diff --git a/web/src/shopping/SupplyRunPage.tsx b/web/src/shopping/SupplyRunPage.tsx
index 6bc4bf5..30072ef 100644
--- a/web/src/shopping/SupplyRunPage.tsx
+++ b/web/src/shopping/SupplyRunPage.tsx
@@ -1,4 +1,5 @@
 import { Archive, Check, CloudUpload, MessageSquare } from 'lucide-react'
+import { useState } from 'react'
 import { Link, useSearchParams } from 'react-router'
 import { Unavailable } from '../plan/PlanPage.tsx'
 import { defaultWeek, localNow, weekdayKicker, weekLabel, weekStart as weekOf } from '../plan/week.ts'
@@ -249,12 +250,15 @@ function ChosenSupplyRun() {
   const settings = useHouseholdSettings()
   const [params] = useSearchParams()
   const chosen = params.get(WEEK_PARAM)
+  // Read once, not on every render: a failed read reports a problem, which
+  // renders this again.
+  const [saved] = useState(() => keep(savedSchedule))
 
   if (chosen !== null && !isMonday(chosen)) {
     return <ErrorBanner>{`“${chosen}” is not the Monday of a week, as YYYY-MM-DD.`}</ErrorBanner>
   }
   // fetch rejects with a TypeError only when the network fails.
-  const schedule = settings.data ?? (settings.error instanceof TypeError ? keep(savedSchedule) : null)
+  const schedule = settings.data ?? (settings.error instanceof TypeError ? saved : null)
   if (settings.isError && !schedule) {
     return <ErrorBanner onRetry={() => void settings.refetch()}>Couldn't load the household settings. {settings.error.message}</ErrorBanner>
   }
diff --git a/web/src/shopping/api.ts b/web/src/shopping/api.ts
index 343b4f8..e9b5430 100644
--- a/web/src/shopping/api.ts
+++ b/web/src/shopping/api.ts
@@ -7,7 +7,7 @@ import {
   type MutationObserverOptions,
   type QueryClient,
 } from '@tanstack/react-query'
-import { useEffect, useReducer, useSyncExternalStore } from 'react'
+import { useEffect, useReducer, useRef, useSyncExternalStore } from 'react'
 import { ApiError, useApi, type ApiClient } from '../api/index.ts'
 import { isRecord } from '../api/errors.ts'
 import { meQueryKey } from '../AuthBootstrap.tsx'
@@ -200,6 +200,10 @@ function toggleKey(weekStart: string) {
   return ['shopping', weekStart, 'toggle'] as const
 }
 
+// TOGGLE_SCOPE is the one mutation scope of every toggle of every week, made
+// here or replayed from the queue saved on this device.
+const TOGGLE_SCOPE = 'shopping toggle'
+
 // Toggles is the toggles of one week's Supply run: shown, the Supply run
 // with those still pending laid over it, the items whose toggles will sync
 // once the server can be reached, the latest failed toggle no later toggle
@@ -228,12 +232,13 @@ function reachable(network: NetworkStatus): Promise<void> {
 // made on the Supply run screen (useToggles) or replayed from the queue saved
 // on this device (useSupplyRunSync).
 //
-// The week's toggles are sent one at a time, in the order made (one
-// mutation scope), so the counts each is answered with include every toggle
-// before it and none after. While the server cannot be reached — the device
-// is offline, or the toggle's PATCH failed with a network error (fetch
-// rejected with a TypeError) — a toggle waits, pending, and is sent once it
-// can be: those after it wait behind it. Any answer from the server settles
+// Toggles are sent one at a time, in the order made, whatever their week
+// (one mutation scope, TOGGLE_SCOPE), so the counts each is answered with
+// include every toggle before it and none after, and a replayed toggle never
+// overlaps another replayed or made here. While the server cannot be
+// reached — the device is offline, or the toggle's PATCH failed with a
+// network error (fetch rejected with a TypeError) — a toggle waits, pending,
+// and is sent once it can be: those after it wait behind it. Any answer from the server settles
 // it: a refusal (a 400, 404, 409 or any other error response) or a response
 // that is not the item as toggled fails it, and it is not sent again. Before
 // a toggle is sent, GET /api/v1/me has answered, so it carries the session's
@@ -250,7 +255,7 @@ function toggleOptions(
   const mutationKey = toggleKey(weekStart)
   return {
     mutationKey,
-    scope: { id: mutationKey.join(' ') },
+    scope: { id: TOGGLE_SCOPE },
     networkMode: 'always',
     retry: false,
     gcTime: Infinity,
@@ -312,8 +317,9 @@ function toggleOptions(
 // the counts it answers with there. Until then the toggle is pending and is
 // laid over the Supply run shown, so the item and the needed count change at
 // once; a refused toggle just stops being pending, which puts both back.
