diff --git a/deno.json b/deno.json
index 4e8887e505..8cdc8d79c1 100644
--- a/deno.json
+++ b/deno.json
@@ -478,9 +478,9 @@
     "storybook": "npm --prefix storybook run storybook",
     "build:storybook": "npm --prefix storybook run build-storybook",
     "storybook:check": "deno test --no-lock --config=scripts/test.deno.json --no-check --allow-read scripts/storybook/storybook-workbench.test.ts",
-    "lint": "DENO_NO_PACKAGE_JSON=1 deno lint src/ cli/ react/ && deno lint --config=scripts/test.deno.json scripts/test/ scripts/build/dnt-polyfill.ts scripts/build/dnt-polyfill.test.ts scripts/build/npm-package-metadata.test.ts && deno lint --config=scripts/codemods/deno.json scripts/codemods/",
-    "fmt": "deno fmt src/ cli/ react/ && deno fmt --config=scripts/test.deno.json scripts/test/ scripts/build/dnt-polyfill.ts scripts/build/dnt-polyfill.test.ts && deno fmt --config=scripts/codemods/deno.json scripts/codemods/",
-    "fmt:check": "deno fmt --check src/ cli/ react/ && deno fmt --check --config=scripts/test.deno.json scripts/test/ scripts/build/dnt-polyfill.ts scripts/build/dnt-polyfill.test.ts && deno fmt --check --config=scripts/codemods/deno.json scripts/codemods/",
+    "lint": "DENO_NO_PACKAGE_JSON=1 deno lint src/ cli/ react/ && deno lint --config=scripts/test.deno.json scripts/test/ scripts/build/dnt-polyfill.ts scripts/build/dnt-polyfill.test.ts scripts/build/npm-package-metadata.test.ts scripts/build/prepare-framework-sources.test.ts && deno lint --config=scripts/codemods/deno.json scripts/codemods/",
+    "fmt": "deno fmt src/ cli/ react/ && deno fmt --config=scripts/test.deno.json scripts/test/ scripts/build/dnt-polyfill.ts scripts/build/dnt-polyfill.test.ts scripts/build/prepare-framework-sources.test.ts && deno fmt --config=scripts/codemods/deno.json scripts/codemods/",
+    "fmt:check": "deno fmt --check src/ cli/ react/ && deno fmt --check --config=scripts/test.deno.json scripts/test/ scripts/build/dnt-polyfill.ts scripts/build/dnt-polyfill.test.ts scripts/build/prepare-framework-sources.test.ts && deno fmt --check --config=scripts/codemods/deno.json scripts/codemods/",
     "typecheck": "deno task generate:manifests:check && deno check src/index.ts cli/main.ts src/server/index.ts src/routing/api/index.ts src/rendering/index.ts src/platform/index.ts src/platform/adapters/index.ts src/build/index.ts src/build/production-build/index.ts src/transforms/index.ts src/config/index.ts src/utils/index.ts src/data/index.ts src/security/index.ts src/middleware/index.ts src/server/handlers/dev/index.ts src/server/handlers/request/api/index.ts src/rendering/cache/index.ts src/rendering/cache/stores/index.ts src/rendering/rsc/actions/index.ts src/html/index.ts src/html/hydration-script-builder/runtime/main.ts src/modules/index.ts src/proxy/main.ts src/react/components/ui/index.ts src/chat/index.ts src/markdown/index.ts src/mdx/index.ts src/fs/index.ts src/oauth/index.ts src/agent/index.ts src/agent/service/route-export.check.ts src/eval/index.ts src/tool/index.ts src/workflow/index.ts src/prompt/index.ts src/resource/index.ts src/runs/index.ts src/mcp/index.ts src/provider/index.ts",
     "verify": "deno task generate:manifests:check && deno task fmt:check && deno task lint && deno task lint:style && deno task lint:chat-composability && deno task lint:chat-ratchets && deno task lint:esm-sh-codemod && deno task lint:cli-boundary && deno task lint:wildcard-exports && deno task lint:barrel-jsdoc && deno task lint:ban-test-only && deno task lint:sanitizer-baseline && deno task lint:skipped-tests && deno task lint:ban-zod && deno task lint:core-deps && deno task lint:dependency-boundaries && deno task lint:module-boundaries && deno task lint:extension-contracts && deno task lint:extension-capabilities && deno task docs:validate && deno task typecheck && deno task typecheck:consumer && deno task test && deno task test:e2e:binary",
     "verify:quick": "deno task generate:manifests:check && deno task fmt:check && deno task lint && deno task lint:style && deno task lint:chat-composability && deno task lint:chat-ratchets && deno task lint:esm-sh-codemod && deno task lint:cli-boundary && deno task lint:wildcard-exports && deno task lint:barrel-jsdoc && deno task lint:ban-test-only && deno task lint:sanitizer-baseline && deno task lint:skipped-tests && deno task lint:ban-zod && deno task lint:core-deps && deno task lint:dependency-boundaries && deno task lint:module-boundaries && deno task lint:extension-contracts && deno task lint:extension-capabilities && deno task docs:validate && deno task typecheck",
@@ -519,7 +519,7 @@
     "lint:ban-test-only": "deno run --allow-read scripts/lint/ban-test-only.ts",
     "lint:sanitizer-baseline": "deno run --allow-read scripts/lint/check-sanitizer-baseline.ts",
     "lint:skipped-tests": "deno run --allow-read scripts/lint/check-skipped-tests-baseline.ts",
-    "test:scripts": "deno test --config=scripts/test.deno.json --no-check --allow-read --allow-write --allow-run scripts/ci/publish-npm-packages.test.ts scripts/build/dnt-polyfill.test.ts scripts/build/generate-sbom.test.ts scripts/build/npm-dependency-sources.test.ts scripts/build/npm-extension-package-metadata.test.ts scripts/build/npm-package-metadata.test.ts scripts/build/npm-react-shims.test.ts scripts/docs/docs-coverage.test.ts scripts/docs/generate-api-reference.test.ts scripts/docs/guide-validation.test.ts scripts/lint/audit-core-deps.test.ts scripts/lint/audit-dependency-boundaries.test.ts scripts/lint/audit-extension-capabilities.test.ts scripts/lint/audit-extension-contracts.test.ts scripts/lint/audit-deps.test.ts scripts/lint/check-module-boundaries.test.ts scripts/lint/ban-test-only.test.ts scripts/lint/check-sanitizer-baseline.test.ts scripts/lint/check-skipped-tests-baseline.test.ts scripts/lint/check-test-typecheck-baseline.test.ts scripts/lint/check-coverage.test.ts scripts/security/audit-npm.test.ts scripts/security/submit-dependency-snapshot.test.ts && deno task test:tool-search-live",
+    "test:scripts": "deno test --config=scripts/test.deno.json --no-check --allow-read --allow-write --allow-run scripts/ci/publish-npm-packages.test.ts scripts/build/dnt-polyfill.test.ts scripts/build/generate-sbom.test.ts scripts/build/npm-dependency-sources.test.ts scripts/build/npm-extension-package-metadata.test.ts scripts/build/npm-package-metadata.test.ts scripts/build/npm-react-shims.test.ts scripts/build/prepare-framework-sources.test.ts scripts/docs/docs-coverage.test.ts scripts/docs/generate-api-reference.test.ts scripts/docs/guide-validation.test.ts scripts/lint/audit-core-deps.test.ts scripts/lint/audit-dependency-boundaries.test.ts scripts/lint/audit-extension-capabilities.test.ts scripts/lint/audit-extension-contracts.test.ts scripts/lint/audit-deps.test.ts scripts/lint/check-module-boundaries.test.ts scripts/lint/ban-test-only.test.ts scripts/lint/check-sanitizer-baseline.test.ts scripts/lint/check-skipped-tests-baseline.test.ts scripts/lint/check-test-typecheck-baseline.test.ts scripts/lint/check-coverage.test.ts scripts/security/audit-npm.test.ts scripts/security/submit-dependency-snapshot.test.ts && deno task test:tool-search-live",
     "test:sentry-runtime-packages": "deno test --config=scripts/test.deno.json --no-check --no-lock --allow-read --allow-write --allow-run --allow-env=DENO_DIR,HOME,XDG_CACHE_HOME,LOCALAPPDATA,USERPROFILE scripts/build/sentry-runtime-packages.test.ts",
     "test:tool-search-live": "VF_DISABLE_LRU_INTERVAL=1 deno test --no-check -A tests/agent/verify-tool-search-live.test.ts",
     "test:cross-runtime": "deno run --allow-all src/platform/compat/cross-runtime.test.ts",
diff --git a/scripts/build/prepare-framework-sources.test.ts b/scripts/build/prepare-framework-sources.test.ts
new file mode 100644
index 0000000000..c0c8fb1ea9
--- /dev/null
+++ b/scripts/build/prepare-framework-sources.test.ts
@@ -0,0 +1,61 @@
+import { assertEquals } from "#std/assert";
+import { join } from "#std/path.ts";
+import { describe, it } from "#std/testing/bdd";
+import { prepareFrameworkSources } from "./prepare-framework-sources.ts";
+
+describe("prepareFrameworkSources", () => {
+  it("excludes tests and test helpers from binary framework sources", async () => {
+    const temporaryRoot = await Deno.makeTempDir();
+    const sourceRoot = join(temporaryRoot, "src");
+    const outputRoot = join(temporaryRoot, "dist");
+
+    try {
+      await Deno.mkdir(sourceRoot, { recursive: true });
+      await Promise.all([
+        Deno.writeTextFile(
+          join(sourceRoot, "runtime.ts"),
+          "export const runtime = true;\n",
+        ),
+        Deno.writeTextFile(
+          join(sourceRoot, "runtime.test.ts"),
+          "throw new Error('test');\n",
+        ),
+        Deno.writeTextFile(
+          join(sourceRoot, "react-root.test-helpers.ts"),
+          "throw new Error('test helper');\n",
+        ),
+      ]);
+
+      const result = await prepareFrameworkSources({
+        srcRoot: sourceRoot,
+        outputDir: outputRoot,
+      });
+
+      assertEquals(result.fileCount, 1);
+      assertEquals(
+        await Deno.readTextFile(join(outputRoot, "runtime.ts.src")),
+        "export const runtime = true;\n",
+      );
+      assertEquals(
+        await exists(join(outputRoot, "runtime.test.ts.src")),
+        false,
+      );
+      assertEquals(
+        await exists(join(outputRoot, "react-root.test-helpers.ts.src")),
+        false,
+      );
+    } finally {
+      await Deno.remove(temporaryRoot, { recursive: true });
+    }
+  });
+});
+
+async function exists(path: string): Promise<boolean> {
+  try {
+    await Deno.stat(path);
+    return true;
+  } catch (error) {
+    if (error instanceof Deno.errors.NotFound) return false;
+    throw error;
+  }
+}
diff --git a/scripts/build/prepare-framework-sources.ts b/scripts/build/prepare-framework-sources.ts
index 7a9fc9b54e..07f18f70a4 100644
--- a/scripts/build/prepare-framework-sources.ts
+++ b/scripts/build/prepare-framework-sources.ts
@@ -16,7 +16,7 @@
  * This is run automatically before `deno compile` in production builds.
  */
 
-import { walk } from "@std/fs";
+import { walk } from "#std/fs";
 import { dirname, fromFileUrl, join, relative } from "#std/path.ts";
 
 const FRAMEWORK_ROOT = fromFileUrl(new URL("../..", import.meta.url));
@@ -54,10 +54,12 @@ export async function prepareFrameworkSources(
   let totalBytes = 0;
   const encoder = new TextEncoder();
 
-  for await (const entry of walk(srcRoot, {
-    exts: SOURCE_EXTENSIONS.map((extension) => extension.slice(1)),
-    includeDirs: false,
-  })) {
+  for await (
+    const entry of walk(srcRoot, {
+      exts: SOURCE_EXTENSIONS.map((extension) => extension.slice(1)),
+      includeDirs: false,
+    })
+  ) {
     const relativePath = relative(srcRoot, entry.path);
     const normalizedPath = relativePath.replaceAll("\\", "/");
     if (
@@ -90,7 +92,11 @@ async function main(): Promise<void> {
 
   const { fileCount, totalBytes } = await prepareFrameworkSources();
 
-  console.log(`[prepare-framework-sources] Complete: ${fileCount} files, ${(totalBytes / 1024).toFixed(1)} KB`);
+  console.log(
+    `[prepare-framework-sources] Complete: ${fileCount} files, ${
+      (totalBytes / 1024).toFixed(1)
+    } KB`,
+  );
 }
 
 if (import.meta.main) await main();
diff --git a/src/react/components/chat/agent-picker.test.tsx b/src/react/components/chat/agent-picker.test.tsx
index 177e63c235..4ef855504e 100644
--- a/src/react/components/chat/agent-picker.test.tsx
+++ b/src/react/components/chat/agent-picker.test.tsx
@@ -2,6 +2,7 @@ import { createRoot } from "react-dom/client";
 import { flushSync } from "react-dom";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert";
 import { describe, it } from "#veryfront/testing/bdd";
 import type { AgentOption } from "./agent-picker.tsx";
@@ -111,7 +112,7 @@ describe("AgentPicker — preset (back-compat)", () => {
       assertEquals(loading.getAttribute("aria-selected"), "false");
       assertEquals(loading.querySelectorAll('[aria-hidden="true"]').length, 3);
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       dom.restore();
@@ -228,7 +229,7 @@ describe("AgentPicker — composability contract", () => {
       assertEquals(created, 1);
       assertEquals(managed, 0);
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       dom.restore();
diff --git a/src/react/components/chat/chat-agent-picker.test.tsx b/src/react/components/chat/chat-agent-picker.test.tsx
index 2622492576..5a135167cc 100644
--- a/src/react/components/chat/chat-agent-picker.test.tsx
+++ b/src/react/components/chat/chat-agent-picker.test.tsx
@@ -1,6 +1,7 @@
 import { createRoot } from "react-dom/client";
 import { flushSync } from "react-dom";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { agentsToPickerOptions, ChatAgentPicker } from "./chat-agent-picker.tsx";
@@ -109,7 +110,7 @@ describe("react/components/chat/chat-agent-picker: connected", () => {
       assert(trigger, "picker trigger renders after the agents resolve");
       assertStringIncludes(trigger.textContent ?? "", "Select agent");
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreFetch();
@@ -134,7 +135,7 @@ describe("react/components/chat/chat-agent-picker: connected", () => {
       assert(trigger, "picker trigger renders");
       assertStringIncludes(trigger.textContent ?? "", "Sales Agent");
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreFetch();
@@ -155,7 +156,7 @@ describe("react/components/chat/chat-agent-picker: connected", () => {
       assertEquals(rootElement.querySelector("button"), null);
       assertEquals(rootElement.textContent, "");
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreFetch();
@@ -181,7 +182,7 @@ describe("react/components/chat/chat-agent-picker: connected", () => {
       assertEquals(fetches, 0);
       assertEquals(rootElement.querySelector("button"), null);
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       globalThis.fetch = previousFetch;
diff --git a/src/react/components/chat/chat/chat.controlled.test.tsx b/src/react/components/chat/chat/chat.controlled.test.tsx
index 6bcbe85f5f..386df93032 100644
--- a/src/react/components/chat/chat/chat.controlled.test.tsx
+++ b/src/react/components/chat/chat/chat.controlled.test.tsx
@@ -6,6 +6,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert";
 import { describe, it } from "#veryfront/testing/bdd";
 import type { ChatMessage, UseChatResult } from "#veryfront/agent/react";
@@ -117,7 +118,7 @@ describe("Chat — controlled via chat={useChat()}", () => {
     );
   });
 
