diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a34d0ea26d..8538b37d4b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -91,6 +91,12 @@ jobs:
       - name: Check Windows test inventory
         run: npm run windows:inventory
 
+      # Deliberately here and not in the e2e job: that job is conditional, and a
+      # tier this guard only checks when the tier already ran is a guard that
+      # grows back (#4761). Pure Node, no build -- it reads the spec sources.
+      - name: Check Electron e2e budget
+        run: npm run check:e2e-budget
+
       # Runs on the PR merge result: after a sibling protocol change lands on
       # main with the same epoch text, the silently merged tree still carries
       # the current base parent's epoch and this fails instead of shipping two
@@ -357,37 +363,7 @@ jobs:
 
       - name: Desktop e2e
         if: steps.plan.outputs.e2e == 'true'
-        run: |
-          set -euo pipefail
-          display_base=90
-          worker_count=4
-          xvfb_pids=()
-          cleanup() {
-            kill "${xvfb_pids[@]}" 2>/dev/null || true
-            wait "${xvfb_pids[@]}" 2>/dev/null || true
-          }
-          trap cleanup EXIT
-          for ((index = 0; index < worker_count; index += 1)); do
-            display=$((display_base + index))
-            Xvfb ":$display" -screen 0 1280x1024x24 -nolisten tcp \
-              >"$RUNNER_TEMP/xvfb-$display.log" 2>&1 &
-            xvfb_pids+=("$!")
-          done
-          for ((index = 0; index < worker_count; index += 1)); do
-            display=$((display_base + index))
-            for _ in {1..50}; do
-              [[ -S "/tmp/.X11-unix/X$display" ]] && break
-              kill -0 "${xvfb_pids[$index]}" 2>/dev/null || break
-              sleep 0.1
-            done
-            if [[ ! -S "/tmp/.X11-unix/X$display" ]]; then
-              cat "$RUNNER_TEMP/xvfb-$display.log"
-              exit 1
-            fi
-          done
-          MAKA_E2E_X_DISPLAY_BASE="$display_base" \
-            npm exec -w @maka/desktop -- playwright test \
-              --config e2e/playwright.config.ts --workers="$worker_count"
+        run: xvfb-run -a npm exec -w @maka/desktop -- playwright test --config e2e/playwright.config.ts
 
       # Playwright keeps a trace, a video and a screenshot for every failed
       # test. Without this they die with the runner, and an e2e flake can only
diff --git a/apps/desktop/e2e-budget.json b/apps/desktop/e2e-budget.json
new file mode 100644
index 0000000000..383cff4e3c
--- /dev/null
+++ b/apps/desktop/e2e-budget.json
@@ -0,0 +1,73 @@
+{
+  "policy": [
+    "A test belongs in this tier only when it needs a real Electron window: an OS dialog, a main-process round trip, input released outside the window, persistence across a renderer reload, or a cross-process lifecycle.",
+    "Layout geometry, renderer state machines and pure CSS go to a Storybook play function; main-process logic goes to node --test. See #4761.",
+    "Every spec below records the Electron-owned mechanism it needs. If you cannot name one, the test does not belong here."
+  ],
+  "specs": {
+    "composer-directory-reference.spec.ts": {
+      "tests": 1,
+      "electron": "the folder reference has to survive a renderer reload and still agree with the Host's session record"
+    },
+    "context-window-save.spec.ts": {
+      "tests": 1,
+      "electron": "the saved window is read back from the Host's connection snapshot, not from renderer state"
+    },
+    "new-task-reload.spec.ts": {
+      "tests": 1,
+      "electron": "renderer reload is the whole contract: an explicit new task must not reopen history"
+    },
+    "proxy-password-editing.spec.ts": {
+      "tests": 1,
+      "electron": "the password never reaches the renderer; only the Host can report passwordConfigured and authenticate offline"
+    },
+    "quote-window-boundary.spec.ts": {
+      "tests": 1,
+      "electron": "a pointer capture released outside the window -- there is no window edge to leave in a browser tab"
+    },
+    "session-draft-focus.spec.ts": {
+      "tests": 1,
+      "electron": "needs a second real Session (Host round trip) to switch to; the focus and draft-restore halves alone would not earn a window"
+    },
+    "session-workbar.spec.ts": {
+      "tests": 5,
+      "electron": "Git changes re-read on window focus, terminal PTY ownership across Sessions, Side Chat's fork lifecycle, and a first send that has to reach the Host; the composer-usage test is renderer-only and rides along on those windows until app-shell.tsx's composer-to-workbar wiring has a story host"
+    },
+    "settings.spec.ts": {
+      "tests": 4,
+      "electron": "the preload makaE2eLatch holds the settings chunk mid-load, and the rename it commits is a Host write; the workbar-chrome test rides along on that window and would move to a story the day app-shell.tsx's settings wiring has one"
+    },
+    "sidebar-project-reload.spec.ts": {
+      "tests": 1,
+      "electron": "rail grouping has to be rebuilt from persisted project state after a renderer reload"
+    },
+    "skill-draft-lifecycle.spec.ts": {
+      "tests": 2,
+      "electron": "revision retry and cancel are Host-owned draft transitions across a parent and a child Session"
+    },
+    "slash-command-compact.spec.ts": {
+      "tests": 1,
+      "electron": "/compact is a Host round trip that ends in a real terminal Turn state"
+    },
+    "streaming-remount.spec.ts": {
+      "tests": 4,
+      "electron": "observation seeding, reconnect and settle are Host subscriptions surviving a renderer remount"
+    },
+    "transcript-scroll-cost.spec.ts": {
+      "tests": 3,
+      "electron": "the perf budget is measured from CDP wheel input and the browser's own render skipping"
+    },
+    "workhub-layout.spec.ts": {
+      "tests": 1,
+      "electron": "Coordination startup failure comes from the Host, and recovery needs a default model written back to it"
+    },
+    "workhub-reconstruction.spec.ts": {
+      "tests": 2,
+      "electron": "delegation linkage is rebuilt by the Host across navigation and across Sessions"
+    },
+    "zh-tw-locale.spec.ts": {
+      "tests": 1,
+      "electron": "the locale is a persisted Host setting and only takes effect through a renderer reload"
+    }
+  }
+}
diff --git a/apps/desktop/e2e/fixture-thread-search.spec.ts b/apps/desktop/e2e/fixture-thread-search.spec.ts
deleted file mode 100644
index 43a675a2ab..0000000000
--- a/apps/desktop/e2e/fixture-thread-search.spec.ts
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import { PROMPT_RAIL_SESSION_ID } from '../src/main/e2e-fixture/seed-helpers.js';
-import {
-  desktopSessionKey,
-  parseDesktopSessionKey,
-} from '../src/shared/runtime-host-identity.js';
-import { expect, test } from './fixtures.js';
-
-test('fixture-seeded transcripts return content hits with turn ids', async ({
-  threadSearchWindow: page,
-}) => {
-  const outcome = await page.evaluate(async () =>
-    window.maka.search.thread({
-      source: 'thread',
-      query: '第 3 个问题',
-      limit: 10,
-    }),
-  );
-
-  expect(Array.isArray(outcome), JSON.stringify(outcome)).toBe(true);
-  if (!Array.isArray(outcome)) return;
-
-  const content = outcome.find(
-    (hit) =>
-      hit.target?.kind === 'thread' &&
-      hit.target.turnId === 'turn-prompt-rail-3',
-  );
-  expect(content?.summary).toBe('用户消息');
-  if (!content || content.target?.kind !== 'thread') {
-    throw new Error(`expected a thread search hit, got ${JSON.stringify(content)}`);
-  }
-  const { hostId } = parseDesktopSessionKey(content.target.sessionId);
-  expect(content.target).toEqual({
-    kind: 'thread',
-    sessionId: desktopSessionKey({ hostId, sessionId: PROMPT_RAIL_SESSION_ID }),
-    turnId: 'turn-prompt-rail-3',
-    sequence: 4,
-  });
-});
diff --git a/apps/desktop/e2e/fixtures.ts b/apps/desktop/e2e/fixtures.ts
index aa5f733143..b3eac80252 100644
--- a/apps/desktop/e2e/fixtures.ts
+++ b/apps/desktop/e2e/fixtures.ts
@@ -523,34 +523,13 @@ type E2eTestFixtures = {
   parentRemovalWindow: Page;
   railRenderWindow: Page;
   promptRailWindow: Page;
-  threadSearchWindow: Page;
   requestHeaderRowWindow: Page;
   newTaskTargetWindow: Page;
   directoryReferenceWindow: { page: Page; folder: string };
   accessibilityNarrativeWindow: Page;
 };
 
