: "paragraph", content: "After" },
+    ]);
+  });
+
+  it("Move the only block out of the first column", () => {
+    getEditor().setTextCursorPosition("only-0");
+
+    getEditor().moveBlocksUp();
+
+    expect(getEditor().document).toMatchSnapshot();
+  });
+
+  it("Move the only block out of the last column", () => {
+    getEditor().setTextCursorPosition("only-1");
+
+    getEditor().moveBlocksDown();
+
+    expect(getEditor().document).toMatchSnapshot();
+  });
+});
diff --git a/packages/xl-multi-column/src/test/commands/nestBlock.test.ts b/packages/xl-multi-column/src/test/commands/nestBlock.test.ts
new file mode 100644
index 0000000000..a19ea0034b
--- /dev/null
+++ b/packages/xl-multi-column/src/test/commands/nestBlock.test.ts
@@ -0,0 +1,71 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { setupTestEnv } from "../setupTestEnv.js";
+
+const getEditor = setupTestEnv();
+
+// Tab and Shift-Tab with a selection spanning two columns. There is no
+// nestable range inside the column list — it holds only `column`s — so the
+// range has to resolve outside it and move the list as a unit. Nesting used to
+// resolve the range at the columns themselves, where the preconditions can
+// never hold, making both keys silent no-ops.
+describe("Nest & unnest a selection spanning two columns", () => {
+  it("Nests the whole column list under its previous sibling", () => {
+    const editor = getEditor();
+
+    editor.setSelection("column-paragraph-1", "column-paragraph-2");
+
+    expect(editor.canNestBlock()).toBe(true);
+    editor.nestBlock();
+
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "paragraph-0",
+      "paragraph-1",
+      "paragraph-2",
+    ]);
+    expect(editor.getBlock("paragraph-1")!.children.map((c) => c.id)).toEqual([
+      "column-list-0",
+    ]);
+    // The list itself is untouched — only its position changed.
+    expect(editor.getBlock("column-list-0")!.children.map((c) => c.id)).toEqual(
+      ["column-0", "column-1"],
+    );
+  });
+
+  it("Unnests the whole column list out of its parent", () => {
+    const editor = getEditor();
+
+    editor.setSelection("column-paragraph-1", "column-paragraph-2");
+    editor.nestBlock();
+
+    editor.setSelection("column-paragraph-1", "column-paragraph-2");
+    expect(editor.canUnnestBlock()).toBe(true);
+    editor.unnestBlock();
+
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "paragraph-0",
+      "paragraph-1",
+      "column-list-0",
+      "paragraph-2",
+    ]);
+    expect(editor.getBlock("paragraph-1")!.children).toEqual([]);
+    expect(editor.getBlock("column-list-0")!.children.map((c) => c.id)).toEqual(
+      ["column-0", "column-1"],
+    );
+  });
+
+  it("Reports no nesting when the column list has no previous sibling", () => {
+    const editor = getEditor();
+    editor.replaceBlocks(editor.document, [
+      editor.getBlock("column-list-0")!,
+      { id: "after", type: "paragraph", content: "After" },
+    ]);
+
+    editor.setSelection("column-paragraph-1", "column-paragraph-2");
+
+    const before = editor.document;
+    expect(editor.canNestBlock()).toBe(false);
+    editor.nestBlock();
+    expect(editor.document).toEqual(before);
+  });
+});
diff --git a/packages/xl-multi-column/src/test/commands/util/__snapshots__/fixColumnLists.test.ts.snap b/packages/xl-multi-column/src/test/commands/util/__snapshots__/fixColumnLists.test.ts.snap
deleted file mode 100644
index 87b5f2e588..0000000000
--- a/packages/xl-multi-column/src/test/commands/util/__snapshots__/fixColumnLists.test.ts.snap
+++ /dev/null
@@ -1,408 +0,0 @@
-// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
-
-exports[`Test fixColumnList > First of two columns empty 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "backgroundColor": "default",
-                "textAlignment": "left",
-                "textColor": "default",
-              },
-              "content": [
-                {
-                  "text": "Paragraph 1",
-                  "type": "text",
-                },
-              ],
-              "type": "paragraph",
-            },
-          ],
-          "type": "blockContainer",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
-
-exports[`Test fixColumnList > Last of two columns empty 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "backgroundColor": "default",
-                "textAlignment": "left",
-                "textColor": "default",
-              },
-              "content": [
-                {
-                  "text": "Paragraph 1",
-                  "type": "text",
-                },
-              ],
-              "type": "paragraph",
-            },
-          ],
-          "type": "blockContainer",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
-
-exports[`Test fixColumnList > Two empty columns 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "backgroundColor": "default",
-                "textAlignment": "left",
-                "textColor": "default",
-              },
-              "type": "paragraph",
-            },
-          ],
-          "type": "blockContainer",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
-
-exports[`Test removeEmptyColumns > First of two columns empty 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "content": [
-                        {
-                          "text": "Paragraph 1",
-                          "type": "text",
-                        },
-                      ],
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-          ],
-          "type": "columnList",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
-
-exports[`Test removeEmptyColumns > Last of two columns empty 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "content": [
-                        {
-                          "text": "Paragraph 1",
-                          "type": "text",
-                        },
-                      ],
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-          ],
-          "type": "columnList",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
-
-exports[`Test removeEmptyColumns > Start and end columns empty 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "content": [
-                        {
-                          "text": "Paragraph 1",
-                          "type": "text",
-                        },
-                      ],
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "content": [
-                        {
-                          "text": "Paragraph 2",
-                          "type": "text",
-                        },
-                      ],
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-          ],
-          "type": "columnList",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
-
-exports[`Test removeEmptyColumns > Two empty columns 1`] = `
-{
-  "content": [
-    {
-      "content": [
-        {
-          "attrs": {
-            "id": null,
-          },
-          "content": [
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-            {
-              "attrs": {
-                "id": null,
-                "width": 1,
-              },
-              "content": [
-                {
-                  "attrs": {
-                    "id": null,
-                  },
-                  "content": [
-                    {
-                      "attrs": {
-                        "backgroundColor": "default",
-                        "textAlignment": "left",
-                        "textColor": "default",
-                      },
-                      "type": "paragraph",
-                    },
-                  ],
-                  "type": "blockContainer",
-                },
-              ],
-              "type": "column",
-            },
-          ],
-          "type": "columnList",
-        },
-      ],
-      "type": "blockGroup",
-    },
-  ],
-  "type": "doc",
-}
-`;
diff --git a/packages/xl-multi-column/src/test/commands/util/__snapshots__/fixContainer.test.ts.snap b/packages/xl-multi-column/src/test/commands/util/__snapshots__/fixContainer.test.ts.snap
new file mode 100644
index 0000000000..393ab225ed
--- /dev/null
+++ b/packages/xl-multi-column/src/test/commands/util/__snapshots__/fixContainer.test.ts.snap
@@ -0,0 +1,183 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`Test fixContainer drops emptied columns > First of two columns empty 1`] = `
+{
+  "content": [
+    {
+      "content": [
+        {
+          "attrs": {
+            "id": null,
+          },
+          "content": [
+            {
+              "attrs": {
+                "backgroundColor": "default",
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "content": [
+                {
+                  "text": "Paragraph 1",
+                  "type": "text",
+                },
+              ],
+              "type": "paragraph",
+            },
+          ],
+          "type": "blockContainer",
+        },
+      ],
+      "type": "blockGroup",
+    },
+  ],
+  "type": "doc",
+}
+`;
+
+exports[`Test fixContainer drops emptied columns > Last of two columns empty 1`] = `
+{
+  "content": [
+    {
+      "content": [
+        {
+          "attrs": {
+            "id": null,
+          },
+          "content": [
+            {
+              "attrs": {
+                "backgroundColor": "default",
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "content": [
+                {
+                  "text": "Paragraph 1",
+                  "type": "text",
+                },
+              ],
+              "type": "paragraph",
+            },
+          ],
+          "type": "blockContainer",
+        },
+      ],
+      "type": "blockGroup",
+    },
+  ],
+  "type": "doc",
+}
+`;
+
+exports[`Test fixContainer drops emptied columns > Start and end columns empty 1`] = `
+{
+  "content": [
+    {
+      "content": [
+        {
+          "attrs": {
+            "id": null,
+          },
+          "content": [
+            {
+              "attrs": {
+                "id": null,
+                "width": 1,
+              },
+              "content": [
+                {
+                  "attrs": {
+                    "id": null,
+                  },
+                  "content": [
+                    {
+                      "attrs": {
+                        "backgroundColor": "default",
+                        "textAlignment": "left",
+                        "textColor": "default",
+                      },
+                      "content": [
+                        {
+                          "text": "Paragraph 1",
+                          "type": "text",
+                        },
+                      ],
+                      "type": "paragraph",
+                    },
+                  ],
+                  "type": "blockContainer",
+                },
+              ],
+              "type": "column",
+            },
+            {
+              "attrs": {
+                "id": null,
+                "width": 1,
+              },
+              "content": [
+                {
+                  "attrs": {
+                    "id": null,
+                  },
+                  "content": [
+                    {
+                      "attrs": {
+                        "backgroundColor": "default",
+                        "textAlignment": "left",
+                        "textColor": "default",
+                      },
+                      "content": [
+                        {
+                          "text": "Paragraph 2",
+                          "type": "text",
+                        },
+                      ],
+                      "type": "paragraph",
+                    },
+                  ],
+                  "type": "blockContainer",
+                },
+              ],
+              "type": "column",
+            },
+          ],
+          "type": "columnList",
+        },
+      ],
+      "type": "blockGroup",
+    },
+  ],
+  "type": "doc",
+}
+`;
+
+exports[`Test fixContainer drops emptied columns > Two empty columns 1`] = `
+{
+  "content": [
+    {
+      "content": [
+        {
+          "attrs": {
+            "id": null,
+          },
+          "content": [
+            {
+              "attrs": {
+                "backgroundColor": "default",
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "type": "paragraph",
+            },
+          ],
+          "type": "blockContainer",
+        },
+      ],
+      "type": "blockGroup",
+    },
+  ],
+  "type": "doc",
+}
+`;
diff --git a/packages/xl-multi-column/src/test/commands/util/fixColumnLists.test.ts b/packages/xl-multi-column/src/test/commands/util/fixColumnLists.test.ts
deleted file mode 100644
index b5bd190c6d..0000000000
--- a/packages/xl-multi-column/src/test/commands/util/fixColumnLists.test.ts
+++ /dev/null
@@ -1,283 +0,0 @@
-import { describe, expect, it } from "vite-plus/test";
-
-import { setupTestEnv } from "../../setupTestEnv.js";
-import {
-  fixColumnList,
-  isEmptyColumn,
-  removeEmptyColumns,
-} from "@blocknote/core";
-
-const getEditor = setupTestEnv();
-
-describe("Test isEmptyColumn", () => {
-  it("Empty blocks", () => {
-    const schema = getEditor()._tiptapEditor.schema;
-
-    const column = schema.nodes["column"].create(undefined, [
-      schema.nodes["blockContainer"].create(undefined, [
-        schema.nodes["paragraph"].create(),
-      ]),
-    ]);
-
-    expect(isEmptyColumn(column)).toBeTruthy();
-  });
-
-  it("Multiple blocks", () => {
-    const schema = getEditor()._tiptapEditor.schema;
-
-    const column = schema.nodes["column"].create(undefined, [
-      schema.nodes["blockContainer"].create(undefined, [
-        schema.nodes["paragraph"].create(undefined),
-      ]),
-      schema.nodes["blockContainer"].create(undefined, [
-        schema.nodes["paragraph"].create(),
-      ]),
-    ]);
-
-    expect(isEmptyColumn(column)).toBeFalsy();
-  });
-
-  it("Block with children", () => {
-    const schema = getEditor()._tiptapEditor.schema;
-
-    const column = schema.nodes["column"].create(undefined, [
-      schema.nodes["blockContainer"].create(undefined, [
-        schema.nodes["paragraph"].create(undefined),
-        schema.nodes["blockGroup"].create(undefined, [
-          schema.nodes["blockContainer"].create(undefined, [
-            schema.nodes["paragraph"].create(),
-          ]),
-        ]),
-      ]),
-    ]);
-
-    expect(isEmptyColumn(column)).toBeFalsy();
-  });
-
-  it("Block with text", () => {
-    const schema = getEditor()._tiptapEditor.schema;
-
-    const column = schema.nodes["column"].create(undefined, [
-      schema.nodes["blockContainer"].create(undefined, [
-        schema.nodes["paragraph"].create(undefined, [
-          schema.text("Paragraph 1"),
-        ]),
-      ]),
-    ]);
-
-    expect(isEmptyColumn(column)).toBeFalsy();
-  });
-
-  it("Non-text block", () => {
-    const schema = getEditor()._tiptapEditor.schema;
-
-    const column = schema.nodes["column"].create(undefined, [
-      schema.nodes["blockContainer"].create(undefined, [
-        schema.nodes["image"].create(),
-      ]),
-    ]);
-
-    expect(isEmptyColumn(column)).toBeFalsy();
-  });
-});
-
-describe("Test removeEmptyColumns", () => {
-  it("Start and end columns empty", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(undefined, [
-            schema.text("Paragraph 1"),
-          ]),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(undefined, [
-            schema.text("Paragraph 2"),
-          ]),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    removeEmptyColumns(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-
-  it("First of two columns empty", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(undefined, [
-            schema.text("Paragraph 1"),
-          ]),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    removeEmptyColumns(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-
-  it("Last of two columns empty", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(undefined, [
-            schema.text("Paragraph 1"),
-          ]),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    removeEmptyColumns(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-
-  it("Two empty columns", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    removeEmptyColumns(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-});
-
-describe("Test fixColumnList", () => {
-  it("First of two columns empty", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(undefined, [
-            schema.text("Paragraph 1"),
-          ]),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    fixColumnList(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-
-  it("Last of two columns empty", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(undefined, [
-            schema.text("Paragraph 1"),
-          ]),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    fixColumnList(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-
-  it("Two empty columns", () => {
-    const editor = getEditor();
-    const schema = editor._tiptapEditor.schema;
-
-    const columnList = schema.nodes["columnList"].create(undefined, [
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-      schema.nodes["column"].create(undefined, [
-        schema.nodes["blockContainer"].create(undefined, [
-          schema.nodes["paragraph"].create(),
-        ]),
-      ]),
-    ]);
-
-    const tr = editor.prosemirrorState.tr;
-
-    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
-    fixColumnList(tr, 1);
-
-    expect(tr.doc).toMatchSnapshot();
-  });
-});
diff --git a/packages/xl-multi-column/src/test/commands/util/fixContainer.test.ts b/packages/xl-multi-column/src/test/commands/util/fixContainer.test.ts
new file mode 100644
index 0000000000..2ae649678e
--- /dev/null
+++ b/packages/xl-multi-column/src/test/commands/util/fixContainer.test.ts
@@ -0,0 +1,107 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { setupTestEnv } from "../../setupTestEnv.js";
+import { fixContainer, isEmptyContainerChild } from "@blocknote/core";
+
+const getEditor = setupTestEnv();
+
+describe("Test isEmptyContainerChild", () => {
+  it("Empty blocks", () => {
+    const schema = getEditor()._tiptapEditor.schema;
+
+    const column = schema.nodes["column"].create(undefined, [
+      schema.nodes["blockContainer"].create(undefined, [
+        schema.nodes["paragraph"].create(),
+      ]),
+    ]);
+
+    expect(isEmptyContainerChild(column)).toBeTruthy();
+  });
+
+  it("Multiple blocks", () => {
+    const schema = getEditor()._tiptapEditor.schema;
+
+    const column = schema.nodes["column"].create(undefined, [
+      schema.nodes["blockContainer"].create(undefined, [
+        schema.nodes["paragraph"].create(undefined),
+      ]),
+      schema.nodes["blockContainer"].create(undefined, [
+        schema.nodes["paragraph"].create(),
+      ]),
+    ]);
+
+    expect(isEmptyContainerChild(column)).toBeFalsy();
+  });
+
+  it("Block with children", () => {
+    const schema = getEditor()._tiptapEditor.schema;
+
+    const column = schema.nodes["column"].create(undefined, [
+      schema.nodes["blockContainer"].create(undefined, [
+        schema.nodes["paragraph"].create(undefined),
+        schema.nodes["blockGroup"].create(undefined, [
+          schema.nodes["blockContainer"].create(undefined, [
+            schema.nodes["paragraph"].create(),
+          ]),
+        ]),
+      ]),
+    ]);
+
+    expect(isEmptyContainerChild(column)).toBeFalsy();
+  });
+
+  it("Block with text", () => {
+    const schema = getEditor()._tiptapEditor.schema;
+
+    const column = schema.nodes["column"].create(undefined, [
+      schema.nodes["blockContainer"].create(undefined, [
+        schema.nodes["paragraph"].create(undefined, [
+          schema.text("Paragraph 1"),
+        ]),
+      ]),
+    ]);
+
+    expect(isEmptyContainerChild(column)).toBeFalsy();
+  });
+
+  it("Non-text block", () => {
+    const schema = getEditor()._tiptapEditor.schema;
+