-  it("submits externally controlled attachments through the chat session", () => {
+  it("submits externally controlled attachments through the chat session", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -171,7 +172,7 @@ describe("Chat — controlled via chat={useChat()}", () => {
         }],
       });
       assertEquals(removed, ["file-1"]);
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
diff --git a/src/react/components/chat/chat/components/code-block.test.tsx b/src/react/components/chat/chat/components/code-block.test.tsx
index ee1ba87bb1..d4eae00d64 100644
--- a/src/react/components/chat/chat/components/code-block.test.tsx
+++ b/src/react/components/chat/chat/components/code-block.test.tsx
@@ -2,6 +2,7 @@ import { flushSync } from "react-dom";
 import { createRoot, type Root } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert";
 import { describe, it } from "#veryfront/testing/bdd";
 import { RichCodeBlock } from "./code-block.tsx";
@@ -48,12 +49,20 @@ async function settle(): Promise<void> {
   flushSync(() => {});
 }
 
-// Unmounting leaves a scheduler callback queued; drain it so the leak
-// sanitizer does not attribute that timer to the test.
-async function unmount(root: Root | undefined): Promise<void> {
-  if (!root) return;
-  flushSync(() => root.unmount());
-  await new Promise((resolve) => setTimeout(resolve, 0));
+/**
+ * Poll for a state transition instead of assuming `settle()` covered it.
+ *
+ * A copy result travels through a promise chain and then a React commit, and a
+ * single macrotask does not always cover both under load.
+ */
+async function waitFor(condition: () => boolean, timeoutMs = 3000): Promise<void> {
+  const startedAt = Date.now();
+  while (!condition()) {
+    if (Date.now() - startedAt > timeoutMs) {
+      throw new Error("Timed out waiting for code block state");
+    }
+    await settle();
+  }
 }
 
 describe("RichCodeBlock — inline mode", () => {
@@ -133,7 +142,7 @@ describe("RichCodeBlock — block mode", () => {
       );
       assertEquals(document.querySelectorAll("textarea").length, 0);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       dom.restore();
     }
   });
@@ -170,8 +179,7 @@ describe("RichCodeBlock — block mode", () => {
       assertEquals(pending.length, 2);
 
       pending[1]?.();
-      await settle();
-      assertEquals(secondButton.textContent?.trim(), "Copied");
+      await waitFor(() => secondButton.textContent?.trim() === "Copied");
 
       pending[0]?.();
       await settle();
@@ -179,7 +187,7 @@ describe("RichCodeBlock — block mode", () => {
       assertStringIncludes(rootElement.textContent ?? "", "new code");
       assert(!(rootElement.textContent ?? "").includes("old code"));
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       dom.restore();
     }
   });
diff --git a/src/react/components/chat/chat/components/inline-citation.test.tsx b/src/react/components/chat/chat/components/inline-citation.test.tsx
index 3aeefb6715..7b21dfc36f 100644
--- a/src/react/components/chat/chat/components/inline-citation.test.tsx
+++ b/src/react/components/chat/chat/components/inline-citation.test.tsx
@@ -1,6 +1,7 @@
 import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { waitFor } from "#veryfront/testing/deno-compat.ts";
@@ -84,7 +85,7 @@ describe("InlineCitation", () => {
       assert(card, "Expected citation card to render after hover");
       assertEquals(card.textContent, "Custom citation card");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
diff --git a/src/react/components/chat/chat/components/message-actions.test.tsx b/src/react/components/chat/chat/components/message-actions.test.tsx
index 1d1e807948..2fcc3171ab 100644
--- a/src/react/components/chat/chat/components/message-actions.test.tsx
+++ b/src/react/components/chat/chat/components/message-actions.test.tsx
@@ -2,6 +2,7 @@ import { createRoot, type Root } from "react-dom/client";
 import { flushSync } from "react-dom";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { MessageActionBar } from "./message-actions.tsx";
@@ -42,18 +43,20 @@ function installDom(): { restore: () => void; window: JSDOM["window"] } {
   };
 }
 
-/**
- * Unmount and drain the one-shot tasks the runtime leaves behind.
- *
- * The `execCommand` copy fallback selects a textarea, and jsdom queues that
- * `select` event on a bare `setTimeout` it never registers with the window, so
- * `window.close()` cannot clear it. React's scheduler likewise holds a
- * `setImmediate` until it next runs. Both complete on their own, but the test
- * has to yield once more or Deno's leak sanitizer sees them still pending.
- */
-async function unmount(root: Root): Promise<void> {
-  flushSync(() => root.unmount());
+async function settle(): Promise<void> {
+  await Promise.resolve();
   await new Promise((resolve) => setTimeout(resolve, 0));
+  flushSync(() => {});
+}
+
+async function waitFor(condition: () => boolean, timeoutMs = 3000): Promise<void> {
+  const startedAt = Date.now();
+  while (!condition()) {
+    if (Date.now() - startedAt > timeoutMs) {
+      throw new Error("Timed out waiting for message action state");
+    }
+    await settle();
+  }
 }
 
 describe("MessageActionBar", () => {
@@ -103,6 +106,7 @@ describe("MessageActionBar", () => {
 
   it("renders the composed copied-state leaf after copying", async () => {
     const dom = installDom();
+    let root: Root | undefined;
     const writes: string[] = [];
     Object.defineProperty(dom.window.navigator, "clipboard", {
       configurable: true,
@@ -116,9 +120,10 @@ describe("MessageActionBar", () => {
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "root element exists");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <MessageActionBar content="Answer">
             <MessageActionBar.Copy icon={<span data-testid="custom-copy">copy</span>} />
             <MessageActionBar.Copied
@@ -134,16 +139,14 @@ describe("MessageActionBar", () => {
       );
       assert(copy, "copy action renders");
       flushSync(() => copy.dispatchEvent(new dom.window.MouseEvent("click", { bubbles: true })));
-      // Let the clipboard promise settle without outwaiting the transient copied state.
-      await new Promise((resolve) => setTimeout(resolve, 0));
-      flushSync(() => {});
+      await waitFor(() => rootElement.querySelector('[data-testid="custom-copied"]') !== null);
 
       assertEquals(writes, ["Answer"]);
       assert(rootElement.querySelector('[data-testid="custom-copied"]'));
       assertStringIncludes(rootElement.innerHTML, "vf-copied");
 
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <MessageActionBar content="Updated answer">
             <MessageActionBar.Copy icon={<span data-testid="custom-copy">copy</span>} />
             <MessageActionBar.Copied icon={<span data-testid="custom-copied">copied</span>} />
@@ -152,15 +155,15 @@ describe("MessageActionBar", () => {
       });
       assert(rootElement.querySelector('[data-testid="custom-copy"]'));
       assert(!rootElement.querySelector('[data-testid="custom-copied"]'));
-
-      await unmount(root);
     } finally {
+      if (root) await unmountReactRoot(root);
       dom.restore();
     }
   });
 
   it("keeps the copy action available when every clipboard mechanism fails", async () => {
     const dom = installDom();
+    let root: Root | undefined;
     Object.defineProperty(dom.window.navigator, "clipboard", {
       configurable: true,
       value: { writeText: () => Promise.reject(new Error("denied")) },
@@ -173,9 +176,10 @@ describe("MessageActionBar", () => {
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "root element exists");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <MessageActionBar content="Answer">
             <MessageActionBar.Copy icon={<span data-testid="custom-copy">copy</span>} />
             <MessageActionBar.Copied icon={<span data-testid="custom-copied">copied</span>} />
@@ -188,8 +192,7 @@ describe("MessageActionBar", () => {
       );
       assert(copy, "copy action renders");
       copy.dispatchEvent(new dom.window.MouseEvent("click", { bubbles: true }));
-      await new Promise((resolve) => setTimeout(resolve, 0));
-      flushSync(() => {});
+      await waitFor(() => copy.getAttribute("aria-label") === "Unable to copy. Try again");
 
       assert(rootElement.querySelector('[data-testid="custom-copy"]'));
       assert(!rootElement.querySelector('[data-testid="custom-copied"]'));
@@ -199,9 +202,8 @@ describe("MessageActionBar", () => {
         "Unable to copy to clipboard",
       );
       assertEquals(document.querySelectorAll("textarea").length, 0);
-
-      await unmount(root);
     } finally {
+      if (root) await unmountReactRoot(root);
       dom.restore();
     }
   });
diff --git a/src/react/components/chat/chat/components/sidebar.test.tsx b/src/react/components/chat/chat/components/sidebar.test.tsx
index edc43a4ad9..55a831ad4e 100644
--- a/src/react/components/chat/chat/components/sidebar.test.tsx
+++ b/src/react/components/chat/chat/components/sidebar.test.tsx
@@ -8,6 +8,7 @@ import { flushSync } from "react-dom";
 import { renderToString } from "react-dom/server";
 import * as React from "react";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { ChatSidebar, useChatSidebarItem } from "./sidebar.tsx";
@@ -100,7 +101,7 @@ describe("ChatSidebar — conversation-native", () => {
       assert(html.includes("First chat"), "lists the first conversation from context");
       assert(html.includes("Second chat"), "lists the second conversation from context");
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreDom();
@@ -136,7 +137,7 @@ describe("ChatSidebar — conversation-native", () => {
         "the primary action carries the conversation label",
       );
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreDom();
@@ -249,7 +250,7 @@ describe("ChatSidebar.Item — menu compound (E4 acid test)", () => {
       );
       assert(itemRef.current.querySelector("input"), "the ref targets the active rename row");
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreDom();
@@ -284,7 +285,7 @@ describe("ChatSidebarRenameEditor", () => {
         input.dispatchEvent(new FocusEvent("focusout", { bubbles: true }));
       });
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       return [commits, cancels];
     } finally {
@@ -318,7 +319,7 @@ describe("ChatSidebarRenameEditor", () => {
 
       flushSync(() => root.render(renderEditor("Edited title")));
       assertEquals(input.getAttribute("aria-label"), "Rename Original title");
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreDom();
diff --git a/src/react/components/chat/chat/composition/chat-composer.test.tsx b/src/react/components/chat/chat/composition/chat-composer.test.tsx
index ad5688db97..6783ab761e 100644
--- a/src/react/components/chat/chat/composition/chat-composer.test.tsx
+++ b/src/react/components/chat/chat/composition/chat-composer.test.tsx
@@ -1,5 +1,5 @@
 import { flushSync } from "react-dom";
-import { createRoot } from "react-dom/client";
+import { createRoot, type Root } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import {
   type AnchorHTMLAttributes,
@@ -11,6 +11,7 @@ import {
   type ReactElement,
 } from "react";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { ChatInput } from "./chat-composer.tsx";
@@ -105,7 +106,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     assertEquals(sends, 1, "the additive API must not break a legacy owned submit");
   });
 
-  it("leaves legacy controlled submit policy with the caller", () => {
+  it("leaves legacy controlled submit policy with the caller", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -113,6 +114,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     const restore = installDomGlobals(dom);
     let submits = 0;
     let defaultPrevented: boolean | undefined;
+    let root: Root | undefined;
     function Capture(): ReactElement {
       const submit = useChatInputContext().onSubmit;
       return <form onSubmit={(event) => submit(event)} data-submit-probe />;
@@ -121,9 +123,10 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "Expected root element to exist");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <ChatInput.Root
             input=""
             onChange={() => {}}
@@ -143,13 +146,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
 
       assertEquals(submits, 1, "controlled submit remains caller-owned");
       assertEquals(defaultPrevented, false, "controlled submit receives the event unchanged");
-      root.unmount();
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("prevents native submission from the default controlled composer form", () => {
+  it("prevents native submission from the default controlled composer form", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -190,7 +193,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       assertEquals(submitEvent.defaultPrevented, true);
       assertEquals(dispatchResult, false, "cancelled native submission must report false");
     } finally {
-      root?.unmount();
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -247,7 +250,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     assert(pending.includes("disabled"), "a pending upload disables the send control");
   });
 
-  it("renders an accessible textarea with its native attributes and ref", () => {
+  it("renders an accessible textarea with its native attributes and ref", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -281,13 +284,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       assertEquals(textarea.rows, 4);
       assertEquals(textarea.cols, 40);
       assertEquals(textarea.wrap, "soft");
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
   });
 
-  it("opens upload and select document actions from the attachment button", () => {
+  it("opens upload and select document actions from the attachment button", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -359,13 +362,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       });
 
       assertEquals(selectCalls, 1);
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
   });
 
-  it("submits multiline input on Enter and keeps Shift+Enter for newlines", () => {
+  it("submits multiline input on Enter and keeps Shift+Enter for newlines", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -427,13 +430,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
 
       assertEquals(submitCalls, 1);
       assertEquals(preventDefaultCalls, 1);
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
   });
 
-  it("enables send for a resolved attachment without text", () => {
+  it("enables send for a resolved attachment without text", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -476,13 +479,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       });
 
       assertEquals(submitCalls, 1, "attachment-only send should submit");
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
   });
 
-  it("composer owns submit: folds resolved attachments, clears, and guards uploads", () => {
+  it("composer owns submit: folds resolved attachments, clears, and guards uploads", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -540,13 +543,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       assertEquals(inputSetTo, "", "clears the input after send");
       assertEquals(cleared, 1, "clears attachments after send");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
   });
 
-  it("uses the copied Studio prompt shell and non-scaling primary submit button", () => {
+  it("uses the copied Studio prompt shell and non-scaling primary submit button", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -591,7 +594,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       );
       // Studio's submit button does not scale on press.
       assertEquals(submitButton.className.includes("active:scale"), false);
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -643,7 +646,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     assert(voice.includes('aria-describedby="voice-help"'));
   });
 
