web/src/plan/PlanPage.test.tsx

@@ -467,6 +467,57 @@ describe('PlanPage', () => {
     expect(posts(fetchMock)).toEqual([`${PUSH} undefined`, `${PUSH} undefined`])
   })
 
+  it("pushes nothing again while the changed plan's read is answered from the cache", async () => {
+    let read = () => jsonResponse(200, planBody('draft'))
+    let push = () => errorResponse(409, 'plan_changed')
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => read(),
+      [`POST ${PUSH}`]: () => push(),
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    // The server can't be reached: the service worker answers the read of
+    // the changed plan with the plan it cached before.
+    read = () => {
+      const response = jsonResponse(200, planBody('draft'))
+      response.headers.set(cacheFallbackHeader, '1')
+      return response
+    }
+    fireEvent.click(screen.getByRole('button', { name: 'Looks good — push to Calendar' }))
+    const cachedCopy = "The plan changed while it was being pushed. The plan shown came from this device's cache, not the server; read it again before pushing."
+    const failed = await screen.findByRole('alert')
+    expect(planReads(fetchMock)).toBe(2)
+    expect(screen.getByText('Beef tacos')).toBeInTheDocument()
+    const pushButton = screen.getByRole('button', { name: 'Looks good — push to Calendar' })
+    expect(pushButton).toBeDisabled()
+    fireEvent.click(pushButton)
+    expect(failed).toHaveTextContent(cachedCopy)
+
+    // Retry reads the plan again rather than pushing: still the cache, so
+    // nothing is pushed.
+    fireEvent.click(within(screen.getByRole('alert')).getByRole('button', { name: 'Retry' }))
+    await waitFor(() => expect(planReads(fetchMock)).toBe(3))
+    expect(await screen.findByRole('alert')).toHaveTextContent(cachedCopy)
+    expect(screen.getByRole('button', { name: 'Looks good — push to Calendar' })).toBeDisabled()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`])
+
+    // The server is back: Retry shows the changed plan, and only then may it
+    // be pushed.
+    read = () => jsonResponse(200, planBody('draft', ['Lasagna', ...NAMES.slice(1)]))
+    fireEvent.click(within(screen.getByRole('alert')).getByRole('button', { name: 'Retry' }))
+    expect(await screen.findByText('Lasagna')).toBeInTheDocument()
+    const alert = screen.getByRole('alert')
+    expect(alert).toHaveTextContent("Couldn't push to Calendar. The plan changed while it was being pushed; push it again.")
+    expect(screen.getByRole('button', { name: 'Looks good — push to Calendar' })).toBeEnabled()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`])
+
+    push = () => jsonResponse(200, syncedNow())
+    fireEvent.click(within(alert).getByRole('button', { name: 'Retry' }))
+    expect(await screen.findByText('Synced to Google Calendar just now')).toBeInTheDocument()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`, `${PUSH} undefined`])
+  })
+
   it('shows the changed plan read while the week was left, and pushes it', async () => {
     let read: () => Response | Promise<Response> = () => jsonResponse(200, planBody('draft'))
     let push = () => errorResponse(409, 'plan_changed')

web/src/plan/PlanPage.tsx

@@ -303,8 +303,11 @@ function WeekBoard({
 
   // A push sends the plan shown: it waits for a draft or a swap of the week
   // to settle, and neither starts while it runs, even across leaving the
-  // week and coming back.
+  // week and coming back. Nor does it send a plan from this device's cache,
-  const canPush = plan.isSuccess && plan.data !== null && !drafting && !swap.pending && !pushing
+  // which may not be the server's: after a push refused because the plan
+  // changed, the read of the changed plan may be answered from the cache.
+  const cached = plan.isSuccess && plan.data !== null && plan.data.cached
+  const canPush = plan.isSuccess && plan.data !== null && !cached && !drafting && !swap.pending && !pushing
   function pushToCalendar() {
     if (!canPush) return
     swap.dismiss()
@@ -339,7 +342,7 @@ function WeekBoard({
   }
 
   const failure = push.error !== null ? (
-    <PushFailure error={push.error} onRetry={pushToCalendar} />
+    <PushFailure error={push.error} cached={cached} onRetry={cached ? () => void plan.refetch() : pushToCalendar} />
   ) : swap.failed !== null ? (
     <ErrorBanner onRetry={() => swapIn(swap.failed!.swap)}>
       Couldn't swap {weekdayName(swap.failed.swap.date)}'s dinner. {swap.failed.error.message}
@@ -569,8 +572,10 @@ function SyncStatus({ plan, className }: { plan: Plan; className?: string }) {
 }
 