+    const column = schema.nodes["column"].create(undefined, [
+      schema.nodes["blockContainer"].create(undefined, [
+        schema.nodes["image"].create(),
+      ]),
+    ]);
+
+    expect(isEmptyContainerChild(column)).toBeFalsy();
+  });
+});
+
+describe("Test fixContainer drops emptied columns", () => {
+  it.each<[string, string[]]>([
+    ["Start and end columns empty", ["", "Paragraph 1", "Paragraph 2", ""]],
+    ["First of two columns empty", ["", "Paragraph 1"]],
+    ["Last of two columns empty", ["Paragraph 1", ""]],
+    ["Two empty columns", ["", ""]],
+  ])("%s", (_name, texts) => {
+    const editor = getEditor();
+    const schema = editor._tiptapEditor.schema;
+    const columnList = schema.nodes["columnList"].create(
+      undefined,
+      texts.map((text) =>
+        schema.nodes["column"].create(undefined, [
+          schema.nodes["blockContainer"].create(undefined, [
+            schema.nodes["paragraph"].create(
+              undefined,
+              text ? schema.text(text) : undefined,
+            ),
+          ]),
+        ]),
+      ),
+    );
+    const tr = editor.prosemirrorState.tr;
+    tr.replaceRangeWith(1, tr.doc.firstChild!.content.size, columnList);
+    fixContainer(tr, 1);
+    expect(tr.doc).toMatchSnapshot();
+  });
+});
diff --git a/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/external.html b/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/external.html
index 2237513b6b..78534582b8 100644
--- a/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/external.html
+++ b/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/external.html
@@ -1 +1 @@
-<div class="bn-block-column-list" data-node-type="columnList" data-id="1" style="display: flex;"><div class="bn-block-column" data-node-type="column" data-id="2" data-width="1" style="flex-grow: 1;" data-nesting-level="1"><p data-nesting-level="2">Column Paragraph 0</p><p data-nesting-level="2">Column Paragraph 1</p></div><div class="bn-block-column" data-node-type="column" data-id="5" data-width="1" style="flex-grow: 1;" data-nesting-level="1"><p data-nesting-level="2">Column Paragraph 2</p><p data-nesting-level="2">Column Paragraph 3</p></div></div>
\ No newline at end of file
+<div class="bn-block-column-list" style="display: flex;" data-node-type="columnList" data-children-of="columnList"><div class="bn-block-column" style="flex-grow: 1;" data-node-type="column" data-children-of="column" data-nesting-level="1"><p data-nesting-level="2">Column Paragraph 0</p><p data-nesting-level="2">Column Paragraph 1</p></div><div class="bn-block-column" style="flex-grow: 1;" data-node-type="column" data-children-of="column" data-nesting-level="1"><p data-nesting-level="2">Column Paragraph 2</p><p data-nesting-level="2">Column Paragraph 3</p></div></div>
\ No newline at end of file
diff --git a/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/internal.html b/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/internal.html
index 5876b3bd03..0d6612056e 100644
--- a/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/internal.html
+++ b/packages/xl-multi-column/src/test/conversions/__snapshots__/multi-column/undefined/internal.html
@@ -1 +1 @@
-<div class="bn-block-group" data-node-type="blockGroup"><div class="bn-block-column-list" data-node-type="columnList" data-id="1" style="display: flex;"><div class="bn-block-column" data-node-type="column" data-id="2" data-width="1" style="flex-grow: 1;"><div class="bn-block-outer" data-node-type="blockOuter" data-id="3"><div class="bn-block" data-node-type="blockContainer" data-id="3"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 0</p></div></div></div><div class="bn-block-outer" data-node-type="blockOuter" data-id="4"><div class="bn-block" data-node-type="blockContainer" data-id="4"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 1</p></div></div></div></div><div class="bn-block-column" data-node-type="column" data-id="5" data-width="1" style="flex-grow: 1;"><div class="bn-block-outer" data-node-type="blockOuter" data-id="6"><div class="bn-block" data-node-type="blockContainer" data-id="6"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 2</p></div></div></div><div class="bn-block-outer" data-node-type="blockOuter" data-id="7"><div class="bn-block" data-node-type="blockContainer" data-id="7"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 3</p></div></div></div></div></div></div>
\ No newline at end of file
+<div class="bn-block-group" data-node-type="blockGroup"><div class="bn-block-column-list" style="display: flex;" data-node-type="columnList" data-id="1" data-children-of="columnList"><div class="bn-block-column" style="flex-grow: 1;" data-node-type="column" data-id="2" data-children-of="column"><div class="bn-block-outer" data-node-type="blockOuter" data-id="3"><div class="bn-block" data-node-type="blockContainer" data-id="3"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 0</p></div></div></div><div class="bn-block-outer" data-node-type="blockOuter" data-id="4"><div class="bn-block" data-node-type="blockContainer" data-id="4"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 1</p></div></div></div></div><div class="bn-block-column" style="flex-grow: 1;" data-node-type="column" data-id="5" data-children-of="column"><div class="bn-block-outer" data-node-type="blockOuter" data-id="6"><div class="bn-block" data-node-type="blockContainer" data-id="6"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 2</p></div></div></div><div class="bn-block-outer" data-node-type="blockOuter" data-id="7"><div class="bn-block" data-node-type="blockContainer" data-id="7"><div class="bn-block-content" data-content-type="paragraph"><p class="bn-inline-content">Column Paragraph 3</p></div></div></div></div></div></div>
\ No newline at end of file
diff --git a/packages/xl-multi-column/src/test/extensions/columnDrop.test.ts b/packages/xl-multi-column/src/test/extensions/columnDrop.test.ts
new file mode 100644
index 0000000000..1a2ed28305
--- /dev/null
+++ b/packages/xl-multi-column/src/test/extensions/columnDrop.test.ts
@@ -0,0 +1,95 @@
+import { getNodeById } from "@blocknote/core";
+import { Fragment, Slice } from "prosemirror-model";
+import { describe, expect, it, vi } from "vite-plus/test";
+
+import { createMultiColumnHandleDropPlugin } from "../../extensions/DropCursor/multiColumnHandleDropPlugin.js";
+import { detectEdgePosition } from "../../extensions/DropCursor/multiColumnDropCursor.js";
+import { setupTestEnv } from "../setupTestEnv.js";
+
+vi.mock("../../extensions/DropCursor/multiColumnDropCursor.js", () => ({
+  detectEdgePosition: vi.fn(),
+}));
+
+const getEditor = setupTestEnv();
+
+function dropOnColumn(
+  ids: string[],
+  target: string,
+  position: "left" | "right",
+) {
+  const editor = getEditor();
+  const view = editor.prosemirrorView;
+  const column = getNodeById(target, view.state.doc)!;
+  vi.mocked(detectEdgePosition).mockReturnValue({ ...column, position });
+  const nodes = ids.map((id) => getNodeById(id, view.state.doc)!.node);
+  const plugin = createMultiColumnHandleDropPlugin(editor);
+  return plugin.props.handleDrop!.call(
+    plugin,
+    view,
+    Object.assign(new MouseEvent("drop"), { dataTransfer: null }),
+    new Slice(Fragment.from(nodes), 0, 0),
+    true,
+  );
+}
+
+describe("column edge drops", () => {
+  it.each(["left", "right"] as const)(
+    "moves a mixed selection to an emptied target's %s edge",
+    (edge) => {
+      const editor = getEditor();
+      editor.insertBlocks(
+        [
+          {
+            id: "column-last",
+            type: "column",
+            children: [{ id: "last", type: "paragraph", content: "Last" }],
+          },
+        ],
+        "column-1",
+        "after",
+      );
+      const dragged = [
+        "column-paragraph-1",
+        "column-paragraph-2",
+        "column-paragraph-3",
+      ];
+      expect(dropOnColumn(dragged, "column-1", edge)).toBe(true);
+      expect(
+        editor
+          .getBlock("column-list-0")!
+          .children.map((column) => column.children.map((block) => block.id)),
+      ).toEqual([["column-paragraph-0"], dragged, ["last"]]);
+      expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+    },
+  );
+
+  it("preserves the column when dropping only its own children", () => {
+    const editor = getEditor();
+    const before = editor.document;
+    dropOnColumn(
+      ["column-paragraph-0", "column-paragraph-1"],
+      "column-0",
+      "right",
+    );
+    expect(editor.document).toEqual(before);
+  });
+
+  it("unwraps the layout when all its blocks are dropped together", () => {
+    const editor = getEditor();
+    const dragged = [
+      "column-paragraph-0",
+      "column-paragraph-1",
+      "column-paragraph-2",
+      "column-paragraph-3",
+    ];
+    dropOnColumn(dragged, "column-0", "left");
+    expect(editor.getBlock("column-list-0")).toBeUndefined();
+    expect(editor.document.map((block) => block.id)).toEqual([
+      "paragraph-0",
+      "paragraph-1",
+      ...dragged,
+      "paragraph-2",
+    ]);
+    expect(() => editor.prosemirrorState.doc.check()).not.toThrow();
+  });
+});
diff --git a/packages/xl-multi-column/src/test/extensions/columnResize.test.ts b/packages/xl-multi-column/src/test/extensions/columnResize.test.ts
new file mode 100644
index 0000000000..c8cf8e909b
--- /dev/null
+++ b/packages/xl-multi-column/src/test/extensions/columnResize.test.ts
@@ -0,0 +1,176 @@
+import { getNodeById } from "@blocknote/core";
+import { describe, expect, it } from "vite-plus/test";
+
+import {
+  ColumnState,
+  columnResizePluginKey,
+} from "../../extensions/ColumnResize/ColumnResizeExtension.js";
+import { setupTestEnv } from "../setupTestEnv.js";
+
+const getEditor = setupTestEnv();
+
+// Puts the column resize plugin into the state it would be in when the user
+// hovers the boundary between the two columns of "column-list-0" in the test
+// document, as the plugin's mouse handlers would.
+function hoverColumnBoundary() {
+  const editor = getEditor();
+  const view = editor._tiptapEditor.view;
+
+  const columnList = getNodeById("column-list-0", view.state.doc);
+  const leftColumn = getNodeById("column-0", view.state.doc);
+  const rightColumn = getNodeById("column-1", view.state.doc);
+
+  if (!columnList || !leftColumn || !rightColumn) {
+    throw new Error("Test document is missing expected columns");
+  }
+
+  const hoverState: ColumnState = {
+    type: "hover-column",
+    columnList: {
+      element: document.createElement("div"),
+      id: "column-list-0",
+      ...columnList,
+    },
+    leftColumn: {
+      element: document.createElement("div"),
+      id: "column-0",
+      ...leftColumn,
+    },
+    rightColumn: {
+      element: document.createElement("div"),
+      id: "column-1",
+      ...rightColumn,
+    },
+  };
+
+  view.dispatch(view.state.tr.setMeta(columnResizePluginKey, hoverState));
+}
+
+describe("Column resize plugin state after doc changes", () => {
+  it("falls back to default when a hovered column's removal unwraps the column list", () => {
+    const editor = getEditor();
+
+    hoverColumnBoundary();
+
+    // Removing one of the two columns brings the column list below its
+    // minimum of 2 children, so it gets unwrapped entirely. This used to
+    // throw a RangeError from the plugin's decorations, as they were built
+    // from positions resolved against the old, larger doc.
+    editor.removeBlocks(["column-1"]);
+
+    expect(
+      columnResizePluginKey.getState(editor._tiptapEditor.view.state),
+    ).toEqual({ type: "default" });
+    // The surviving column's two paragraphs are unwrapped to the top level.
+    expect(editor.document.map((block) => block.type)).toEqual([
+      "paragraph",
+      "paragraph",
+      "paragraph",
+      "paragraph",
+      "paragraph",
+    ]);
+  });
+
+  it("falls back to default when the whole doc is replaced", () => {
+    const editor = getEditor();
+
+    hoverColumnBoundary();
+
+    // Mimics select-all + backspace clearing the document while columns are
+    // hovered.
+    editor.replaceBlocks(editor.document, [{ type: "paragraph" }]);
+
+    expect(
+      columnResizePluginKey.getState(editor._tiptapEditor.view.state),
+    ).toEqual({ type: "default" });
+    expect(editor.document).toHaveLength(1);
+  });
+
+  it("keeps the hover state when an unrelated block changes", () => {
+    const editor = getEditor();
+
+    hoverColumnBoundary();
+
+    editor.updateBlock("paragraph-1", { content: "Updated Paragraph 1" });
+
+    const pluginState = columnResizePluginKey.getState(
+      editor._tiptapEditor.view.state,
+    );
+    expect(pluginState?.type).toBe("hover-column");
+  });
+});
+
+describe.each(["hover-column", "resize"] as const)(
+  "%s pair validation",
+  (mode) => {
+    function startPair() {
+      hoverColumnBoundary();
+      if (mode === "resize") {
+        const view = getEditor().prosemirrorView;
+        const state = columnResizePluginKey.getState(view.state);
+        if (state?.type !== "hover-column") {
+          throw new Error("Expected a hovered column pair");
+        }
+        const resize: ColumnState = {
+          ...state,
+          type: "resize",
+          startPos: 0,
+          leftColumn: { ...state.leftColumn, widthPx: 100, widthPercent: 1 },
+          rightColumn: { ...state.rightColumn, widthPx: 100, widthPercent: 1 },
+        };
+        view.dispatch(view.state.tr.setMeta(columnResizePluginKey, resize));
+      }
+    }
+
+    it.each(["reorder", "separate", "reparent"] as const)(
+      "clears the pair after %s",
+      (change) => {
+        const editor = getEditor();
+        startPair();
+        const columns = editor.getBlock("column-list-0")!.children;
+        const extra = {
+          id: "extra-column",
+          type: "column" as const,
+          children: [{ type: "paragraph" as const, content: "Extra" }],
+        };
+        if (change === "reorder") {
+          editor.updateBlock("column-list-0", {
+            children: [columns[1], columns[0]],
+          });
+        } else if (change === "separate") {
+          editor.updateBlock("column-list-0", {
+            children: [columns[0], extra, columns[1]],
+          });
+        } else {
+          editor.replaceBlocks(editor.document, [
+            {
+              type: "columnList",
+              id: "column-list-0",
+              children: [columns[0], extra],
+            },
+            {
+              type: "columnList",
+              id: "other-list",
+              children: [
+                columns[1],
+                { type: "column", children: [{ type: "paragraph" }] },
+              ],
+            },
+          ]);
+        }
+        expect(columnResizePluginKey.getState(editor.prosemirrorState)).toEqual(
+          { type: "default" },
+        );
+      },
+    );
+
+    it("keeps an adjacent pair after an unrelated edit", () => {
+      const editor = getEditor();
+      startPair();
+      editor.updateBlock("paragraph-1", { content: "Changed" });
+      expect(
+        columnResizePluginKey.getState(editor.prosemirrorState)?.type,
+      ).toBe(mode);
+    });
+  },
+);
diff --git a/packages/xl-odt-exporter/src/odt/odtExporter.test.ts b/packages/xl-odt-exporter/src/odt/odtExporter.test.ts
index 4883fd0387..a6681e6917 100644
--- a/packages/xl-odt-exporter/src/odt/odtExporter.test.ts
+++ b/packages/xl-odt-exporter/src/odt/odtExporter.test.ts
@@ -1,9 +1,12 @@
 import {
   BlockNoteSchema,
+  createBlockSpec,
   createPageBreakBlockSpec,
   defaultBlockSpecs,
 } from "@blocknote/core";
 import { testODTDocumentAgainstSnapshot } from "@shared/util/odtTestUtil.js";
+import { partialBlocksToBlocksForTesting } from "@shared/formatConversionTestUtil.js";
+import { BlobReader, FileEntry, TextWriter, ZipReader } from "@zip.js/zip.js";
 import { testDocument } from "@shared/testDocument.js";
 import { beforeAll, describe, expect, it } from "vite-plus/test";
 import { createElement } from "react";
@@ -101,3 +104,113 @@ describe("exporter", () => {
     );
   });
 });
+
+describe("titled blocks", () => {
+  // A titled block: inline content (the title) plus children (the body). The
+  // mapping renders the title and places the children inside its own
+  // section; because the block counts as a container, transformBlocks must
+  // not append them after it as tab-indented siblings.
+  const Alert = createBlockSpec(
+    {
+      type: "alert" as const,
+      propSchema: {},
+      content: "inline",
+      children: { allow: "blocks" },
+    },
+    {
+      render: (block: any) => {
+        const dom = document.createElement("div");
+        dom.setAttribute("data-node-type", "alert");
+        dom.setAttribute("data-id", block.id);
+        return { dom, contentDOM: dom };
+      },
+      renderFrame: (_block: any) => {
+        const dom = document.createElement("div");
+        dom.className = "alert-box";
+        return { dom, slot: dom };
+      },
+    },
+  )();
+
+  const alertSchema = BlockNoteSchema.create({
+    blockSpecs: {
+      ...defaultBlockSpecs,
+      alert: Alert,
+    },
+  });
+
+  const alertDocument = partialBlocksToBlocksForTesting(alertSchema, [
+    {
+      type: "alert",
+      content: "Heads up",
+      children: [
+        { type: "paragraph", content: "First" },
+        { type: "paragraph", content: "Second" },
+      ],
+    },
+  ] as any);
+
+  it("throws a clear error for an unmapped container block", async () => {
+    const exporter = new ODTExporter(
+      alertSchema,
+      odtDefaultSchemaMappings as any,
+      { resolveFileUrl: testResolveFileUrl },
+    );
+
+    await expect(
+      exporter.transformBlocks(alertDocument as any),
+    ).rejects.toThrow(/container block type "alert"/);
+  });
+
+  it("renders a titled block's title and places its children inside", async () => {
+    const exporter = new ODTExporter(
+      alertSchema,
+      {
+        ...odtDefaultSchemaMappings,
+        blockMapping: {
+          ...odtDefaultSchemaMappings.blockMapping,
+          alert: (
+            block: any,
+            exporter: any,
+            _nesting: any,
+            _index: any,
+            children: any,
+          ) =>
+            createElement(
+              "text:section",
+              { "text:name": "alert-body" },
+              createElement(
+                "text:p",
+                null,
+                "ALERT:",
+                ...exporter.transformInlineContent(block.content),
+              ),
+              ...((children ?? []) as any[]),
+            ),
+        },
+      } as any,
+      { resolveFileUrl: testResolveFileUrl },
+    );
+
+    const odt = await exporter.toODTDocument(alertDocument as any);
+    const entries = await new ZipReader(new BlobReader(odt)).getEntries();
+    const contentEntry = entries.find(
+      (entry) => entry.filename === "content.xml",
+    ) as FileEntry;
+    expect(contentEntry).toBeDefined();
+    const xml = await contentEntry.getData(new TextWriter());
+
+    // Title and children all sit inside the mapping's own section - placed
+    // by the mapping, not appended after it.
+    const sectionOpen = xml.indexOf("<text:section");
+    const sectionClose = xml.indexOf("</text:section>");
+    expect(sectionOpen).toBeGreaterThan(-1);
+    const titleIdx = xml.indexOf("Heads up");
+    expect(titleIdx).toBeGreaterThan(sectionOpen);
+    const firstIdx = xml.indexOf(">First<");
+    expect(firstIdx).toBeGreaterThan(titleIdx);
+    const secondIdx = xml.indexOf(">Second<");
+    expect(secondIdx).toBeGreaterThan(firstIdx);
+    expect(secondIdx).toBeLessThan(sectionClose);
+  });
+});
diff --git a/packages/xl-odt-exporter/src/odt/odtExporter.tsx b/packages/xl-odt-exporter/src/odt/odtExporter.tsx
index fc72dc1be0..f254a4fc63 100644
--- a/packages/xl-odt-exporter/src/odt/odtExporter.tsx
+++ b/packages/xl-odt-exporter/src/odt/odtExporter.tsx
@@ -59,7 +59,7 @@ export class ODTExporter<
   public readonly options: ExporterOptions;
 
