diff --git a/web/src/settings/SettingsPage.test.tsx b/web/src/settings/SettingsPage.test.tsx
index c520ecd..afb28dd 100644
--- a/web/src/settings/SettingsPage.test.tsx
+++ b/web/src/settings/SettingsPage.test.tsx
@@ -1,11 +1,12 @@
 import { QueryClientProvider } from '@tanstack/react-query'
 import { fireEvent, render, screen, within } from '@testing-library/react'
-import { MemoryRouter, Route, Routes, useLocation } from 'react-router'
+import { Route, Routes, useLocation } from 'react-router'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { ApiProvider, createApiClient, createQueryClient, createVerifiedSession } from '../api/index.ts'
 import { createNetworkStatus } from '../pwa/networkStatus.ts'
 import { AI_SETTINGS, HOUSEHOLD_SETTINGS, SETTINGS_API } from '../test/ApiProviders.tsx'
 import { declaredStyle } from '../test/cssRules.ts'
+import { InDataRouter } from '../test/dataRouter.tsx'
 import { errorResponse, fakeLocation, jsonResponse, stubFetchByPath } from '../test/fetchStub.ts'
 import { expectMinHitArea } from '../test/hitArea.ts'
 import { mockViewport } from '../test/matchMedia.ts'
@@ -39,7 +40,8 @@ function CurrentPath() {
   return <p data-testid="path">{useLocation().pathname}</p>
 }
 
-// renderSettings renders the settings home on a 390 px phone (mock 1p);
+// renderSettings renders the settings home on a 390 px phone (mock 1p) in a
+// data router (the hidden sub-tabs' leave guard needs one);
 // SettingsTabs.test.tsx covers 768 px and up.
 function renderSettings() {
   mockViewport(390)
@@ -47,12 +49,12 @@ function renderSettings() {
   return render(
     <ApiProvider client={api}>
       <QueryClientProvider client={createQueryClient()}>
-        <MemoryRouter initialEntries={['/settings']}>
+        <InDataRouter path="/settings">
           <Routes>
             <Route path="/settings" element={<SettingsPage />} />
             <Route path="*" element={<CurrentPath />} />
           </Routes>
-        </MemoryRouter>
+        </InDataRouter>
       </QueryClientProvider>
     </ApiProvider>,
   )
@@ -95,9 +97,11 @@ describe('SettingsPage', () => {
     expect(fetchMock.mock.calls.map(([input]) => String(input)).sort()).toEqual([
       REGULARS_PATH,
       '/api/v1/settings/ai',
+      '/api/v1/settings/ai/models',
       CALENDAR_PATH,
       '/api/v1/settings/household',
       NOTIFICATIONS_PATH,
+      '/api/v1/settings/recipe-search',
     ])
   })
 
diff --git a/web/src/settings/SettingsPage.tsx b/web/src/settings/SettingsPage.tsx
index 7d5f066..e96881e 100644
--- a/web/src/settings/SettingsPage.tsx
+++ b/web/src/settings/SettingsPage.tsx
@@ -25,9 +25,17 @@ import styles from './SettingsPage.module.css'
 import { SettingsTabs } from './SettingsTabs.tsx'
 
 // Settings home: the list of settings pages on mobile (mock 1p), one page
-// with sub-tabs from 768 px (mock 2e).
+// with sub-tabs from 768 px (mock 2e). The sub-tabs stay mounted, hidden, on
+// mobile, so an unsaved draft survives the viewport crossing 768 px and its
+// leave guard keeps asking before the list navigates away.
 export function SettingsPage() {
-  return useBreakpoint() === 'mobile' ? <SettingsList /> : <SettingsTabs />
+  const mobile = useBreakpoint() === 'mobile'
+  return (
+    <>
+      {mobile && <SettingsList />}
+      <SettingsTabs hidden={mobile} />
+    </>
+  )
 }
 
 // The mobile settings list (handoff mock 1p). Each row opens its settings
diff --git a/web/src/settings/SettingsTabs.module.css b/web/src/settings/SettingsTabs.module.css
index c447360..180b236 100644
--- a/web/src/settings/SettingsTabs.module.css
+++ b/web/src/settings/SettingsTabs.module.css
@@ -59,7 +59,8 @@
   color: var(--color-bg);
 }
 