-type E2eWorkerFixtures = {
-  isolatedDisplay: void;
-};
-
-export const test = base.extend<E2eTestFixtures, E2eWorkerFixtures>({
-  isolatedDisplay: [async ({}, use, workerInfo) => {
-    const base = process.env.MAKA_E2E_X_DISPLAY_BASE;
-    if (base === undefined) {
-      await use();
-      return;
-    }
-    if (!/^\d+$/.test(base)) throw new Error(`Invalid E2E X display base: ${base}`);
-    const previous = process.env.DISPLAY;
-    process.env.DISPLAY = `:${Number(base) + workerInfo.parallelIndex}`;
-    try {
-      await use();
-    } finally {
-      if (previous === undefined) delete process.env.DISPLAY;
-      else process.env.DISPLAY = previous;
-    }
-  }, { scope: 'worker', auto: true }],
+export const test = base.extend<E2eTestFixtures>({
   directoryReferenceWindow: async ({}, use) => {
     await withE2eWindow(
       { seed: true, readinessSelector: COMPOSER_INPUT, locale: 'zh-CN', showWindow: true },
@@ -661,18 +640,6 @@ export const test = base.extend<E2eTestFixtures, E2eWorkerFixtures>({
       showWindow: true,
     }, use);
   },
-  // The same seeded transcript, on a window of its own. Search reads the Host
-  // through the bridge and renders nothing, so it needs neither the warm
-  // window's compositor nor its between-test reset — and taking it off the
-  // reused window is what retires the readiness gate's cross-test bleed (#4707).
-  threadSearchWindow: async ({}, use) => {
-    await withE2eWindow({
-      seed: false,
-      readinessSelector: '[data-turn-id]',
-      e2eFixtureScenario: 'chat-prompt-rail',
-      locale: 'zh-CN',
-    }, use);
-  },
   // Settings → 模型, where `no-models` is the seeded openai-compatible relay —
   // the connection type whose detail page owns the custom request headers
   // editor. Shown, because what this window is for is a rendered box
diff --git a/apps/desktop/e2e/playwright.config.ts b/apps/desktop/e2e/playwright.config.ts
index 00f23ac63d..df971180a4 100644
--- a/apps/desktop/e2e/playwright.config.ts
+++ b/apps/desktop/e2e/playwright.config.ts
@@ -22,26 +22,19 @@ import { defineConfig } from '@playwright/test';
 /**
  * Playwright config for the desktop Electron E2E suite.
  *
- * Most tests launch a real Electron window backed by the deterministic fake
- * backend (MAKA_E2E=1) against their OWN throwaway userData dir. The read-only
- * prompt-rail scenario instead keeps its Electron + Host composition warm for
- * a worker and resets its Host range and renderer state per test. Keep the
- * local default at one worker: concurrent windows share OS focus, invalidating
- * geometry and focus contracts. Developers can still pass `--workers`
- * explicitly for a subset that has neither concern.
+ * Every test launches a real Electron window backed by the deterministic fake
+ * backend (MAKA_E2E=1) against its OWN throwaway userData dir. One worker,
+ * everywhere: what is left in this tier is here because it needs a native
+ * window, and concurrent windows share OS focus, which invalidates exactly the
+ * focus, pointer and geometry contracts that kept these tests here.
  * Deliberately no test count here — the previous note carried a stale one that
  * outlived two rounds of pruning. `playwright test --list` is the only figure
  * that cannot rot.
  *
- * CI gives every Playwright worker an isolated X display, so they overlap
- * without sharing focus or a compositor. Local parallelism is opt-in for the
- * same reason.
- *
  * Run from apps/desktop via `npm run e2e`, which builds the app first.
  */
 export default defineConfig({
   testDir: '.',
-  fullyParallel: true,
   workers: 1,
   // CI publishes no Playwright report that consumes Git metadata. Disable its
   // best-effort shallow-history fetch, which otherwise waits on a fixed timeout.
diff --git a/apps/desktop/e2e/session-workbar.spec.ts b/apps/desktop/e2e/session-workbar.spec.ts
index 22a6ae701d..34bad85d39 100644
--- a/apps/desktop/e2e/session-workbar.spec.ts
+++ b/apps/desktop/e2e/session-workbar.spec.ts
@@ -143,219 +143,6 @@ async function waitForCompanionForkId(page: Page, sourceSessionId: string) {
   return forkId!;
 }
 