-  it("omits an unavailable Stop action while preserving an explicit custom action", () => {
+  it("omits an unavailable Stop action while preserving an explicit custom action", async () => {
     const unavailable = renderToString(
       <ChatInput.Root input="" onChange={() => {}} isLoading>
         <ChatInput.Stop data-action="stop" />
@@ -667,10 +670,12 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     );
     const restore = installDomGlobals(dom);
     let customStops = 0;
+    let root: Root | undefined;
     try {
-      const root = createRoot(document.getElementById("root")!);
+      const createdRoot = createRoot(document.getElementById("root")!);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <ChatInput.Root input="" onChange={() => {}} isLoading>
             <ChatInput.Stop onClick={() => customStops += 1} />
           </ChatInput.Root>,
@@ -680,13 +685,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
         document.querySelector<HTMLButtonElement>('button[aria-label="Stop"]')?.click()
       );
       assertEquals(customStops, 1, "the explicit custom Stop action remains functional");
-      flushSync(() => root.unmount());
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("asChild action leaves preserve Button styling, refs, and event composition", () => {
+  it("asChild action leaves preserve Button styling, refs, and event composition", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -695,13 +700,15 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     const actionRef = createRef<HTMLAnchorElement>();
     const childRef = createRef<HTMLAnchorElement>();
     const order: string[] = [];
+    let root: Root | undefined;
 
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "Expected root element to exist");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <ChatInput.Root
             input="ready"
             onChange={() => {}}
@@ -749,8 +756,8 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
         link.dispatchEvent(new MouseEvent("click", { bubbles: true, cancelable: true }));
       });
       assertEquals(order, ["child", "wrapper", "submit"]);
-      root.unmount();
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -849,7 +856,7 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     );
   });
 
-  it("lets an opaque forwardRef button own its native form semantics", () => {
+  it("lets an opaque forwardRef button own its native form semantics", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -861,13 +868,15 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     >((props, ref) => <button ref={ref} {...props} />);
     let actionSubmits = 0;
     let nativeSubmits = 0;
+    let root: Root | undefined;
 
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "Expected root element to exist");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <ChatInput.Root
             input="ready"
             onChange={() => {}}
@@ -893,13 +902,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       flushSync(() => button.click());
       assertEquals(actionSubmits, 1);
       assertEquals(nativeSubmits, 0, "the enclosing form must not submit a second time");
-      root.unmount();
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("asChild respects child cancellation before invoking the action wrapper", () => {
+  it("asChild respects child cancellation before invoking the action wrapper", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -907,13 +916,15 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     const restore = installDomGlobals(dom);
     let wrapperCalls = 0;
     let submitCalls = 0;
+    let root: Root | undefined;
 
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "Expected root element to exist");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <ChatInput.Root
             input="ready"
             onChange={() => {}}
@@ -939,13 +950,13 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       assert(event.defaultPrevented, "child cancellation is preserved");
       assertEquals(wrapperCalls, 0, "cancelled child event skips the action wrapper");
       assertEquals(submitCalls, 0, "cancelled child event skips submit");
-      root.unmount();
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("disabled asChild actions block link, auxiliary, and keyboard activation", () => {
+  it("disabled asChild actions block link, auxiliary, and keyboard activation", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { url: "https://example.com/" },
@@ -954,13 +965,15 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
     let childActivations = 0;
     let wrapperActivations = 0;
     let submitCalls = 0;
+    let root: Root | undefined;
 
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement, "Expected root element to exist");
-      const root = createRoot(rootElement);
+      const createdRoot = createRoot(rootElement);
+      root = createdRoot;
       flushSync(() => {
-        root.render(
+        createdRoot.render(
           <ChatInput.Root
             input="ready"
             onChange={() => {}}
@@ -1009,8 +1022,8 @@ describe("react/components/chat/chat/composition/chat-composer", () => {
       assertEquals(childActivations, 0, "disabled state skips child handlers");
       assertEquals(wrapperActivations, 0, "disabled state skips action handlers");
       assertEquals(submitCalls, 0, "disabled state skips submit");
-      root.unmount();
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
diff --git a/src/react/components/chat/chat/composition/chat-empty.test.tsx b/src/react/components/chat/chat/composition/chat-empty.test.tsx
index 93206beb07..2b41b17b36 100644
--- a/src/react/components/chat/chat/composition/chat-empty.test.tsx
+++ b/src/react/components/chat/chat/composition/chat-empty.test.tsx
@@ -1,6 +1,7 @@
 import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import type { AgentMetadata, PromptSuggestion } from "#veryfront/agent/react";
@@ -66,7 +67,7 @@ describe("getAgentPromptSuggestionItems", () => {
 });
 
 describe("ChatEmpty suggestions", () => {
-  it("renders labels and hands the { label, prompt } object to onSuggestionSelect", () => {
+  it("renders labels and hands the { label, prompt } object to onSuggestionSelect", async () => {
     const restoreDom = installDom();
     const clicked: PromptSuggestion[] = [];
     try {
@@ -90,13 +91,13 @@ describe("ChatEmpty suggestions", () => {
         { label: "Triage login", prompt: "Triage a user who cannot sign in." },
       ], "click sends the full { label, prompt } — no .find needed");
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
     } finally {
       restoreDom();
     }
   });
 
-  it("keeps legacy onSuggestionClick handlers receiving prompt text", () => {
+  it("keeps legacy onSuggestionClick handlers receiving prompt text", async () => {
     const restoreDom = installDom();
     const clicked: string[] = [];
     try {
@@ -116,7 +117,7 @@ describe("ChatEmpty suggestions", () => {
       assert(button, "renders the legacy suggestion chip");
       flushSync(() => button.click());
       assertEquals(clicked, ["Triage the login incident."]);
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
     } finally {
       restoreDom();
     }
diff --git a/src/react/components/chat/chat/composition/message.test.tsx b/src/react/components/chat/chat/composition/message.test.tsx
index 8c1c6e03d6..c9e4b98dde 100644
--- a/src/react/components/chat/chat/composition/message.test.tsx
+++ b/src/react/components/chat/chat/composition/message.test.tsx
@@ -2,6 +2,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert";
 import { describe, it } from "#veryfront/testing/bdd";
 import type { ChatDynamicToolPart, ChatMessage } from "#veryfront/agent/react";
@@ -457,7 +458,7 @@ describe("Message.CopyAction", () => {
       flushSync(() => {});
 
       assertEquals(writes, ["Answer body."]);
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
     } finally {
       Object.assign(globalThis, previous);
       dom.window.close();
diff --git a/src/react/components/chat/chat/hooks/use-conversation-chat.test.tsx b/src/react/components/chat/chat/hooks/use-conversation-chat.test.tsx
index 977ff2c55b..8b8a836a89 100644
--- a/src/react/components/chat/chat/hooks/use-conversation-chat.test.tsx
+++ b/src/react/components/chat/chat/hooks/use-conversation-chat.test.tsx
@@ -1,6 +1,7 @@
 import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import type { ChatMessage } from "#veryfront/agent/react";
 import { assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
@@ -144,7 +145,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       ]);
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -203,7 +204,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       );
       assertEquals(saved.at(-1)?.messages, [nextMessage]);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -265,7 +266,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(saved.at(-1)?.id, syntheticId);
       assertEquals("agentId" in saved.at(-1)!, false);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -302,7 +303,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(saved.at(-1)?.id, bound.id);
       assertEquals(saved.at(-1)?.agentId, "agent-b");
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -392,7 +393,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(saved[0]?.messages, [...second.messages, reply]);
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -440,7 +441,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(latest!.chat.streamingMessageId, null);
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -494,7 +495,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       );
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -545,7 +546,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(latest!.chat.messages, first.messages);
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -634,7 +635,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(latest!.chat.data, null);
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -714,7 +715,7 @@ describe("react/components/chat/hooks/useConversationChat", () => {
       assertEquals(saved.at(-1)?.messages, [...second.messages, reply]);
     } finally {
       globalThis.fetch = originalFetch;
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
diff --git a/src/react/components/chat/chat/hooks/use-conversation.test.tsx b/src/react/components/chat/chat/hooks/use-conversation.test.tsx
index 4663dfe510..4fea1708d4 100644
--- a/src/react/components/chat/chat/hooks/use-conversation.test.tsx
+++ b/src/react/components/chat/chat/hooks/use-conversation.test.tsx
@@ -5,6 +5,7 @@
 import { createRoot } from "react-dom/client";
 import { flushSync } from "react-dom";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import {
@@ -108,7 +109,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       await settle();
       assertEquals(view.get().conversation?.title, "Alpha");
       assertEquals(view.get().isLoading, false);
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -122,7 +123,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       const view = mount(store, "does-not-exist");
       await settle();
       assert(view.get().conversation === null, "unknown id resolves to null");
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -197,7 +198,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       assertEquals(latest!.conversation?.title, "Provider record");
       assertEquals(latest!.isLoading, false);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -244,7 +245,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       assertEquals(loadCalls, 2);
       assertEquals(latest!.conversation?.title, "Reloaded provider record");
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -302,7 +303,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       flushSync(() => latest!.clearError());
       assertEquals(latest!.error, null);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -355,7 +356,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       assertEquals(latest!.error, null);
       assertEquals(provider!.error, deleteFailure);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
       restoreDom();
     }
@@ -382,7 +383,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       flushSync(() => view.get().clearError());
       assertEquals(persistenceError(view.get()), null);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -414,7 +415,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       assertEquals(persistenceError(view.get())?.cause, loadFailure);
       assertEquals(callbackErrors, [callbackFailure]);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       if (previousReportError) {
@@ -443,7 +444,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       const view = mount(store, "a");
       await Promise.resolve();
       assert(rejectLoad);
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       rejectLoad(new Error("late load failure"));
       await settle();
     } finally {
@@ -481,7 +482,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       assertEquals(view.get().isLoading, false);
       assertEquals(persistenceError(view.get()), null);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -527,7 +528,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       await settle();
       assertEquals([firstLoads, secondLoads], [1, 1]);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       retained.reload();
       retained.clearError();
       await settle();
@@ -567,7 +568,7 @@ describe("react/components/chat/hooks/useConversation", () => {
       await settle();
       assertEquals([firstDisposals, secondDisposals], [0, 0]);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
       assertEquals([firstDisposals, secondDisposals], [0, 0]);
     } finally {
diff --git a/src/react/components/chat/chat/hooks/use-conversations.hook.test.tsx b/src/react/components/chat/chat/hooks/use-conversations.hook.test.tsx
index ac532f3db1..d7bbe0e42b 100644
--- a/src/react/components/chat/chat/hooks/use-conversations.hook.test.tsx
+++ b/src/react/components/chat/chat/hooks/use-conversations.hook.test.tsx
@@ -8,6 +8,7 @@ import * as React from "react";
 import { createRoot } from "react-dom/client";
 import { flushSync } from "react-dom";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import type { ChatMessage } from "#veryfront/agent/react";
@@ -167,7 +168,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assertEquals(view.get().activeConversation?.id, "b");
       assertEquals(activeConversationLoading(view.get()), false);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -218,7 +219,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assertEquals(view.get().activeConversation?.title, "Current scope");
       assertEquals(activeConversationLoading(view.get()), false);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -250,7 +251,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assert(view.get().activeConversation?.id !== "missing");
       assertEquals(activeConversationLoading(view.get()), false);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -283,7 +284,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assertEquals(persistenceError(view.get())?.operation, "load");
       assertEquals(persistenceError(view.get())?.cause, failure);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -318,7 +319,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assertEquals(activeConversationLoading(view.get()), false);
       assertEquals(betaLoads, 0);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -367,7 +368,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assertEquals(view.get().activeConversation?.title, "Updated Beta");
       assertEquals(activeConversationLoading(view.get()), false);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -394,7 +395,7 @@ describe("react/components/chat/hooks/useConversations — active conversation l
       assert(rejectLoad);
       assertEquals(activeConversationLoading(view.get()), true);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       rejectLoad(new Error("late active load failure"));
       await settle();
       assertEquals(reported, []);
@@ -428,7 +429,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       flushSync(() => view.get().clearError?.());
       assertEquals(persistenceError(view.get()), null);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -451,7 +452,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       const view = mount(store);
       await Promise.resolve();
       assert(rejectList);
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       rejectList(new Error("late list failure"));
       await settle();
     } finally {
@@ -471,7 +472,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().active, view.get().activeConversation);
       assertEquals(view.get().activeId, view.get().activeConversationId);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -501,7 +502,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(reused?.agentId, "");
       assertEquals(view.get().conversations.map((item) => item.id), ["empty"]);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -536,7 +537,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         ["agent-a-draft", created.id].sort(),
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -564,7 +565,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "active conversation should load",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -593,7 +594,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(summary.messageCount, 1);
 
       // Persistence is debounced; unmount flushes the pending save.
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
       await settle();
       assertEquals((await store.load("new"))?.title, "Hello world");
@@ -617,7 +618,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(matches[0]?.title, "Renamed");
 
       // Persistence is debounced; unmount flushes the pending save.
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
       await settle();
       assertEquals((await store.load("seed"))?.title, "Renamed");
@@ -650,7 +651,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(persisted?.messages.length, 1);
       assertEquals(view.get().conversations[0]?.title, "Command snapshot");
       assertEquals(view.get().conversations[0]?.messageCount, 1);
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -682,7 +683,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().conversations[0]?.title, "Client title (server)");
       assertEquals(view.get().conversations[0]?.updatedAt, 109);
       assertEquals(view.get().activeConversation?.title, "Client title (server)");
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -711,7 +712,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       await settle();
 
       assertEquals(await store.load("seed"), null, "removed conversation must stay deleted");
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -741,7 +742,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(persistenceError(view.get())?.operation, "delete");
       assertEquals(persistenceError(view.get())?.cause, failure);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -796,7 +797,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         false,
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -828,7 +829,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(persistenceError(view.get()), failure);
       assertEquals(persistenceError(view.get())?.cause, cause);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -877,7 +878,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         { type: "text", text: "persisted" },
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -929,7 +930,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "unsaved",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -997,7 +998,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         { type: "text", text: "persisted" },
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1021,7 +1022,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       const view = mount(store);
       await settle();
       view.get().save(conversation({ title: "Pending", updatedAt: 2 }));
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
       assert(rejectSave);
       rejectSave(new Error("late save failure"));
@@ -1057,7 +1058,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(await store.load("draft"), null);
       assert(await store.load(replacementId));
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1108,7 +1109,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().conversations.map((item) => item.id), ["active"]);
       assertEquals(await base.load("target"), null);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1149,7 +1150,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().conversations[0]?.agentId, "agent-latest");
       assertEquals(view.get().conversations[0]?.updatedAt, persisted?.updatedAt);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1199,7 +1200,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(persisted?.title, "Renamed");
       assertEquals(persisted?.agentId, "agent-2");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1236,7 +1237,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "a failed load must roll back metadata that was never applied",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1278,7 +1279,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       );
       assertEquals((await base.load("target"))?.title, "Target");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1327,7 +1328,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "a later failure must retain the newest successfully persisted revision",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1375,7 +1376,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       );
       assertEquals((await base.load("target"))?.title, "Target");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1436,7 +1437,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "retained",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1498,7 +1499,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "retained",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1530,7 +1531,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals((view.get().error?.cause as Error)?.name, "ConversationNotFoundError");
       assertEquals(view.get().conversations.some((item) => item.id === "target"), false);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1580,7 +1581,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(await base.load("seed"), null);
       assertEquals(view.get().conversations.map((item) => item.id), ["other"]);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1626,7 +1627,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       await settle();
       assertEquals((await base.load("seed"))?.title, "Explicit recreation");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1674,7 +1675,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(persistenceError(view.get())?.cause, failure);
       assertEquals(view.get().conversations.map((item) => item.id), ["seed"]);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1719,7 +1720,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(newSaveCalls, 1);
       assertEquals((await newBase.load("seed"))?.title, "Version two");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1770,7 +1771,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "a retired scope completion must not schedule work in its replacement",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1842,7 +1843,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "Saved from child layout",
       );
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreDom();
@@ -1880,7 +1881,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().conversations.map((item) => item.id), ["b"]);
       assertEquals(view.get().activeConversationId, "b");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1933,7 +1934,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().conversations.map((item) => item.id), ["b"]);
       assertEquals(view.get().activeConversationId, "b");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -1994,7 +1995,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(callsB, afterSwitchB);
 
       const retainedB = view.get();
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       retainedB.save(conversation({ title: "After unmount" }));
       retainedB.remove("seed");
       let unmountedCreateThrew = false;
@@ -2065,7 +2066,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(disposalsA, 0);
       assertEquals(disposalsB, 0);
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
       assertEquals(unsubscribesA, 1);
       assertEquals(unsubscribesB, 1);
@@ -2120,7 +2121,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
         "remote",
       );
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -2163,7 +2164,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().conversations[0]?.title, "Optimistic");
       assertEquals((await base.load("seed"))?.title, "Optimistic");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       restoreDom();
@@ -2202,7 +2203,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(view.get().error, null);
       assertEquals((continuationErrors[0] as Error)?.message, "router failed");
 