-/* A panel's display would override the hidden attribute. */
+/* A page's or panel's display would override the hidden attribute. */
+.page[hidden],
 .single[hidden],
 .columns[hidden] {
   display: none;
diff --git a/web/src/settings/SettingsTabs.test.tsx b/web/src/settings/SettingsTabs.test.tsx
index b4c2831..87a4983 100644
--- a/web/src/settings/SettingsTabs.test.tsx
+++ b/web/src/settings/SettingsTabs.test.tsx
@@ -1,17 +1,15 @@
 import { QueryClientProvider } from '@tanstack/react-query'
-import { fireEvent, render, screen, within } from '@testing-library/react'
+import { fireEvent, render, screen, waitFor, within } from '@testing-library/react'
 import { afterEach, describe, expect, it, vi, type Mock } from 'vitest'
 import { ApiProvider, createApiClient, createQueryClient, createVerifiedSession } from '../api/index.ts'
 import { createNetworkStatus } from '../pwa/networkStatus.ts'
-import { AI_SETTINGS, HOUSEHOLD_SETTINGS, RECIPE_SEARCH_SETTINGS } from '../test/ApiProviders.tsx'
+import { AI_MODELS, AI_SETTINGS, HOUSEHOLD_SETTINGS, RECIPE_SEARCH_SETTINGS } from '../test/ApiProviders.tsx'
 import { InDataRouter } from '../test/dataRouter.tsx'
 import { errorResponse, fakeLocation, jsonResponse, ME } from '../test/fetchStub.ts'
 import { expectMinHitArea } from '../test/hitArea.ts'
 import { mockViewport } from '../test/matchMedia.ts'
 import { SettingsPage } from './SettingsPage.tsx'
 
-const MODELS = { models: [{ id: 'claude-sonnet-4-5', display_name: 'Claude Sonnet' }] }
-
 type Responder = (body: unknown) => Response
 
 // stubAPI answers "METHOD path" from responders, each called with the
@@ -22,7 +20,7 @@ function stubAPI(responders: Record<string, Responder> = {}): Mock<typeof fetch>
     'GET /api/v1/me': () => jsonResponse(200, ME),
     'GET /api/v1/settings/household': () => jsonResponse(200, HOUSEHOLD_SETTINGS),
     'GET /api/v1/settings/ai': () => jsonResponse(200, AI_SETTINGS),
-    'GET /api/v1/settings/ai/models': () => jsonResponse(200, MODELS),
+    'GET /api/v1/settings/ai/models': () => jsonResponse(200, AI_MODELS),
     'GET /api/v1/settings/recipe-search': () => jsonResponse(200, RECIPE_SEARCH_SETTINGS),
     ...responders,
   }
@@ -167,4 +165,29 @@ describe('SettingsPage across the 768 px breakpoint', () => {
     expect(screen.getByRole('tablist', { name: 'Settings sections' })).toBeInTheDocument()
     expect(screen.queryByRole('link')).not.toBeInTheDocument()
   })
+
+  it('keeps an unsaved draft and its leave guard across 1180 px, 390 px and back', async () => {
+    stubAPI({
+      'GET /api/v1/dinners?status=regular': () => errorResponse(404, 'not_found'),
+      'GET /api/v1/settings/calendar': () => errorResponse(404, 'not_found'),
+      'GET /api/v1/settings/notifications': () => errorResponse(404, 'not_found'),
+    })
+    const resize = await renderAt(1180)
+    fireEvent.change(await screen.findByRole('textbox', { name: 'System prompt' }), {
+      target: { value: 'A draft' },
+    })
+
+    resize(390)
+    expect(screen.queryByRole('tablist')).not.toBeInTheDocument()
+    fireEvent.click(screen.getByRole('link', { name: /^AI assistant/ }))
+    const confirm = await screen.findByRole('dialog', { name: 'Leave without saving?' })
+    fireEvent.click(within(confirm).getByRole('button', { name: 'Keep editing' }))
+    await waitFor(() => expect(screen.queryByRole('dialog')).not.toBeInTheDocument())
+
+    resize(1180)
+    expect(screen.getByRole('textbox', { name: 'System prompt' })).toHaveValue('A draft')
+    const unload = new Event('beforeunload', { cancelable: true })
+    window.dispatchEvent(unload)
+    expect(unload.defaultPrevented).toBe(true)
+  })
 })
diff --git a/web/src/settings/SettingsTabs.tsx b/web/src/settings/SettingsTabs.tsx
index 0bfc6a4..1a4ffc9 100644
--- a/web/src/settings/SettingsTabs.tsx
+++ b/web/src/settings/SettingsTabs.tsx
@@ -19,7 +19,8 @@ const step: Record<string, number> = { ArrowRight: 1, ArrowLeft: -1 }
 // Settings at tablet and desktop widths (handoff mock 2e): one page with
 // sub-tabs instead of the mobile list. Every tab stays mounted while hidden,
 // so a draft survives switching tabs, and one leave guard covers them all.
-export function SettingsTabs() {
+// hidden hides the page but keeps it mounted, drafts and leave guard included.
+export function SettingsTabs({ hidden = false }: { hidden?: boolean }) {
   const [tab, setTab] = useState<Tab>('notifications-ai')
   const [householdDirty, setHouseholdDirty] = useState(false)
   const [aiDirty, setAIDirty] = useState(false)
@@ -61,7 +62,7 @@ export function SettingsTabs() {
   }
 
