diff --git a/apps/pwa/e2e/layout.spec.ts b/apps/pwa/e2e/layout.spec.ts
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+/**
+ * layout.spec.ts — TEST-01
+ *
+ * Cross-route structural quality-bar assertions (UI-SPEC Rules 1-4):
+ *   Rule 1: Touch-target minimum ≥44×44px (FAB ≥56×56px)
+ *   Rule 2: No horizontal overflow (scrollWidth ≤ clientWidth)
+ *   Rule 3: Critical elements visible and in-viewport on initial load
+ *   Rule 4: Accessible names on all interactive elements (role+name locators)
+ *
+ * Runs on both device profiles automatically (playwright.config.ts matrix):
+ *   iphone: iPhone 14 / WebKit / 390×844
+ *   pixel:  Pixel 7 / Chromium / 412×915
+ *
+ * STRICT-MODE NOTE:
+ *   On mobile viewports (≤767px), AppNav renders PhoneNav as a <header> element
+ *   (NOT a nav landmark) — it does NOT expose a navigation landmark. BottomTabBar
+ *   renders the sole <nav aria-label="Main navigation"> on mobile. There is no
+ *   strict-mode collision on these profiles.
+ *   The DesktopNav <nav aria-label="Main navigation"> is only rendered at ≥768px
+ *   and is not visible on either test profile.
+ *
+ * Run:
+ *   pnpm --filter @familysync/pwa test:e2e
+ *   pnpm --filter @familysync/pwa exec playwright test --project=pixel layout.spec.ts
+ */
+import { test, expect } from '@playwright/test'
+
+// ── Rule 1 + Rule 3 + Rule 4: BottomTabBar tap targets, visibility, accessible names ──
+
+test.describe('Rule 1/3/4 — BottomTabBar tap targets and in-viewport position', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.goto('/calendar')
+  })
+
+  test('BottomTabBar navigation landmark is visible (Rule 4 — accessible name)', async ({
+    page,
+  }) => {
+    // On mobile profiles the sole navigation landmark is the BottomTabBar nav.
+    // getByRole succeeds ↔ accessible name exists — doubles as Rule 4 gate.
+    await expect(
+      page.getByRole('navigation', { name: 'Main navigation' }),
+    ).toBeVisible()
+  })
+
+  test('Calendar tab meets 44×44px touch-target minimum (Rule 1)', async ({ page }) => {
+    // Scope to the navigation landmark to stay robust if desktop nav ever appears.
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    const calTab = nav.getByRole('link', { name: 'Calendar' })
+    const box = await calTab.boundingBox()
+    expect(box, 'Calendar tab bounding box must not be null').not.toBeNull()
+    expect(box!.width, 'Calendar tab width ≥ 44px').toBeGreaterThanOrEqual(44)
+    expect(box!.height, 'Calendar tab height ≥ 44px').toBeGreaterThanOrEqual(44)
+  })
+
+  test('Lists tab meets 44×44px touch-target minimum (Rule 1)', async ({ page }) => {
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    const listsTab = nav.getByRole('link', { name: 'Lists' })
+    const box = await listsTab.boundingBox()
+    expect(box, 'Lists tab bounding box must not be null').not.toBeNull()
+    expect(box!.width, 'Lists tab width ≥ 44px').toBeGreaterThanOrEqual(44)
+    expect(box!.height, 'Lists tab height ≥ 44px').toBeGreaterThanOrEqual(44)
+  })
+
+  test('BottomTabBar is fully in-viewport (Rule 3 — safe-area-inset)', async ({ page }) => {
+    // The bar uses env(safe-area-inset-bottom, 0px). In emulation there is no
+    // safe-area-inset, so the bar's bottom edge must be ≤ viewport height.
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    await expect(nav).toBeVisible()
+    const box = await nav.boundingBox()
+    expect(box, 'BottomTabBar bounding box must not be null').not.toBeNull()
+    const viewportHeight = page.viewportSize()!.height
+    expect(
+      box!.y + box!.height,
+      `BottomTabBar bottom edge (${box!.y + box!.height}) must be ≤ viewport height (${viewportHeight})`,
+    ).toBeLessThanOrEqual(viewportHeight)
+  })
+
+  test('PhoneNav header is visible (Rule 3)', async ({ page }) => {
+    // PhoneNav renders a <header> with exact text "FamilySync" (not a nav landmark).