-      flushSync(() => view.root.unmount());
+      await unmountReactRoot(view.root);
       await settle();
     } finally {
       if (previousReportError) {
@@ -2280,7 +2281,7 @@ describe("react/components/chat/hooks/useConversations — save", () => {
       assertEquals(abandonedErrors, []);
       assertEquals((committed as unknown as ConversationsHookResult).error?.cause, failure);
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await settle();
     } finally {
       restoreDom();
diff --git a/src/react/components/chat/chat/hooks/use-drop-zone.test.tsx b/src/react/components/chat/chat/hooks/use-drop-zone.test.tsx
index 9c7084c16b..763632243d 100644
--- a/src/react/components/chat/chat/hooks/use-drop-zone.test.tsx
+++ b/src/react/components/chat/chat/hooks/use-drop-zone.test.tsx
@@ -2,6 +2,7 @@ import * as React from "react";
 import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { useDropZone, type UseDropZoneResult } from "./use-drop-zone.ts";
@@ -42,7 +43,7 @@ describe("useDropZone", () => {
       assert(typeof result.onDragOver === "function");
       assert(typeof result.onDrop === "function");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       Object.assign(globalThis, previous);
       dom.window.close();
diff --git a/src/react/components/chat/chat/hooks/use-uploads-registry.test.tsx b/src/react/components/chat/chat/hooks/use-uploads-registry.test.tsx
index 56e1ffeb5a..18d1e18af4 100644
--- a/src/react/components/chat/chat/hooks/use-uploads-registry.test.tsx
+++ b/src/react/components/chat/chat/hooks/use-uploads-registry.test.tsx
@@ -2,6 +2,7 @@ import * as React from "react";
 import { createRoot } from "react-dom/client";
 import { flushSync } from "react-dom";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import {
@@ -188,13 +189,13 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       assertEquals(items[0]!.id, "srv-1", "the server id is captured (needed for DELETE)");
       assertEquals(items[0]!.type, "text/plain");
       assert((localStorage.getItem(key) ?? "").includes("srv-1"), "persisted to localStorage");
-      flushSync(() => a.root.unmount());
+      await unmountReactRoot(a.root);
       await flush(() => {});
 
       // Remount → the item is loaded back from localStorage.
       const b = mount(key);
       assertEquals(b.get().items.map((f) => f.id), ["srv-1"]);
-      flushSync(() => b.root.unmount());
+      await unmountReactRoot(b.root);
       await flush(() => {});
     } finally {
       fetchStub.restore();
@@ -211,7 +212,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       assertEquals(reg.get().isLoading, true, "loading immediately after mount");
       await flush(() => {});
       assertEquals(reg.get().isLoading, false, "cleared once the initial fetch resolves");
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
       await flush(() => {});
     } finally {
       fetchStub.restore();
@@ -239,7 +240,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
 
       assertEquals((latest as unknown as UseUploadsRegistryResult).isLoading, false);
       assertEquals(fetchStub.gets.length, 1, "inline headers should not retrigger refresh");
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await flush(() => {});
     } finally {
       fetchStub.restore();
@@ -299,7 +300,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
         ["new"],
       );
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await flush(() => {});
     } finally {
       globalThis.fetch = previousFetch;
@@ -322,7 +323,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
 
       assert(fetchStub.deletes.includes(id), "a DELETE was sent for the removed id");
       assertEquals(reg.get().items.length, 0, "the item is gone from the registry");
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
       await flush(() => {});
     } finally {
       fetchStub.restore();
@@ -354,7 +355,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
         "/api/uploads?source=panel&id=current#details",
       );
       assertEquals(reg.get().items, []);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       fetchStub.restore();
       restoreDom();
@@ -377,7 +378,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       assert(reg.get().removeError instanceof Error);
       flushSync(() => reg.get().clearRemoveError());
       assertEquals(reg.get().removeError, null);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
       await flush(() => {});
     } finally {
       fetchStub.restore();
@@ -385,7 +386,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
     }
   });
 
-  it("rejects malformed, oversized, and executable persisted registry data", () => {
+  it("rejects malformed, oversized, and executable persisted registry data", async () => {
     const restoreDom = installDom();
     const fetchStub = stubFetch();
     try {
@@ -400,13 +401,13 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       const invalid = mount("test-invalid-cache");
       assertEquals(invalid.get().items, []);
       assert(invalid.get().storageError instanceof Error);
-      flushSync(() => invalid.root.unmount());
+      await unmountReactRoot(invalid.root);
 
       localStorage.setItem("test-oversized-cache", `"${"x".repeat(1_100_000)}"`);
       const oversized = mount("test-oversized-cache");
       assertEquals(oversized.get().items, []);
       assert(oversized.get().storageError instanceof Error);
-      flushSync(() => oversized.root.unmount());
+      await unmountReactRoot(oversized.root);
 
       localStorage.setItem(
         "test-duplicate-cache",
@@ -418,7 +419,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       const duplicate = mount("test-duplicate-cache");
       assertEquals(duplicate.get().items, []);
       assert(duplicate.get().storageError instanceof Error);
-      flushSync(() => duplicate.root.unmount());
+      await unmountReactRoot(duplicate.root);
     } finally {
       fetchStub.restore();
       restoreDom();
@@ -469,7 +470,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       await flush(() => reg.get().upload([fakeFile("unsafe.html")]));
       assertEquals(reg.get().items.map((item) => item.id), ["cached"]);
       assert(reg.get().uploadError instanceof Error);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -502,7 +503,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
 
       assertEquals(reg.get().items.map((item) => item.id), ["cached"]);
       assert(reg.get().refreshError instanceof Error);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -546,7 +547,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
         "an ambiguous snapshot must not replace the validated cache",
       );
       assert(reg.get().refreshError instanceof Error);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -568,7 +569,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       await flush(() => {});
       assertEquals(reg.get().items, []);
       assert(reg.get().refreshError instanceof Error);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -610,7 +611,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       if (originalDescriptor) {
         Object.defineProperty(storagePrototype, "setItem", originalDescriptor);
       }
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       fetchStub.restore();
       restoreDom();
@@ -643,7 +644,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
         null,
         "the oversized payload must not be handed to localStorage",
       );
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       fetchStub.restore();
       restoreDom();
@@ -705,7 +706,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       assertEquals(reg.get().uploadError, null);
       assertEquals(reg.get().isUploading, false);
 
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -757,7 +758,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       await flush(() => {});
       assertEquals(reg.get().items.map((item) => item.name), ["current.txt"]);
 
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -792,7 +793,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       first.resolve(Response.json({ items: [{ id: "old", name: "old.txt" }] }));
       await flush(() => {});
       assertEquals(reg.get().items.map((item) => item.id), ["new"]);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -844,7 +845,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
         ["newest", "older"],
       );
       assertEquals(reg.get().refreshError, null);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -884,7 +885,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       ]);
       assertEquals(reg.get().items.map((item) => item.id), ["cached"]);
       assert(reg.get().refreshError instanceof Error);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
@@ -915,7 +916,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
         ),
         ["b"],
       );
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       fetchStub.restore();
       restoreDom();
@@ -945,7 +946,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       });
 
       assertEquals(reg.get().items.map((item) => item.id), ["b"]);
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
     } finally {
       fetchStub.restore();
       restoreDom();
@@ -979,7 +980,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
       assertEquals(pending.length, 3, "GET, DELETE, and POST are all pending");
 
       const retained = reg.get();
-      flushSync(() => reg.root.unmount());
+      await unmountReactRoot(reg.root);
       assert(
         pending.every((request) => request.signal?.aborted),
         "all operation signals are aborted during cleanup",
@@ -1077,7 +1078,7 @@ describe("react/components/chat/hooks/useUploadsRegistry", () => {
           </React.Suspense>,
         )
       );
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
     } finally {
       globalThis.fetch = previousFetch;
       restoreDom();
diff --git a/src/react/components/chat/csp-nonce.test.tsx b/src/react/components/chat/csp-nonce.test.tsx
index 3f1a01c3d9..6607f0ab08 100644
--- a/src/react/components/chat/csp-nonce.test.tsx
+++ b/src/react/components/chat/csp-nonce.test.tsx
@@ -2,6 +2,7 @@ import * as React from "react";
 import { hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert";
 import { describe, it } from "#veryfront/testing/bdd";
 import { Head } from "../Head.tsx";
@@ -102,7 +103,7 @@ async function hydrateAndReadStyleNonce(element: React.ReactElement): Promise<st
     assert(style, "Expected hydrated tree to contain an inline style tag");
 
     const nonce = style.getAttribute("nonce");
-    hydratedRoot.unmount();
+    await unmountReactRoot(hydratedRoot);
     await flushHydrationTimers();
     return nonce;
   } finally {
@@ -128,7 +129,7 @@ async function hydrateAndReadScriptNonce(element: React.ReactElement): Promise<s
     assert(script, "Expected hydrated tree to contain an inline script tag");
 
     const nonce = script.getAttribute("nonce");
-    hydratedRoot.unmount();
+    await unmountReactRoot(hydratedRoot);
     await flushHydrationTimers();
     return nonce;
   } finally {
@@ -159,7 +160,7 @@ async function hydrateAndReadManagedHeadStyleNonce(
     assert(style, "Expected Head to append a managed inline style tag");
 
     const nonce = style.getAttribute("nonce");
-    hydratedRoot.unmount();
+    await unmountReactRoot(hydratedRoot);
     await flushHydrationTimers();
     return nonce;
   } finally {
diff --git a/src/react/components/clipboard.test.tsx b/src/react/components/clipboard.test.tsx
index 3ffcb6beb8..f151286bf8 100644
--- a/src/react/components/clipboard.test.tsx
+++ b/src/react/components/clipboard.test.tsx
@@ -1,6 +1,7 @@
 import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStrictEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { type ClipboardFeedback, copyTextToClipboard, useClipboardFeedback } from "./clipboard.ts";
@@ -260,7 +261,7 @@ describe("useClipboardFeedback", () => {
       assertEquals(rootElement.textContent, "copied:second");
       assertEquals(fallbackCalls, 0);
 
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -291,7 +292,7 @@ describe("useClipboardFeedback", () => {
       assert(feedback, "hook result is available");
 
       const pendingCopy = feedback.copy("late", document);
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       release();
       assertStrictEquals(await pendingCopy, false);
       await settle();
diff --git a/src/react/components/ui/accordion.behaviour.test.tsx b/src/react/components/ui/accordion.behaviour.test.tsx
index 0b6e8179e7..0f1fef6422 100644
--- a/src/react/components/ui/accordion.behaviour.test.tsx
+++ b/src/react/components/ui/accordion.behaviour.test.tsx
@@ -10,6 +10,7 @@ import { flushSync } from "react-dom";
 import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { Accordion, AccordionContent, AccordionItem, AccordionTrigger } from "./accordion.tsx";
@@ -37,9 +38,9 @@ function render(el: React.ReactElement) {
   flushSync(() => root.render(el));
   return {
     host: host as unknown as HTMLElement,
-    unmount: () => {
+    unmount: async () => {
       try {
-        root.unmount();
+        await unmountReactRoot(root);
       } finally {
         restore();
       }
@@ -84,7 +85,7 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
     }
   });
 
-  it("single mode: opening one section closes the other", () => {
+  it("single mode: opening one section closes the other", async () => {
     const { host, unmount } = render(
       <Accordion type="single" collapsible>
         <AccordionItem value="a">
@@ -120,11 +121,11 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
       click(triggerB!);
       assert(bodyB.closest<HTMLElement>("[data-state]")?.hidden, "collapsible closes B");
     } finally {
-      unmount();
+      await unmount();
     }
   });
 
-  it("wraps triggers in headings and wires custom ids bidirectionally", () => {
+  it("wraps triggers in headings and wires custom ids bidirectionally", async () => {
     const { host, unmount } = render(
       <Accordion>
         <AccordionItem
@@ -146,7 +147,7 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
       assert(trigger.getAttribute("aria-controls") === content.id, "trigger controls region");
       assert(content.getAttribute("aria-labelledby") === trigger.id, "region names trigger");
     } finally {
-      unmount();
+      await unmount();
     }
   });
 
@@ -219,7 +220,7 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
     assert(label?.contains(trigger), "the SSR label contains the composed trigger text");
   });
 
-  it("does not notify controlled or uncontrolled consumers for a non-collapsible no-op", () => {
+  it("does not notify controlled or uncontrolled consumers for a non-collapsible no-op", async () => {
     for (const controlled of [false, true]) {
       const values: string[] = [];
       const item = (
@@ -248,7 +249,7 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
           "the open item stays open",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     }
   });
@@ -297,13 +298,13 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
         "hydrated content names trigger",
       );
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       await new Promise((resolve) => setTimeout(resolve, 0));
       restore();
     }
   });
 