-async function setRightWorkbarWidth(page: Page, width: number) {
-  const layoutOwner = page.locator('.maka-workbar-layout-vars');
-  const workbar = page.locator('.maka-session-workbar[data-placement="right"]');
-  await expect(layoutOwner).toHaveCount(1);
-  await expect(workbar).toBeVisible();
-  await layoutOwner.evaluate((element, nextWidth) => {
-    (element as HTMLElement).style.setProperty(
-      '--maka-session-workbar-width',
-      `${nextWidth}px`,
-    );
-  }, width);
-  await expect
-    .poll(async () => (await workbar.boundingBox())?.width)
-    .toBeCloseTo(width, 0);
-  return workbar;
-}
-
-test('narrow right workbar keeps launcher shortcuts and side-chat send button inside', async ({
-  window: page,
-}) => {
-  const composer = page.locator(COMPOSER_INPUT);
-  await composer.fill('create narrow workbar session');
-  await composer.press('Enter');
-  await expect(page.getByText(/Fake backend received: create narrow workbar session/)).toBeVisible();
-
-  await page.getByRole('button', { name: '展开任务工作栏' }).click();
-  const launcher = page.getByRole('list', { name: '打开工具' });
-  await expect(launcher).toBeVisible();
-  const workbar = await setRightWorkbarWidth(page, 320);
-
-  const workbarBox = await workbar.boundingBox();
-  const shortcutBoxes = await launcher
-    .locator('kbd')
-    .evaluateAll((elements) =>
-      elements.map((element) => {
-        const box = element.getBoundingClientRect();
-        return { left: box.left, right: box.right };
-      }),
-    );
-  expect(workbarBox).not.toBeNull();
-  expect(shortcutBoxes.length).toBeGreaterThan(0);
-  for (const shortcutBox of shortcutBoxes) {
-    expect.soft(shortcutBox.left).toBeGreaterThanOrEqual(workbarBox!.x);
-    expect.soft(shortcutBox.right).toBeLessThanOrEqual(workbarBox!.x + workbarBox!.width);
-  }
-
-  await page
-    .getByRole('button', {
-      name: /侧边对话.*在不打断主任务的情况下追问和只读探索/,
-    })
-    .click();
-  const companion = page.locator('.maka-quote-companion');
-  await expect(companion).toBeVisible();
-  await setRightWorkbarWidth(page, 320);
-  const sideChatPanel = page
-    .locator('.maka-session-workbar-panel[data-overlay][data-placement="right"]')
-    .filter({ has: companion });
-  await expect(sideChatPanel).toBeVisible();
-  await expect
-    .poll(async () => (await sideChatPanel.boundingBox())?.width)
-    .toBeCloseTo(320, 0);
-
-  const composerCard = companion.locator('.maka-composer-astryx');
-  // Keep ChatComposer's inner elevation visible.
-  await expect(composerCard).toHaveCSS('overflow', 'visible');
-
-  // #3452: Side Chat is a branch of the main conversation, not a second
-  // conversation surface, so its dock rounds like the main dock. Both resolve
-  // Astryx's `--radius-chat`, the same token `ChatMessageBubble` defaults to —
-  // a side-only `--_chat-composer-radius` split the bubble from the dock the
-  // moment the bubbles moved back to that default. Compared against the main
-  // composer rather than a literal so an upstream token change moves both or
-  // fails here.
-  const composerRadii = await page.evaluate(() => {
-    const wrappers = [...document.querySelectorAll('.maka-composer-astryx')];
-    const inCompanion = (element: Element) => element.closest('.maka-quote-companion') !== null;
-    const effectiveRadius = (element: Element | undefined) => {
-      if (!element) return null;
-      const styles = getComputedStyle(element);
-      return (
-        styles.getPropertyValue('--_chat-composer-radius').trim() ||
-        styles.getPropertyValue('--radius-chat').trim()
-      );
-    };
-    return {
-      side: effectiveRadius(wrappers.find(inCompanion)),
-      main: effectiveRadius(wrappers.find((element) => !inCompanion(element))),
-    };
-  });
-  expect(composerRadii.side).toBeTruthy();
-  expect(composerRadii.side).toBe(composerRadii.main);
-  // Match the long model-label pressure from the reported side-chat screenshot
-  // without coupling the fixture's globally useful default model to this test.
-  await companion.locator('.maka-composer-model-chip-text').evaluate((element) => {
-    element.textContent = 'Nemotron 3 Ultra Long Context Model';
-  });
-  const sendButton = companion.getByRole('button', { name: '发送' });
-  await expect(sendButton).toBeVisible();
-  const [composerBox, sendBox] = await Promise.all([
-    composerCard.boundingBox(),
-    sendButton.boundingBox(),
-  ]);
-  expect(composerBox).not.toBeNull();
-  expect(sendBox).not.toBeNull();
-  expect(sendBox!.x).toBeGreaterThanOrEqual(composerBox!.x);
-  expect(sendBox!.x + sendBox!.width).toBeLessThanOrEqual(
-    composerBox!.x + composerBox!.width,
-  );
-});
-
-// #2188: the address field, not the nav buttons, absorbs the column's free
-// width. The rule reaches into Astryx Toolbar's slot div, which nothing else
-// pins — an upstream slot-wrapper change would silently regress it.
-test('browser address field tracks the workbar column width', async ({ window: page }) => {
-  const composer = page.locator(COMPOSER_INPUT);
-  await composer.fill('create browser session');
-  await composer.press('Enter');
-  await expect(page.getByText(/Fake backend received: create browser session/)).toBeVisible();
-  await page.getByRole('button', { name: '展开任务工作栏' }).click();
-  await expect(page.getByRole('list', { name: '打开工具' })).toBeVisible();
-  await page.getByRole('button', { name: /浏览器.*打开内置浏览器/ }).click();
-  await expect(page.getByRole('region', { name: '嵌入式浏览器' })).toBeVisible();
-
-  const addressInput = page.getByRole('textbox', { name: '浏览器地址' });
-  const inputWidth = async () => (await addressInput.boundingBox())!.width;
-  // The tab's content lives in the overlay panel next to the workbar frame,
-  // so the width override must land there, not on `.maka-session-workbar`.
-  const setPanelWidth = async (width: number) => {
-    const panel = page.locator('.maka-session-workbar-panel[data-overlay][data-placement="right"]');
-    await panel.evaluate((element, nextWidth) => {
-      (element as HTMLElement).style.setProperty('--maka-session-workbar-width', `${nextWidth}px`);
-    }, width);
-    await expect.poll(async () => (await panel.boundingBox())?.width).toBeCloseTo(width, 0);
-  };
-  await setPanelWidth(480);
-  await expect.poll(inputWidth).toBeGreaterThan(250);
-  await setPanelWidth(320);
-  // Fails at a flat width without the slot rule: 480 and 320 would measure the same.
-  await expect.poll(inputWidth).toBeLessThan(220);
-  await expect.poll(inputWidth).toBeGreaterThan(100);
-});
-
-test('titlebar workbar action restores an existing tool instead of the picker', async ({
-  gitReviewWindow,
-}) => {
-  const page = gitReviewWindow.page;
-  const workspaceActions = page.getByRole('toolbar', { name: '工作区辅助操作' });
-  const panel = await openGitChanges(page);
-  const panelToolbar = page.getByRole('toolbar', { name: '任务工作栏标签' }).first();
-  const collapseButton = panelToolbar.getByRole('button', { name: '收起任务工作栏' });
-  await expect(workspaceActions).toHaveCount(0);
-  await expect(collapseButton).toBeVisible();
-  await expect(workspaceActions.getByRole('button', { name: '打开工作栏工具' })).toHaveCount(0);
-
-  const activeTab = panelToolbar.getByRole('tab', { selected: true });
-  await expect(activeTab).toBeVisible();
-  const [toolbarBox, tabBox, toggleBox] = await Promise.all([
-    panelToolbar.boundingBox(),
-    activeTab.boundingBox(),
-    collapseButton.boundingBox(),
-  ]);
-  expect(toolbarBox).not.toBeNull();
-  expect(tabBox).not.toBeNull();
-  expect(toggleBox).not.toBeNull();
-  expect(
-    Math.abs(tabBox!.y + tabBox!.height / 2 - (toggleBox!.y + toggleBox!.height / 2)),
-  ).toBeLessThanOrEqual(1);
-
-  const simulatedCaptionWidth = 80;
-  await page.evaluate((width) => {
-    document.documentElement.style.setProperty(
-      '--maka-titlebar-overlay-right-width',
-      `${width}px`,
-    );
-  }, simulatedCaptionWidth);
-  await expect
-    .poll(async () => (await collapseButton.boundingBox())?.x)
-    .toBe(toggleBox!.x - simulatedCaptionWidth);
-  const safeAreaToggleBox = await collapseButton.boundingBox();
-  expect(safeAreaToggleBox).not.toBeNull();
-
-  // [+] is a menu over the panel now, not a swap to the launcher: the face you
-  // are reading stays on screen while you pick another one.
-  await page.getByRole('button', { name: '打开或关闭工作栏的面' }).click();
-  const faceMenu = page.getByRole('menu');
-  await expect(faceMenu).toBeVisible();
-  await expect(panel).toBeVisible();
-  await page.keyboard.press('Escape');
-  await expect(faceMenu).toBeHidden();
-  const picker = page.getByRole('list', { name: '打开工具' });
-  await expect(picker).not.toBeVisible();
-
-  await collapseButton.click();
-  const expandButton = workspaceActions.getByRole('button', { name: '展开任务工作栏' });
-  await expect(expandButton).toBeVisible();
-  const expandButtonBox = await expandButton.boundingBox();
-  expect(expandButtonBox).not.toBeNull();
-  expect(Math.abs(expandButtonBox!.y - safeAreaToggleBox!.y)).toBeLessThanOrEqual(1);
-  expect(Math.abs(expandButtonBox!.x - safeAreaToggleBox!.x)).toBeLessThanOrEqual(1);
-  await expandButton.click();
-
-  await expect(panel).toBeVisible();
-  await expect(picker).not.toBeVisible();
-  const restoredCollapseButton = panelToolbar.getByRole('button', {
-    name: '收起任务工作栏',
-  });
-  await expect(restoredCollapseButton).toBeVisible();
-  const restoredToggleBox = await restoredCollapseButton.boundingBox();
-  expect(restoredToggleBox).not.toBeNull();
-  expect(Math.abs(restoredToggleBox!.y - safeAreaToggleBox!.y)).toBeLessThanOrEqual(1);
-  expect(Math.abs(restoredToggleBox!.x - safeAreaToggleBox!.x)).toBeLessThanOrEqual(1);
-});
-
 test('Git changes re-read the workspace after the app regains focus', async ({
   gitReviewWindow,
 }) => {
diff --git a/apps/desktop/e2e/transcript-scroll-cost.spec.ts b/apps/desktop/e2e/transcript-scroll-cost.spec.ts
index 9762f7948e..b6954c2486 100644
--- a/apps/desktop/e2e/transcript-scroll-cost.spec.ts
+++ b/apps/desktop/e2e/transcript-scroll-cost.spec.ts
@@ -268,7 +268,7 @@ test('paging back through the whole history keeps the mounted range bounded', as
   // Coming back from the far end is a range reload, not a scroll: the Host
   // resolves a new window around the tail and the renderer mounts it. The
   // suite's 10s expect timeout is sized for UI that is already on screen, and
-  // this step measured past it on a CI runner with four workers competing.
+  // this step measured past it on a loaded CI runner.
   await returnToLatest(page);
   await expect(page.locator(`[data-turn-id="turn-prompt-rail-${PROMPT_RAIL_PROMPT_COUNT}"]`))
     .toHaveCount(1, { timeout: 30_000 });
diff --git a/apps/desktop/e2e/workhub-layout.spec.ts b/apps/desktop/e2e/workhub-layout.spec.ts
index 53c5dc39db..059b43d2e6 100644
--- a/apps/desktop/e2e/workhub-layout.spec.ts
+++ b/apps/desktop/e2e/workhub-layout.spec.ts
@@ -17,46 +17,7 @@
  * under the License.
  */
 