   constructor(
-    protected readonly schema: BlockNoteSchema<B, I, S>,
+    schema: BlockNoteSchema<B, I, S>,
     mappings: Exporter<
       NoInfer<B>,
       NoInfer<I>,
@@ -155,32 +155,23 @@ export class ODTExporter<
         numberedListIndex = 0;
       }
 
-      if (["columnList", "column"].includes(block.type)) {
-        const children = await this.transformBlocks(block.children, 0);
-        const content = await this.mapBlock(
-          block as any,
-          0,
-          numberedListIndex,
-          children,
-        );
-
-        ret.push(content);
-      } else {
-        const children = await this.transformBlocks(
-          block.children,
-          nestingLevel + 1,
-        );
-        const content = await this.mapBlock(
-          block as any,
-          nestingLevel,
+      const isContainer = this.isContainerBlock(block);
+      // Container mappings own the layout: table cells start a fresh
+      // indentation context instead of inheriting literal <text:tab>s.
+      const children = await this.transformBlocks(
+        block.children,
+        isContainer ? 0 : nestingLevel + 1,
+      );
+      ret.push(
+        await this.mapBlock(
+          block,
+          isContainer ? 0 : nestingLevel,
           numberedListIndex,
           children,
-        );
-
-        ret.push(content);
-        if (children.length > 0) {
-          ret.push(...children);
-        }
+        ),
+      );
+      if (!isContainer) {
+        ret.push(...children);
       }
     }
 
diff --git a/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.test.tsx b/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.test.tsx
index 8be64289e2..22364d427d 100644
--- a/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.test.tsx
+++ b/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.test.tsx
@@ -1,11 +1,14 @@
 import {
   BlockNoteSchema,
+  createBlockSpec,
   createPageBreakBlockSpec,
   defaultBlockSpecs,
 } from "@blocknote/core";
 import { ColumnBlock, ColumnListBlock } from "@blocknote/xl-multi-column";
-import { Text } from "@react-pdf/renderer";
+import { Text, View } from "@react-pdf/renderer";
+import { partialBlocksToBlocksForTesting } from "@shared/formatConversionTestUtil.js";
 import { testDocument } from "@shared/testDocument.js";
+import { Fragment } from "react";
 import reactElementToJSXString from "react-element-to-jsx-string";
 import { describe, expect, it } from "vite-plus/test";
 import { pdfDefaultSchemaMappings } from "./defaultSchema/index.js";
@@ -59,3 +62,98 @@ describe("exporter", () => {
     );
   });
 });
+
+describe("titled blocks", () => {
+  // A titled block: inline content (the title) plus children (the body). The
+  // mapping renders the title and places the children inside its own view;
+  // because the block counts as a container, transformBlocks must not wrap
+  // them after it in padded sibling views.
+  const Alert = createBlockSpec(
+    {
+      type: "alert" as const,
+      propSchema: {},
+      content: "inline",
+      children: { allow: "blocks" },
+    },
+    {
+      render: (block: any) => {
+        const dom = document.createElement("div");
+        dom.setAttribute("data-node-type", "alert");
+        dom.setAttribute("data-id", block.id);
+        return { dom, contentDOM: dom };
+      },
+      renderFrame: (_block: any) => {
+        const dom = document.createElement("div");
+        dom.className = "alert-box";
+        return { dom, slot: dom };
+      },
+    },
+  )();
+
+  const alertSchema = BlockNoteSchema.create({
+    blockSpecs: {
+      ...defaultBlockSpecs,
+      alert: Alert,
+    },
+  });
+
+  const alertDocument = partialBlocksToBlocksForTesting(alertSchema, [
+    {
+      type: "alert",
+      content: "Heads up",
+      children: [
+        { type: "paragraph", content: "First" },
+        { type: "paragraph", content: "Second" },
+      ],
+    },
+  ] as any);
+
+  it("throws a clear error for an unmapped container block", async () => {
+    const exporter = new PDFExporter(
+      alertSchema,
+      pdfDefaultSchemaMappings as any,
+    );
+
+    await expect(
+      exporter.transformBlocks(alertDocument as any),
+    ).rejects.toThrow(/container block type "alert"/);
+  });
+
+  it("renders a titled block's title and places its children inside", async () => {
+    const exporter = new PDFExporter(alertSchema, {
+      ...pdfDefaultSchemaMappings,
+      blockMapping: {
+        ...pdfDefaultSchemaMappings.blockMapping,
+        alert: (
+          block: any,
+          exporter: any,
+          _nestingLevel: any,
+          _numberedListIndex: any,
+          children: any,
+        ) => (
+          <View>
+            <Text>ALERT:{exporter.transformInlineContent(block.content)}</Text>
+            {children}
+          </View>
+        ),
+      },
+    } as any);
+
+    const transformed = await exporter.transformBlocks(alertDocument as any);
+    const str = reactElementToJSXString(
+      <Fragment>{transformed as any}</Fragment>,
+    );
+
+    // The mapping's own view holds the title and both children - the block
+    // took the container branch, so no marginLeft wrapper view was added
+    // around the children (react-element-to-jsx-string prints the primitives
+    // upper case, as in the document snapshots). The children themselves
+    // arrive pre-wrapped in their usual padded views, exactly as column
+    // children do.
+    expect(str).not.toContain("marginLeft");
+    const titleIdx = str.indexOf("Heads up");
+    expect(titleIdx).toBeGreaterThan(-1);
+    expect(str.indexOf("First")).toBeGreaterThan(titleIdx);
+    expect(str).toContain("Second");
+  });
+});
diff --git a/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.tsx b/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.tsx
index f6242c0bb7..5ff077fa6d 100644
--- a/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.tsx
+++ b/packages/xl-pdf-exporter/src/react-pdf/pdfExporter.tsx
@@ -106,7 +106,7 @@ export class PDFExporter<
     /**
      * The schema of your editor. The mappings are automatically typed checked against this schema.
      */
-    protected readonly schema: BlockNoteSchema<B, I, S>,
+    schema: BlockNoteSchema<B, I, S>,
     /**
      * The mappings that map the BlockNote schema to the react-pdf content.
      *
@@ -178,13 +178,13 @@ export class PDFExporter<
       }
       const children = await this.transformBlocks(b.children, nestingLevel + 1);
       const self = await this.mapBlock(
-        b as any,
+        b,
         nestingLevel,
         numberedListIndex,
         children,
-      ); // TODO: any
+      );
 
-      if (["pageBreak", "columnList", "column"].includes(b.type)) {
+      if (b.type === "pageBreak" || this.isContainerBlock(b)) {
         ret.push(self);
         continue;
       }
diff --git a/packages/xl-typst-exporter/src/__snapshots__/testDocument.typ b/packages/xl-typst-exporter/src/__snapshots__/testDocument.typ
index 7beb8b3135..51eeea8aab 100644
--- a/packages/xl-typst-exporter/src/__snapshots__/testDocument.typ
+++ b/packages/xl-typst-exporter/src/__snapshots__/testDocument.typ
@@ -169,19 +169,20 @@
 
 #block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#strong("Some inline code: ")#raw("var foo = 'bar';")]
 
-#grid(
-  columns: (0.8fr, 1.4fr, 0.8fr),
-  column-gutter: 1em,
-  [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"This paragraph is in a column!"]],
-  [#block(width: 100%, inset: (top: (8pt + 6.9pt), bottom: 6.9pt))[#heading(level: 1, outlined: true)[#"So is this heading!"]]],
-  [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"You can have multiple blocks in a column too"]
+#{
+  let cols = (
+    (width: 0.8, body: [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"This paragraph is in a column!"]]),
+    (width: 1.4, body: [#block(width: 100%, inset: (top: (8pt + 6.9pt), bottom: 6.9pt))[#heading(level: 1, outlined: true)[#"So is this heading!"]]]),
+    (width: 0.8, body: [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"You can have multiple blocks in a column too"]
 
 #list(
   [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"Block 1"]],
   [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"Block 2"]],
   [#block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#"Block 3"]]
-)]
-)
+)]),
+  )
+  grid(columns: cols.map(c => c.width * 1fr), column-gutter: 1em, ..cols.map(c => c.body))
+}
 