+    // Use exact:true to avoid matching the "Install FamilySync" install-prompt text.
+    await expect(page.getByText('FamilySync', { exact: true })).toBeVisible()
+  })
+
+  test('PhoneNav settings button meets 44×44px touch-target minimum (Rule 1)', async ({
+    page,
+  }) => {
+    // aria-label: "${displayName} — open settings" (AppNav.tsx PhoneNav)
+    const settingsBtn = page.getByRole('button', { name: /open settings/i })
+    const box = await settingsBtn.boundingBox()
+    expect(box, 'Settings button bounding box must not be null').not.toBeNull()
+    expect(box!.width, 'Settings button width ≥ 44px').toBeGreaterThanOrEqual(44)
+    expect(box!.height, 'Settings button height ≥ 44px').toBeGreaterThanOrEqual(44)
+  })
+
+  test('New Event FAB meets 56×56px touch-target minimum (Rule 1)', async ({ page }) => {
+    // Phone-only FAB — aria-label="New Event", fixed 56×56px (CalendarShell.tsx)
+    const fab = page.getByRole('button', { name: 'New Event' })
+    const box = await fab.boundingBox()
+    expect(box, 'New Event FAB bounding box must not be null').not.toBeNull()
+    expect(box!.width, 'New Event FAB width ≥ 56px').toBeGreaterThanOrEqual(56)
+    expect(box!.height, 'New Event FAB height ≥ 56px').toBeGreaterThanOrEqual(56)
+  })
+})
+
+// ── Rule 1/3/4 repeated on /lists ──
+
+test.describe('Rule 1/3/4 — BottomTabBar on /lists', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.goto('/lists')
+  })
+
+  test('BottomTabBar navigation landmark is visible on /lists (Rule 4)', async ({ page }) => {
+    await expect(
+      page.getByRole('navigation', { name: 'Main navigation' }),
+    ).toBeVisible()
+  })
+
+  test('Calendar tab meets 44×44px on /lists (Rule 1)', async ({ page }) => {
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    const calTab = nav.getByRole('link', { name: 'Calendar' })
+    const box = await calTab.boundingBox()
+    expect(box).not.toBeNull()
+    expect(box!.width).toBeGreaterThanOrEqual(44)
+    expect(box!.height).toBeGreaterThanOrEqual(44)
+  })
+
+  test('Lists tab meets 44×44px on /lists (Rule 1)', async ({ page }) => {
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    const listsTab = nav.getByRole('link', { name: 'Lists' })
+    const box = await listsTab.boundingBox()
+    expect(box).not.toBeNull()
+    expect(box!.width).toBeGreaterThanOrEqual(44)
+    expect(box!.height).toBeGreaterThanOrEqual(44)
+  })
+
+  test('BottomTabBar is fully in-viewport on /lists (Rule 3)', async ({ page }) => {
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    await expect(nav).toBeVisible()
+    const box = await nav.boundingBox()
+    expect(box).not.toBeNull()
+    const viewportHeight = page.viewportSize()!.height
+    expect(box!.y + box!.height).toBeLessThanOrEqual(viewportHeight)
+  })
+})
+
+// ── Rule 2: No horizontal overflow ──
+
+test.describe('Rule 2 — No horizontal overflow', () => {
+  test('no overflow on /calendar', async ({ page }) => {
+    await page.goto('/calendar')
+    const overflow = await page.evaluate(() => ({
+      scrollWidth: document.documentElement.scrollWidth,
+      clientWidth: document.documentElement.clientWidth,
+    }))
+    expect(
+      overflow.scrollWidth,
+      `scrollWidth (${overflow.scrollWidth}) must be ≤ clientWidth (${overflow.clientWidth}) on /calendar`,
+    ).toBeLessThanOrEqual(overflow.clientWidth)
+  })
+
+  test('no overflow on /lists', async ({ page }) => {
+    await page.goto('/lists')
+    const overflow = await page.evaluate(() => ({
+      scrollWidth: document.documentElement.scrollWidth,
+      clientWidth: document.documentElement.clientWidth,
+    }))
+    expect(
+      overflow.scrollWidth,
+      `scrollWidth (${overflow.scrollWidth}) must be ≤ clientWidth (${overflow.clientWidth}) on /lists`,
+    ).toBeLessThanOrEqual(overflow.clientWidth)
+  })
+})
+
+// ── Harness self-validation — injected-defect proofs (TEST-01 acceptance bar) ──
+//
+// Each test is a PASSING test that proves the assertion would have failed under a
+// deliberately injected defect and recovers once the injection is removed.