   return (
-    <div className={styles.page}>
+    <div className={styles.page} hidden={hidden}>
       <header className={styles.header}>
         <div className={styles.heading}>
           <h1 className={styles.title}>Settings</h1>
diff --git a/web/src/shell/BottomBar.test.tsx b/web/src/shell/BottomBar.test.tsx
index b8c5d3b..500261d 100644
--- a/web/src/shell/BottomBar.test.tsx
+++ b/web/src/shell/BottomBar.test.tsx
@@ -1,9 +1,9 @@
 import { fireEvent, render, screen, within } from '@testing-library/react'
-import { MemoryRouter } from 'react-router'
 import { afterEach, beforeEach, describe, expect, it, vi, type Mock } from 'vitest'
 import { AppRoutes } from '../App.tsx'
 import { ApiProviders, SETTINGS_API } from '../test/ApiProviders.tsx'
 import { declaredStyle } from '../test/cssRules.ts'
+import { InDataRouter } from '../test/dataRouter.tsx'
 import { stubFetchByPath } from '../test/fetchStub.ts'
 import { mockViewport } from '../test/matchMedia.ts'
 import styles from './BottomBar.module.css'
@@ -74,11 +74,11 @@ function renderAt(path: string, reducedMotion = false) {
   mockViewport(MOBILE, { reducedMotion })
   stubFetchByPath(SETTINGS_API)
   render(
-    <MemoryRouter initialEntries={[path]}>
+    <InDataRouter path={path}>
       <ApiProviders>
         <AppRoutes />
       </ApiProviders>
-    </MemoryRouter>,
+    </InDataRouter>,
   )
 }
 
diff --git a/web/src/test/ApiProviders.tsx b/web/src/test/ApiProviders.tsx
index 76d5f47..cca07f8 100644
--- a/web/src/test/ApiProviders.tsx
+++ b/web/src/test/ApiProviders.tsx
@@ -16,6 +16,10 @@ export const AI_SETTINGS = {
   updated_at: '2026-10-01T15:00:00.000Z',
 }
 
+// AI_MODELS is a GET /api/v1/settings/ai/models body: the model AI_SETTINGS
+// chooses.
+export const AI_MODELS = { models: [{ id: 'claude-sonnet-4-5', display_name: 'Claude Sonnet' }] }
+
 // HOUSEHOLD_SETTINGS is a GET /api/v1/settings/household body: the seed
 // times in New York.
 export const HOUSEHOLD_SETTINGS = {
@@ -49,13 +53,15 @@ export const RECIPE_SEARCH_SETTINGS = {
 
 // SETTINGS_API answers the settings home's requests, for stubFetchByPath, as
 // today's server does: the dinners, Google Calendar and notifications status
-// endpoints do not exist yet.
+// endpoints do not exist yet. The home's sub-tabs stay mounted on mobile, so
+// it also reads the AI models and recipe search settings.
 export const SETTINGS_API = {
   '/api/v1/dinners?status=regular': () => errorResponse(404, 'not_found'),
   '/api/v1/settings/calendar': () => errorResponse(404, 'not_found'),
   '/api/v1/settings/notifications': () => errorResponse(404, 'not_found'),
   '/api/v1/settings/household': () => jsonResponse(200, HOUSEHOLD_SETTINGS),
   '/api/v1/settings/ai': () => jsonResponse(200, AI_SETTINGS),
+  '/api/v1/settings/ai/models': () => jsonResponse(200, AI_MODELS),
   '/api/v1/settings/recipe-search': () => jsonResponse(200, RECIPE_SEARCH_SETTINGS),
 }