-  it("normalizes retained uncontrolled values when mode changes", () => {
+  it("normalizes retained uncontrolled values when mode changes", async () => {
     function Probe(): React.ReactElement {
       const [multiple, setMultiple] = React.useState(true);
       const items = (
@@ -334,7 +335,7 @@ describe("Accordion: disclosure-slot behaviour (builtin)", () => {
       assert(triggers[0]?.getAttribute("aria-expanded") === "true", "first value remains open");
       assert(triggers[1]?.getAttribute("aria-expanded") === "false", "extra value closes");
     } finally {
-      unmount();
+      await unmount();
     }
   });
 });
diff --git a/src/react/components/ui/adapter/disclosure.conformance.test.tsx b/src/react/components/ui/adapter/disclosure.conformance.test.tsx
index a4025c5abd..6637a0874a 100644
--- a/src/react/components/ui/adapter/disclosure.conformance.test.tsx
+++ b/src/react/components/ui/adapter/disclosure.conformance.test.tsx
@@ -13,6 +13,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { UIAdapterProvider } from "./context.tsx";
@@ -36,7 +37,9 @@ function installDom(dom: JSDOM): () => void {
   };
 }
 
-function render(element: React.ReactElement): { host: HTMLElement; unmount: () => void } {
+function render(
+  element: React.ReactElement,
+): { host: HTMLElement; unmount: () => Promise<void> } {
   const dom = new JSDOM(`<!doctype html><html><body><div id="root"></div></body></html>`);
   const restore = installDom(dom);
   const host = dom.window.document.getElementById("root")!;
@@ -44,9 +47,9 @@ function render(element: React.ReactElement): { host: HTMLElement; unmount: () =
   flushSync(() => root.render(element));
   return {
     host: host as unknown as HTMLElement,
-    unmount: () => {
+    unmount: async () => {
       try {
-        root.unmount();
+        await unmountReactRoot(root);
       } finally {
         restore();
       }
@@ -107,7 +110,7 @@ function runDisclosureConformance(
       assert(content.getAttribute("aria-labelledby") === null, "SSR emits no dangling label id");
     });
 
-    it("starts closed, toggles content + aria-expanded on trigger click", () => {
+    it("starts closed, toggles content + aria-expanded on trigger click", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureProbe />
@@ -131,11 +134,11 @@ function runDisclosureConformance(
         assert(trigger.getAttribute("aria-expanded") === "false", "collapsed after second click");
         assert(content.hidden, "content hidden after collapse");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("honours disabled state and a consumer-cancelled trigger event", () => {
+    it("honours disabled state and a consumer-cancelled trigger event", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureProbe disabled preventToggle />
@@ -146,7 +149,7 @@ function runDisclosureConformance(
         click(trigger);
         assert(trigger.getAttribute("aria-expanded") === "false", "disabled trigger stays closed");
       } finally {
-        unmount();
+        await unmount();
       }
 
       const second = render(
@@ -162,11 +165,11 @@ function runDisclosureConformance(
           "preventDefault cancels the internal toggle",
         );
       } finally {
-        second.unmount();
+        await second.unmount();
       }
     });
 
-    it("prevents disabled asChild link navigation", () => {
+    it("prevents disabled asChild link navigation", async () => {
       let disabledWrapperClickCount = 0;
       let disabledChildClickCount = 0;
       let disabledWrapperAuxClickCount = 0;
@@ -209,11 +212,11 @@ function runDisclosureConformance(
           "disabled composed trigger skips its child auxiliary handler",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("keeps realized trigger and content ids wired in both directions", () => {
+    it("keeps realized trigger and content ids wired in both directions", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureCustomIdProbe />
@@ -228,11 +231,11 @@ function runDisclosureConformance(
           "region names trigger",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("preserves ids declared directly on public Collapsible parts", () => {
+    it("preserves ids declared directly on public Collapsible parts", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosurePartIdProbe />
@@ -252,11 +255,11 @@ function runDisclosureConformance(
           "declared content is named by declared trigger",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("preserves an id declared on a composed trigger child", () => {
+    it("preserves an id declared on a composed trigger child", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureComposedIdProbe />
@@ -271,11 +274,11 @@ function runDisclosureConformance(
           "content is named by the composed trigger",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("preserves ids declared by opaque public-part wrappers", () => {
+    it("preserves ids declared by opaque public-part wrappers", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureWrappedPartIdProbe />
@@ -295,11 +298,11 @@ function runDisclosureConformance(
           "wrapped content is named by the realized trigger id",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("preserves a composed child id declared by an opaque trigger wrapper", () => {
+    it("preserves a composed child id declared by an opaque trigger wrapper", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureWrappedComposedIdProbe />
@@ -309,11 +312,11 @@ function runDisclosureConformance(
         const trigger = host.querySelector("a")!;
         assert(trigger.id === "wrapped-composed-trigger", "keeps the wrapped child id");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("supports several distinct triggers for one collapsible region", () => {
+    it("supports several distinct triggers for one collapsible region", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureMultipleTriggerProbe />
@@ -334,11 +337,11 @@ function runDisclosureConformance(
           "the region is named by every trigger in DOM order",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("generates unique ids for several id-less triggers", () => {
+    it("generates unique ids for several id-less triggers", async () => {
       const { host, unmount } = render(
         <Wrap>
           <DisclosureGeneratedMultipleTriggerProbe />
@@ -357,11 +360,11 @@ function runDisclosureConformance(
           "the region references both generated trigger ids",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("preserves an Accordion asChild trigger id and its region relationship", () => {
+    it("preserves an Accordion asChild trigger id and its region relationship", async () => {
       const { host, unmount } = render(
         <Wrap>
           <Accordion>
@@ -387,7 +390,7 @@ function runDisclosureConformance(
           "the item region references the composed child id",
         );
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
diff --git a/src/react/components/ui/adapter/toast.conformance.test.tsx b/src/react/components/ui/adapter/toast.conformance.test.tsx
index eacca2971e..cf96c960c2 100644
--- a/src/react/components/ui/adapter/toast.conformance.test.tsx
+++ b/src/react/components/ui/adapter/toast.conformance.test.tsx
@@ -16,6 +16,7 @@ import { createPortal, flushSync } from "react-dom";
 import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertThrows } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { ToastProvider, ToastViewport, useToast } from "../toast.tsx";
@@ -94,10 +95,13 @@ export function runToastConformance(
     return {
       dom,
       text: () => document.body.textContent ?? "",
-      cleanup: () => {
-        root.unmount();
-        restore();
-        api = null;
+      cleanup: async () => {
+        try {
+          await unmountReactRoot(root);
+        } finally {
+          restore();
+          api = null;
+        }
       },
     };
   }
@@ -112,7 +116,7 @@ export function runToastConformance(
         flushSync(() => api!.dismiss(id));
         await waitFor(() => !h.text().includes("Saved"));
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
@@ -125,7 +129,7 @@ export function runToastConformance(
         assert(item.textContent?.includes("0") === true, "renders a numeric zero title");
         assert(item.querySelector("p"), "retains an empty-string description node");
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
@@ -148,7 +152,7 @@ export function runToastConformance(
         assert(ran, "action onClick fired");
         await waitFor(() => !h.text().includes("Undo"));
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
@@ -159,7 +163,7 @@ export function runToastConformance(
         await waitFor(() => h.text().includes("custom "));
         assert(h.text().includes("custom "), "custom node rendered");
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
@@ -175,7 +179,7 @@ export function runToastConformance(
         assert(!h.text().includes("First"), "oldest toast was evicted");
         assert(h.text().includes("Second") && h.text().includes("Third"), "newest toasts remain");
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
@@ -199,7 +203,7 @@ export function runToastConformance(
         assert(h.text().includes("Persistent override"), "per-toast duration overrides provider");
         flushSync(() => api!.dismiss(persistentId));
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
@@ -213,11 +217,11 @@ export function runToastConformance(
           "active adapter realizes the manual viewport",
         );
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
 
-    it("shares public provider and per-call validation across adapters", () => {
+    it("shares public provider and per-call validation across adapters", async () => {
       assertThrows(
         () =>
           renderToString(
@@ -238,7 +242,7 @@ export function runToastConformance(
           "2147483647",
         );
       } finally {
-        h.cleanup();
+        await h.cleanup();
       }
     });
   });
@@ -275,7 +279,7 @@ describe("Toast presentational parts", () => {
 });
 
 describe("Builtin Toast viewport and timer lifecycle", () => {
-  it("renders zero and empty-string structured content", () => {
+  it("renders zero and empty-string structured content", async () => {
     const dom = new JSDOM('<!doctype html><html><body><div id="root"></div></body></html>');
     const restore = installDomGlobals(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -303,7 +307,7 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
       assert(body.children[0]!.textContent === "0", "renders a numeric zero title");
       assert(body.children[1]!.textContent === "", "renders an empty-string description");
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -334,15 +338,14 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
         document.body.querySelectorAll('[aria-label="Notifications"]').length === 1
       );
       assert(recoverableErrors.length === 0, "hydration reports no recoverable errors");
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       unmounted = true;
       assert(
         document.body.querySelectorAll('[aria-label="Notifications"]').length === 0,
         "portal viewport is removed on unmount",
       );
     } finally {
-      if (!unmounted) flushSync(() => root.unmount());
-      await new Promise((resolve) => setTimeout(resolve, 0));
+      if (!unmounted) await unmountReactRoot(root);
       restore();
     }
   });
@@ -376,7 +379,7 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
         "shell document is untouched",
       );
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
       foreignDom.window.close();
     }
@@ -396,7 +399,7 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
       );
       assert(document.querySelectorAll('[aria-label="Notifications"]').length === 1, "one owner");
       assert(document.querySelector("[data-manual]"), "manual viewport is realized");
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -453,7 +456,7 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
       document.dispatchEvent(new dom.window.Event("visibilitychange"));
       await waitFor(() => !document.body.textContent?.includes("Paused"));
     } finally {
-      root.unmount();
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -491,7 +494,7 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
       action.blur();
       await waitFor(() => !document.body.textContent?.includes("Focused"));
     } finally {
-      root.unmount();
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -551,7 +554,7 @@ describe("Builtin Toast viewport and timer lifecycle", () => {
       flushSync(() => item.dispatchEvent(new dom.window.MouseEvent("mouseout", { bubbles: true })));
       await waitFor(() => !document.body.contains(item));
     } finally {
-      root.unmount();
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -744,7 +747,7 @@ const altToastWithAdditionalState: ToastParts = {
 };
 
 describe("Toast adapter switching", () => {
-  it("remounts the adapter hook bridge when hook implementations differ", () => {
+  it("remounts the adapter hook bridge when hook implementations differ", async () => {
     const dom = new JSDOM('<!doctype html><html><body><div id="root"></div></body></html>');
     const restore = installDomGlobals(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -780,7 +783,7 @@ describe("Toast adapter switching", () => {
       flushSync(() => button.click());
       assert(api, "replacement adapter state is available");
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
diff --git a/src/react/components/ui/adapter/toggle-group.conformance.test.tsx b/src/react/components/ui/adapter/toggle-group.conformance.test.tsx
index 4320ae6fa7..d432e58275 100644
--- a/src/react/components/ui/adapter/toggle-group.conformance.test.tsx
+++ b/src/react/components/ui/adapter/toggle-group.conformance.test.tsx
@@ -10,6 +10,7 @@ import * as React from "react";
 import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { ToggleGroup, ToggleGroupItem } from "../toggle-group.tsx";
@@ -32,7 +33,9 @@ function installDom(dom: JSDOM): () => void {
   };
 }
 
-function render(element: React.ReactElement): { host: HTMLElement; unmount: () => void } {
+function render(
+  element: React.ReactElement,
+): { host: HTMLElement; unmount: () => Promise<void> } {
   const dom = new JSDOM(`<!doctype html><html><body><div id="root"></div></body></html>`);
   const restore = installDom(dom);
   const host = dom.window.document.getElementById("root")!;
@@ -40,9 +43,9 @@ function render(element: React.ReactElement): { host: HTMLElement; unmount: () =
   flushSync(() => root.render(element));
   return {
     host: host as unknown as HTMLElement,
-    unmount: () => {
+    unmount: async () => {
       try {
-        root.unmount();
+        await unmountReactRoot(root);
       } finally {
         restore();
       }
@@ -62,7 +65,7 @@ function runToggleGroupConformance(
   Wrap: React.FC<{ children: React.ReactNode }>,
 ): void {
   describe(`ToggleGroup adapter conformance: ${label}`, () => {
-    it("single-select: click sets aria-pressed/data-state; click again clears", () => {
+    it("single-select: click sets aria-pressed/data-state; click again clears", async () => {
       const { host, unmount } = render(
         <Wrap>
           <ToggleGroup type="single">
@@ -88,11 +91,11 @@ function runToggleGroupConformance(
         click(b!);
         assert(b!.getAttribute("aria-pressed") === "false", "click selected again clears it");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("blocks native, composed-link, and consumer-cancelled toggles", () => {
+    it("blocks native, composed-link, and consumer-cancelled toggles", async () => {
       let disabledWrapperClickCount = 0;
       let disabledChildClickCount = 0;
       let disabledWrapperAuxClickCount = 0;
@@ -167,11 +170,11 @@ function runToggleGroupConformance(
         );
         assert(cancelled.getAttribute("aria-pressed") === "false", "cancelled item stays off");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("normalizes retained uncontrolled state when selection mode changes", () => {
+    it("normalizes retained uncontrolled state when selection mode changes", async () => {
       function Probe(): React.ReactElement {
         const [multiple, setMultiple] = React.useState(true);
         return (
@@ -200,7 +203,7 @@ function runToggleGroupConformance(
         assert(items[0]?.dataset.state === "on", "first retained selection remains");
         assert(items[1]?.dataset.state === "off", "single mode drops extra retained selections");
       } finally {
-        unmount();
+        await unmount();
       }
     });
   });
diff --git a/src/react/components/ui/adapter/toolbar.conformance.test.tsx b/src/react/components/ui/adapter/toolbar.conformance.test.tsx
index 3121d84180..4de3d809e4 100644
--- a/src/react/components/ui/adapter/toolbar.conformance.test.tsx
+++ b/src/react/components/ui/adapter/toolbar.conformance.test.tsx
@@ -12,6 +12,7 @@ import { flushSync } from "react-dom";
 import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { Toolbar, ToolbarButton, ToolbarLink, ToolbarSeparator } from "../toolbar.tsx";
@@ -43,7 +44,9 @@ function installDom(dom: JSDOM): () => void {
   };
 }
 
-function render(element: React.ReactElement): { host: HTMLElement; unmount: () => void } {
+function render(
+  element: React.ReactElement,
+): { host: HTMLElement; unmount: () => Promise<void> } {
   const dom = new JSDOM(`<!doctype html><html><body><div id="root"></div></body></html>`);
   const restore = installDom(dom);
   const host = dom.window.document.getElementById("root")!;
@@ -51,9 +54,9 @@ function render(element: React.ReactElement): { host: HTMLElement; unmount: () =
   flushSync(() => root.render(element));
   return {
     host: host as unknown as HTMLElement,
-    unmount: () => {
+    unmount: async () => {
       try {
-        root.unmount();
+        await unmountReactRoot(root);
       } finally {
         restore();
       }
@@ -126,7 +129,7 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
       assert(document.querySelector<HTMLElement>("[data-toolbar-item]")!.tabIndex === -1);
     });
 