-import { COMPOSER_INPUT, expect, test, waitForWorkHubReady } from './fixtures';
-
-test('WorkHub target metadata remains within the submitted Session control', async ({
-  window: page,
-}) => {
-  const composer = page.locator(COMPOSER_INPUT);
-  await composer.fill('支付回调幂等性');
-  await composer.press('Enter');
-  await expect(page.getByRole('button', { name: '重新生成' })).toHaveCount(1, {
-    timeout: 20_000,
-  });
-
-  const sessionName = await page.evaluate(async () =>
-    (await window.maka.sessions.list())[0]?.name,
-  );
-  expect(sessionName).toBeTruthy();
-  await page.evaluate(async () => {
-    await window.maka.settings.updateClient({ workHub: { enabled: true } });
-  });
-  await waitForWorkHubReady(page, 1);
-
-  const routedPrompt = `继续${sessionName}，补充重复投递测试点。`;
-  const workHubComposer = page.locator(
-    '.workhub-surface .maka-composer-editor [contenteditable="true"]',
-  );
-  await workHubComposer.fill(routedPrompt);
-  await workHubComposer.press('Enter');
-  const submittedTurn = page.locator('.workhub-turn', { hasText: routedPrompt });
-  await expect(submittedTurn.locator('.workhub-submitted-session small')).toBeVisible();
-
-  const buttonContainsProject = await submittedTurn.evaluate((turn) => {
-    const button = turn.querySelector<HTMLElement>('.workhub-submitted > button')!;
-    const project = button.querySelector<HTMLElement>('.workhub-submitted-session small')!;
-    const buttonBox = button.getBoundingClientRect();
-    const projectBox = project.getBoundingClientRect();
-    return buttonBox.bottom >= projectBox.bottom;
-  });
-
-  expect(buttonContainsProject).toBe(true);
-});
+import { expect, test } from './fixtures';
 
 test('WorkHub explains Coordination startup failure and recovers after a default model is set', async ({
   window: page,
diff --git a/apps/desktop/package.json b/apps/desktop/package.json
index ac41d0e15e..6d8cb8e6f8 100644
--- a/apps/desktop/package.json
+++ b/apps/desktop/package.json
@@ -23,6 +23,7 @@
     "presmoke:storybook": "npm --workspace @maka/core run build",
     "smoke:storybook": "node ../../scripts/storybook-visual-smoke.mjs",
     "check:architecture": "node --test scripts/check-renderer-architecture.test.mjs && node scripts/check-renderer-architecture.mjs",
+    "check:e2e-budget": "node --test scripts/check-e2e-budget.test.mjs && node scripts/check-e2e-budget.mjs",
     "build": "npm run build:resources && npm run build:main && npm run build:preload && npm run build:overlay && npm run build:renderer",
     "build:resources": "node scripts/copy-runtime-filesystem-worker.mjs",
     "build:test": "npm run build:main && npm run build:preload && npm run build:overlay",
diff --git a/apps/desktop/scripts/check-e2e-budget.mjs b/apps/desktop/scripts/check-e2e-budget.mjs
new file mode 100644
index 0000000000..f1bda5b891
--- /dev/null
+++ b/apps/desktop/scripts/check-e2e-budget.mjs
@@ -0,0 +1,133 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { readdirSync, readFileSync } from 'node:fs';
+import { dirname, join, relative, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const SCRIPT_PATH = fileURLToPath(import.meta.url);
+const DESKTOP_ROOT = resolve(dirname(SCRIPT_PATH), '..');
+const LEDGER_PATH = join(DESKTOP_ROOT, 'e2e-budget.json');
+const E2E_ROOT = join(DESKTOP_ROOT, 'e2e');
+
+// Playwright's own default `testMatch`, because `playwright.config.ts` sets
+// `testDir: '.'` and overrides neither: anything this pattern misses would run
+// in the tier while the budget stayed silent about it.
+const SPEC_PATTERN = /\.(?:spec|test)\.[cm]?[jt]sx?$/u;
+
+// Every spec writes its tests as a bare `test(` at column 0. A dotted top-level
+// form would need a counting rule of its own (`test.describe` nests its tests
+// where a line scanner cannot see them), and an indented `test(` is a test this
+// scanner cannot attribute -- a loop or a helper generating them counts as
+// zero. Both are refused rather than silently undercounted.
+export function countSpecTests(source, file) {
+  let tests = 0;
+  for (const [index, line] of source.split(/\r?\n/u).entries()) {
+    const top = /^test(\.[A-Za-z]+)?\s*\(/u.exec(line);
+    if (top) {
+      if (top[1] === undefined) tests += 1;
+      else {
+        throw new Error(
+          `${file}:${index + 1}: unrecognised top-level \`test${top[1]}(\` -- teach check-e2e-budget.mjs how many tests it creates`,
+        );
+      }
+      continue;
+    }
+    if (/\btest\s*\(/u.test(line)) {
+      throw new Error(
+        `${file}:${index + 1}: \`test(\` away from column 0 -- check-e2e-budget.mjs cannot count it`,
+      );
+    }
+  }
+  return tests;
+}
+
+export function collectSpecs(root = E2E_ROOT) {
+  const specs = {};
+  const walk = (directory) => {
+    for (const entry of readdirSync(directory, { withFileTypes: true }).sort((left, right) =>
+      left.name.localeCompare(right.name),
+    )) {
+      if (entry.name === 'node_modules') continue;
+      const absolute = join(directory, entry.name);
+      if (entry.isDirectory()) {
+        walk(absolute);
+        continue;
+      }
+      if (!SPEC_PATTERN.test(entry.name)) continue;
+      const file = relative(root, absolute).replaceAll('\\', '/');
+      specs[file] = countSpecTests(readFileSync(absolute, 'utf8'), file);
+    }
+  };
+  walk(root);
+  return specs;
+}
+
+export function compare(ledger, actual) {
+  const violations = [];
+  const recorded = ledger.specs ?? {};
+  for (const file of Object.keys(actual)) {
+    if (!(file in recorded)) {
+      violations.push(
+        `${file}: not in the budget (${actual[file]} test(s)) -- add it with a reason it needs a real window`,
+      );
+      continue;
+    }
+    const entry = recorded[file];
+    if (entry.tests !== actual[file]) {
+      violations.push(`${file}: budget records ${entry.tests} test(s), the file has ${actual[file]}`);
+    }
+    if (typeof entry.electron !== 'string' || entry.electron.trim() === '') {
+      violations.push(`${file}: no reason recorded for needing a real Electron window`);
+    }
+  }
+  for (const file of Object.keys(recorded)) {
+    if (!(file in actual)) violations.push(`${file}: in the budget but no longer on disk`);
+  }
+  return violations;
+}
+
+function main() {
+  const ledger = JSON.parse(readFileSync(LEDGER_PATH, 'utf8'));
+  const actual = collectSpecs();
+  const violations = compare(ledger, actual);
+  if (violations.length === 0) {
+    const total = Object.values(actual).reduce((sum, count) => sum + count, 0);
+    console.log(`E2E budget holds: ${total} tests in ${Object.keys(actual).length} files.`);
+    return;
+  }
+  console.error(
+    [
+      'The Electron E2E tier drifted from apps/desktop/e2e-budget.json:',
+      ...violations.map((line) => `- ${line}`),
+      '',
+      ...(ledger.policy ?? []),
+    ].join('\n'),
+  );
+  process.exit(1);
+}
+
+if (process.argv[1] && resolve(process.argv[1]) === SCRIPT_PATH) {
+  try {
+    main();
+  } catch (error) {
+    console.error(error instanceof Error ? error.message : error);
+    process.exit(1);
+  }
+}
diff --git a/apps/desktop/scripts/check-e2e-budget.test.mjs b/apps/desktop/scripts/check-e2e-budget.test.mjs
new file mode 100644
index 0000000000..1f7be98a91
--- /dev/null
+++ b/apps/desktop/scripts/check-e2e-budget.test.mjs
@@ -0,0 +1,93 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { deepEqual, equal, throws } from 'node:assert/strict';
+import { test } from 'node:test';
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { collectSpecs, compare, countSpecTests } from './check-e2e-budget.mjs';
+
+test('counts the top-level tests and nothing configuring them', () => {
+  const source = [
+    "import { test } from './fixtures';",
+    "test('one', async () => {});",
+    '  test.setTimeout(120_000);',
+    "test('two', async () => {});",
+  ].join('\n');
+  equal(countSpecTests(source, 'sample.spec.ts'), 2);
+});
+
+test('refuses a top-level form whose test count it cannot read', () => {
+  throws(
+    () => countSpecTests("test.describe('group', () => {});", 'sample.spec.ts'),
+    /unrecognised top-level `test\.describe\(`/u,
+  );
+});
+
+// A loop or a helper creates tests Playwright runs and this scanner cannot
+// attribute. Counting them as zero is how the tier grows back in silence.
+test('refuses a `test(` it cannot attribute to a line of its own', () => {
+  throws(
+    () => countSpecTests('for (const n of [1, 2]) {\n  test(`generated ${n}`, fn);\n}', 'a.spec.ts'),
+    /`test\(` away from column 0/u,
+  );
+});
+
+// playwright.config.ts sets `testDir: '.'` and no `testMatch`, so the tier is
+// everything Playwright's default pattern reaches -- subdirectories and the
+// `.test.ts` suffix included.
+test('finds every file Playwright would run, not just top-level .spec.ts', () => {
+  const root = mkdtempSync(join(tmpdir(), 'maka-e2e-budget-'));
+  try {
+    mkdirSync(join(root, 'nested'));
+    writeFileSync(join(root, 'plain.spec.ts'), "test('a', fn);\n");
+    writeFileSync(join(root, 'suffix.test.ts'), "test('b', fn);\n");
+    writeFileSync(join(root, 'nested', 'deep.spec.ts'), "test('c', fn);\ntest('d', fn);\n");
+    writeFileSync(join(root, 'fixtures.ts'), "test('not a spec file', fn);\n");
+    deepEqual(collectSpecs(root), {
+      'nested/deep.spec.ts': 2,
+      'plain.spec.ts': 1,
+      'suffix.test.ts': 1,
+    });
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test('reports every way the tier and the budget can disagree', () => {
+  deepEqual(
+    compare(
+      {
+        specs: {
+          'drifted.spec.ts': { tests: 1, electron: 'needs a window' },
+          'blank.spec.ts': { tests: 1, electron: '  ' },
+          'gone.spec.ts': { tests: 1, electron: 'needs a window' },
+        },
+      },
+      { 'drifted.spec.ts': 2, 'blank.spec.ts': 1, 'new.spec.ts': 1 },
+    ),
+    [
+      'drifted.spec.ts: budget records 1 test(s), the file has 2',
+      'blank.spec.ts: no reason recorded for needing a real Electron window',
+      'new.spec.ts: not in the budget (1 test(s)) -- add it with a reason it needs a real window',
+      'gone.spec.ts: in the budget but no longer on disk',
+    ],
+  );
+});
diff --git a/apps/desktop/src/main/__tests__/runtime-host-search-ipc-main.test.ts b/apps/desktop/src/main/__tests__/runtime-host-search-ipc-main.test.ts
index 3f127d52a9..8ddd3391a7 100644
--- a/apps/desktop/src/main/__tests__/runtime-host-search-ipc-main.test.ts
+++ b/apps/desktop/src/main/__tests__/runtime-host-search-ipc-main.test.ts
@@ -24,6 +24,16 @@ import type { SessionCatalogProjection } from '@maka/runtime-host/protocol';
 import type { IpcHandler } from '../ipc-reconnect-policy.js';
 import type { DesktopRuntimeHostClient } from '../runtime-host-client.js';
 import { registerRuntimeHostSearchIpc } from '../runtime-host-search-ipc-main.js';
+import { desktopSessionKey } from '../../shared/runtime-host-identity.js';
+
+// The catalog hands search a composed Desktop key, not a bare Runtime Host id.
+// Naming it here is what makes the passthrough in runtime-host-search-ipc-main
+// observable: a hit whose target carried the bare id would open nothing on a
+// second Host.
+const SEARCHABLE_SESSION = desktopSessionKey({
+  hostId: 'host-b',
+  sessionId: 'searchable-session',
+});
 