-// While the server cannot be reached, the items with pending toggles will
-// sync.
+// An item whose pending toggle was made, or waited, while the server could
+// not be reached will sync: it says so until that toggle settles, even once
+// the server can be reached again.
 //
 // The Supply run and the toggles are read straight from the query and
 // mutation caches as each render begins, never from the caches' batched
@@ -339,6 +345,9 @@ export function useToggles(weekStart: string): Toggles {
   useMutationState({ filters: { mutationKey } })
   const offline = useSyncExternalStore(api.network.subscribe, api.network.offline)
   const [, renderAgain] = useReducer((n: number) => n + 1, 0)
+  // The keys of the pending toggles seen while the server could not be
+  // reached: every change of the network status renders again.
+  const waited = useRef<ReadonlySet<string>>(new Set())
   const run = queryClient.getQueryData<SupplyRun | null>(key)
   if (!run) throw new Error(`The week of ${weekStart} has no Supply run read to toggle items of.`)
   const toggles = queryClient
@@ -346,13 +355,14 @@ export function useToggles(weekStart: string): Toggles {
     .findAll({ mutationKey })
     .map((mutation) => ({ status: mutation.state.status, toggle: mutation.state.variables as KeyedToggle, error: mutation.state.error }))
   const pending = toggles.filter((t) => t.status === 'pending').map((t) => t.toggle)
+  waited.current = new Set(pending.filter((t) => offline || waited.current.has(t.key)).map((t) => t.key))
   const failed = toggles
     .filter((t, i) => t.status === 'error' && !toggles.slice(i + 1).some((later) => later.toggle.id === t.toggle.id))
     .at(-1)
   const { mutate } = useMutation(toggleOptions(weekStart, api, queryClient))
   return {
     shown: shown(run, pending),
-    willSync: new Set(offline ? pending.map((toggle) => toggle.id) : []),
+    willSync: new Set(pending.filter((t) => waited.current.has(t.key)).map((t) => t.id)),
     failed: failed === undefined ? null : { toggle: { id: failed.toggle.id, needed: failed.toggle.needed }, error: failed.error! },
     toggle: ({ id, needed }) => {
       const queuedToggle = { key: crypto.randomUUID(), weekStart, id, needed }
@@ -367,9 +377,18 @@ export function useToggles(weekStart: string): Toggles {
 // to open offline — the household's schedule and each Supply run the server
 // sends (saveRun) — and replays, in the order made, the toggles saved in the
 // queue that are not already pending here: those of a page reloaded before
-// the server answered them. A replayed toggle's answer is written over the
-// Supply run saved, so the week's Supply run is cached from it first; it
-// is still read again (updatedAt 0) when the Supply run screen opens.
+// the server answered them.
+//
+// Replay is at-least-once, not exactly-once: a toggle leaves the saved queue
+// only once its answer settles here, so one the server applied just before a
+// reload is sent again. That duplicate is safe because a toggle sets needed
+// to a fixed value — the same PATCH applied twice leaves the item and the
+// counts as applying it once does — so no key is sent for the server to
+// deduplicate by.
