fix(mcp): keep preview snapshots usable by the agent and let it save them (#10501)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

Author: t3dotgg

apps/desktop/src/preview/Manager.ts

@@ -117,6 +117,12 @@ const ZOOM_EPSILON = 0.001;
 const MAX_EVALUATION_BYTES = 64_000;
 const MAX_VISIBLE_TEXT_LENGTH = 20_000;
 const MAX_INTERACTIVE_ELEMENTS = 200;
+/**
+ * A `[role]` container's innerText is its whole subtree, which turned one
+ * snapshot's element list into 60 KB of repeated page text. Names are labels,
+ * not content, so cap them where they are read.
+ */
+const MAX_INTERACTIVE_ELEMENT_NAME_LENGTH = 200;
 const MAX_SCREENSHOT_WIDTH = 1280;
 /** How long an armed tab keeps the exclusive display-media slot before another tab may take it. */
 const RECORDING_ARM_GRACE_MS = 10_000;
@@ -3582,7 +3588,7 @@ const makeNativeOperations = Effect.fn("PreviewManager.makeOperations")(function
             return {
               tag: element.tagName.toLowerCase(),
               role: element.getAttribute("role"),
-              name: element.getAttribute("aria-label") || element.innerText || element.getAttribute("name") || "",
+              name: (element.getAttribute("aria-label") || element.innerText || element.getAttribute("name") || "").slice(0, ${MAX_INTERACTIVE_ELEMENT_NAME_LENGTH}),
               selector: selectorFor(element),
               x: rect.x,
               y: rect.y,

apps/server/src/config.ts

@@ -38,6 +38,8 @@ export interface ServerDerivedPaths {
   readonly providerStatusCacheDir: string;
   readonly worktreesDir: string;
   readonly attachmentsDir: string;
+  /** Screenshots the agent asks the collaborative browser to keep for the user. */
+  readonly browserArtifactsDir: string;
   readonly logsDir: string;
   readonly serverLogPath: string;
   readonly serverTracePath: string;
@@ -125,6 +127,7 @@ export const deriveServerPaths = Effect.fn(function* (
     providerStatusCacheDir,
     worktreesDir: join(baseDir, "worktrees"),
     attachmentsDir,
+    browserArtifactsDir: join(stateDir, "browser-artifacts"),
     logsDir,
     serverLogPath: join(logsDir, "server.log"),
     serverTracePath: join(logsDir, "server.trace.ndjson"),