 test('Runtime Host transcripts produce title and content hits with turn ids', async () => {
   const handlers = new Map<string, IpcHandler>();
@@ -38,15 +48,21 @@ test('Runtime Host transcripts produce title and content hits with turn ids', as
       },
     },
     client: searchClient({
-      listSessions: async () => [catalogSession('searchable-session', '长对话提示词导航示例')],
+      listSessions: async () => [catalogSession(SEARCHABLE_SESSION, '长对话提示词导航示例')],
       openSession: async () =>
         ({
+          // Three earlier messages so the hit's `sequence` is its real position
+          // in the transcript. With a single message every projection, correct
+          // or not, reports 0.
           loadTranscript: async () => [
+            { type: 'user', id: 'host-user-0', turnId: 'turn-host-0', ts: 1, text: '第 0 个问题' },
+            { type: 'assistant', id: 'host-reply-0', turnId: 'turn-host-0', ts: 2, text: '回答 0' },
+            { type: 'user', id: 'host-user-1', turnId: 'turn-host-1', ts: 3, text: '第 1 个问题' },
             {
               type: 'user',
               id: 'host-user',
               turnId: 'turn-host-3',
-              ts: 1,
+              ts: 4,
               text: '第 3 个问题：这一段的调用链路是怎样的？',
             },
           ],
@@ -69,7 +85,7 @@ test('Runtime Host transcripts produce title and content hits with turn ids', as
   assert.equal(titleHits[0]?.summary, '任务标题');
   assert.deepEqual(titleHits[0]?.target, {
     kind: 'thread',
-    sessionId: 'searchable-session',
+    sessionId: SEARCHABLE_SESSION,
   });
 
   const contentHits = expectResults(
@@ -83,9 +99,9 @@ test('Runtime Host transcripts produce title and content hits with turn ids', as
   assert.equal(contentHits[0]?.summary, '用户消息');
   assert.deepEqual(contentHits[0]?.target, {
     kind: 'thread',
-    sessionId: 'searchable-session',
+    sessionId: SEARCHABLE_SESSION,
     turnId: 'turn-host-3',
-    sequence: 0,
+    sequence: 3,
   });
   assert.equal(closed, 2);
 });
diff --git a/apps/desktop/src/renderer/styles/workbar/shell.css b/apps/desktop/src/renderer/styles/workbar/shell.css
index f62b09e407..c19291701f 100644
--- a/apps/desktop/src/renderer/styles/workbar/shell.css
+++ b/apps/desktop/src/renderer/styles/workbar/shell.css
@@ -170,7 +170,7 @@
   );
   /* The right pad is the window titlebar strip's own gutter, not this bar's:
      the collapse toggle is one control that moves between the two bands, and
-     `session-workbar.spec.ts` holds it to the same x in both. Narrowing this to
+     `app-shell.stories.tsx` holds it to the same x in both. Narrowing this to
      the bar's own gutter would slide it 16px on every collapse. On top of it,
      the caption buttons where the platform draws them on the right (Windows);
      macOS puts them on the left, over the sidebar, and reports 0 here. */
diff --git a/apps/desktop/src/renderer/styles/workbar/side-chat.css b/apps/desktop/src/renderer/styles/workbar/side-chat.css
index b041086329..e8c4f61894 100644
--- a/apps/desktop/src/renderer/styles/workbar/side-chat.css
+++ b/apps/desktop/src/renderer/styles/workbar/side-chat.css
@@ -64,7 +64,7 @@
    bubble; a side-only radius token forked the pair the moment the bubbles moved
    to the primitive's default. The wrapper is also left unclipped — `overflow:
    hidden` here would hide the body's hover/focus shadow against the white side
-   panel, and `session-workbar.spec.ts` asserts `overflow: visible`. */
+   panel, and `session-workbar.stories.tsx` asserts `overflow: visible`. */
 