 #block(width: 100%, inset: (top: 6.9pt, bottom: 6.9pt))[#line(length: 100%, stroke: 1pt + rgb("#7D797A"))]
 
diff --git a/packages/xl-typst-exporter/src/defaultSchema/blocks.ts b/packages/xl-typst-exporter/src/defaultSchema/blocks.ts
index daeb3733bf..12dc1349da 100644
--- a/packages/xl-typst-exporter/src/defaultSchema/blocks.ts
+++ b/packages/xl-typst-exporter/src/defaultSchema/blocks.ts
@@ -159,11 +159,36 @@ export const typstBlockMappingForDefaultSchema: BlockMapping<
   divider: () => `#line(length: 100%, stroke: 1pt + rgb("#7D797A"))`,
   pageBreak: () => `#pagebreak(weak: true)`,
 
-  // Multi-column layout is assembled by TypstExporter.transformBlocks (columns
-  // become grid cells). These entries exist only to satisfy the BlockMapping
-  // type — they are never invoked.
-  column: () => "",
-  columnList: () => "",
+  // A column only ever exists as a columnList's child (its config is
+  // `placeable: "namedOnly"`), so rather than content it returns the
+  // Typst *value* its parent needs: the width and the cell body. Typst takes
+  // a grid's track sizes on the grid, not on the cell, so the width has to
+  // reach the parent - the same reason the DOCX mapping hands its columnList
+  // a width-carrying table cell.
+  column: (block, _exporter, _nestingLevel, _numberedListIndex, children) =>
+    `(width: ${block.props.width ?? 1}, body: [${(children ?? []).join("\n\n")}])`,
+
+  // Lays the columns out side-by-side as a Typst `grid`, assembled in Typst
+  // code from the columns' (width, body) pairs so the fractional (`fr`)
+  // tracks keep their relative sizes. `grid` is a layout primitive (not a
+  // `table`), so it isn't tagged as a data table in the PDF. The trailing
+  // comma matters: `(x)` in Typst is a parenthesized value, not a one-element
+  // array.
+  columnList: (
+    _block,
+    _exporter,
+    _nestingLevel,
+    _numberedListIndex,
+    children,
+  ) =>
+    [
+      `#{`,
+      `  let cols = (`,
+      ...(children ?? []).map((c) => `    ${c},`),
+      `  )`,
+      `  grid(columns: cols.map(c => c.width * 1fr), column-gutter: 1em, ..cols.map(c => c.body))`,
+      `}`,
+    ].join("\n"),
 
   // --- media -> Figure + Alt --------------------------------------------------
   image: (block, exporter) =>
diff --git a/packages/xl-typst-exporter/src/typstExporter.test.ts b/packages/xl-typst-exporter/src/typstExporter.test.ts
index 890545d4d2..5ed9e05e0b 100644
--- a/packages/xl-typst-exporter/src/typstExporter.test.ts
+++ b/packages/xl-typst-exporter/src/typstExporter.test.ts
@@ -1,5 +1,6 @@
 import {
   BlockNoteSchema,
+  createBlockSpec,
   createPageBreakBlockSpec,
   defaultBlockSpecs,
 } from "@blocknote/core";
@@ -29,6 +30,101 @@ const fullSchema = BlockNoteSchema.create({
   },
 });
 
+// A minimal custom container, standing in for a callout/card: content-less,
+// holding child blocks. Its mapping is what has to place them.
+const Box = createBlockSpec(
+  {
+    type: "box" as const,
+    propSchema: {},
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    render: (block: any) => {
+      const dom = document.createElement("div");
+      dom.setAttribute("data-node-type", "box");
+      dom.setAttribute("data-id", block.id);
+      return { dom, contentDOM: dom };
+    },
+  },
+)();
+
+const boxSchema = BlockNoteSchema.create({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    box: Box,
+  },
+});
+
+const boxDocument = partialBlocksToBlocksForTesting(boxSchema, [
+  {
+    type: "box",
+    children: [
+      { type: "paragraph", content: "First" },
+      { type: "paragraph", content: "Second" },
+    ],
+  },
+] as any);
+
+// A titled block: inline content (the title) plus children (the body). The
+// schema build marks it as a titled block rather than a container node, but
+// for export the contract is the same - the mapping renders the title and
+// places the children, so they must arrive as the mapping's `children` arg.
+const Alert = createBlockSpec(
+  {
+    type: "alert" as const,
+    propSchema: {},
+    content: "inline",
+    children: { allow: "blocks" },
+  },
+  {
+    render: (block: any) => {
+      const dom = document.createElement("div");
+      dom.setAttribute("data-node-type", "alert");
+      dom.setAttribute("data-id", block.id);
+      return { dom, contentDOM: dom };
+    },
+    renderFrame: (_block: any) => {
+      const dom = document.createElement("div");
+      dom.className = "alert-box";
+      return { dom, slot: dom };
+    },
+  },
+)();
+
+const alertSchema = BlockNoteSchema.create({
+  blockSpecs: {
+    ...defaultBlockSpecs,
+    alert: Alert,
+  },
+});
+
+const alertDocument = partialBlocksToBlocksForTesting(alertSchema, [
+  {
+    type: "alert",
+    content: "Heads up",
+    children: [
+      { type: "paragraph", content: "First" },
+      { type: "paragraph", content: "Second" },
+    ],
+  },
+] as any);
+
+const alertMappings = {
+  ...typstDefaultSchemaMappings,
+  blockMapping: {
+    ...typstDefaultSchemaMappings.blockMapping,
+    alert: (
+      block: any,
+      exporter: any,
+      _nestingLevel: any,
+      _numberedListIndex: any,
+      children?: string[],
+    ) =>
+      `#rect[#strong[${exporter.transformInlineContent(block.content).join("")}]\n\n${(children ?? []).join("\n\n")}]`,
+  },
+} as any;
+
 describe("TypstExporter", () => {
   it("exports a real BlockNote document to Typst", async () => {
     // fullSchema (incl. multi-column) matches the shared testDocument. The
@@ -435,3 +531,94 @@ describe("TypstExporter", () => {
     ).toHaveLength(0);
   });
 });
+
+describe("container blocks", () => {
+  it("lays a columnList out as a grid with proportional tracks", async () => {
+    const exporter = new TypstExporter(fullSchema, typstDefaultSchemaMappings);
+
+    const typ = await exporter.toTypst(
+      partialBlocksToBlocksForTesting(fullSchema, [
+        {
+          type: "columnList",
+          children: [
+            {
+              type: "column",
+              props: { width: 2 },
+              children: [{ type: "paragraph", content: "Left" }],
+            },
+            {
+              type: "column",
+              children: [{ type: "paragraph", content: "Right" }],
+            },
+          ],
+        },
+      ] as any),
+    );
+
+    // Each column contributes its width and body; the grid derives its
+    // fractional tracks from them, so the relative sizes survive.
+    expect(typ).toContain("(width: 2, body: [");
+    expect(typ).toContain("(width: 1, body: [");
+    expect(typ).toContain(
+      "grid(columns: cols.map(c => c.width * 1fr), column-gutter: 1em, ..cols.map(c => c.body))",
+    );
+    // A layout grid, not a `table` - it must not be tagged as a data table.
+    expect(typ).not.toContain("#table(");
+
+    // The assembled markup is real Typst, not just a plausible string.
+    await compileTypstForTesting(typ, { assets: exporter.assetFiles });
+  });
+
+  it("passes its children to a custom container's mapping", async () => {
+    const typ = await new TypstExporter(boxSchema, {
+      ...typstDefaultSchemaMappings,
+      blockMapping: {
+        ...typstDefaultSchemaMappings.blockMapping,
+        box: (
+          _block: any,
+          _exporter: any,
+          _nestingLevel: any,
+          _numberedListIndex: any,
+          children?: string[],
+        ) => `#rect[${(children ?? []).join("\n\n")}]`,
+      },
+    } as any).toTypst(boxDocument);
+
+    // The children sit *inside* the container's own output - the mapping
+    // owns their placement - rather than following it as an indented run.
+    expect(typ).toContain("#rect[");
+    expect(typ.indexOf('#"First"')).toBeGreaterThan(typ.indexOf("#rect["));
+    expect(typ).toContain('#"Second"');
+    expect(typ).not.toContain("#pad(left: 1.5em)");
+  });
+
+  it("throws a clear error for an unmapped container block", async () => {
+    // The missing `box` mapping is the point of the test, and it's exactly
+    // what `BlockMapping` refuses to type - hence the cast (as in the DOCX
+    // exporter's equivalent test).
+    const exporter = new TypstExporter(
+      boxSchema,
+      typstDefaultSchemaMappings as any,
+    );
+
+    await expect(exporter.toTypst(boxDocument)).rejects.toThrow(
+      /container block type "box"/,
+    );
+  });
+
+  it("renders a titled block's title and places its children inside", async () => {
+    const typ = await new TypstExporter(alertSchema, alertMappings).toTypst(
+      alertDocument,
+    );
+
+    // The title sits inside the container's own output, and the children
+    // follow it there - placed by the mapping, not appended after as an
+    // indented run.
+    expect(typ).toContain("#rect[");
+    const titleIdx = typ.indexOf('#"Heads up"');
+    expect(titleIdx).toBeGreaterThan(typ.indexOf("#rect["));
+    expect(typ.indexOf('#"First"')).toBeGreaterThan(titleIdx);
+    expect(typ).toContain('#"Second"');
+    expect(typ).not.toContain("#pad(left: 1.5em)");
+  });
+});
diff --git a/packages/xl-typst-exporter/src/typstExporter.ts b/packages/xl-typst-exporter/src/typstExporter.ts
index 1c8f6af33c..f45a27105c 100644
--- a/packages/xl-typst-exporter/src/typstExporter.ts
+++ b/packages/xl-typst-exporter/src/typstExporter.ts
@@ -253,23 +253,15 @@ export class TypstExporter<
         continue;
       }
 
-      // A columnList lays its column children out side-by-side. transformBlocks
-      // owns this (rather than the block mapping) because the columns must
-      // become grid cells, not the generic indented-children wrapper.
-      if (b.type === "columnList") {
-        out.push(await this.renderColumnList(b, nestingLevel));
-        i++;
-        continue;
-      }
-
+      const isContainer = this.isContainerBlock(b);
       const children = await this.transformBlocks(b.children, nestingLevel + 1);
-      const self = (await this.mapBlock(
-        b as any,
+      const self = await this.mapBlock(
+        b,
         nestingLevel,
         0,
-        [],
-      )) as string;
-      out.push(this.wrapBlock(b, self, children));
+        isContainer ? children : [],
+      );
+      out.push(isContainer ? self : this.wrapBlock(b, self, children));
       i++;
     }
     return out;
@@ -279,12 +271,7 @@ export class TypstExporter<
     block: Block<B, I, S>,
     nestingLevel: number,
   ): Promise<string> {
-    const body = (await this.mapBlock(
-      block as any,
-      nestingLevel,
-      0,
-      [],
-    )) as string;
+    const body = await this.mapBlock(block, nestingLevel, 0, []);
     const children = await this.transformBlocks(
       block.children,
       nestingLevel + 1,
@@ -324,32 +311,6 @@ export class TypstExporter<
     );
   }
 
-  /**
-   * Render a columnList as a Typst `grid`: each child column becomes a grid
-   * cell, its `width` prop mapped to a fractional (`fr`) track so relative
-   * column sizes are preserved. `grid` is a layout primitive (not a `table`),
-   * so it isn't tagged as a data table in the PDF.
-   */
-  private async renderColumnList(
-    block: Block<B, I, S>,
-    nestingLevel: number,
-  ): Promise<string> {
-    const columns = block.children;
-    const tracks = columns
-      .map((c) => `${(c.props as { width?: number }).width ?? 1}fr`)
-      .join(", ");
-    const cells: string[] = [];
-    for (const col of columns) {
-      const inner = (
-        await this.transformBlocks(col.children, nestingLevel)
-      ).join("\n\n");
-      cells.push(`[${inner}]`);
-    }
-    return `#grid(\n  columns: (${tracks}),\n  column-gutter: 1em,\n  ${cells.join(
-      ",\n  ",
-    )}\n)`;
-  }
-
   private wrapList(
     kind: "bullet" | "numbered" | "check",
     items: string[],
diff --git a/playground/src/examples.gen.tsx b/playground/src/examples.gen.tsx
index 2d32e8c524..2e793bfe93 100644
--- a/playground/src/examples.gen.tsx
+++ b/playground/src/examples.gen.tsx
@@ -1487,6 +1487,33 @@ export const examples = {
         readme:
           "In this example, we create a custom block which renders a simple HTML paragraph with placeholder text. The block has no editable content.\n\n**Relevant Docs:**\n\n- [Custom Blocks](/docs/features/custom-schemas/custom-blocks)\n- [Editor Setup](/docs/getting-started/editor-setup)",
       },
+      {
+        projectSlug: "container-block",
+        fullSlug: "custom-schema/container-block",
+        pathFromRoot: "examples/06-custom-schema/09-container-block",
+        config: {
+          playground: true,
+          docs: true,
+          author: "nickthesick",
+          tags: [
+            "Intermediate",
+            "Blocks",
+            "Custom Schemas",
+            "Suggestion Menus",
+            "Slash Menu",
+          ],
+          dependencies: {
+            "react-icons": "^5.5.0",
+          } as any,
+        },
+        title: "Container Block",
+        group: {
+          pathFromRoot: "examples/06-custom-schema",
+          slug: "custom-schema",
+        },
+        readme:
+          'In this example, we create a custom `Panel` block that holds other blocks as its body, like a Notion-style callout wrapping a paragraph followed by a code block.\n\nThe block declares the `children` config on `BlockConfig`. `children: { allow: "blocks" }` makes it a container: its child blocks mount into the frame\'s `slot` (attached with `ref={contentRef}`), and live on `block.children` at runtime. A pure container like this draws its box in `renderFrame` alone, which re-renders live when props change — click the icon to cycle the panel\'s flavor and watch the box follow without rebuilding the body.\n\nWe also wire up a Slash Menu item to insert the panel, and render the document JSON next to the editor so you can inspect the structure of the nested blocks.\n\n**Try it out:**\n\n- Press the "/" key inside the panel\'s body and add a code block, heading, or list.\n- Click the panel\'s icon to cycle its flavor. The box re-renders in place; the children are untouched.\n- Watch the JSON panel on the right update as you edit; the panel\'s children appear in `block.children`.\n- Insert a new panel via the Slash Menu (search "panel").\n\n**Relevant Docs:**\n\n- [Container Blocks](/docs/features/custom-schemas/container-blocks)\n- [Custom Blocks](/docs/features/custom-schemas/custom-blocks)\n- [Editor Setup](/docs/getting-started/editor-setup)',
+      },
       {
         projectSlug: "math-block",
         fullSlug: "custom-schema/math-block",
@@ -1566,6 +1593,33 @@ export const examples = {
         readme:
           'In this example, we build custom blocks on the source-with-preview pattern — the same building blocks behind BlockNote\'s math and diagram blocks. A custom "CSV table" block renders its comma-separated source as a table, and a custom "color" inline content renders a CSS color as a swatch. Both show the rendered preview in place, while the source is edited in a popup.\n\n**Try it out:** Click the table or a color chip to edit its source!\n\n**Relevant Docs:**\n\n- [Source with Preview Blocks](/docs/features/custom-schemas/source-with-preview)\n- [Custom Blocks](/docs/features/custom-schemas/custom-blocks)\n- [Custom Inline Content](/docs/features/custom-schemas/custom-inline-content)',
       },
+      {
+        projectSlug: "callout-block",
+        fullSlug: "custom-schema/callout-block",
+        pathFromRoot: "examples/06-custom-schema/13-callout-block",
+        config: {
+          playground: true,
+          docs: true,
+          author: "nickthesick",
+          tags: [
+            "Intermediate",
+            "Blocks",
+            "Custom Schemas",
+            "Suggestion Menus",
+            "Slash Menu",
+          ],
+          dependencies: {
+            "react-icons": "^5.5.0",
+          } as any,
+        },
+        title: "Callout Block",
+        group: {
+          pathFromRoot: "examples/06-custom-schema",
+          slug: "custom-schema",
+        },
+        readme:
+          'In this example, we create a custom `Callout` block with a real rich-text title and a body of child blocks (a titled block), like a Notion-style callout.\n\nThe block combines `content: "inline"` with the `children` config on `BlockConfig`. The title is ordinary inline content — formatting, links, and multiplayer cursors all work — while `children: { allow: "blocks" }` hosts the body blocks, which live on `block.children` at runtime. `render` draws the title row and `renderFrame` draws the box around the title and body together.\n\nWe also wire up a Slash Menu item to insert the callout, and render the document JSON next to the editor so you can inspect the structure of the titled block and its nested children.\n\n**Try it out:**\n\n- Press Enter at the end of the callout\'s title to jump into its body.\n- Press Backspace at the start of the first body block to merge it back into the title.\n- Press "/" inside the body and add a code block, heading, or list.\n- Watch the JSON panel on the right update as you edit; the title is `content` and the body is `block.children`.\n\n**Relevant Docs:**\n\n- [Container Blocks](/docs/features/custom-schemas/container-blocks)\n- [Custom Blocks](/docs/features/custom-schemas/custom-blocks)\n- [Editor Setup](/docs/getting-started/editor-setup)',
+      },
       {
         projectSlug: "draggable-inline-content",
         fullSlug: "custom-schema/draggable-inline-content",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0a4aeb2f0e..03bd5b9292 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -3511,6 +3511,52 @@ importers:
         specifier: ^8.0.0
         version: 8.0.8(@types/node@25.6.0)(esbuild@0.27.5)(jiti@2.6.1)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0)
 