-    it("renders role=toolbar with one roving tab stop; items click", () => {
+    it("renders role=toolbar with one roving tab stop; items click", async () => {
       let clicked = false;
       const { host, unmount } = render(
         <Wrap>
@@ -148,11 +151,11 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         click(items[0]!);
         assert(clicked, "item click fires");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("moves focus with arrows and preserves the focused stop across rerenders", () => {
+    it("moves focus with arrows and preserves the focused stop across rerenders", async () => {
       function Probe(): React.ReactElement {
         const [renders, setRenders] = React.useState(0);
         return (
@@ -177,11 +180,11 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         assert(bar.dataset.renders === "1", "parent rerender occurred");
         assert(second!.tabIndex === 0 && first!.tabIndex === -1, "focused stop survives rerender");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("skips disabled items and honors a consumer-cancelled navigation event", () => {
+    it("skips disabled items and honors a consumer-cancelled navigation event", async () => {
       let cancel = true;
       const { host, unmount } = render(
         <Wrap>
@@ -205,11 +208,11 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         assert(document.activeElement === last, "navigation skips disabled item");
         assert(disabled!.tabIndex === -1, "disabled item is never the resting stop");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("blocks and skips a disabled toolbar link", () => {
+    it("blocks and skips a disabled toolbar link", async () => {
       const linkActivations: string[] = [];
       const { host, unmount } = render(
         <Wrap>
@@ -259,11 +262,11 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         keydown(bar, "ArrowRight");
         assert(document.activeElement === last, "roving focus skips the disabled link");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("moves focus when the active item becomes disabled", () => {
+    it("moves focus when the active item becomes disabled", async () => {
       let disableActive!: () => void;
       function Probe(): React.ReactElement {
         const [disabled, setDisabled] = React.useState(false);
@@ -290,11 +293,11 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         assert(second!.tabIndex === 0, "next enabled item becomes the roving stop");
         assert(document.activeElement === second, "focus follows the enabled fallback");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("updates the resting stop on focus and isolates nested, hidden, inert, and editable content", () => {
+    it("updates the resting stop on focus and isolates nested, hidden, inert, and editable content", async () => {
       const { host, unmount } = render(
         <Wrap>
           <Toolbar>
@@ -333,11 +336,11 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         assert(document.activeElement === nestedItems[1], "nested toolbar owns its event");
         assert(direct[2]!.tabIndex !== 0 && direct[3]!.tabIndex !== 0, "hidden and inert excluded");
       } finally {
-        unmount();
+        await unmount();
       }
     });
 
-    it("uses visual arrow direction in RTL and runs React 19 callback-ref cleanup", () => {
+    it("uses visual arrow direction in RTL and runs React 19 callback-ref cleanup", async () => {
       let firstCleanups = 0;
       let secondCleanups = 0;
       function Probe(): React.ReactElement {
@@ -358,14 +361,19 @@ function runToolbarConformance(label: string, Wrap: React.FC<{ children: React.R
         );
       }
       const { host, unmount } = render(<Probe />);
-      const bar = host.querySelector<HTMLElement>('[role="toolbar"]')!;
-      const [first, second] = Array.from(host.querySelectorAll<HTMLElement>("[data-toolbar-item]"));
-      first!.focus();
-      keydown(bar, "ArrowLeft");
-      assert(second === document.activeElement, "ArrowLeft moves forward in RTL");
-      click(second!);
-      assert(firstCleanups === 1, "old callback ref cleanup runs when the ref changes");
-      unmount();
+      try {
+        const bar = host.querySelector<HTMLElement>('[role="toolbar"]')!;
+        const [first, second] = Array.from(
+          host.querySelectorAll<HTMLElement>("[data-toolbar-item]"),
+        );
+        first!.focus();
+        keydown(bar, "ArrowLeft");
+        assert(second === document.activeElement, "ArrowLeft moves forward in RTL");
+        click(second!);
+        assert(firstCleanups === 1, "old callback ref cleanup runs when the ref changes");
+      } finally {
+        await unmount();
+      }
       assert(secondCleanups === 1, "current callback ref cleanup runs on unmount");
     });
   });
@@ -415,8 +423,7 @@ describe("Builtin Toolbar SSR ownership", () => {
       assert(items[0]?.tabIndex === 0, "first enabled item owns the hydrated tab stop");
       assert(items.slice(1).every((item) => item.tabIndex === -1), "other items remain untabbable");
     } finally {
-      flushSync(() => reactRoot.unmount());
-      await new Promise((resolve) => setTimeout(resolve, 0));
+      await unmountReactRoot(reactRoot);
       restore();
     }
   });
diff --git a/src/react/components/ui/app-shell.test.tsx b/src/react/components/ui/app-shell.test.tsx
index aa1743f67c..fd3dc0d811 100644
--- a/src/react/components/ui/app-shell.test.tsx
+++ b/src/react/components/ui/app-shell.test.tsx
@@ -1,8 +1,9 @@
 import * as React from "react";
 import { flushSync } from "react-dom";
-import { createRoot, hydrateRoot } from "react-dom/client";
+import { createRoot, hydrateRoot, type Root } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { AppShell } from "./app-shell.tsx";
@@ -109,20 +110,19 @@ describe("AppShell", () => {
     dom.window.localStorage.setItem("shell-left", "false");
     const restore = installDom(dom);
     const recoverableErrors: unknown[] = [];
+    let root: Root | undefined;
 
     try {
       const rootElement = document.getElementById("root");
       assert(rootElement);
-      const root = hydrateRoot(rootElement, <Shell />, {
+      root = hydrateRoot(rootElement, <Shell />, {
         onRecoverableError: (error) => recoverableErrors.push(error),
       });
 
       await waitFor(() => document.querySelector("[data-sidebar='left']") === null);
       assertEquals(recoverableErrors, []);
-
-      root.unmount();
-      await new Promise((resolve) => setTimeout(resolve, 0));
     } finally {
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -162,7 +162,7 @@ describe("AppShell", () => {
       await waitFor(() => document.querySelectorAll('[role="dialog"]').length === 2);
       assertEquals(document.body.style.overflow, "hidden");
 
-      flushSync(() => rootA?.unmount());
+      await unmountReactRoot(rootA);
       rootA = undefined;
       assertEquals(document.querySelectorAll('[role="dialog"]').length, 1);
       assertEquals(
@@ -171,7 +171,7 @@ describe("AppShell", () => {
         "the remaining overlay still owns the document lock",
       );
 
-      flushSync(() => rootB?.unmount());
+      await unmountReactRoot(rootB);
       rootB = undefined;
       assertEquals(
         document.body.style.overflow,
@@ -179,8 +179,8 @@ describe("AppShell", () => {
         "the final release restores the exact pre-lock value",
       );
     } finally {
-      if (rootA) flushSync(() => rootA?.unmount());
-      if (rootB) flushSync(() => rootB?.unmount());
+      if (rootA) await unmountReactRoot(rootA);
+      if (rootB) await unmountReactRoot(rootB);
       restore();
     }
   });
@@ -235,7 +235,7 @@ describe("AppShell", () => {
       assertEquals(documentShortcut.defaultPrevented, true);
       assertEquals(document.querySelector('[data-sidebar="left"]'), null);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -304,7 +304,7 @@ describe("AppShell", () => {
       assertEquals(shell.getAttribute("data-vf-ui"), "");
       assertEquals(shell.getAttribute("data-vf-chat"), "");
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
diff --git a/src/react/components/ui/color-mode.test.tsx b/src/react/components/ui/color-mode.test.tsx
index f413be3417..9ba5eaed58 100644
--- a/src/react/components/ui/color-mode.test.tsx
+++ b/src/react/components/ui/color-mode.test.tsx
@@ -1,8 +1,9 @@
 import * as React from "react";
 import { flushSync } from "react-dom";
-import { createRoot, hydrateRoot, type Root } from "react-dom/client";
+import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { ColorModeProvider, ColorModeScript, useColorMode } from "./color-mode.tsx";
@@ -116,18 +117,6 @@ function readSingleInlineScript(markup: string): string {
   }
 }
 
-/**
- * Unmount and drain the scheduler task React leaves behind.
- *
- * React's scheduler holds a `setImmediate` until it next runs. It completes on
- * its own, but the test has to yield once more or Deno's leak sanitizer sees
- * the timer still pending.
- */
-async function unmount(root: Root): Promise<void> {
-  flushSync(() => root.unmount());
-  await new Promise((resolve) => setTimeout(resolve, 0));
-}
-
 describe("react/components/ui/color-mode", () => {
   it("escapes storage keys before embedding them in the inline color-mode script", () => {
     const storageKey = `vf";</script><script>alert(1)</script>//`;
@@ -176,7 +165,7 @@ describe("react/components/ui/color-mode", () => {
       await waitFor(() => document.documentElement.classList.contains("light"));
       assertEquals(document.documentElement.style.colorScheme, "light");
 
-      await unmount(root);
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -211,7 +200,7 @@ describe("react/components/ui/color-mode", () => {
       assertEquals(document.querySelector("button")?.getAttribute("data-mode"), "dark");
       assertEquals(document.documentElement.style.colorScheme, "dark");
 
-      await unmount(root);
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -240,9 +229,11 @@ describe("react/components/ui/color-mode", () => {
       });
 
       await waitFor(() => document.querySelector("button")?.getAttribute("data-mode") === "dark");
-      assertEquals(document.documentElement.style.colorScheme, "dark");
+      // The rendered mode and the colorScheme the provider writes to the root
+      // element land in separate commits, so wait for the second one too.
+      await waitFor(() => document.documentElement.style.colorScheme === "dark");
 
-      await unmount(root);
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -280,7 +271,7 @@ describe("react/components/ui/color-mode", () => {
       await waitFor(() => document.querySelector("button")?.getAttribute("data-mode") === "dark");
       assertEquals(recoverableErrors, []);
 
-      await unmount(root);
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
diff --git a/src/react/components/ui/floating.test.tsx b/src/react/components/ui/floating.test.tsx
index e429fc19e2..ef145543ea 100644
--- a/src/react/components/ui/floating.test.tsx
+++ b/src/react/components/ui/floating.test.tsx
@@ -1,8 +1,9 @@
 import * as React from "react";
 import { flushSync } from "react-dom";
-import { createRoot, hydrateRoot, type Root } from "react-dom/client";
+import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertStringIncludes } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { DropdownMenu, DropdownMenuContent, DropdownMenuTrigger } from "./dropdown-menu.tsx";
@@ -101,15 +102,16 @@ const surfaceCases: SurfaceCase[] = [
 ];
 
 /**
- * Unmount and drain the scheduler task React leaves behind.
+ * Wait for the Escape dismissal layer to be registered.
  *
- * React's scheduler holds a `setImmediate` until it next runs. It completes on
- * its own, but the test has to yield once more or Deno's leak sanitizer sees
- * the timer still pending.
+ * `Floating` registers its dismissable layer from a passive effect, so the
+ * surface is committed one tick before the document listener exists. A keydown
+ * is one-shot, so an Escape dispatched in that window is dropped for good and
+ * the surface never closes. Yield the macrotask React's scheduler queued at
+ * commit time first.
  */
-async function unmount(root: Root): Promise<void> {
-  flushSync(() => root.unmount());
-  await new Promise((resolve) => setTimeout(resolve, 0));
+function escapeLayerRegistered(): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, 0));
 }
 
 describe("Floating SSR and hydration", () => {
@@ -157,13 +159,13 @@ describe("Floating SSR and hydration", () => {
         );
         assertEquals(recoverableErrors, []);
 
-        await unmount(root);
+        await unmountReactRoot(root);
         root = undefined;
         await waitFor(() =>
           document.querySelector(`[data-floating-surface="${surfaceId}"]`) === null
         );
       } finally {
-        if (root) await unmount(root);
+        if (root) await unmountReactRoot(root);
         restore();
       }
     });
@@ -206,7 +208,7 @@ describe("Floating SSR and hydration", () => {
       assertEquals(rootElement.contains(surface), false);
       assertEquals(recoverableErrors, []);
     } finally {
-      if (root) await unmount(root);
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -280,6 +282,7 @@ describe("Floating SSR and hydration", () => {
 
       inside.focus();
       assertEquals(document.activeElement, inside);
+      await escapeLayerRegistered();
       document.dispatchEvent(
         new KeyboardEvent("keydown", {
           bubbles: true,
@@ -290,7 +293,7 @@ describe("Floating SSR and hydration", () => {
       await waitFor(() => document.querySelector('[data-floating-surface="geometry"]') === null);
       await waitFor(() => document.activeElement === trigger);
     } finally {
-      if (root) await unmount(root);
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -365,7 +368,7 @@ describe("Floating SSR and hydration", () => {
       );
       assert(document.querySelector("[data-reanchored-surface]"));
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -419,6 +422,7 @@ describe("Floating SSR and hydration", () => {
       assertEquals(surface.parentElement, scope);
       assertEquals(globalDom.window.document.querySelector("[data-owner-surface]"), null);
 
+      await escapeLayerRegistered();
       ownerDom.window.document.dispatchEvent(
         new ownerDom.window.KeyboardEvent("keydown", {
           bubbles: true,
@@ -429,7 +433,7 @@ describe("Floating SSR and hydration", () => {
       await waitFor(() => ownerDom.window.document.querySelector("[data-owner-surface]") === null);
       assertEquals(reasons, ["escape"]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
       ownerDom.window.close();
     }
diff --git a/src/react/components/ui/focus-management.test.ts b/src/react/components/ui/focus-management.test.ts
index 581f4e3c0c..2b13c0b815 100644
--- a/src/react/components/ui/focus-management.test.ts
+++ b/src/react/components/ui/focus-management.test.ts
@@ -25,7 +25,7 @@ describe("focus management", () => {
     }
   });
 
-  it("falls back to the container when a reported candidate cannot receive focus", () => {
+  it("falls back to the container when a reported candidate cannot receive focus", async () => {
     const dom = new JSDOM(
       '<!doctype html><body><button id="outside">Outside</button><div id="panel" tabindex="-1"><button id="broken">Broken</button></div></body>',
       { pretendToBeVisual: true },
@@ -41,6 +41,10 @@ describe("focus management", () => {
       focusFirst(panel);
 
       assertEquals(document.activeElement, panel);
+      // Moving focus collapses the selection, and jsdom fires the resulting
+      // `selectionchange` from a 0ms timer the way a browser does. Yield once so
+      // it completes before Deno's leak sanitizer inspects the test.
+      await new Promise((resolve) => setTimeout(resolve, 0));
     } finally {
       dom.window.close();
     }
diff --git a/src/react/components/ui/list.test.tsx b/src/react/components/ui/list.test.tsx
index 6c7821e14b..439dc68d19 100644
--- a/src/react/components/ui/list.test.tsx
+++ b/src/react/components/ui/list.test.tsx
@@ -3,6 +3,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { ListItem } from "./list.tsx";
@@ -103,7 +104,7 @@ describe("ListItem", () => {
     }
   });
 