+//
+// A replayed toggle's answer is written over the Supply run saved, so the
+// week's Supply run is cached from it first; it is still read again
+// (updatedAt 0) when the Supply run screen opens.
 export function useSupplyRunSync() {
   const api = useApi()
   const queryClient = useQueryClient()
diff --git a/web/src/shopping/offlineQueue.test.tsx b/web/src/shopping/offlineQueue.test.tsx
index 8ec514c..e711612 100644
--- a/web/src/shopping/offlineQueue.test.tsx
+++ b/web/src/shopping/offlineQueue.test.tsx
@@ -21,6 +21,18 @@ const ITEMS = [
   { id: 'i3', name: 'Taco seasoning', qty: '1 packet', needed: false },
 ]
 
+// Next week's curry: one item to buy.
+const NEXT_ITEMS = [{ id: 'n1', name: 'Chicken thighs', qty: '2 lb', needed: true }]
+
+// The items of each week, by its Monday.
+const WEEKS: Record<string, typeof ITEMS> = { '2026-10-05': ITEMS, '2026-10-12': NEXT_ITEMS }
+
+function itemsOf(week: string) {
+  const items = WEEKS[week]
+  if (items === undefined) throw new Error(`no week ${week}`)
+  return items
+}
+
 // The browser's online flag; goOffline and goOnline change it and send the
 // page's window the event a browser sends.
 let onLine: boolean
@@ -53,51 +65,78 @@ function goOnline() {
   act(() => void win.dispatchEvent(new Event('online')))
 }
 
-// stubServer is the server's Supply run of the week: a PATCH marks its item
-// and answers with its counts, unless refuse answers it instead. It counts
-// as archived once archive is called.
-function stubServer(refuse: (id: string) => Response | undefined = () => undefined) {
-  const needed = new Map(ITEMS.map((item) => [item.id, item.needed]))
+// stubServer is the server's Supply runs of this week and next: a PATCH
+// marks its item and answers with its week's counts, unless refuse answers
+// it instead; when hold is given, the item is marked at once but the answer
+// waits for the promise hold returns. This week's counts as archived once
+// archive is called.
+function stubServer(refuse: (id: string) => Response | undefined = () => undefined, hold?: () => Promise<void>) {
+  const needed = new Map(Object.values(WEEKS).flatMap((items) => items.map((item) => [item.id, item.needed] as const)))
   let status = 'current'
-  const counts = () => ({ needed_count: [...needed.values()].filter(Boolean).length, total_count: needed.size })
-  const run = () => ({
-    weekStart: '2026-10-05',
-    label: 'Week 41 · Oct 5 – 11',
+  // How many PATCHes are unanswered now, and the most there have been at once.
+  let inFlight = 0
+  let mostInFlight = 0
+  const counts = (week: string) => {
+    const marks = itemsOf(week).map((item) => needed.get(item.id)!)
+    return { needed_count: marks.filter(Boolean).length, total_count: marks.length }
+  }
+  const run = (week: string) => ({
+    weekStart: week,
+    label: week === '2026-10-05' ? 'Week 41 · Oct 5 – 11' : 'Week 42 · Oct 12 – 18',
     title: null,
-    status,
+    status: week === '2026-10-05' ? status : 'current',
     sent_to_chat_at: null,
-    ...counts(),
+    ...counts(week),
     groups: [
       {
-        dinner: { id: 'd0', name: 'Beef tacos' },
-        date: '2026-10-05',
-        items: ITEMS.map((item) => ({ ...item, needed: needed.get(item.id)! })),
+        dinner: { id: week === '2026-10-05' ? 'd0' : 'd1', name: week === '2026-10-05' ? 'Beef tacos' : 'Chicken curry' },
+        date: week,
+        items: itemsOf(week).map((item) => ({ ...item, needed: needed.get(item.id)! })),
       },
     ],
   })
-  const fetchMock = vi.fn<typeof fetch>((input, init) => {
-    if (!onLine || !reachable) return Promise.reject(new TypeError('Failed to fetch'))
+  const fetchMock = vi.fn<typeof fetch>(async (input, init) => {
+    if (!onLine || !reachable) throw new TypeError('Failed to fetch')