+  examples/06-custom-schema/09-container-block:
+    dependencies:
+      '@blocknote/ariakit':
+        specifier: latest
+        version: link:../../../packages/ariakit
+      '@blocknote/core':
+        specifier: latest
+        version: link:../../../packages/core
+      '@blocknote/mantine':
+        specifier: latest
+        version: link:../../../packages/mantine
+      '@blocknote/react':
+        specifier: latest
+        version: link:../../../packages/react
+      '@blocknote/shadcn':
+        specifier: latest
+        version: link:../../../packages/shadcn
+      '@mantine/core':
+        specifier: ^9.0.2
+        version: 9.1.1(@mantine/hooks@9.1.1(react@19.2.5))(@types/react@19.2.14)(react-dom@19.2.5(react@19.2.5))(react@19.2.5)
+      '@mantine/hooks':
+        specifier: ^9.0.2
+        version: 9.1.1(react@19.2.5)
+      react:
+        specifier: ^19.2.3
+        version: 19.2.5
+      react-dom:
+        specifier: ^19.2.3
+        version: 19.2.5(react@19.2.5)
+      react-icons:
+        specifier: ^5.5.0
+        version: 5.6.0(react@19.2.5)
+    devDependencies:
+      '@types/react':
+        specifier: ^19.2.3
+        version: 19.2.14
+      '@types/react-dom':
+        specifier: ^19.2.3
+        version: 19.2.3(@types/react@19.2.14)
+      '@vitejs/plugin-react':
+        specifier: ^6.0.1
+        version: 6.0.1(babel-plugin-react-compiler@1.0.0)(vite@8.0.8(@types/node@25.6.0)(esbuild@0.27.5)(jiti@2.6.1)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0))
+      vite:
+        specifier: ^8.0.0
+        version: 8.0.8(@types/node@25.6.0)(esbuild@0.27.5)(jiti@2.6.1)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0)
+
   examples/06-custom-schema/09-math-block:
     dependencies:
       '@blocknote/ariakit':
@@ -3661,6 +3707,52 @@ importers:
         specifier: ^8.0.0
         version: 8.0.8(@types/node@25.6.0)(esbuild@0.27.5)(jiti@2.6.1)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0)
 
+  examples/06-custom-schema/13-callout-block:
+    dependencies:
+      '@blocknote/ariakit':
+        specifier: latest
+        version: link:../../../packages/ariakit
+      '@blocknote/core':
+        specifier: latest
+        version: link:../../../packages/core
+      '@blocknote/mantine':
+        specifier: latest
+        version: link:../../../packages/mantine
+      '@blocknote/react':
+        specifier: latest
+        version: link:../../../packages/react
+      '@blocknote/shadcn':
+        specifier: latest
+        version: link:../../../packages/shadcn
+      '@mantine/core':
+        specifier: ^9.0.2
+        version: 9.1.1(@mantine/hooks@9.1.1(react@19.2.5))(@types/react@19.2.14)(react-dom@19.2.5(react@19.2.5))(react@19.2.5)
+      '@mantine/hooks':
+        specifier: ^9.0.2
+        version: 9.1.1(react@19.2.5)
+      react:
+        specifier: ^19.2.3
+        version: 19.2.5
+      react-dom:
+        specifier: ^19.2.3
+        version: 19.2.5(react@19.2.5)
+      react-icons:
+        specifier: ^5.5.0
+        version: 5.6.0(react@19.2.5)
+    devDependencies:
+      '@types/react':
+        specifier: ^19.2.3
+        version: 19.2.14
+      '@types/react-dom':
+        specifier: ^19.2.3
+        version: 19.2.3(@types/react@19.2.14)
+      '@vitejs/plugin-react':
+        specifier: ^6.0.1
+        version: 6.0.1(babel-plugin-react-compiler@1.0.0)(vite@8.0.8(@types/node@25.6.0)(esbuild@0.27.5)(jiti@2.6.1)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0))
+      vite:
+        specifier: ^8.0.0
+        version: 8.0.8(@types/node@25.6.0)(esbuild@0.27.5)(jiti@2.6.1)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0)
+
   examples/06-custom-schema/draggable-inline-content:
     dependencies:
       '@blocknote/ariakit':
diff --git a/tests/src/end-to-end/exporters/exporterTestUtil.tsx b/tests/src/end-to-end/exporters/exporterTestUtil.tsx
index bd857d6ef9..a8e740b163 100644
--- a/tests/src/end-to-end/exporters/exporterTestUtil.tsx
+++ b/tests/src/end-to-end/exporters/exporterTestUtil.tsx
@@ -1,4 +1,5 @@
 import { BlockNoteSchema, defaultBlockSpecs } from "@blocknote/core";
+import { ColumnBlock, ColumnListBlock } from "@blocknote/xl-multi-column";
 import { expect } from "vite-plus/test";
 import { screenshotFull } from "../../utils/screenshotFull.js";
 
@@ -38,8 +39,19 @@ export const invalidMathBlock = {
   children: [],
 } as any;
 
+// Includes the multi-column blocks, which the shared test document contains.
+// They have to be in the *schema*, not just the mappings: the exporters read
+// the schema to tell a container block from a regular one, and a container
+// the exporter doesn't recognize gets its children appended after it instead
+// of placed by its mapping.
 export function schema() {
-  return BlockNoteSchema.create({ blockSpecs: defaultBlockSpecs });
+  return BlockNoteSchema.create({
+    blockSpecs: {
+      ...defaultBlockSpecs,
+      column: ColumnBlock,
+      columnList: ColumnListBlock,
+    },
+  });
 }
 
 /**
diff --git a/tests/src/end-to-end/keyboardhandlers/__snapshots__/enterPreservesNestedBlocks.json b/tests/src/end-to-end/keyboardhandlers/__snapshots__/enterPreservesNestedBlocks.json
index fe2cca639a..c849beeff2 100644
--- a/tests/src/end-to-end/keyboardhandlers/__snapshots__/enterPreservesNestedBlocks.json
+++ b/tests/src/end-to-end/keyboardhandlers/__snapshots__/enterPreservesNestedBlocks.json
@@ -25,28 +25,6 @@
                   "text": "H"
                 }
               ]
-            }
-          ]
-        },
-        {
-          "type": "blockContainer",
-          "attrs": {
-            "id": "3"
-          },
-          "content": [
-            {
-              "type": "paragraph",
-              "attrs": {
-                "backgroundColor": "default",
-                "textColor": "default",
-                "textAlignment": "left"
-              },
-              "content": [
-                {
-                  "type": "text",
-                  "text": "eading"
-                }
-              ]
             },
             {
               "type": "blockGroup",
@@ -102,6 +80,28 @@
               ]
             }
           ]
+        },
+        {
+          "type": "blockContainer",
+          "attrs": {
+            "id": "3"
+          },
+          "content": [
+            {
+              "type": "paragraph",
+              "attrs": {
+                "backgroundColor": "default",
+                "textColor": "default",
+                "textAlignment": "left"
+              },
+              "content": [
+                {
+                  "type": "text",
+                  "text": "eading"
+                }
+              ]
+            }
+          ]
         }
       ]
     }
diff --git a/tests/src/end-to-end/multicolumn/multicolumn.test.tsx b/tests/src/end-to-end/multicolumn/multicolumn.test.tsx
index 77cd1cd21d..d0c44f19b2 100644
--- a/tests/src/end-to-end/multicolumn/multicolumn.test.tsx
+++ b/tests/src/end-to-end/multicolumn/multicolumn.test.tsx
@@ -11,6 +11,7 @@ import {
 import {
   compareDocToSnapshot,
   focusOnEditor,
+  sleep,
   waitForSelector,
 } from "../../utils/editor.js";
 import {
@@ -134,3 +135,49 @@ describe("Check Multi-Column Behaviour", () => {
     await compareDocToSnapshot("deleteEndOfColumnList");
   });
 });
+
+// Which block the side menu attaches to is resolved from live layout
+// (`elementsFromPoint` / `posAtCoords`); the geometry pieces below that are
+// unit-tested in `packages/core/src/extensions/SideMenu/
+// sideMenuContainerGeometry.browser.test.ts`. This tests the whole path,
+// through a real column list. Columns have no drag handles themselves, but
+// hovering their gutter must still resolve the child on the hovered row.
+describe("Check side menu placement inside a column list", () => {
+  /** Vertical centre of a rect, which the menu lines itself up with. */
+  const centerY = (rect: DOMRect) => rect.y + rect.height / 2;
+
+  test("Check drag handle resolves the block on the hovered row of a column", async () => {
+    await focusOnEditor();
+
+    // The last column is the only one holding several blocks, so it's the only
+    // place a wrongly resolved block is distinguishable by its row.
+    const target = page.getByText("Block 2").element();
+    const columnRect = getRect(target.closest(".bn-block-column")!);
+
+    await mouseSequence([
+      {
+        type: "move",
+        x: columnRect.x + 5,
+        y: centerY(getRect(target)),
+        steps: 5,
+      },
+    ]);
+    await waitForSelector(DRAG_HANDLE_SELECTOR);
+    await sleep(150);
+    const handleRect = getRect(DRAG_HANDLE_SELECTOR);
+
+    expect(handleRect.x).toBeLessThan(getRect(target).x);
+
+    // The handle lines up with the hovered block's row rather than any other
+    // block's. This is a stronger check than a pixel tolerance, since every
+    // candidate is only a line-height away, and it is what distinguishes
+    // this column's blocks from the neighbouring column's.
+    const distance = (rect: DOMRect) =>
+      Math.abs(centerY(handleRect) - centerY(rect));
+    for (const other of ["Block 1", "Block 3", "So is this heading!"]) {
+      expect(distance(getRect(target))).toBeLessThan(
+        distance(getRect(page.getByText(other).element())),
+      );
+    }
+  });
+});
diff --git a/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerChildToSiblingAfter.html b/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerChildToSiblingAfter.html
new file mode 100644
index 0000000000..d6a266cb63
--- /dev/null
+++ b/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerChildToSiblingAfter.html
@@ -0,0 +1,7 @@
+<div class="callout" data-node-type="callout">
+  <div class="callout-body" data-children-of="callout">
+    <p data-nesting-level="1">Callout child 2</p>
+  </div>
+  <button>UI LABEL</button>
+</div>
+<p>After callout</p>
\ No newline at end of file
diff --git a/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerChildren.html b/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerChildren.html
new file mode 100644
index 0000000000..e9ef47b051
--- /dev/null
+++ b/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerChildren.html
@@ -0,0 +1,7 @@
+<div class="callout" data-node-type="callout">
+  <div class="callout-body" data-children-of="callout">
+    <p data-nesting-level="1">Callout child 1</p>
+    <p data-nesting-level="1">Callout child 2</p>
+  </div>
+  <button>UI LABEL</button>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerNestedChild.html b/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerNestedChild.html
new file mode 100644
index 0000000000..65339aa967
--- /dev/null
+++ b/tests/src/unit/core/clipboard/copy/__snapshots__/text/html/containerNestedChild.html
@@ -0,0 +1 @@
+Inner child
\ No newline at end of file
diff --git a/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerChildToSiblingAfter.md b/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerChildToSiblingAfter.md
new file mode 100644
index 0000000000..94e29d44e1
--- /dev/null
+++ b/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerChildToSiblingAfter.md
@@ -0,0 +1,3 @@
+Callout child 2
+
+UI LABELAfter callout
diff --git a/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerChildren.md b/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerChildren.md
new file mode 100644
index 0000000000..8d71d6bc10
--- /dev/null
+++ b/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerChildren.md
@@ -0,0 +1,5 @@
+Callout child 1
+
+Callout child 2
+
+UI LABEL
diff --git a/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerNestedChild.md b/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerNestedChild.md
new file mode 100644
index 0000000000..72d309cf51
--- /dev/null
+++ b/tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/containerNestedChild.md
@@ -0,0 +1 @@
+Inner child
diff --git a/tests/src/unit/core/clipboard/copy/copyTestInstances.ts b/tests/src/unit/core/clipboard/copy/copyTestInstances.ts
index 4bd34489c0..996d90b2c4 100644
--- a/tests/src/unit/core/clipboard/copy/copyTestInstances.ts
+++ b/tests/src/unit/core/clipboard/copy/copyTestInstances.ts
@@ -722,6 +722,80 @@ export const copyTestInstancesHTML: TestInstance<
     },
     executeTest: testCopyHTML,
   },
+  {
+    // The whole of a container's children, selected from inside it.
+    testCase: {
+      name: "containerChildren",
+      document: [
+        {
+          type: "callout",
+          children: [
+            { type: "paragraph", content: "Callout child 1" },
+            { type: "paragraph", content: "Callout child 2" },
+          ],
+        },
+      ],
+      getCopySelection: (doc) => {
+        const startPos = getPosOfTextNode(doc, "Callout child 1");
+        const endPos = getPosOfTextNode(doc, "Callout child 2", true);
+
+        return TextSelection.create(doc, startPos, endPos);
+      },
+    },
+    executeTest: testCopyHTML,
+  },
+  {
+    // A selection that leaves the container partway through, so the copied
+    // fragment is cut open on one side.
+    testCase: {
+      name: "containerChildToSiblingAfter",
+      document: [
+        {
+          type: "callout",
+          children: [
+            { type: "paragraph", content: "Callout child 1" },
+            { type: "paragraph", content: "Callout child 2" },
+          ],
+        },
+        { type: "paragraph", content: "After callout" },
+      ],
+      getCopySelection: (doc) => {
+        const startPos = getPosOfTextNode(doc, "Callout child 2");
+        const endPos = getPosOfTextNode(doc, "After callout", true);
+
+        return TextSelection.create(doc, startPos, endPos);
+      },
+    },
+    executeTest: testCopyHTML,
+  },
+  {
+    // A single block two containers deep, so the fragment is cut open on both
+    // sides at two different levels.
+    testCase: {
+      name: "containerNestedChild",
+      document: [
+        {
+          type: "callout",
+          props: { flavor: "warning" },
+          children: [
+            { type: "paragraph", content: "Outer child" },
+            {
+              type: "callout",
+              props: { flavor: "info" },
+              children: [{ type: "paragraph", content: "Inner child" }],
+            },
+          ],
+        },
+      ],
+      getCopySelection: (doc) => {
+        const startPos = getPosOfTextNode(doc, "Inner child");
+        const endPos = getPosOfTextNode(doc, "Inner child", true);
+
+        return TextSelection.create(doc, startPos, endPos);
+      },
+    },
+    executeTest: testCopyHTML,
+  },
 ];
 
