diff --git a/core/http/react-ui/e2e/addons-runtime.spec.js b/core/http/react-ui/e2e/addons-runtime.spec.js
index 23ad3ab72..e30d8cd7f 100644
--- a/core/http/react-ui/e2e/addons-runtime.spec.js
+++ b/core/http/react-ui/e2e/addons-runtime.spec.js
@@ -88,7 +88,8 @@ test.describe('Add-on UI runtime', () => {
     await expect(surface(page)).toBeVisible({ timeout: 20_000 })
     await expect(page.getByTestId('fx-title')).toHaveText('Hello fixture')
     await expect(page.getByTestId('fx-where')).toHaveText('page=home path=')
-    await expect(page.locator('h1.page-title')).toHaveText('UI fixture')
+    // The shell draws no title over the page: the add-on draws its own.
+    await expect(page.locator('h1.page-title')).toHaveCount(0)
     // Every file came from the owner through the asset route, under one digest.
     const js = answers.find(a => a.url.endsWith('/ui.js'))
     const css = answers.find(a => a.url.endsWith('/ui/style.css'))
@@ -142,8 +143,9 @@ test.describe('Add-on UI runtime', () => {
       return {
         sheet: document.querySelector('style[data-addon-style="uifixture"]')?.textContent || '',
         title: style(document.querySelector('[data-testid="fx-title"]')).color,
-        hostTitle: style(document.querySelector('h1.page-title')).color,
-        hostTitleSize: style(document.querySelector('h1.page-title')).fontSize,
+        hostNavColor: style(document.querySelector('.sidebar-nav a, .sidebar-nav button')).color,
+        hostNavSize: style(document.querySelector('.sidebar-nav a, .sidebar-nav button')).fontSize,
+        shellTitles: document.querySelectorAll('h1.page-title').length,
         bodyBackground: style(document.body).backgroundColor,
         token: style(root).getPropertyValue('--fx-token').trim(),
         rootToken: style(document.documentElement).getPropertyValue('--fx-token').trim(),
@@ -151,8 +153,9 @@ test.describe('Add-on UI runtime', () => {
       }
     })
     expect(probe.title).toBe('rgb(1, 2, 3)')
-    expect(probe.hostTitle).not.toBe('rgb(255, 0, 0)')
-    expect(probe.hostTitleSize).not.toBe('11px')
+    expect(probe.shellTitles).toBe(0)
+    expect(probe.hostNavColor).not.toBe('rgb(255, 0, 0)')
+    expect(probe.hostNavSize).not.toBe('11px')
     expect(probe.bodyBackground).not.toBe('rgb(255, 0, 255)')
     expect(probe.token).toBe('1')
     expect(probe.rootToken).toBe('')
@@ -173,8 +176,8 @@ test.describe('Add-on UI runtime', () => {
     await expect(card).toBeVisible({ timeout: 20_000 })
     await expect(card).toContainText('This add-on had a problem')
     await shoot(page, 'esm-error-boundary')
-    // The page header, the sidebar and the other routes are untouched.
-    await expect(page.locator('h1.page-title')).toHaveText('UI fixture')
+    // The sidebar and the other routes are untouched, and the shell adds no title.
+    await expect(page.locator('h1.page-title')).toHaveCount(0)
     await expect(page.locator('.sidebar-nav')).toBeVisible()
     await page.goto('/app/addons/uifixture/home')
     await expect(page.getByTestId('fx-title')).toBeVisible({ timeout: 20_000 })
@@ -328,7 +331,7 @@ test.describe('Add-on UI runtime', () => {
       // The router error page never replaces the host.
       await expect(page.getByText('Unexpected Application Error')).toHaveCount(0)
       await expect(page.locator('.sidebar-nav')).toBeVisible()
-      await expect(page.locator('h1.page-title')).toHaveText('UI fixture')
+      await expect(page.locator('h1.page-title')).toHaveCount(0)
       await layer.getByRole('button', { name: 'Close' }).last().click()
       await expect(layer).toHaveCount(0)
     }
diff --git a/core/http/react-ui/e2e/addons-shell.spec.js b/core/http/react-ui/e2e/addons-shell.spec.js
index f15a81b78..1df8067be 100644
--- a/core/http/react-ui/e2e/addons-shell.spec.js
+++ b/core/http/react-ui/e2e/addons-shell.spec.js
@@ -46,8 +46,10 @@ test.describe('Add-on shell', () => {
     await expect(page.getByTestId('fx-title')).toHaveText('Hello fixture')
     await page.getByRole('button', { name: 'Increment' }).click()
     await expect(surface.getByText('hooks 1')).toBeVisible()
-    // The sheet's `h1` rule never reaches the host's own page title.
-    await expect(page.locator('h1.page-title')).not.toHaveCSS('font-size', '11px')
+    // The shell draws no title over the add-on page, and the sheet's `h1`
+    // rule never reaches the host's own chrome.
+    await expect(page.locator('h1.page-title')).toHaveCount(0)
+    await expect(page.locator('.sidebar-nav a, .sidebar-nav button').first()).not.toHaveCSS('font-size', '11px')
     await expect(page.locator('style[data-addon-style="uifixture"]')).toHaveCount(1)
     // The detail view of the add-on links the declared navigation page.
     await page.goto('/app/addons?detail=uifixture')
diff --git a/core/http/react-ui/src/addons/AddonRoute.jsx b/core/http/react-ui/src/addons/AddonRoute.jsx
index 45926adbf..5d20d5114 100644
--- a/core/http/react-ui/src/addons/AddonRoute.jsx
+++ b/core/http/react-ui/src/addons/AddonRoute.jsx
@@ -154,7 +154,7 @@ export default function AddonRoute() {
   if (registry.status === 'idle' || (registry.status === 'error' && !app)) {
     if (registry.status === 'error') return unavailable('import_failed', reloadButton)
     return (
-      <div className="page ad-page" data-testid="addon-loading"><PageHeader title={title} /><LoadingSpinner /></div>
+      <div className="page ad-page" data-testid="addon-loading"><LoadingSpinner /></div>
     )
   }
   const isStale = Boolean(instance && instance.status === 'stale')
@@ -184,7 +184,6 @@ export default function AddonRoute() {
   if (!instance || instance.status === 'loading') {
     return (
       <div className="page ad-page" data-testid="addon-loading">
-        <PageHeader title={title} />
         <LoadingSpinner />
       </div>
     )
@@ -193,7 +192,7 @@ export default function AddonRoute() {
   // survives the moment it is withdrawn.
   return (
     <div className="page ad-page" data-testid={isStale ? 'addon-stale' : 'addon-page'}>
-      <PageHeader title={title} />
+      {/* The add-on draws its own title; the shell adds none. */}
       {isStale && (
         <div className="ad-banner" role="alert">
           <span>{t('shell.stale', { title })}</span>