     const key = `${init?.method ?? 'GET'} ${String(input)}`
-    if (key === 'GET /api/v1/me') return Promise.resolve(jsonResponse(200, ME))
-    if (key === 'GET /api/v1/settings/household') return Promise.resolve(jsonResponse(200, HOUSEHOLD_SETTINGS))
-    if (key === `GET ${THIS_WEEK}`) return Promise.resolve(jsonResponse(200, run()))
-    const item = ITEMS.find((i) => key === `PATCH ${ITEM(i.id)}`)
-    if (item === undefined) throw new Error(`unexpected fetch: ${key}`)
-    const refusal = refuse(item.id)
-    if (refusal !== undefined) return Promise.resolve(refusal)
+    if (key === 'GET /api/v1/me') return jsonResponse(200, ME)
+    if (key === 'GET /api/v1/settings/household') return jsonResponse(200, HOUSEHOLD_SETTINGS)
+    if (key === `GET ${THIS_WEEK}`) return jsonResponse(200, run('2026-10-05'))
+    const week = Object.keys(WEEKS).find((w) => itemsOf(w).some((i) => key === `PATCH ${ITEM(i.id)}`))
+    if (week === undefined) throw new Error(`unexpected fetch: ${key}`)
+    const id = itemsOf(week).find((i) => key === `PATCH ${ITEM(i.id)}`)!.id
+    const refusal = refuse(id)
+    if (refusal !== undefined) return refusal
     const body = JSON.parse(String(init?.body)) as { needed: boolean }
-    needed.set(item.id, body.needed)
-    return Promise.resolve(jsonResponse(200, { id: item.id, needed: body.needed, ...counts() }))
+    needed.set(id, body.needed)
+    const answer = jsonResponse(200, { id, needed: body.needed, ...counts(week) })
+    inFlight++
+    mostInFlight = Math.max(mostInFlight, inFlight)
+    await hold?.()
+    inFlight--
+    return answer
   })
   vi.stubGlobal('fetch', fetchMock)
   return {
     fetchMock,
+    run,
+    mostInFlight: () => mostInFlight,
     archive: () => {
       status = 'archived'
     },
   }
 }
 
+// held is a hold for stubServer whose answers wait until release is called,
+// each one released in turn.
+function held() {
+  const waiting: (() => void)[] = []
+  return {
+    hold: () => new Promise<void>((resolve) => waiting.push(resolve)),
+    waiting: () => waiting.length,
+    release: () => waiting.shift()!(),
+  }
+}
+
 // patches lists the PATCHes sent, as "path body".
 function patches(fetchMock: Mock<typeof fetch>) {
   return fetchMock.mock.calls.filter(([, init]) => init?.method === 'PATCH').map(([input, init]) => `${String(input)} ${String(init?.body)}`)
@@ -145,6 +184,7 @@ beforeEach(() => {
 })
 
 afterEach(() => {
+  vi.restoreAllMocks()
   vi.useRealTimers()
   vi.unstubAllGlobals()
   Reflect.deleteProperty(window, 'matchMedia')
@@ -277,3 +317,94 @@ describe('offline toggle queue', () => {
     await waitFor(() => expect(patches(server.fetchMock)).toEqual([`${ITEM('i1')} {"needed":false}`]))
   })
 })
+
+describe('offline toggle queue, replay', () => {
+  it('replays a queue spanning two weeks strictly in order, one PATCH at a time, a toggle made meanwhile after it', async () => {
+    const answers = held()
+    const server = stubServer(undefined, answers.hold)
+    const queued = [
+      { key: 'k1', weekStart: '2026-10-05', id: 'i3', needed: true },
+      { key: 'k2', weekStart: '2026-10-12', id: 'n1', needed: false },
+      { key: 'k3', weekStart: '2026-10-05', id: 'i1', needed: false },
+    ]
+    const runs = { '2026-10-05': server.run('2026-10-05'), '2026-10-12': server.run('2026-10-12') }
+    localStorage.setItem(SAVED_KEY, JSON.stringify({ schedule: null, runs, queue: queued }))
+
+    await openPage()
+    await waitFor(() => expect(answers.waiting()).toBe(1))
+    fireEvent.click(await screen.findByRole('checkbox', { name: 'Corn tortillas' }))
+    for (let sent = 1; sent <= 4; sent++) {
+      await waitFor(() => expect(patches(server.fetchMock)).toHaveLength(sent))
+      // The next one is not sent before this one is answered.
