diff --git a/.changeset/reduced-motion.md b/.changeset/reduced-motion.md
new file mode 100644
index 000000000..0ce1a65ad
--- /dev/null
+++ b/.changeset/reduced-motion.md
@@ -0,0 +1,10 @@
+---
+"@executor-js/react": patch
+---
+
+fix: honor prefers-reduced-motion in the shared stylesheet
+
+Adds a `prefers-reduced-motion: reduce` block to the global stylesheet that
+caps transition/animation durations to 0.01ms and disables smooth scrolling,
+so motion-sensitive users get a stable UI. The loading spinner renders
+statically under reduced motion (its meaning is preserved via `role="status"`).
diff --git a/apps/cloud/src/mcp/session-build-semaphore.test.ts b/apps/cloud/src/mcp/session-build-semaphore.test.ts
index 3d4ad7634..584b65ee0 100644
--- a/apps/cloud/src/mcp/session-build-semaphore.test.ts
+++ b/apps/cloud/src/mcp/session-build-semaphore.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it, beforeEach } from "@effect/vitest";
+import { describe, expect, it, beforeEach, afterEach, vi } from "@effect/vitest";
 
 import {
   acquireBuildSlot,
@@ -13,6 +13,10 @@ describe("session-build-semaphore", () => {
     resetBuildSlotsForTest();
   });
 
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
   it("grants up to the cap immediately, with no wait", async () => {
     const results = await Promise.all([
       acquireBuildSlot().promise,
@@ -214,6 +218,7 @@ describe("session-build-semaphore", () => {
   });
 
   it("proceeds without a slot when the queue wait exceeds the timeout, and does not count it as active", async () => {
+    vi.useFakeTimers();
     await Promise.all([
       acquireBuildSlot().promise,
       acquireBuildSlot().promise,
@@ -223,6 +228,10 @@ describe("session-build-semaphore", () => {
     expect(currentActiveBuildsForTest()).toBe(4);
 
     const timedOutHandle = acquireBuildSlot(10);
+    await vi.advanceTimersByTimeAsync(9);
+    expect(currentQueueLengthForTest()).toBe(1);
+    expect(currentActiveBuildsForTest()).toBe(4);
+    await vi.advanceTimersByTimeAsync(1);
     const result = await timedOutHandle.promise;
 
     expect(result).toEqual({ acquired: false, waitMs: expect.any(Number), timedOut: true });
diff --git a/e2e/scenarios/reduced-motion.test.ts b/e2e/scenarios/reduced-motion.test.ts
new file mode 100644
index 000000000..f2e751421
--- /dev/null
+++ b/e2e/scenarios/reduced-motion.test.ts
@@ -0,0 +1,59 @@
+import { expect } from "@effect/vitest";
+import { Effect } from "effect";
+
+import { scenario } from "../src/scenario";
+import { Browser, Target } from "../src/services";
+import { visit } from "../src/surfaces/browser";
+
+scenario(
+  "Accessibility · reduced motion removes dialog animation and control transitions",
+  {},
+  Effect.gen(function* () {
+    const target = yield* Target;
+    const browser = yield* Browser;
+    const identity = yield* target.newIdentity();
+
+    yield* browser.session(identity, async ({ page, step }) => {
+      await step("Open the API key dialog with normal motion", async () => {
+        await page.emulateMedia({ reducedMotion: "no-preference" });
+        await visit(page, "/api-keys");
+        await page.getByRole("button", { name: "New key" }).click();
+        await page.getByRole("dialog").waitFor();
+        const duration = await page
+          .getByRole("dialog")
+          .evaluate((element) => Number.parseFloat(getComputedStyle(element).transitionDuration));
+        expect(duration, "normal motion retains the dialog transition").toBeGreaterThan(0.00001);
+      });
+
+      await step("Enable reduced motion while the dialog is open", async () => {
+        await page.emulateMedia({ reducedMotion: "reduce" });
+        const styles = await page.getByRole("dialog").evaluate((element) => {
+          const style = getComputedStyle(element);
+          return {
+            animation: Number.parseFloat(style.animationDuration),
+            iterations: style.animationIterationCount,
+            transition: Number.parseFloat(style.transitionDuration),
+            scroll: style.scrollBehavior,
+          };
+        });
+        expect(styles).toEqual({
+          animation: 0.00001,
+          iterations: "1",
+          transition: 0.00001,
+          scroll: "auto",
+        });
+        await page.locator("#create-key-name").fill("Reduced motion check");
+        expect(await page.locator("#create-key-name").inputValue()).toBe("Reduced motion check");
+      });
+
+      await step("Restore normal motion without losing the form", async () => {
+        await page.emulateMedia({ reducedMotion: "no-preference" });
+        expect(await page.locator("#create-key-name").inputValue()).toBe("Reduced motion check");
+        const duration = await page
+          .getByRole("dialog")
+          .evaluate((element) => Number.parseFloat(getComputedStyle(element).transitionDuration));
+        expect(duration).toBeGreaterThan(0.00001);
+      });
+    });
+  }),
+);
diff --git a/packages/react/src/styles/globals.css b/packages/react/src/styles/globals.css
index e82bae6ca..97977327b 100644
--- a/packages/react/src/styles/globals.css
+++ b/packages/react/src/styles/globals.css
@@ -319,3 +319,24 @@
     opacity: 0.25;
   }
 }
+
+/* ---------------------------------------------------------------------------
+ * Reduced motion — WCAG 2.2 (motion-sensitive users).
+ *
+ * Neutralizes transitions/animations/scroll-behavior when the OS requests
+ * reduced motion, per the standard modern-CSS-reset pattern. The spinner
+ * (ios-spinner-fade) is capped to a single 0.01ms iteration — effectively
+ * static — which is the standard behavior: its meaning is preserved by
+ * `role="status"` (announced by assistive tech), and an opacity pulse would
+ * be a non-motion affordance but is not required for reduced-motion users.
+ * ------------------------------------------------------------------------- */
+@media (prefers-reduced-motion: reduce) {
+  *,
+  *::before,
+  *::after {
+    animation-duration: 0.01ms !important;
+    animation-iteration-count: 1 !important;
+    transition-duration: 0.01ms !important;
+    scroll-behavior: auto !important;
+  }
+}