-  it("activates on Enter and Space with native-button timing", () => {
+  it("activates on Enter and Space with native-button timing", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -148,12 +149,12 @@ describe("ListItem", () => {
       assertEquals(keyDownCalls, 2);
       assertEquals(keyUpCalls, 1);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("lets caller handlers cancel synthesized activation", () => {
+  it("lets caller handlers cancel synthesized activation", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -184,12 +185,12 @@ describe("ListItem", () => {
       flushSync(() => item.dispatchEvent(keyboardEvent("keyup", " ")));
       assertEquals(activations, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("renders primary and trailing actions as independently accessible controls", () => {
+  it("renders primary and trailing actions as independently accessible controls", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -260,13 +261,13 @@ describe("ListItem", () => {
       assertEquals(legacyRowClicks, 0);
       assertEquals(activationCurrentTarget, primaryAction);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       assertEquals(primaryActionRef.current, null);
       restore();
     }
   });
 
-  it("delegates the non-action row surface to its native primary action", () => {
+  it("delegates the non-action row surface to its native primary action", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -306,12 +307,12 @@ describe("ListItem", () => {
       assertEquals(primaryActivations, 1);
       assertEquals(actionActivations, 1);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("does not fall through to legacy onClick after synchronous primary removal", () => {
+  it("does not fall through to legacy onClick after synchronous primary removal", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -345,12 +346,12 @@ describe("ListItem", () => {
       assertEquals(primaryActivations, 1);
       assertEquals(legacyRowClicks, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("retains primary-action provenance without Event.composedPath", () => {
+  it("retains primary-action provenance without Event.composedPath", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const composedPathDescriptor = Object.getOwnPropertyDescriptor(
@@ -386,7 +387,7 @@ describe("ListItem", () => {
       assertEquals(primaryActivations, 1);
       assertEquals(legacyRowClicks, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       if (composedPathDescriptor) {
         Object.defineProperty(
           dom.window.Event.prototype,
@@ -401,7 +402,7 @@ describe("ListItem", () => {
     }
   });
 
-  it("preserves React 19 callback-ref cleanup for the primary action", () => {
+  it("preserves React 19 callback-ref cleanup for the primary action", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     let root: ReturnType<typeof createRoot> | undefined;
@@ -433,13 +434,13 @@ describe("ListItem", () => {
       assert(renderedPrimaryAction);
       assertEquals(primaryAction, renderedPrimaryAction);
 
-      flushSync(() => root?.unmount());
+      await unmountReactRoot(root);
       root = undefined;
       assertEquals(primaryAction, null);
       assertEquals(cleanupCalls, 1);
       assertEquals(nullCalls, 0);
     } finally {
-      if (root) flushSync(() => root?.unmount());
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -468,7 +469,7 @@ describe("ListItem", () => {
     }
   });
 
-  it("cancels a pending Space activation when focus leaves the row", () => {
+  it("cancels a pending Space activation when focus leaves the row", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -494,12 +495,12 @@ describe("ListItem", () => {
       flushSync(() => item.dispatchEvent(keyboardEvent("keyup", " ")));
       assertEquals(activations, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("does not re-arm Space when the caller moves focus during keydown", () => {
+  it("does not re-arm Space when the caller moves focus during keydown", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -527,12 +528,12 @@ describe("ListItem", () => {
       flushSync(() => item.dispatchEvent(keyboardEvent("keyup", " ")));
       assertEquals(activations, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("does not synthesize activation while an IME composition is active", () => {
+  it("does not synthesize activation while an IME composition is active", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -559,12 +560,12 @@ describe("ListItem", () => {
       assertEquals(composingEnter.defaultPrevented, false);
       assertEquals(activations, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("forwards refs without replacing structural active state", () => {
+  it("forwards refs without replacing structural active state", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     const root = createRoot(document.getElementById("root")!);
@@ -595,7 +596,7 @@ describe("ListItem", () => {
       });
       assertEquals(itemRef.current.getAttribute("data-active"), null);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       assertEquals(itemRef.current, null);
       restore();
     }
diff --git a/src/react/components/ui/select.test.tsx b/src/react/components/ui/select.test.tsx
index 7021e110fa..1e9942abbc 100644
--- a/src/react/components/ui/select.test.tsx
+++ b/src/react/components/ui/select.test.tsx
@@ -1,8 +1,9 @@
 import type * as React from "react";
 import { flushSync } from "react-dom";
-import { createRoot, hydrateRoot, type Root } from "react-dom/client";
+import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals, assertThrows } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import {
@@ -109,18 +110,6 @@ function selectedText(trigger: HTMLElement): string | undefined {
   return activeId ? trigger.ownerDocument.getElementById(activeId)?.textContent?.trim() : undefined;
 }
 
-/**
- * Unmount and drain the scheduler task React leaves behind.
- *
- * React's scheduler holds a `setImmediate` until it next runs. It completes on
- * its own, but the test has to yield once more or Deno's leak sanitizer sees
- * the timer still pending.
- */
-async function unmount(root: Root): Promise<void> {
-  flushSync(() => root.unmount());
-  await new Promise((resolve) => setTimeout(resolve, 0));
-}
-
 describe("Select", () => {
   it("links the combobox and listbox and supports the complete keyboard lifecycle", async () => {
     const dom = createDom();
@@ -201,7 +190,7 @@ describe("Select", () => {
       assertEquals(trigger.hasAttribute("aria-activedescendant"), false);
       assertEquals(trigger.textContent?.includes("Gamma"), true);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -337,7 +326,7 @@ describe("Select", () => {
       assertEquals(calls, ["cancel-trigger", "cancel-key", "cancel-item"]);
       assertEquals(trigger.getAttribute("aria-expanded"), "true");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -400,7 +389,7 @@ describe("Select", () => {
       assertEquals(values, ["beta"]);
       assertEquals(document.activeElement, trigger);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -467,7 +456,7 @@ describe("Select", () => {
       assertEquals(trigger.getAttribute("aria-expanded"), "false");
       assertEquals(openChanges, [true, false, true, false]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -528,7 +517,7 @@ describe("Select", () => {
         "controlled owner re-enables its still-open value",
       );
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -576,7 +565,7 @@ describe("Select", () => {
       assertEquals(trigger.getAttribute("aria-expanded"), "false");
       assertEquals(document.getElementById("root-transition-list"), null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -645,7 +634,7 @@ describe("Select", () => {
       );
       assertEquals(openChanges, [false, true]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -702,7 +691,7 @@ describe("Select", () => {
       press(trigger, "Home");
       await waitFor(() => selectedText(trigger) === "Gamma", "reordered first option");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -762,7 +751,7 @@ describe("Select", () => {
       );
     } finally {
       nodePrototype.compareDocumentPosition = compareDocumentPosition;
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -839,7 +828,7 @@ describe("Select", () => {
       assertEquals(document.activeElement, outside);
       outside.remove();
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -875,7 +864,7 @@ describe("Select", () => {
       await waitFor(() => trigger.getAttribute("aria-expanded") === "false", "blur close");
       assertEquals(document.activeElement, outside);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       outside.remove();
       restore();
     }
@@ -934,7 +923,7 @@ describe("Select", () => {
       assertEquals(listbox.getAttribute("aria-labelledby"), "hydrated-trigger");
       assertEquals(group.getAttribute("aria-labelledby"), "models-label");
     } finally {
-      if (root) await unmount(root);
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -1067,7 +1056,7 @@ describe("Select", () => {
       assertEquals(trigger.getAttribute("aria-expanded"), "false");
       assertEquals(openChanges, [true, false]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1126,7 +1115,7 @@ describe("Select", () => {
       assertEquals(trigger.disabled, true);
       assertEquals(openChanges, [false]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1263,7 +1252,7 @@ describe("Select", () => {
       );
       assertEquals(calls, ["trigger:attach", "item:attach"]);
 
-      await unmount(root);
+      await unmountReactRoot(root);
       assertEquals(calls, [
         "trigger:attach",
         "item:attach",
diff --git a/src/react/components/ui/slot.test.tsx b/src/react/components/ui/slot.test.tsx
index 0eb5e66fb8..48b25e43be 100644
--- a/src/react/components/ui/slot.test.tsx
+++ b/src/react/components/ui/slot.test.tsx
@@ -3,6 +3,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import {
   assert,
   assertEquals,
@@ -109,7 +110,7 @@ describe("Slot", () => {
     assertStringIncludes(ownedOpaqueButton, 'type="button"');
   });
 
-  it("preserves React 19 callback-ref cleanup for both composed refs", () => {
+  it("preserves React 19 callback-ref cleanup for both composed refs", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { pretendToBeVisual: true, url: "https://example.com/" },
@@ -146,13 +147,13 @@ describe("Slot", () => {
       assertEquals(attached, ["outer", "child"]);
       assertEquals(cleaned, []);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       assertEquals(cleaned, ["child", "outer"]);
       restore();
     }
   });
 
-  it("does not run slot behavior after a child handler cancels the event", () => {
+  it("does not run slot behavior after a child handler cancels the event", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { pretendToBeVisual: true, url: "https://example.com/" },
@@ -183,12 +184,12 @@ describe("Slot", () => {
       );
       assertEquals(slotCalls, 0);
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("blocks disabled activation, handlers, and propagation", () => {
+  it("blocks disabled activation, handlers, and propagation", async () => {
     const dom = new JSDOM(
       '<!doctype html><html><body><div id="root"></div></body></html>',
       { pretendToBeVisual: true, url: "https://example.com/start" },
@@ -276,7 +277,7 @@ describe("Slot", () => {
         assertEquals(calls, []);
       }
     } finally {
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       restore();
     }
   });
diff --git a/src/react/components/ui/tooltip.test.tsx b/src/react/components/ui/tooltip.test.tsx
index 8863000ff0..489e3be3c2 100644
--- a/src/react/components/ui/tooltip.test.tsx
+++ b/src/react/components/ui/tooltip.test.tsx
@@ -1,8 +1,9 @@
 import type { RefCallback } from "react";
 import { flushSync } from "react-dom";
-import { createRoot, hydrateRoot, type Root } from "react-dom/client";
+import { createRoot, hydrateRoot } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "./tooltip.tsx";
@@ -100,12 +101,21 @@ function escape(window: JSDOM["window"], target: EventTarget): KeyboardEvent {
   return event;
 }
 
-// Unmounting leaves a scheduler callback queued; drain it so the leak
-// sanitizer does not attribute that timer to the test.
-async function unmount(root: Root | undefined): Promise<void> {
-  if (!root) return;
-  flushSync(() => root.unmount());
-  await new Promise((resolve) => setTimeout(resolve, 0));
+/**
+ * Wait for the Escape dismissal layer to be registered.
+ *
+ * `tooltip.tsx` picks its effect hook at module load, and `document` only
+ * exists once a test installs a JSDOM, so under Deno every one of its "layout"
+ * effects is really a passive effect. The tooltip node therefore lands one
+ * commit before `registerDismissableLayer` runs. A keydown is one-shot -- an
+ * Escape dispatched in that window is dropped for good -- so yield the
+ * macrotask React's scheduler queued at commit time before pressing it.
+ *
+ * Browsers define `document` at module load, bind `useLayoutEffect`, and
+ * register within the commit, so this gap is a test-environment artifact.
+ */
+function escapeLayerRegistered(): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, 0));
 }
 
 describe("Tooltip", () => {
@@ -148,7 +158,7 @@ describe("Tooltip", () => {
       assert(tooltipId);
       assertEquals(defaultTrigger.getAttribute("aria-describedby"), tooltipId);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -233,7 +243,7 @@ describe("Tooltip", () => {
       assertEquals(childFocusCalls, 1);
       assertEquals(recoverableErrors, []);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -271,7 +281,7 @@ describe("Tooltip", () => {
       await waitFor(() => document.querySelector('[role="tooltip"]') === null);
       assertEquals(trigger.hasAttribute("aria-describedby"), false);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -301,6 +311,7 @@ describe("Tooltip", () => {
       assert(trigger);
       flushSync(() => hover(dom.window, trigger));
       await waitFor(() => document.querySelector('[role="tooltip"]') !== null);
+      await escapeLayerRegistered();
 
       const cancelledEscape = escape(dom.window, trigger);
       assertEquals(cancelledEscape.defaultPrevented, true);
@@ -321,7 +332,7 @@ describe("Tooltip", () => {
       });
       await waitFor(() => document.querySelector('[role="tooltip"]') !== null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -364,7 +375,7 @@ describe("Tooltip", () => {
       assertEquals(calls, ["child", "trigger"]);
       assert(document.querySelector('[role="tooltip"]') === null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -399,7 +410,7 @@ describe("Tooltip", () => {
       flushSync(() => unhover(dom.window, trigger));
       await waitFor(() => document.querySelector('[role="tooltip"]') === null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -442,12 +453,12 @@ describe("Tooltip", () => {
       const unmountedTrigger = document.querySelector<HTMLButtonElement>("button");
       assert(unmountedTrigger);
       flushSync(() => hover(dom.window, unmountedTrigger));
-      flushSync(() => root.unmount());
+      await unmountReactRoot(root);
       rootMounted = false;
       await new Promise((resolve) => setTimeout(resolve, 50));
       assert(document.querySelector('[role="tooltip"]') === null);
     } finally {
-      if (rootMounted) await unmount(root);
+      if (rootMounted) await unmountReactRoot(root);
       restore();
     }
   });
@@ -538,7 +549,7 @@ describe("Tooltip", () => {
       flushSync(() => escape(targetDom.window, targetDocument));
       await waitFor(() => targetDocument.querySelector('[role="tooltip"]') === null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       targetDom.window.close();
       restore();
     }
@@ -579,7 +590,7 @@ describe("Tooltip", () => {
       assertEquals(tooltip.style.overflowWrap, "normal");
       assertEquals(tooltip.style.whiteSpace, "pre-wrap");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -607,7 +618,7 @@ describe("Tooltip", () => {
       flushSync(() => hover(dom.window, trigger));
       await waitFor(() => document.querySelector('[role="tooltip"]') !== null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -662,7 +673,7 @@ describe("Tooltip", () => {
       flushSync(() => unhover(dom.window, trigger));
       assertEquals(clearedHandles, [47]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       if (setTimeoutDescriptor) {
         Object.defineProperty(dom.window, "setTimeout", setTimeoutDescriptor);
       } else delete (dom.window as unknown as Record<string, unknown>).setTimeout;
@@ -712,7 +723,7 @@ describe("Tooltip", () => {
       assertEquals(cleanupCalls, 0);
       assertEquals(nullCalls, 0);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       assertEquals(attachedElement, null);
       assertEquals(cleanupCalls, 1);
       assertEquals(nullCalls, 0);
@@ -762,7 +773,7 @@ describe("Tooltip", () => {
       assert(document.querySelector('[role="tooltip"]'));
       assertEquals(refCalls, ["attach:1", "cleanup:1", "attach:2"]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       assertEquals(refCalls, [
         "attach:1",
         "cleanup:1",
diff --git a/src/react/primitives/input-box.test.tsx b/src/react/primitives/input-box.test.tsx
index 312e0c4d98..ab5af980ef 100644
--- a/src/react/primitives/input-box.test.tsx
+++ b/src/react/primitives/input-box.test.tsx
@@ -2,6 +2,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import type * as React from "react";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assert, assertEquals } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { handleInputBoxKeyDown, InputBox, SubmitButton } from "./input-box.tsx";
@@ -119,11 +120,11 @@ describe("InputBox", () => {
       await waitFor(() => textarea.style.height === "120px");
       assert(refValues.includes(textarea));
 