 // text/plain payloads — exercises the same selections as above but snapshots
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/basic.html b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/basic.html
new file mode 100644
index 0000000000..e26ee72a29
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/basic.html
@@ -0,0 +1,14 @@
+<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="callout" data-node-type="callout" data-id="1">
+    <div class="callout-body" data-children-of="callout">
+      <div class="bn-block-outer" data-node-type="blockOuter" data-id="2">
+        <div class="bn-block" data-node-type="blockContainer" data-id="2">
+          <div class="bn-block-content" data-content-type="paragraph">
+            <p class="bn-inline-content">Callout child</p>
+          </div>
+        </div>
+      </div>
+    </div>
+    <button>UI LABEL</button>
+  </div>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/emptyChildren.html b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/emptyChildren.html
new file mode 100644
index 0000000000..acc0a7fb0c
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/emptyChildren.html
@@ -0,0 +1,6 @@
+<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="callout" data-node-type="callout" data-id="1">
+    <div class="callout-body" data-children-of="callout"></div>
+    <button>UI LABEL</button>
+  </div>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/nested.html b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/nested.html
new file mode 100644
index 0000000000..a77a72a56b
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/container/nested.html
@@ -0,0 +1,26 @@
+<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="callout" data-flavor="warning" data-node-type="callout" data-id="1">
+    <div class="callout-body" data-children-of="callout">
+      <div class="bn-block-outer" data-node-type="blockOuter" data-id="2">
+        <div class="bn-block" data-node-type="blockContainer" data-id="2">
+          <div class="bn-block-content" data-content-type="heading">
+            <h1 class="bn-inline-content">Nested heading</h1>
+          </div>
+        </div>
+      </div>
+      <div class="callout" data-flavor="info" data-node-type="callout" data-id="3">
+        <div class="callout-body" data-children-of="callout">
+          <div class="bn-block-outer" data-node-type="blockOuter" data-id="4">
+            <div class="bn-block" data-node-type="blockContainer" data-id="4">
+              <div class="bn-block-content" data-content-type="paragraph">
+                <p class="bn-inline-content">Inner callout child</p>
+              </div>
+            </div>
+          </div>
+        </div>
+        <button>UI LABEL</button>
+      </div>
+    </div>
+    <button>UI LABEL</button>
+  </div>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/titledBlock/basic.html b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/titledBlock/basic.html
new file mode 100644
index 0000000000..4027ff9eee
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/blocknoteHTML/titledBlock/basic.html
@@ -0,0 +1,36 @@
+<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="bn-block-outer" data-node-type="blockOuter" data-id="1">
+    <div class="bn-block" data-node-type="blockContainer" data-id="1">
+      <div class="alert-frame">
+        <div class="alert-slot">
+          <div class="bn-block-content" data-content-type="alert">
+            <div class="bn-inline-content alert">Heads up</div>
+          </div>
+          <div class="bn-block-group" data-node-type="blockGroup">
+            <div class="bn-block-outer" data-node-type="blockOuter" data-id="2">
+              <div class="bn-block" data-node-type="blockContainer" data-id="2">
+                <div class="bn-block-content" data-content-type="paragraph">
+                  <p class="bn-inline-content">First</p>
+                </div>
+              </div>
+            </div>
+            <div class="bn-block-outer" data-node-type="blockOuter" data-id="3">
+              <div class="bn-block" data-node-type="blockContainer" data-id="3">
+                <div class="bn-block-content" data-content-type="paragraph">
+                  <p class="bn-inline-content">Second</p>
+                </div>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+  <div class="bn-block-outer" data-node-type="blockOuter" data-id="4">
+    <div class="bn-block" data-node-type="blockContainer" data-id="4">
+      <div class="bn-block-content" data-content-type="alert">
+        <div class="bn-inline-content alert">Title</div>
+      </div>
+    </div>
+  </div>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/basic.html b/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/basic.html
new file mode 100644
index 0000000000..ede3d1ad38
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/basic.html
@@ -0,0 +1,6 @@
+<div class="callout" data-node-type="callout">
+  <div class="callout-body" data-children-of="callout">
+    <p data-nesting-level="1">Callout child</p>
+  </div>
+  <button>UI LABEL</button>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/emptyChildren.html b/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/emptyChildren.html
new file mode 100644
index 0000000000..54690f4f5d
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/emptyChildren.html
@@ -0,0 +1,4 @@
+<div class="callout" data-node-type="callout">
+  <div class="callout-body" data-children-of="callout"></div>
+  <button>UI LABEL</button>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/nested.html b/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/nested.html
new file mode 100644
index 0000000000..3a3fc433c6
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/html/container/nested.html
@@ -0,0 +1,17 @@
+<div class="callout" data-flavor="warning" data-node-type="callout">
+  <div class="callout-body" data-children-of="callout">
+    <h1 data-nesting-level="1">Nested heading</h1>
+    <div
+      class="callout"
+      data-flavor="info"
+      data-node-type="callout"
+      data-nesting-level="1"
+    >
+      <div class="callout-body" data-children-of="callout">
+        <p data-nesting-level="2">Inner callout child</p>
+      </div>
+      <button>UI LABEL</button>
+    </div>
+  </div>
+  <button>UI LABEL</button>
+</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/html/titledBlock/basic.html b/tests/src/unit/core/formatConversion/export/__snapshots__/html/titledBlock/basic.html
new file mode 100644
index 0000000000..fbb4149097
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/html/titledBlock/basic.html
@@ -0,0 +1,8 @@
+<div class="alert-frame">
+  <div class="alert-slot">
+    <div class="alert">Heads up</div>
+    <p data-nesting-level="1">First</p>
+    <p data-nesting-level="1">Second</p>
+  </div>
+</div>
+<div class="alert">Title</div>
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/basic.md b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/basic.md
new file mode 100644
index 0000000000..6ce86c1ffa
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/basic.md
@@ -0,0 +1,3 @@
+Callout child
+
+UI LABEL
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/emptyChildren.md b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/emptyChildren.md
new file mode 100644
index 0000000000..79f979cb57
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/emptyChildren.md
@@ -0,0 +1 @@
+UI LABEL
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/nested.md b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/nested.md
new file mode 100644
index 0000000000..f2a5876e69
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/container/nested.md
@@ -0,0 +1,5 @@
+# Nested heading
+
+Inner callout child
+
+UI LABELUI LABEL
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/titledBlock/basic.md b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/titledBlock/basic.md
new file mode 100644
index 0000000000..ff8d5b841b
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/markdown/titledBlock/basic.md
@@ -0,0 +1,5 @@
+Heads upFirst
+
+Second
+
+Title
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/basic.json b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/basic.json
new file mode 100644
index 0000000000..cd4b7fa368
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/basic.json
@@ -0,0 +1,33 @@
+[
+  {
+    "attrs": {
+      "flavor": "tip",
+      "id": "1",
+    },
+    "content": [
+      {
+        "attrs": {
+          "id": "2",
+        },
+        "content": [
+          {
+            "attrs": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "content": [
+              {
+                "text": "Callout child",
+                "type": "text",
+              },
+            ],
+            "type": "paragraph",
+          },
+        ],
+        "type": "blockContainer",
+      },
+    ],
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/emptyChildren.json b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/emptyChildren.json
new file mode 100644
index 0000000000..7b02725a5d
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/emptyChildren.json
@@ -0,0 +1,27 @@
+[
+  {
+    "attrs": {
+      "flavor": "tip",
+      "id": "1",
+    },
+    "content": [
+      {
+        "attrs": {
+          "id": "1",
+        },
+        "content": [
+          {
+            "attrs": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "type": "blockContainer",
+      },
+    ],
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/nested.json b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/nested.json
new file mode 100644
index 0000000000..4a45ff2fa9
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/container/nested.json
@@ -0,0 +1,66 @@
+[
+  {
+    "attrs": {
+      "flavor": "warning",
+      "id": "1",
+    },
+    "content": [
+      {
+        "attrs": {
+          "id": "2",
+        },
+        "content": [
+          {
+            "attrs": {
+              "backgroundColor": "default",
+              "isToggleable": false,
+              "level": 1,
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "content": [
+              {
+                "text": "Nested heading",
+                "type": "text",
+              },
+            ],
+            "type": "heading",
+          },
+        ],
+        "type": "blockContainer",
+      },
+      {
+        "attrs": {
+          "flavor": "info",
+          "id": "3",
+        },
+        "content": [
+          {
+            "attrs": {
+              "id": "4",
+            },
+            "content": [
+              {
+                "attrs": {
+                  "backgroundColor": "default",
+                  "textAlignment": "left",
+                  "textColor": "default",
+                },
+                "content": [
+                  {
+                    "text": "Inner callout child",
+                    "type": "text",
+                  },
+                ],
+                "type": "paragraph",
+              },
+            ],
+            "type": "blockContainer",
+          },
+        ],
+        "type": "callout",
+      },
+    ],
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/titledBlock/basic.json b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/titledBlock/basic.json
new file mode 100644
index 0000000000..44e5e45d26
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/export/__snapshots__/nodes/titledBlock/basic.json
@@ -0,0 +1,85 @@
+[
+  {
+    "attrs": {
+      "id": "1",
+    },
+    "content": [
+      {
+        "content": [
+          {
+            "text": "Heads up",
+            "type": "text",
+          },
+        ],
+        "type": "alert",
+      },
+      {
+        "content": [
+          {
+            "attrs": {
+              "id": "2",
+            },
+            "content": [
+              {
+                "attrs": {
+                  "backgroundColor": "default",
+                  "textAlignment": "left",
+                  "textColor": "default",
+                },
+                "content": [
+                  {
+                    "text": "First",
+                    "type": "text",
+                  },
+                ],
+                "type": "paragraph",
+              },
+            ],
+            "type": "blockContainer",
+          },
+          {
+            "attrs": {
+              "id": "3",
+            },
+            "content": [
+              {
+                "attrs": {
+                  "backgroundColor": "default",
+                  "textAlignment": "left",
+                  "textColor": "default",
+                },
+                "content": [
+                  {
+                    "text": "Second",
+                    "type": "text",
+                  },
+                ],
+                "type": "paragraph",
+              },
+            ],
+            "type": "blockContainer",
+          },
+        ],
+        "type": "blockGroup",
+      },
+    ],
+    "type": "blockContainer",
+  },
+  {
+    "attrs": {
+      "id": "4",
+    },
+    "content": [
+      {
+        "content": [
+          {
+            "text": "Title",
+            "type": "text",
+          },
+        ],
+        "type": "alert",
+      },
+    ],
+    "type": "blockContainer",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/export/exportTestInstances.ts b/tests/src/unit/core/formatConversion/export/exportTestInstances.ts
index 1d901c81a9..84c1886fc6 100644
--- a/tests/src/unit/core/formatConversion/export/exportTestInstances.ts
+++ b/tests/src/unit/core/formatConversion/export/exportTestInstances.ts
@@ -3107,6 +3107,91 @@ export const exportTestInstancesBlockNoteHTML: TestInstance<
     },
     executeTest: testExportBlockNoteHTML,
   },
+  {
+    testCase: {
+      name: "container/basic",
+      content: [
+        {
+          type: "callout",
+          children: [
+            {
+              type: "paragraph",
+              content: "Callout child",
+            },
+          ],
+        },
+      ],
+    },
+    executeTest: testExportBlockNoteHTML,
+  },
+  {
+    testCase: {
+      name: "container/nested",
+      content: [
+        {
+          type: "callout",
+          props: { flavor: "warning" },
+          children: [
+            {
+              type: "heading",
+              content: "Nested heading",
+            },
+            {
+              type: "callout",
+              props: { flavor: "info" },
+              children: [
+                {
+                  type: "paragraph",
+                  content: "Inner callout child",
+                },
+              ],
+            },
+          ],
+        },
+      ],
+    },
+    executeTest: testExportBlockNoteHTML,
+  },
+  {
+    // Partial input omits the required child. Export snapshots record this
+    // raw form; full-HTML equality tests normalize it to a valid block first.
+    testCase: {
+      name: "container/emptyChildren",
+      content: [
+        {
+          type: "callout",
+        },
+      ],
+    },
+    executeTest: testExportBlockNoteHTML,
+  },
+  {
+    // A titled block: inline content (the title) plus a body of two
+    // paragraphs. The title is rendered once, by the block's own output; the
+    // children follow it inside the frame rather than being duplicated.
+    testCase: {
+      name: "titledBlock/basic",
+      content: [
+        {
+          type: "alert",
+          content: "Heads up",
+          children: [
+            {
+              type: "paragraph",
+              content: "First",
+            },
+            {
+              type: "paragraph",
+              content: "Second",
+            },
+          ],
+        },
+        // Omitted children still reach the frame callback as an empty array.
+        { type: "alert", content: "Title" },
+      ],
+    },
+    executeTest: testExportBlockNoteHTML,
+  },
 ];
 