+      await new Promise((resolve) => setTimeout(resolve, 20))
+      expect(patches(server.fetchMock)).toHaveLength(sent)
+      act(() => answers.release())
+    }
+    await waitFor(() => expect(queue()).toEqual([]))
+    expect(patches(server.fetchMock)).toEqual([
+      `${ITEM('i3')} {"needed":true}`,
+      `${ITEM('n1')} {"needed":false}`,
+      `${ITEM('i1')} {"needed":false}`,
+      `${ITEM('i2')} {"needed":false}`,
+    ])
+    expect(server.mostInFlight()).toBe(1)
+    await waitFor(() => expect(screen.getByText('1 / 3')).toBeInTheDocument())
+  })
+
+  it('replays at least once: a toggle the server applied before a reload is sent again and leaves the item and count the same', async () => {
+    const answers = held()
+    const server = stubServer(undefined, answers.hold)
+    const first = await openPage()
+    expect(await screen.findByText('2 / 3')).toBeInTheDocument()
+    fireEvent.click(checkbox('Taco seasoning'))
+    // The server applied it; the page reloads before its answer arrives.
+    await waitFor(() => expect(answers.waiting()).toBe(1))
+    expect(queue()).toEqual(['i3 true'])
+    first.unmount()
+    act(() => answers.release())
+
+    await openPage()
+    await waitFor(() => expect(answers.waiting()).toBe(1))
+    act(() => answers.release())
+    await waitFor(() => expect(queue()).toEqual([]))
+    expect(patches(server.fetchMock)).toEqual([`${ITEM('i3')} {"needed":true}`, `${ITEM('i3')} {"needed":true}`])
+    await waitFor(() => expect(screen.getByText('3 / 3')).toBeInTheDocument())
+    expect(checkbox('Taco seasoning')).toBeChecked()
+    expect(server.run('2026-10-05')).toMatchObject({ needed_count: 3, total_count: 3 })
+    expect(screen.queryByRole('alert')).not.toBeInTheDocument()
+  })
+
+  it('keeps "will sync" on a queued toggle until its delayed replay is answered', async () => {
+    const answers = held()
+    stubServer(undefined, answers.hold)
+    await openPage()
+    expect(await screen.findByText('2 / 3')).toBeInTheDocument()
+    goOffline()
+    fireEvent.click(checkbox('Ground beef'))
+    expect(within(row('Ground beef')).getByText('will sync')).toBeInTheDocument()
+
+    goOnline()
+    await waitFor(() => expect(answers.waiting()).toBe(1))
+    expect(within(row('Ground beef')).getByText('will sync')).toBeInTheDocument()
+    expect(queue()).toEqual(['i1 false'])
+
+    act(() => answers.release())
+    await waitFor(() => expect(screen.queryByText('will sync')).not.toBeInTheDocument())
+    expect(queue()).toEqual([])
+    expect(screen.getByText('1 / 3')).toBeInTheDocument()
+  })
+
+  it('says the saved list is unreadable when it is corrupt offline, without rendering again and again', async () => {
+    stubServer()
+    onLine = false
+    localStorage.setItem(SAVED_KEY, '{corrupt')
+    const getItem = vi.spyOn(Storage.prototype, 'getItem')
+    await openPage()
+
+    expect(await screen.findByText(/Couldn't load the household settings/)).toBeInTheDocument()
+    expect(screen.getByText(/can't be kept on this device while offline/)).toBeInTheDocument()
+    const reads = getItem.mock.calls.filter(([key]) => key === SAVED_KEY).length
+    await new Promise((resolve) => setTimeout(resolve, 50))
+    expect(getItem.mock.calls.filter(([key]) => key === SAVED_KEY)).toHaveLength(reads)
+  })
+})