 .maka-session-workbar-panel[data-placement="right"]
   .maka-quote-companion
diff --git a/apps/desktop/stories/agent-graph-panel.stories.tsx b/apps/desktop/stories/agent-graph-panel.stories.tsx
index f9de92b649..dcae4eed15 100644
--- a/apps/desktop/stories/agent-graph-panel.stories.tsx
+++ b/apps/desktop/stories/agent-graph-panel.stories.tsx
@@ -142,8 +142,8 @@ function graphBridge(snap: AgentGraphClientSnapshot, fail = false) {
 // `.maka-detail-with-artifacts`). Reuse those wrapper classes so the panel
 // inherits the composer column's seam rather than an arbitrary fixed box. The
 // full AppShell grid and Composer chrome around it are not rebuilt here — that
-// seam lives in Product/Shell Official AppShell, and its geometry is pinned by
-// e2e/session-workbar.spec.ts — so this isolates the panel itself at a
+// seam lives in Product/Shell Official AppShell, where its geometry is pinned
+// by that group's own play functions — so this isolates the panel itself at a
 // composer-column width.
 function panel() {
   return (
diff --git a/apps/desktop/stories/app-shell.stories.tsx b/apps/desktop/stories/app-shell.stories.tsx
index 419f92dc26..89b953e9e9 100644
--- a/apps/desktop/stories/app-shell.stories.tsx
+++ b/apps/desktop/stories/app-shell.stories.tsx
@@ -19,7 +19,7 @@
 
 import type { Meta, StoryObj } from '@storybook/react-vite';
 import { expect, userEvent, waitFor, within } from 'storybook/test';
-import { useEffect, useState, type CSSProperties, type ReactNode } from 'react';
+import { useEffect, useReducer, useState, type CSSProperties, type ReactNode } from 'react';
 import type { ComponentProps } from 'react';
 import type { ProjectRecord } from '@maka/core/project';
 import type { SessionSummary, StoredMessage } from '@maka/core/session';
@@ -29,11 +29,24 @@ import {
   Composer,
   deriveTitlebarProjectName,
   TitlebarSessionIdentity,
+  ToastProvider,
 } from '@maka/ui';
 import type { ChatModelChoice, SessionViewMode, TurnViewModel } from '@maka/ui';
 import { SessionRail, type SessionRailStoryProps } from '../../../packages/ui/stories/session-rail-harness.js';
 import { AppShellTopbarActions } from '../src/renderer/app-shell-chrome-actions';
-import { WorkbarTitlebarActions } from '../src/renderer/features/workbar';
+import {
+  WorkbarServicesProvider,
+  WorkbarTitlebarActions,
+} from '../src/renderer/features/workbar';
+import { WorkbarSurface } from '../src/renderer/features/workbar/stories';
+import {
+  createFakeWorkbarServices,
+  createSessionWorkbarPanelsState,
+  reduceWorkbarLayout,
+  SESSION_BOTTOM_PANEL_DEFAULT_HEIGHT,
+  SESSION_WORKBAR_DEFAULT_WIDTH,
+  type WorkbarLayoutState,
+} from '../src/renderer/features/workbar/testing';
 import { AppShellDetailPanel } from '../src/renderer/app-shell-detail-panel';
 import { deriveAppShellTurnPresentation } from '../src/renderer/app-shell-turn-view-model';
 import {
@@ -341,6 +354,8 @@ function ComposedShell(props: {
   frameHeight?: number | string;
   /** Drives the footer's update action; `undefined` is the silent phase. */
   updateReminder?: SessionListPanelProps['updateReminder'];
+  workbarCollapsed?: boolean;
+  onToggleWorkbar?: () => void;
 }) {
   const [collapsed, setCollapsed] = useState(props.sidebarCollapsed ?? false);
   const [viewMode, setViewMode] = useState<SessionViewMode>(props.initialViewMode ?? 'conversation');
@@ -413,8 +428,8 @@ function ComposedShell(props: {
         )}
         <WorkbarTitlebarActions
           available
-          collapsed={false}
-          onToggle={noop}
+          collapsed={props.workbarCollapsed ?? false}
+          onToggle={props.onToggleWorkbar ?? noop}
         />
       </header>
       <AstryxAppShell
@@ -2811,3 +2826,154 @@ export const RailStaysOnTheVisiblePrompt: Story = {
     ).toBe(true);
   },
 };
+
+// What the real `open` action leaves behind, rather than a hand-written topology.
+const workbarLayoutWithOneFace: WorkbarLayoutState = reduceWorkbarLayout(
+  {
+    panels: createSessionWorkbarPanelsState(),
+    rightCollapsed: true,
+    bottomOpen: false,
+    rightWidth: SESSION_WORKBAR_DEFAULT_WIDTH,
+    bottomHeight: SESSION_BOTTOM_PANEL_DEFAULT_HEIGHT,
+  },
+  { type: 'open', placement: 'right', tab: { id: 'workbar:files', kind: 'files' } },
+);
+
+function WorkbarInShell() {
+  const [layout, dispatch] = useReducer(reduceWorkbarLayout, workbarLayoutWithOneFace);
+  const collapseRight = (collapsed: boolean) =>
+    dispatch({ type: 'collapse', placement: 'right', collapsed });
+  return (
+    <ToastProvider>
+      <WorkbarServicesProvider services={createFakeWorkbarServices()}>
+        <ComposedShell
+          workbarCollapsed={layout.rightCollapsed}
+          onToggleWorkbar={() => collapseRight(!layout.rightCollapsed)}
+          detailChildren={
+            <div
+              className="maka-detail-with-artifacts"
+              style={
+                { '--maka-session-workbar-width': `${layout.rightWidth}px` } as CSSProperties
+              }
+            >
+              <div className="mainColumn" />
+              <WorkbarSurface
+                sessionId="session-active"
+                hidden={false}
+                onDismissPanel={() => collapseRight(true)}
+                panelsState={layout.panels}
+                rightCollapsed={layout.rightCollapsed}
+                bottomOpen={layout.bottomOpen}
+                onActivateTab={(placement, tabId) =>
+                  dispatch({ type: 'activate', placement, tabId })
+                }
+                onCloseTab={(placement, tab) =>
+                  dispatch({ type: 'close', placement, tabIds: [tab.id] })
+                }
+                onCloseTabs={(placement, tabs) =>
+                  dispatch({ type: 'close', placement, tabIds: tabs.map((tab) => tab.id) })
+                }
+                onOpenLauncher={(placement) => dispatch({ type: 'open-launcher', placement })}
+                onRequestOpenTab={(placement, kind) =>
+                  dispatch({
+                    type: 'open',
+                    placement,
+                    tab: { id: `workbar:${kind}`, kind },
+                  })
+                }
+                confirmBypass={async () => true}
+              />
+            </div>
+          }
+        />
+      </WorkbarServicesProvider>
+    </ToastProvider>
+  );
+}
+
+// Real path: 收起一个开着面的工作栏 → 从标题栏再展开. The face is opened by
+// dispatching the app's own `open` action rather than by clicking through the
+// launcher, so the story starts where the app does without re-testing the
+// launcher's own path.
+//
+// The collapse toggle is one control that moves between two bands — the
+// workbar's own bar and the titlebar's right cluster — and `workbar/shell.css`
+// pads the bar with the titlebar strip's gutter precisely so it lands on the
+// same x in both. Only a story that mounts both bands can hold it there, which
+// is why this lives beside the shell rather than with the workbar's own
+// stories.
+export const WorkbarCollapseKeepsOneToggleInPlace: Story = {
+  render: () => <WorkbarInShell />,
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    const frame = canvasElement.querySelector<HTMLElement>(
+      '[data-maka-contract="session-workbar-right"]',
+    );
+    if (!frame) throw new Error('the right workbar is missing');
+    // The face's content is a sibling overlay panel with its own `hidden`
+    // (workbar-surface.tsx), so a visible frame does not mean a visible face.
+    const facePanel = canvasElement.querySelector<HTMLElement>(
+      '.maka-session-workbar-panel[data-overlay][data-placement="right"]',
+    );
+    if (!facePanel) throw new Error('the open face has no panel');
+    const bar = within(frame.querySelector<HTMLElement>('.maka-session-workbar-toolbar')!);
+    const collapse = bar.getByRole('button', { name: '收起任务工作栏' });
+    // The launcher stays mounted behind the face, so "not the picker" is a
+    // claim about reachability: `queryByRole` skips the inactive panel.
+    const pickerIsShowing = () =>
+      canvas.queryByRole('list', { name: '打开工具' }) !== null;
+    const face = await bar.findByRole('tab', { selected: true });
+
+    expect(canvas.queryByRole('toolbar', { name: '工作区辅助操作' })).toBeNull();
+    expect(pickerIsShowing()).toBe(false);
+
+    const faceBox = face.getBoundingClientRect();
+    const openToggleBox = collapse.getBoundingClientRect();
+    expect(
+      Math.abs(
+        faceBox.y + faceBox.height / 2 - (openToggleBox.y + openToggleBox.height / 2),
+      ),
+    ).toBeLessThanOrEqual(1);
+
+    // Windows draws its caption buttons over the right of the strip and reports
+    // their width here; macOS reports 0. The bar has to give that width back.
+    const captionWidth = 80;
+    canvasElement.style.setProperty(
+      '--maka-titlebar-overlay-right-width',
+      `${captionWidth}px`,
+    );
+    await waitFor(() => {
+      expect(collapse.getBoundingClientRect().x).toBeCloseTo(
+        openToggleBox.x - captionWidth,
+        0,
+      );
+    });
+    const parked = collapse.getBoundingClientRect();
+
+    // [+] is a menu over the panel, not a swap to the launcher: the face you
+    // are reading stays on screen while you pick another one.
+    await userEvent.click(bar.getByRole('button', { name: '打开或关闭工作栏的面' }));
+    const menu = await within(document.body).findByRole('menu');
+    await userEvent.keyboard('{Escape}');
+    await waitFor(() => expect(menu).not.toBeVisible());
+    expect(pickerIsShowing()).toBe(false);
+
+    await userEvent.click(collapse);
+    const restore = await canvas.findByRole('button', { name: '展开任务工作栏' });
+    await waitFor(() => expect(frame).not.toBeVisible());
+    expect(facePanel).not.toBeVisible();
+    const restoreBox = restore.getBoundingClientRect();
+    expect(Math.abs(restoreBox.x - parked.x)).toBeLessThanOrEqual(1);
+    expect(Math.abs(restoreBox.y - parked.y)).toBeLessThanOrEqual(1);
+
+    await userEvent.click(restore);
+    await waitFor(() => expect(frame).toBeVisible());
+    expect(facePanel).toBeVisible();
+    expect(pickerIsShowing()).toBe(false);
+    const restoredToggleBox = bar
+      .getByRole('button', { name: '收起任务工作栏' })
+      .getBoundingClientRect();
+    expect(Math.abs(restoredToggleBox.x - parked.x)).toBeLessThanOrEqual(1);
+    expect(Math.abs(restoredToggleBox.y - parked.y)).toBeLessThanOrEqual(1);
+  },
+};
diff --git a/apps/desktop/stories/session-workbar.stories.tsx b/apps/desktop/stories/session-workbar.stories.tsx
index 168856188c..4c25fc3043 100644
--- a/apps/desktop/stories/session-workbar.stories.tsx
+++ b/apps/desktop/stories/session-workbar.stories.tsx
@@ -54,9 +54,8 @@ import {
 //
 // What this group cannot show: the seam. The workbar's surface tone only reads
 // as a seam against the conversation plate it stands beside, and the plate is
-// two levels up in the shell — as is the titlebar clearance the surface bleeds
-// through. Both are pinned by computed-style assertions in
-// e2e/session-workbar.spec.ts instead.
+// two levels up in the shell — as is the titlebar band the collapse toggle
+// moves into. Those belong to app-shell.stories.tsx, which mounts the shell.
 //
 // Read these at a canvas of 990px or wider. The app's own breakpoint is on the
 // viewport, and Storybook's canvas IS the viewport, so a narrower window puts
@@ -1027,6 +1026,28 @@ export const ToolPicker: Story = {
   render: () => <Workbar sourceSession={TOOL_PICKER_SOURCE_SESSION} />,
 };
 