 export const exportTestInstancesHTML: TestInstance<
diff --git a/tests/src/unit/core/formatConversion/parse/__snapshots__/html/container.json b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/container.json
new file mode 100644
index 0000000000..9c1e864bd8
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/container.json
@@ -0,0 +1,29 @@
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Callout child",
+            "type": "text",
+          },
+        ],
+        "id": "2",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+    ],
+    "content": undefined,
+    "id": "1",
+    "props": {
+      "flavor": "tip",
+    },
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerEmptyChildren.json b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerEmptyChildren.json
new file mode 100644
index 0000000000..3333d9ac16
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerEmptyChildren.json
@@ -0,0 +1,23 @@
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [],
+        "id": "1",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+    ],
+    "content": undefined,
+    "id": "1",
+    "props": {
+      "flavor": "tip",
+    },
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerExternalHTML.json b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerExternalHTML.json
new file mode 100644
index 0000000000..7d0dc770cb
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerExternalHTML.json
@@ -0,0 +1,58 @@
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Nested heading",
+            "type": "text",
+          },
+        ],
+        "id": "1",
+        "props": {
+          "backgroundColor": "default",
+          "isToggleable": false,
+          "level": 1,
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "heading",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Inner callout child",
+                "type": "text",
+              },
+            ],
+            "id": "2",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "3",
+        "props": {
+          "flavor": "info",
+        },
+        "type": "callout",
+      },
+    ],
+    "content": undefined,
+    "id": "1",
+    "props": {
+      "flavor": "warning",
+    },
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerNested.json b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerNested.json
new file mode 100644
index 0000000000..f26c42c127
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/containerNested.json
@@ -0,0 +1,58 @@
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Nested heading",
+            "type": "text",
+          },
+        ],
+        "id": "2",
+        "props": {
+          "backgroundColor": "default",
+          "isToggleable": false,
+          "level": 1,
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "heading",
+      },
+      {
+        "children": [
+          {
+            "children": [],
+            "content": [
+              {
+                "styles": {},
+                "text": "Inner callout child",
+                "type": "text",
+              },
+            ],
+            "id": "4",
+            "props": {
+              "backgroundColor": "default",
+              "textAlignment": "left",
+              "textColor": "default",
+            },
+            "type": "paragraph",
+          },
+        ],
+        "content": undefined,
+        "id": "3",
+        "props": {
+          "flavor": "info",
+        },
+        "type": "callout",
+      },
+    ],
+    "content": undefined,
+    "id": "1",
+    "props": {
+      "flavor": "warning",
+    },
+    "type": "callout",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/parse/__snapshots__/html/titledBlock.json b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/titledBlock.json
new file mode 100644
index 0000000000..756e05dfa7
--- /dev/null
+++ b/tests/src/unit/core/formatConversion/parse/__snapshots__/html/titledBlock.json
@@ -0,0 +1,50 @@
+[
+  {
+    "children": [
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "First",
+            "type": "text",
+          },
+        ],
+        "id": "2",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+      {
+        "children": [],
+        "content": [
+          {
+            "styles": {},
+            "text": "Second",
+            "type": "text",
+          },
+        ],
+        "id": "3",
+        "props": {
+          "backgroundColor": "default",
+          "textAlignment": "left",
+          "textColor": "default",
+        },
+        "type": "paragraph",
+      },
+    ],
+    "content": [
+      {
+        "styles": {},
+        "text": "Heads up",
+        "type": "text",
+      },
+    ],
+    "id": "1",
+    "props": {},
+    "type": "alert",
+  },
+]
\ No newline at end of file
diff --git a/tests/src/unit/core/formatConversion/parse/parseTestInstances.ts b/tests/src/unit/core/formatConversion/parse/parseTestInstances.ts
index 536a7ac784..782b0ebab3 100644
--- a/tests/src/unit/core/formatConversion/parse/parseTestInstances.ts
+++ b/tests/src/unit/core/formatConversion/parse/parseTestInstances.ts
@@ -1119,6 +1119,125 @@ l'utilisateur (bouton bleu en haut à droite de la conversation)<o:p></o:p></spa
     },
     executeTest: testParseHTML,
   },
+  {
+    // The internal (`blocksToFullHTML`) form of a container. The children
+    // holder is marked with `data-children-of`.
+    testCase: {
+      name: "container",
+      content: `<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="callout" data-node-type="callout" data-id="1">
+    <div class="callout-body" data-children-of="callout">
+      <div class="bn-block-outer" data-node-type="blockOuter" data-id="2">
+        <div class="bn-block" data-node-type="blockContainer" data-id="2">
+          <div class="bn-block-content" data-content-type="paragraph">
+            <p class="bn-inline-content">Callout child</p>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+</div>`,
+    },
+    executeTest: testParseHTML,
+  },
+  {
+    // A container nested inside another, with a non-default prop on each.
+    testCase: {
+      name: "containerNested",
+      content: `<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="callout" data-flavor="warning" data-node-type="callout" data-id="1">
+    <div class="callout-body" data-children-of="callout">
+      <div class="bn-block-outer" data-node-type="blockOuter" data-id="2">
+        <div class="bn-block" data-node-type="blockContainer" data-id="2">
+          <div class="bn-block-content" data-content-type="heading">
+            <h1 class="bn-inline-content">Nested heading</h1>
+          </div>
+        </div>
+      </div>
+      <div class="callout" data-flavor="info" data-node-type="callout" data-id="3">
+        <div class="callout-body" data-children-of="callout">
+          <div class="bn-block-outer" data-node-type="blockOuter" data-id="4">
+            <div class="bn-block" data-node-type="blockContainer" data-id="4">
+              <div class="bn-block-content" data-content-type="paragraph">
+                <p class="bn-inline-content">Inner callout child</p>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+</div>`,
+    },
+    executeTest: testParseHTML,
+  },
+  {
+    // An empty container children holder is filled to its schema minimum
+    // when parsed into a valid document.
+    testCase: {
+      name: "containerEmptyChildren",
+      content: `<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="callout" data-node-type="callout" data-id="1">
+    <div class="callout-body" data-children-of="callout"></div>
+  </div>
+</div>`,
+    },
+    executeTest: testParseHTML,
+  },
+  {
+    // Container HTML without the `data-children-of` marker our own
+    // serializers add: what a container looks like once it has been through
+    // another app, or has come from an older version. The parse rule has to
+    // fall back to reading the whole element as the children region.
+    testCase: {
+      name: "containerExternalHTML",
+      content: `<div class="callout" data-flavor="warning" data-node-type="callout" data-id="1">
+  <div class="callout-body">
+    <h1 data-nesting-level="1">Nested heading</h1>
+    <div class="callout" data-flavor="info" data-node-type="callout" data-id="3" data-nesting-level="1">
+      <div class="callout-body">
+        <p data-nesting-level="2">Inner callout child</p>
+      </div>
+    </div>
+  </div>
+</div>`,
+    },
+    executeTest: testParseHTML,
+  },
+  {
+    // The internal (`blocksToFullHTML`) form of a titled block: the title in
+    // the block's own content, the body in its nested `blockGroup`. Parses
+    // back to the alert with its title and both children, in order.
+    testCase: {
+      name: "titledBlock",
+      content: `<div class="bn-block-group" data-node-type="blockGroup">
+  <div class="bn-block-outer" data-node-type="blockOuter" data-id="1">
+    <div class="bn-block" data-node-type="blockContainer" data-id="1">
+      <div class="bn-block-content" data-content-type="alert">
+        <div class="bn-inline-content alert">Heads up</div>
+      </div>
+      <div class="bn-block-group" data-node-type="blockGroup">
+        <div class="bn-block-outer" data-node-type="blockOuter" data-id="2">
+          <div class="bn-block" data-node-type="blockContainer" data-id="2">
+            <div class="bn-block-content" data-content-type="paragraph">
+              <p class="bn-inline-content">First</p>
+            </div>
+          </div>
+        </div>
+        <div class="bn-block-outer" data-node-type="blockOuter" data-id="3">
+          <div class="bn-block" data-node-type="blockContainer" data-id="3">
+            <div class="bn-block-content" data-content-type="paragraph">
+              <p class="bn-inline-content">Second</p>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+</div>`,
+    },
+    executeTest: testParseHTML,
+  },
 ];
 
 export const parseTestInstancesMarkdown: TestInstance<
diff --git a/tests/src/unit/core/schema/__snapshots__/blocks.json b/tests/src/unit/core/schema/__snapshots__/blocks.json
index ee48987244..99261ea107 100644
--- a/tests/src/unit/core/schema/__snapshots__/blocks.json
+++ b/tests/src/unit/core/schema/__snapshots__/blocks.json
@@ -1,4 +1,21 @@
 {
+  "alert": {
+    "config": {
+      "children": {
+        "allow": "blocks",
+      },
+      "content": "inline",
+      "propSchema": {},
+      "type": "alert",
+    },
+    "extensions": undefined,
+    "implementation": {
+      "node": null,
+      "render": [Function],
+      "renderFrame": [Function],
+      "toExternalHTML": [Function],
+    },
+  },
   "audio": {
     "config": {
       "content": "none",
@@ -73,6 +90,31 @@
       "toExternalHTML": [Function],
     },
   },
+  "callout": {
+    "config": {
+      "children": {
+        "allow": "blocks",
+      },
+      "content": "none",
+      "propSchema": {
+        "flavor": {
+          "default": "tip",
+          "values": [
+            "tip",
+            "info",
+            "warning",
+          ],
+        },
+      },
+      "type": "callout",
+    },
+    "extensions": undefined,
+    "implementation": {
+      "node": null,
+      "render": [Function],
+      "toExternalHTML": [Function],
+    },
+  },
   "checkListItem": {
     "config": {
       "content": "inline",
diff --git a/tests/src/unit/core/testSchema.ts b/tests/src/unit/core/testSchema.ts
index eca37363fa..c1ddf7b309 100644
--- a/tests/src/unit/core/testSchema.ts
+++ b/tests/src/unit/core/testSchema.ts
@@ -27,7 +27,7 @@ const SimpleImage = createBlockSpec(
   ),
   {
     render(block, editor) {
-      return createImageBlockSpec().implementation.render.call(
+      return createImageBlockSpec().implementation.render!.call(
         this,
         block as any,
         editor as any,
@@ -99,6 +99,96 @@ const SimpleCustomParagraph = createBlockSpec(
   },
 );
 
+// A container block: it holds no inline content of its own, and its `contentDOM`
+// is where its child blocks go. Covers containers in the format-conversion,
+// clipboard and selection matrices, which otherwise never see one.
+const Callout = createBlockSpec(
+  {
+    type: "callout" as const,
+    propSchema: {
+      flavor: {
+        default: "tip" as const,
+        values: ["tip", "info", "warning"] as const,
+      },
+    },
+    content: "none",
+    children: {
+      allow: "blocks",
+    },
+  },
+  {
+    render() {
+      const callout = document.createElement("div");
+      callout.className = "callout";
+      // The serializer must overwrite author attributes with the block props.
+      callout.setAttribute("data-flavor", "author-value");
+
+      const body = document.createElement("div");
+      body.className = "callout-body";
+      callout.appendChild(body);
+
+      if (this.renderType === "dom") {
+        // Exercise fragment roots and chrome outside the children region in
+        // the shared HTML snapshots and full-HTML equality matrix.
+        const chrome = document.createElement("button");
+        chrome.contentEditable = "false";
+        chrome.textContent = "UI LABEL";
+        callout.append(chrome);
+        const fragment = document.createDocumentFragment();
+        fragment.append(callout);
+        return { dom: fragment, contentDOM: body };
+      }
+
+      return {
+        dom: callout,
+        contentDOM: body,
+      };
+    },
+  },
+);
+
+// A titled block: an ordinary block with inline content (the title) whose
+// `children` are a body that belongs to it. Covers titled blocks in the
+// format-conversion, clipboard and selection matrices, which otherwise never
+// see one (the `callout` above only covers pure containers).
+const Alert = createBlockSpec(
+  {
+    type: "alert" as const,
+    propSchema: {},
+    content: "inline",
+    children: {
+      allow: "blocks",
+    },
+  },
+  {
+    render: () => {
+      const alert = document.createElement("div");
+      alert.className = "alert";
+
+      return {
+        dom: alert,
+        contentDOM: alert,
+      };
+    },
+    renderFrame: (block) => {
+      if (block.children.length === 0) {
+        return undefined;
+      }
+      const frame = document.createElement("div");
+      frame.className = "alert-frame";
+
+      const slot = document.createElement("div");
+      slot.className = "alert-slot";
+      frame.appendChild(slot);
+
+      return {
+        dom: frame,
+        slot,
+      };
+    },
+  },
+);
+
 // INLINE CONTENT --------------------------------------------------------------
 