+// The suite stays green; the proofs demonstrate the harness measures rendered
+// geometry rather than CSS source values.
+
+test.describe('harness self-validation — injected defects', () => {
+  test('Rule 1 proof: tap-target assertion fails under 20px injection, passes after removal', async ({
+    page,
+  }) => {
+    await page.goto('/calendar')
+
+    // Confirm the nav is visible before injection
+    const nav = page.getByRole('navigation', { name: 'Main navigation' })
+    await expect(nav).toBeVisible()
+
+    // INJECT: force BottomTabBar links to 20px height — simulates a broken tap target
+    const styleHandle = await page.addStyleTag({
+      content:
+        'nav[aria-label="Main navigation"] a { min-height: 20px !important; height: 20px !important; max-height: 20px !important; }',
+    })
+
+    // Measure WHILE injected — must be < 44px to prove the assertion tracks geometry
+    const calTab = nav.getByRole('link', { name: 'Calendar' })
+    const boxWithDefect = await calTab.boundingBox()
+    expect(
+      boxWithDefect,
+      'Calendar tab bounding box must not be null even with defect injected',
+    ).not.toBeNull()
+    expect(
+      boxWithDefect!.height,
+      'Height must be < 44px with 20px injection (proving measurement tracks rendered geometry)',
+    ).toBeLessThan(44)
+
+    // REMOVE the injected style by navigating (page.reload drops inline style tags)
+    // then re-measure — must be ≥ 44px again
+    await styleHandle.evaluate((el) => el.remove())
+    const boxAfterRemoval = await calTab.boundingBox()
+    expect(
+      boxAfterRemoval,
+      'Calendar tab bounding box must not be null after defect removal',
+    ).not.toBeNull()
+    expect(
+      boxAfterRemoval!.height,
+      'Height must be ≥ 44px after defect style is removed',
+    ).toBeGreaterThanOrEqual(44)
+  })
+
+  test('Rule 2 proof: overflow assertion fails under 2000px injection, passes after removal', async ({
+    page,
+  }) => {
+    await page.goto('/calendar')
+
+    // Confirm baseline — no overflow before injection
+    const baseOverflow = await page.evaluate(() => ({
+      scrollWidth: document.documentElement.scrollWidth,
+      clientWidth: document.documentElement.clientWidth,
+    }))
+    expect(baseOverflow.scrollWidth).toBeLessThanOrEqual(baseOverflow.clientWidth)
+
+    // INJECT: force body width to 2000px — simulates Schedule-X overflow defect
+    const styleHandle = await page.addStyleTag({
+      content: 'body { width: 2000px !important; }',
+    })
+
+    // Measure WHILE injected — scrollWidth must exceed clientWidth
+    const overflowWithDefect = await page.evaluate(() => ({
+      scrollWidth: document.documentElement.scrollWidth,
+      clientWidth: document.documentElement.clientWidth,
+    }))
+    expect(
+      overflowWithDefect.scrollWidth,
+      `scrollWidth (${overflowWithDefect.scrollWidth}) must be > clientWidth (${overflowWithDefect.clientWidth}) with 2000px injection (proving overflow detection works)`,
+    ).toBeGreaterThan(overflowWithDefect.clientWidth)
+
+    // REMOVE the injected style — overflow must clear
+    await styleHandle.evaluate((el) => el.remove())
+    const overflowAfterRemoval = await page.evaluate(() => ({
+      scrollWidth: document.documentElement.scrollWidth,
+      clientWidth: document.documentElement.clientWidth,
+    }))
+    expect(
+      overflowAfterRemoval.scrollWidth,
+      'scrollWidth must be ≤ clientWidth after 2000px injection is removed',
+    ).toBeLessThanOrEqual(overflowAfterRemoval.clientWidth)
+  })
+})