+// The picker at the column's 320px floor. Every shortcut hint has to stay
+// inside the column: the launcher rows lay the label and the `kbd` on one line,
+// so the first thing a too-narrow column does is push the hints past the edge.
+export const ToolPickerAtColumnFloor: Story = {
+  decorators: [bridge()],
+  render: () => <Workbar sourceSession={TOOL_PICKER_SOURCE_SESSION} width={320} />,
+  play: async ({ canvasElement }) => {
+    const launcher = await within(canvasElement).findByRole('list', { name: '打开工具' });
+    const column = launcher.closest<HTMLElement>('.maka-session-workbar');
+    if (!column) throw new Error('workbar column is missing');
+    const panelBox = column.getBoundingClientRect();
+    const shortcuts = [...launcher.querySelectorAll('kbd')];
+
+    expect(shortcuts.length).toBeGreaterThan(0);
+    for (const shortcut of shortcuts) {
+      const box = shortcut.getBoundingClientRect();
+      expect(box.left).toBeGreaterThanOrEqual(panelBox.left);
+      expect(box.right).toBeLessThanOrEqual(panelBox.right);
+    }
+  },
+};
+
 // Real path: 任务工作栏 → 变更, showing the live branch comparison from the
 // session cwd. The panel is Git-backed; no message or tool-result fixture is
 // involved in this story.
@@ -1226,16 +1247,35 @@ export const BrowserInsecure: Story = {
   render: () => <Workbar tab="browser" />,
 };
 
-// The column's 320px floor — the least room the toolbar row ever gets.
-export const BrowserAtColumnFloor: Story = {
+// #2188: the address field, not the nav buttons, absorbs the column's free
+// width. The rule reaches into Astryx Toolbar's slot div, so an upstream
+// slot-wrapper change regresses it silently. This is also the floor's pixel
+// story: the play leaves the column at 320px, the least room the toolbar row
+// ever gets.
+export const BrowserAddressFieldTracksColumnWidth: Story = {
   decorators: [bridge({ browserState: LOADED_BROWSER_STATE })],
-  render: () => <Workbar tab="browser" width={320} />,
-};
+  render: () => <Workbar tab="browser" />,
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    const address = await canvas.findByRole('textbox', { name: '浏览器地址' });
+    const frame = canvasElement.querySelector<HTMLElement>('.maka-detail-with-artifacts');
+    // The face's content lives in the overlay panel beside the workbar frame,
+    // so the panel is what carries the column width, not `.maka-session-workbar`.
+    const column = address.closest<HTMLElement>('.maka-session-workbar-panel');
+    if (!frame || !column) throw new Error('workbar panel is missing');
+    const widthAt = async (columnWidth: number) => {
+      frame.style.setProperty('--maka-session-workbar-width', `${columnWidth}px`);
+      await waitFor(() => {
+        expect(column.getBoundingClientRect().width).toBeCloseTo(columnWidth, 0);
+      });
+      return address.getBoundingClientRect().width;
+    };
 