-      flushSync(() => root?.unmount());
+      if (root) await unmountReactRoot(root);
       root = undefined;
       assertEquals(refCleanupCalls, 1);
     } finally {
-      if (root) flushSync(() => root?.unmount());
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
@@ -173,7 +174,7 @@ describe("InputBox", () => {
 });
 
 describe("SubmitButton", () => {
-  it("chains stop callbacks while protecting button type and stop availability", () => {
+  it("chains stop callbacks while protecting button type and stop availability", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     let root: ReturnType<typeof createRoot> | undefined;
@@ -223,12 +224,12 @@ describe("SubmitButton", () => {
       assertEquals(stopCalls, 1);
       assertEquals(submitCalls, 0);
     } finally {
-      root?.unmount();
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("chains voice callbacks without allowing a submit type override", () => {
+  it("chains voice callbacks without allowing a submit type override", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     let root: ReturnType<typeof createRoot> | undefined;
@@ -263,12 +264,12 @@ describe("SubmitButton", () => {
       assertEquals(clickCalls, 1);
       assertEquals(voiceCalls, 1);
     } finally {
-      root?.unmount();
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("allows the caller click handler to cancel a stop action deliberately", () => {
+  it("allows the caller click handler to cancel a stop action deliberately", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     let root: ReturnType<typeof createRoot> | undefined;
@@ -302,12 +303,12 @@ describe("SubmitButton", () => {
       assertEquals(clickCalls, 1);
       assertEquals(stopCalls, 0);
     } finally {
-      root?.unmount();
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
 
-  it("keeps a disabled submit state inert", () => {
+  it("keeps a disabled submit state inert", async () => {
     const dom = createDom();
     const restore = installDom(dom);
     let root: ReturnType<typeof createRoot> | undefined;
@@ -336,7 +337,7 @@ describe("SubmitButton", () => {
       flushSync(() => button.dispatchEvent(new MouseEvent("click", { bubbles: true })));
       assertEquals(clickCalls, 0);
     } finally {
-      root?.unmount();
+      if (root) await unmountReactRoot(root);
       restore();
     }
   });
diff --git a/src/react/react-root.test-helpers.ts b/src/react/react-root.test-helpers.ts
new file mode 100644
index 0000000000..6e86f85ab1
--- /dev/null
+++ b/src/react/react-root.test-helpers.ts
@@ -0,0 +1,15 @@
+import { flushSync } from "react-dom";
+import type { Root } from "react-dom/client";
+
+/**
+ * Unmount a React root and drain the scheduler task left by the commit.
+ *
+ * React may retain a pending scheduler callback after `Root.unmount()`. Tests
+ * that use Deno's leak sanitizer must yield once before restoring their DOM
+ * globals or returning.
+ */
+export async function unmountReactRoot(root: Root | undefined): Promise<void> {
+  if (!root) return;
+  flushSync(() => root.unmount());
+  await new Promise<void>((resolve) => setTimeout(resolve, 0));
+}
diff --git a/src/react/runtime/head-client.test.tsx b/src/react/runtime/head-client.test.tsx
index 28aba9757f..66ede830a5 100644
--- a/src/react/runtime/head-client.test.tsx
+++ b/src/react/runtime/head-client.test.tsx
@@ -3,6 +3,7 @@ import { flushSync } from "react-dom";
 import { createRoot, hydrateRoot, type Root } from "react-dom/client";
 import { renderToString } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import {
   assert,
   assertEquals,
@@ -113,12 +114,6 @@ function rootElement(id = "root"): HTMLElement {
   return element;
 }
 
-async function unmount(root: Root | undefined): Promise<void> {
-  if (!root) return;
-  flushSync(() => root.unmount());
-  await nextTask();
-}
-
 describe("Head client management", () => {
   it("suppresses the expected server-only commit-token difference during hydration", async () => {
     const children = <title>Hydrated managed head</title>;
@@ -150,7 +145,7 @@ describe("Head client management", () => {
       assertEquals(consoleErrors, []);
     } finally {
       console.error = previousConsoleError;
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -199,7 +194,7 @@ describe("Head client management", () => {
       assertEquals(thirdParty.getAttribute("data-vf-react-head"), null);
       assertEquals(thirdParty.getAttribute("content"), "Third party");
 
-      await unmount(root);
+      await unmountReactRoot(root);
       root = undefined;
 
       assertStrictEquals(document.head.querySelector("title"), shellTitle);
@@ -218,7 +213,7 @@ describe("Head client management", () => {
         assertEquals(element.getAttribute("data-veryfront-managed"), null);
       }
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -252,7 +247,7 @@ describe("Head client management", () => {
       assertEquals(document.head.querySelector("title"), null);
       assertEquals(document.head.querySelector('meta[name="description"]'), null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -308,7 +303,7 @@ describe("Head client management", () => {
       assertEquals(document.head.querySelectorAll('link[rel="canonical"]').length, 1);
       assertEquals(document.head.querySelectorAll("#route-state").length, 1);
 
-      await unmount(root);
+      await unmountReactRoot(root);
       root = undefined;
 
       for (const element of [routeTitle, routeDescription, routeCanonical, routeScript]) {
@@ -323,7 +318,7 @@ describe("Head client management", () => {
       assertEquals(routeCanonical.getAttribute("href"), "https://example.com/route");
       assertEquals(routeScript.textContent, scriptContent);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -362,7 +357,7 @@ describe("Head client management", () => {
       assertEquals(document.head.querySelectorAll("#route-exec").length, 1);
       assertStrictEquals(document.getElementById("route-exec"), routeScript);
 
-      await unmount(root);
+      await unmountReactRoot(root);
       root = undefined;
 
       assertEquals(scriptWindow.__routeExecRuns, executionsBeforeReactAdoption);
@@ -372,7 +367,7 @@ describe("Head client management", () => {
         "window.__routeExecRuns=(window.__routeExecRuns||0)+1;",
       );
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -427,7 +422,7 @@ describe("Head client management", () => {
       assertEquals(managedManifest.getAttribute("data-vf-react-head"), null);
       assertStrictEquals(document.getElementById("third-party"), thirdParty);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -492,7 +487,7 @@ describe("Head client management", () => {
         assertEquals(element.getAttribute("data-veryfront-managed"), "1");
       }
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -516,7 +511,7 @@ describe("Head client management", () => {
       assertStrictEquals(document.head.querySelector("style"), original);
       assertEquals(original?.getAttribute("nonce"), "response");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -600,7 +595,7 @@ describe("Head client management", () => {
         ".two{}",
       );
 
-      await unmount(root);
+      await unmountReactRoot(root);
       root = undefined;
       assertEquals(
         frameDocument.head.querySelectorAll(
@@ -617,7 +612,7 @@ describe("Head client management", () => {
         primaryMeta,
       );
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -645,7 +640,7 @@ describe("Head client management", () => {
       assertEquals(original?.getAttribute("defer"), "");
       assertEquals(original?.getAttribute("data-enabled"), "false");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -678,7 +673,7 @@ describe("Head client management", () => {
       assertEquals(originalMeta?.getAttribute("content"), "A\nB\nC");
       assertEquals(originalStyle?.textContent, ".a{\ncolor:red\n}");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -704,7 +699,7 @@ describe("Head client management", () => {
       assertStrictEquals(document.head.querySelector("meta[charset]"), charset);
       assertEquals(charset?.hasAttribute("data-vf-react-head"), false);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -739,7 +734,7 @@ describe("Head client management", () => {
       assertEquals(scriptWindow.__payload, "</ScRiPt>");
       assertStrictEquals(document.head.querySelector("#once"), original);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -789,7 +784,7 @@ describe("Head client management", () => {
       assertNotStrictEquals(document.head.querySelector("#versioned"), original);
       assertEquals(document.head.querySelectorAll("#versioned").length, 1);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -865,7 +860,7 @@ describe("Head client management", () => {
       assertEquals(document.head.querySelector("style")?.textContent, ".two{color:blue}");
       assertEquals(scriptWindow.__updateRuns, 1);
 
-      await unmount(root);
+      await unmountReactRoot(root);
       root = undefined;
       assertEquals(document.head.querySelectorAll('[data-vf-react-head="true"]').length, 0);
       assertEquals(document.head.querySelector("title"), null);
@@ -874,7 +869,7 @@ describe("Head client management", () => {
       assertEquals(document.head.querySelector("style"), null);
       assertEquals(document.head.querySelector("#stable"), null);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -951,7 +946,7 @@ describe("Head client management", () => {
       assertEquals(imageOrder(), ["layout.jpg"]);
       assertEquals(document.head.querySelector("#shared")?.getAttribute("src"), "/layout.js");
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -979,7 +974,7 @@ describe("Head client management", () => {
       await nextTask();
       assertEquals(authors(), ["B", "A"]);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1021,7 +1016,7 @@ describe("Head client management", () => {
         1,
       );
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1066,8 +1061,8 @@ describe("Head client management", () => {
         1,
       );
     } finally {
-      await unmount(rootA);
-      await unmount(rootB);
+      await unmountReactRoot(rootA);
+      await unmountReactRoot(rootB);
       restore();
     }
   });
@@ -1118,7 +1113,7 @@ describe("Head client management", () => {
         1,
       );
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1149,7 +1144,7 @@ describe("Head client management", () => {
       assertEquals(scriptWindow.__strictRuns, 1);
       assertEquals(document.head.querySelectorAll("#strict-once").length, 1);
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1197,7 +1192,7 @@ describe("Head client management", () => {
         null,
       );
     } finally {
-      await unmount(root);
+      await unmountReactRoot(root);
       restore();
     }
   });
@@ -1265,7 +1260,7 @@ describe("Head client management", () => {
       assertEquals(meta.hasAttribute("onclick"), false);
       assertEquals(accessorCalls, 0);
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
diff --git a/src/react/runtime/router-provider.test.tsx b/src/react/runtime/router-provider.test.tsx
index fac3557ccc..3ece32ebeb 100644
--- a/src/react/runtime/router-provider.test.tsx
+++ b/src/react/runtime/router-provider.test.tsx
@@ -3,6 +3,7 @@ import { flushSync } from "react-dom";
 import { createRoot } from "react-dom/client";
 import { renderToStaticMarkup } from "react-dom/server";
 import { JSDOM } from "npm:jsdom@28.0.0";
+import { unmountReactRoot } from "#veryfront/react/react-root.test-helpers.ts";
 import { assertEquals, assertStringIncludes } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
 import { waitFor } from "#veryfront/testing/deno-compat.ts";
@@ -159,7 +160,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
       assertStringIncludes(rootElement.textContent ?? "", "thread:b");
       assertEquals(router.navigateCount, 1);
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -196,7 +197,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
 
       assertStringIncludes(rootElement.textContent ?? "", "tab:b");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -231,7 +232,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
 
       assertStringIncludes(rootElement.textContent ?? "", "/|x");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -268,13 +269,13 @@ describe("react/runtime/RouterProvider (reactive)", () => {
       // Router changed → page context's query tracked it; frontmatter unchanged.
       assertStringIncludes(rootElement.textContent ?? "", "match:true|v:2|fm:kept");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
   });
 
-  it("derives a clean query when the URL carries a hash fragment", () => {
+  it("derives a clean query when the URL carries a hash fragment", async () => {
     const restore = installDom("https://example.com/docs?tab=api#install");
     installFakeRouter();
     try {
@@ -297,7 +298,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
       // The hash must not leak into the query — only `tab` is present.
       assertStringIncludes(rootElement.textContent ?? "", "/docs|tab:api|keys:tab");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -332,7 +333,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
 
       assertStringIncludes(rootElement.textContent ?? "", "42|comments|Hello");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -373,7 +374,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
       // query/params.
       assertStringIncludes(rootElement.textContent ?? "", "data:from-server");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -408,7 +409,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
     assertStringIncludes(html, "type:object keys:0");
   });
 
-  it("wrapForHydration seeds the provider from location + params (no React passed in)", () => {
+  it("wrapForHydration seeds the provider from location + params (no React passed in)", async () => {
     // The hydration path wraps a child by calling this export on the app's own
     // React — nothing is threaded across the module boundary. It seeds params
     // and frontmatter and derives pathname/query from the live URL.
@@ -434,7 +435,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
 
       assertStringIncludes(rootElement.textContent ?? "", "/posts/7:7:x:Hi");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
@@ -475,7 +476,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
         { interval: 10, message: "RouterProvider did not finish its client mount" },
       );
       assertStringIncludes(rootElement.textContent ?? "", "m:true");
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restoreClient();
     }
@@ -515,7 +516,7 @@ describe("react/runtime/RouterProvider (reactive)", () => {
 
       assertStringIncludes(rootElement.textContent ?? "", "tab:b");
 
-      root.unmount();
+      await unmountReactRoot(root);
     } finally {
       restore();
     }
diff --git a/src/routing/api/module-loader/esbuild-plugin.test.ts b/src/routing/api/module-loader/esbuild-plugin.test.ts
index 0f20689559..910ed5535d 100644
--- a/src/routing/api/module-loader/esbuild-plugin.test.ts
+++ b/src/routing/api/module-loader/esbuild-plugin.test.ts
@@ -1,6 +1,7 @@
 import "#veryfront/schemas/_test-setup.ts";
 import { assertEquals, assertExists, assertRejects } from "#veryfront/testing/assert.ts";
 import { describe, it } from "#veryfront/testing/bdd.ts";
+import { observeFetchRequestInit } from "#veryfront/testing/mock-fetch.ts";
 import { computeIntegrity, type LockfileManager } from "#veryfront/utils";
 import { MAX_BUNDLE_CHUNK_SIZE_BYTES } from "#veryfront/utils/constants/buffers.ts";
 import { createHTTPPlugin } from "./esbuild-plugin.ts";
@@ -562,7 +563,7 @@ describe("routing/api/module-loader/esbuild-plugin", () => {
       try {
         globalThis.fetch = ((_input, init) => {
           attempts += 1;
-          const signal = init?.signal;
+          const signal = observeFetchRequestInit(init).signal;
           return Promise.resolve(
             new Response(
               new ReadableStream<Uint8Array>({