 const Mention = createInlineContentSpec(
@@ -222,6 +312,8 @@ export const testSchema = BlockNoteSchema.create().extend({
     customParagraph: CustomParagraph(),
     simpleCustomParagraph: SimpleCustomParagraph(),
     simpleImage: SimpleImage(),
+    callout: Callout(),
+    alert: Alert(),
   },
   inlineContentSpecs: {
     mention: Mention,
diff --git a/tests/src/unit/react/reactFrame.test.tsx b/tests/src/unit/react/reactFrame.test.tsx
new file mode 100644
index 0000000000..78c93edee4
--- /dev/null
+++ b/tests/src/unit/react/reactFrame.test.tsx
@@ -0,0 +1,382 @@
+import { BlockNoteEditor, BlockNoteSchema } from "@blocknote/core";
+import {
+  BlockNoteViewRaw,
+  createReactBlockSpec,
+  type ReactCustomBlockFrameProps,
+} from "@blocknote/react";
+import {
+  createContext,
+  useContext,
+  useEffect,
+  useState,
+  type ReactNode,
+} from "react";
+import { flushSync } from "react-dom";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, describe, expect, it, vi } from "vite-plus/test";
+
+// Pure containers continue to draw their outer box through render.
+const createFrameBox = createReactBlockSpec(
+  {
+    type: "frameBox",
+    propSchema: { flavor: { default: "tip" } },
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  {
+    render: function Container(props) {
+      const [alternate, setAlternate] = useState(false);
+      const Tag = alternate ? "section" : "div";
+      return (
+        <Tag className="frame-box">
+          <button
+            className="swap-root"
+            contentEditable={false}
+            onClick={() => setAlternate(!alternate)}
+          >
+            Swap root
+          </button>
+          <div className="frame-slot" ref={props.contentRef} />
+        </Tag>
+      );
+    },
+  },
+);
+
+const FrameContext = createContext("outside");
+let activeFrames = 0;
+const alertConfig = {
+  type: "frameAlert",
+  propSchema: { flavor: { default: "tip" }, framed: { default: true } },
+  content: "inline",
+  children: { allow: "blocks" },
+} as const;
+
+function FrameChrome(props: { children: ReactNode; flavor: string }) {
+  return (
+    <div className="alert-frame" data-flavor={props.flavor}>
+      {props.children}
+    </div>
+  );
+}
+
+function AlertFrame(props: ReactCustomBlockFrameProps<typeof alertConfig>) {
+  const label = useContext(FrameContext);
+  const [clicks, setClicks] = useState(0);
+  useEffect(() => {
+    activeFrames++;
+    return () => {
+      activeFrames--;
+    };
+  }, []);
+  if (!props.block.props.framed) {
+    return null;
+  }
+  return (
+    <FrameChrome flavor={props.block.props.flavor}>
+      <button
+        className="frame-counter"
+        contentEditable={false}
+        onClick={() => setClicks(clicks + 1)}
+      >
+        {label}: {clicks}
+      </button>
+      <button
+        className="frame-flavor"
+        contentEditable={false}
+        onClick={() =>
+          props.editor.updateBlock(props.block, {
+            props: { flavor: "warning" },
+          })
+        }
+      >
+        Change flavor
+      </button>
+      <div className="alert-slot" ref={props.contentRef} />
+    </FrameChrome>
+  );
+}
+
+const createFrameAlert = createReactBlockSpec(alertConfig, {
+  render: (props) => <div className="alert-title" ref={props.contentRef} />,
+  renderFrame: AlertFrame,
+});
+
+// Framing alone must not turn ordinary nesting into an owned body.
+const createToggle = createReactBlockSpec(
+  { type: "frameToggle", propSchema: {}, content: "inline" },
+  {
+    render: (props) => <div ref={props.contentRef} />,
+    renderFrame: (props) => (
+      <div className="toggle-frame" ref={props.contentRef} />
+    ),
+  },
+);
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: {
+    frameBox: createFrameBox(),
+    frameAlert: createFrameAlert(),
+    frameToggle: createToggle(),
+  },
+});
+
+let root: Root | undefined;
+let div: HTMLDivElement | undefined;
+let editor: BlockNoteEditor<any, any, any> | undefined;
+/** Render-phase errors. React 19 reports rather than rethrows these. */
+let uncaught: unknown[] = [];
+
+const tick = () => new Promise((resolve) => setTimeout(resolve, 0));
+
+function mountEditor(initialContent: any[]) {
+  div = document.createElement("div");
+  document.body.appendChild(div);
+
+  editor = BlockNoteEditor.create({
+    schema,
+    trailingBlock: false,
+    initialContent,
+  }) as BlockNoteEditor<any, any, any>;
+
+  uncaught = [];
+  root = createRoot(div, {
+    onUncaughtError: (error) => uncaught.push(error),
+    onCaughtError: (error) => uncaught.push(error),
+  });
+  // Mount during a React commit as applications do. Frame construction must
+  // not depend on a nested synchronous React render succeeding.
+  flushSync(() => {
+    root!.render(
+      <FrameContext.Provider value="inside">
+        <BlockNoteViewRaw editor={editor!} />
+      </FrameContext.Provider>,
+    );
+  });
+
+  return editor;
+}
+
+afterEach(() => {
+  root?.unmount();
+  root = undefined;
+  if (div) {
+    document.body.removeChild(div);
+    div = undefined;
+  }
+  editor?._tiptapEditor.destroy();
+  editor = undefined;
+  expect(activeFrames).toBe(0);
+});
+
+describe("React renderFrame", () => {
+  it("keeps container identity and child DOM through prop and author-root changes", async () => {
+    const mounted = mountEditor([
+      {
+        id: "box-0",
+        type: "frameBox",
+        props: { flavor: "warning" },
+        children: [{ id: "box-child", type: "paragraph", content: "Child" }],
+      },
+    ]);
+    await tick();
+    const child = div!.querySelector('[data-id="box-child"]');
+    const slot = div!.querySelector(".frame-slot");
+    expect(slot?.textContent).toBe("Child");
+    mounted.updateBlock("box-0", { props: { flavor: "success" } });
+    await vi.waitFor(() =>
+      expect(
+        div!.querySelector(".frame-box")?.getAttribute("data-flavor"),
+      ).toBe("success"),
+    );
+    expect(div!.querySelector(".frame-slot")).toBe(slot);
+    flushSync(() =>
+      div!.querySelector<HTMLButtonElement>(".swap-root")!.click(),
+    );
+    const box = div!.querySelector("section.frame-box")!;
+    expect(box).not.toBeNull();
+    expect(box.getAttribute("data-id")).toBe("box-0");
+    expect(box.getAttribute("data-node-type")).toBe("frameBox");
+    expect(box.getAttribute("data-flavor")).toBe("success");
+    expect(box.querySelector('[data-id="box-child"]')).toBe(child);
+    expect(mounted.getBlock("box-child")?.content).toEqual([
+      { type: "text", text: "Child", styles: {} },
+    ]);
+    expect(uncaught).toEqual([]);
+  });
+
+  it("renders plain nesting when the frame mounts no slot", async () => {
+    mountEditor([
+      {
+        id: "alert-0",
+        type: "frameAlert",
+        props: { framed: false },
+        content: "Heads up",
+        children: [{ id: "alert-child", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    await tick();
+
+    expect(div!.querySelector(".alert-frame")).toBeNull();
+    expect(div!.textContent).toContain("Heads up");
+    expect(div!.textContent).toContain("Body");
+    expect(uncaught).toEqual([]);
+  });
+
+  it("keeps React state, context, and child DOM through frame updates", async () => {
+    const mounted = mountEditor([
+      {
+        id: "alert",
+        type: "frameAlert",
+        content: "Title",
+        children: [{ id: "child", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".frame-counter")?.textContent).toBe(
+        "inside: 0",
+      ),
+    );
+    expect(div!.querySelector(".alert-slot")?.textContent).toBe("TitleBody");
+    const child = div!.querySelector('[data-id="child"]');
+    const title = div!.querySelector(".alert-title");
+    div!.querySelector<HTMLButtonElement>(".frame-counter")!.click();
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".frame-counter")?.textContent).toBe(
+        "inside: 1",
+      ),
+    );
+    div!.querySelector<HTMLButtonElement>(".frame-flavor")!.click();
+    await vi.waitFor(() =>
+      expect(
+        div!.querySelector(".alert-frame")?.getAttribute("data-flavor"),
+      ).toBe("warning"),
+    );
+    root!.render(
+      <FrameContext.Provider value="updated">
+        <BlockNoteViewRaw editor={mounted} />
+      </FrameContext.Provider>,
+    );
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".frame-counter")?.textContent).toBe(
+        "updated: 1",
+      ),
+    );
+    expect(div!.querySelector('[data-id="child"]')).toBe(child);
+    expect(div!.querySelector(".alert-title")).toBe(title);
+    expect(mounted.getBlock("child")?.content).toEqual([
+      { type: "text", text: "Body", styles: {} },
+    ]);
+    expect(uncaught).toEqual([]);
+  });
+
+  it("switches framing off and on without losing title or child node views", async () => {
+    const mounted = mountEditor([
+      {
+        id: "alert",
+        type: "frameAlert",
+        content: "Title",
+        children: [{ id: "child", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".alert-slot")?.textContent).toBe("TitleBody"),
+    );
+    const child = div!.querySelector('[data-id="child"]');
+    mounted.updateBlock("alert", { props: { framed: false } });
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".alert-frame")).toBeNull(),
+    );
+    expect(div!.textContent).toContain("TitleBody");
+    expect(div!.querySelector('[data-id="child"]')).toBe(child);
+    mounted.updateBlock("alert", { props: { framed: true } });
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".alert-slot")?.textContent).toBe("TitleBody"),
+    );
+    expect(div!.querySelector('[data-id="child"]')).toBe(child);
+    expect(uncaught).toEqual([]);
+  });
+
+  it("unmounts the frame component when its block is removed", async () => {
+    const mounted = mountEditor([
+      { id: "alert", type: "frameAlert", content: "Title" },
+      { id: "after", type: "paragraph", content: "After" },
+    ]);
+    await vi.waitFor(() => expect(activeFrames).toBe(1));
+    mounted.removeBlocks(["alert"]);
+    await vi.waitFor(() => expect(activeFrames).toBe(0));
+    expect(div!.querySelector(".alert-frame")).toBeNull();
+    expect(uncaught).toEqual([]);
+  });
+
+  it("exports a titled React frame with its content and children in the slot", () => {
+    const headless = BlockNoteEditor.create({ schema });
+    try {
+      const html = headless.blocksToHTMLLossy([
+        {
+          type: "frameAlert",
+          content: "Title",
+          children: [{ type: "paragraph", content: "Body" }],
+        },
+      ]);
+      const output = document.createElement("div");
+      output.innerHTML = html;
+      expect(output.querySelector(".alert-slot")?.textContent).toBe(
+        "TitleBody",
+      );
+      expect(output.querySelector(".frame-counter")?.textContent).toBe(
+        "outside: 0",
+      );
+    } finally {
+      headless._tiptapEditor.destroy();
+    }
+  });
+
+  it("exports a declined frame as plain content and disposes its effects", () => {
+    const headless = BlockNoteEditor.create({ schema });
+    try {
+      const html = headless.blocksToHTMLLossy([
+        {
+          type: "frameAlert",
+          props: { framed: false },
+          content: "Title",
+          children: [{ type: "paragraph", content: "Body" }],
+        },
+      ]);
+      expect(html).not.toContain("alert-frame");
+      expect(html).toContain("Title");
+      expect(html).toContain("Body");
+      expect(activeFrames).toBe(0);
+    } finally {
+      headless._tiptapEditor.destroy();
+    }
+  });
+
+  it("keeps ordinary Shift-Tab behavior inside a frame without declared children", async () => {
+    const mounted = mountEditor([
+      {
+        id: "toggle",
+        type: "frameToggle",
+        content: "Title",
+        children: [{ id: "child", type: "paragraph", content: "Body" }],
+      },
+    ]);
+    await vi.waitFor(() =>
+      expect(div!.querySelector(".toggle-frame")?.textContent).toBe(
+        "TitleBody",
+      ),
+    );
+    mounted.setTextCursorPosition("child", "start");
+    const event = new KeyboardEvent("keydown", {
+      key: "Tab",
+      code: "Tab",
+      keyCode: 9,
+      shiftKey: true,
+      bubbles: true,
+    });
+    mounted._tiptapEditor.view.dom.dispatchEvent(event);
+    expect(mounted.getParentBlock("child")).toBeUndefined();
+    expect(mounted.getBlock("toggle")?.children).toHaveLength(0);
+    expect(uncaught).toEqual([]);
+  });
+});
diff --git a/tests/src/unit/react/useNodeViewBlock.test.tsx b/tests/src/unit/react/useNodeViewBlock.test.tsx
index 71101c7fa7..c20c6aaeb9 100644
--- a/tests/src/unit/react/useNodeViewBlock.test.tsx
+++ b/tests/src/unit/react/useNodeViewBlock.test.tsx
@@ -27,8 +27,20 @@ const createReproBlock = createReactBlockSpec(
   { render: (props) => <p ref={props.contentRef} /> },
 );
 
+// A container block, whose node view's node is itself the bnBlock, resolved
+// directly instead of by position.
+const createBoxBlock = createReactBlockSpec(
+  {
+    type: "box",
+    propSchema: {},
+    content: "none",
+    children: { allow: "blocks" },
+  },
+  { render: (props) => <div ref={props.contentRef} /> },
+);
+
 const schema = BlockNoteSchema.create().extend({
-  blockSpecs: { repro: createReproBlock() },
+  blockSpecs: { repro: createReproBlock(), box: createBoxBlock() },
 });
 
 let editor: BlockNoteEditor<any, any, any>;
@@ -43,6 +55,7 @@ beforeEach(() => {
       { type: "paragraph", content: "first" },
       { type: "repro", content: "target block" },
       { type: "paragraph", content: "last" },
+      { type: "box", children: [{ type: "paragraph", content: "inside" }] },
     ],
   }) as BlockNoteEditor<any, any, any>;
 
@@ -78,11 +91,14 @@ function renderHook(
   return resolved;
 }
 
-// Only the two fields `useNodeViewBlock` reads. Built structurally so `tests`
-// doesn't need a dependency on `@tiptap/react` just for its prop types.
-function makeProps(getPos: () => number | undefined) {
+// Only the fields `useNodeViewBlock` reads. Built structurally so `tests`
+// doesn't need a dependency on `@tiptap/react` just for its prop types. The
+// `node` defaults to a regular (non-container) block's node shape; container
+// tests pass the real PM node instead.
+function makeProps(getPos: () => number | undefined, node?: unknown) {
   return {
     getPos,
+    node: node ?? { type: { isInGroup: () => false } },
     view: { state: { doc: editor.prosemirrorState.doc } },
   } as unknown as Parameters<typeof useNodeViewBlock>[0];
 }
@@ -170,4 +186,14 @@ describe("useNodeViewBlock", () => {
     expect(resolved.id).toBe(target.id);
     expect(resolved).not.toBe(seed);
   });
+
+  it("resolves container blocks directly without consulting their position", () => {
+    const box = editor.document.find((block) => block.type === "box")!;
+    const { node } = getNodeById(box.id, editor.prosemirrorState.doc)!;
+    const getPos = vi.fn(() => undefined);
+    const resolved = renderHook(makeProps(getPos, node), editor.document[0]);
+
+    expect(resolved).toEqual(box);
+    expect(getPos).not.toHaveBeenCalled();
+  });
 });
diff --git a/tests/src/unit/shared/formatConversion/exportParseEquality/exportParseEqualityTestExecutors.ts b/tests/src/unit/shared/formatConversion/exportParseEquality/exportParseEqualityTestExecutors.ts
index 9ac5b7df5f..c5d091deae 100644
--- a/tests/src/unit/shared/formatConversion/exportParseEquality/exportParseEqualityTestExecutors.ts
+++ b/tests/src/unit/shared/formatConversion/exportParseEquality/exportParseEqualityTestExecutors.ts
@@ -26,17 +26,24 @@ export const testExportParseEqualityBlockNoteHTML = <
 
   addIdsToBlocks(testCase.content);
 
-  const exported = editor.blocksToFullHTML(testCase.content);
-
   if (testCase.name.startsWith("malformed/")) {
-    // We purposefully are okay with malformed response, we know they won't match
+    const exported = editor.blocksToFullHTML(testCase.content);
+    // Malformed partial input is intentionally not a lossless document.
     expect(editor.tryParseHTMLToBlocks(exported)).not.toStrictEqual(
       partialBlocksToBlocksForTesting(editor.schema, testCase.content),
     );
   } else {
-    expect(editor.tryParseHTMLToBlocks(exported)).toStrictEqual(
-      partialBlocksToBlocksForTesting(editor.schema, testCase.content),
+    // Round-trip valid blocks, including schema-generated required children.
+    // The shorthand helper defaults all children to [], which is invalid for
+    // containers with a minimum child count.
+    const blocks = testCase.content.map((block) =>
+      nodeToBlock(
+        blockToNode(block, editor.pmSchema),
+        editor.prosemirrorState.doc,
+      ),
     );
+    const exported = editor.blocksToFullHTML(blocks);
+    expect(editor.tryParseHTMLToBlocks(exported)).toStrictEqual(blocks);
   }
 };