-// The width the resize handle lands on most often, between the floor and default.
-export const BrowserAt400: Story = {
-  decorators: [bridge({ browserState: LOADED_BROWSER_STATE })],
-  render: () => <Workbar tab="browser" width={400} />,
+    expect(await widthAt(480)).toBeGreaterThan(250);
+    const atFloor = await widthAt(320);
+    expect(atFloor).toBeLessThan(220);
+    expect(atFloor).toBeGreaterThan(100);
+  },
 };
 
 // Below 990px the grid stacks the same right-placement column under the
@@ -1320,6 +1360,52 @@ export const SideChat: Story = {
   render: () => <Workbar tab="side-chat" />,
 };
 
+// Real path: 侧边对话 at the column's 320px floor, under a long model label.
+export const SideChatAtColumnFloor: Story = {
+  decorators: [bridge()],
+  render: () => <Workbar tab="side-chat" width={320} />,
+  play: async ({ canvasElement }) => {
+    const companion = await waitFor(() => {
+      const found = canvasElement.querySelector<HTMLElement>('.maka-quote-companion');
+      if (!found?.querySelector('.maka-composer-astryx')) {
+        throw new Error('side chat companion is missing');
+      }
+      return found;
+    });
+    const card = companion.querySelector<HTMLElement>('.maka-composer-astryx')!;
+
+    expect(getComputedStyle(card).overflow).toBe('visible');
+
+    // The plate has to round the same as a bubble does; a side-only
+    // `--_chat-composer-radius` is what split the dock from the bubble in
+    // #3452. Measure a probe the token paints instead of reading the token
+    // back — ink-ladder-contract.test.ts forbids the latter.
+    const plate = card.firstElementChild;
+    if (!plate) throw new Error('composer plate is missing');
+    const probe = document.createElement('div');
+    probe.style.borderRadius = 'var(--radius-chat)';
+    card.append(probe);
+    const bubbleRadius = getComputedStyle(probe).borderTopLeftRadius;
+    probe.remove();
+    expect(bubbleRadius).not.toBe('0px');
+    expect(getComputedStyle(plate).borderTopLeftRadius).toBe(bubbleRadius);
+
+    // Written here rather than in the fixture: the fixture's default model is
+    // shared by every other story.
+    const label = companion.querySelector<HTMLElement>('.maka-composer-model-chip-text');
+    if (!label) throw new Error('side chat model chip is missing');
+    label.textContent = 'Nemotron 3 Ultra Long Context Model';
+
+    const send = within(companion).getByRole('button', { name: '发送' });
+    await waitFor(() => {
+      const cardBox = card.getBoundingClientRect();
+      const sendBox = send.getBoundingClientRect();
+      expect(sendBox.left).toBeGreaterThanOrEqual(cardBox.left);
+      expect(sendBox.right).toBeLessThanOrEqual(cardBox.right);
+    });
+  },
+};
+
 // Real path: 任务工作栏 → 追踪, on a session that has run turns — the overview
 // reads a context budget, token/cache figures and the session's facts off a
 // retried model call and a post-compaction call, while a turn that failed on a
diff --git a/apps/desktop/stories/workhub.stories.tsx b/apps/desktop/stories/workhub.stories.tsx
new file mode 100644
index 0000000000..be53b4e57e
--- /dev/null
+++ b/apps/desktop/stories/workhub.stories.tsx
@@ -0,0 +1,138 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import type { Meta, StoryObj } from '@storybook/react-vite';
+import { expect, waitFor } from 'storybook/test';
+import type {
+  WorkHubController,
+  WorkHubCoordinationTurn,
+  WorkHubProjection,
+} from '../src/renderer/workhub-controller';
+import { WorkHubSurface } from '../src/renderer/workhub-surface';
+
+// Fidelity convention (#1433): every story names the real app path that
+// reaches it. See apps/desktop/stories/FIDELITY.md.
+//
+// Real host: app-shell.tsx mounts <WorkHubSurface> in the conversation column
+// when WorkHub is enabled and a Coordination Session exists. The surface takes
+// its `controller` as a prop — the same seam production fills with
+// `createWorkHubController` — so a story serves one pinned projection and
+// conversation instead of driving a live Coordination Session.
+
+const TARGET_SESSION_ID = 'session-workhub-target';
+const SESSION_NAME = '支付回调幂等性';
+const PROJECT_NAME = 'maka-agent';
+const LOCALE = 'zh-CN';
+
+const meta = {
+  title: 'Product/WorkHub',
+  parameters: { layout: 'fullscreen' },
+} satisfies Meta;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+function submittedTurn(): WorkHubCoordinationTurn {
+  return {
+    messageId: 'message-1',
+    turnId: 'turn-1',
+    text: `继续${SESSION_NAME}，补充重复投递测试点。`,
+    state: 'running',
+    assignment: {
+      actionId: 'action-1',
+      delegationId: 'delegation-1',
+      targetSessionId: TARGET_SESSION_ID,
+      targetSessionName: SESSION_NAME,
+      targetMessageId: 'target-message-1',
+      targetTurnId: 'target-turn-1',
+      feedbackState: 'running',
+      linkState: 'active',
+    },
+    updatedAt: 1,
+  };
+}
+
+function projection(): WorkHubProjection {
+  return {
+    sessions: [
+      {
+        target: { sessionId: TARGET_SESSION_ID },
+        projectName: PROJECT_NAME,
+        sessionName: SESSION_NAME,
+        archived: false,
+        state: 'running',
+        updatedAt: 1,
+      },
+    ],
+    turns: [],
+  };
+}
+
+function controller(turns: readonly WorkHubCoordinationTurn[]): WorkHubController {
+  return {
+    read: async () => projection(),
+    submit: async () => {
+      throw new Error('submission is not part of these stories');
+    },
+    openConversation: async (handler) => {
+      handler(turns);
+      return { close: async () => {} };
+    },
+    recordConversationTurn: async ({ turnId }) => ({ turnId }),
+    subscribe: () => () => {},
+    resetVisitContext: () => {},
+  };
+}
+
+function Surface(props: { turns: readonly WorkHubCoordinationTurn[] }) {
+  return (
+    <div className="maka-detail-with-artifacts" style={{ height: '100dvh' }}>
+      <div className="mainColumn">
+        <WorkHubSurface
+          controller={controller(props.turns)}
+          leaseScope="session-workhub-coordination"
+          locale={LOCALE}
+          onOpenSession={() => {}}
+        />
+      </div>
+    </div>
+  );
+}
+
+// Real path: WorkHub routed a prompt to an existing Session and reports where
+// the work went. The target's project name is a `<small>` inside the Button's
+// own label column, so it has to stay inside the control's box: a project name
+// that overflows the button reads as loose text under an unrelated row.
+export const SubmittedWorkKeepsTargetMetadataInside: Story = {
+  render: () => <Surface turns={[submittedTurn()]} />,
+  play: async ({ canvasElement }) => {
+    await waitFor(() => {
+      expect(canvasElement.querySelector('.workhub-submitted-session small')).not.toBeNull();
+    });
+    const button = canvasElement.querySelector<HTMLElement>('.workhub-submitted > button');
+    const project = canvasElement.querySelector<HTMLElement>('.workhub-submitted-session small');
+    if (!button || !project) throw new Error('submitted work control is missing');
+
+    expect(project.textContent).toBe(PROJECT_NAME);
+    expect(button.getBoundingClientRect().bottom).toBeGreaterThanOrEqual(
+      project.getBoundingClientRect().bottom,
+    );
+  },
+};
diff --git a/package.json b/package.json
index 43c10a5ee5..862fe01018 100644
--- a/package.json
+++ b/package.json
@@ -32,6 +32,7 @@
     "lint": "biome lint .",
     "format": "biome format --write .",
     "format:check": "biome format .",
+    "check:e2e-budget": "npm --workspace @maka/desktop run check:e2e-budget",
     "check:renderer-architecture": "npm --workspace @maka/desktop run check:architecture --",
     "typecheck": "npm run typecheck --workspaces --if-present",
     "test": "npm run build:test && node scripts/run-workspace-tests-parallel.mjs --concurrency=3",