 // PushFailure says why Push to Calendar failed. A failure only the Google
-// Calendar settings can fix links there; any other offers to push again.
+// Calendar settings can fix links there; any other offers to push again,
-function PushFailure({ error, onRetry }: { error: Error; onRetry: () => void }) {
+// or, while the plan shown is this device's cached copy, to read it again
+// from the server first.
+function PushFailure({ error, cached, onRetry }: { error: Error; cached: boolean; onRetry: () => void }) {
   const code = error instanceof ApiError ? error.code : null
   const settings = code !== null && Object.hasOwn(settingsFailures, code) ? settingsFailures[code] : undefined
   if (settings !== undefined) {
@@ -586,7 +591,11 @@ function PushFailure({ error, onRetry }: { error: Error; onRetry: () => void })
   return (
     <ErrorBanner onRetry={onRetry}>
       Couldn't push to Calendar.{' '}
-      {code === 'plan_changed' ? 'The plan changed while it was being pushed; push it again.' : error.message}
+      {cached
+        ? `${code === 'plan_changed' ? 'The plan changed while it was being pushed.' : error.message} The plan shown came from this device's cache, not the server; read it again before pushing.`
+        : code === 'plan_changed'
+          ? 'The plan changed while it was being pushed; push it again.'
+          : error.message}
     </ErrorBanner>
   )
 }

web/src/plan/api.test.tsx

@@ -5,7 +5,7 @@ import { afterEach, describe, expect, it, vi } from 'vitest'
 import { ApiProvider, createApiClient, createQueryClient, createVerifiedSession } from '../api/index.ts'
 import { createNetworkStatus } from '../pwa/networkStatus.ts'
 import { errorResponse, fakeLocation, jsonResponse, ME } from '../test/fetchStub.ts'
-import { planKey, usePlan, useSwapDay, type Plan } from './api.ts'
+import { planKey, usePlan, usePushToCalendar, useSwapDay, type Plan } from './api.ts'
 
 const WEEK = '2026-10-05'
 const PLAN = `/api/v1/plans/${WEEK}`
@@ -203,3 +203,70 @@ describe('useSwapDay', () => {
     await act(async () => friday.send(jsonResponse(200, planBody())))
   })
 })
+
+describe('week mutations', () => {
+  const NEXT = '2026-10-12'
+  const LATER = '2026-10-19'
+
+  // weekMutations lists the swaps and pushes the mutation cache holds for
+  // the week starting on weekStart, with their status.
+  function weekMutations(queryClient: QueryClient, weekStart: string) {
+    return queryClient
+      .getMutationCache()
+      .findAll({ mutationKey: ['plans', weekStart] })
+      .map((mutation) => `${String(mutation.options.mutationKey![2])} ${mutation.state.status}`)
+  }
+
+  it('keeps settled swaps and pushes while their week is shown, and leaves them behind once it is not, unless one is pending', async () => {
+    const nextPush = deferred()
+    stubServer({
+      [`GET ${PLAN}`]: () => jsonResponse(200, planBody()),
+      [`PUT ${FRIDAY}`]: () => jsonResponse(200, planBody({ 4: { id: 'q1', name: 'Lemon orzo', is_new: true } })),
+      [`POST ${PLAN}/push-calendar`]: () => errorResponse(500, 'internal'),
+      [`GET /api/v1/plans/${NEXT}`]: () => errorResponse(404, 'not_found'),
+      [`POST /api/v1/plans/${NEXT}/push-calendar`]: () => nextPush.reply,
+      [`GET /api/v1/plans/${LATER}`]: () => errorResponse(404, 'not_found'),
+    })
+    const api = createApiClient(fakeLocation('/plan'), createNetworkStatus(window), createVerifiedSession(localStorage))
+    await api.loadMe()
+    const queryClient = createQueryClient()
+    const wrapper = ({ children }: { children: ReactNode }) => (
+      <ApiProvider client={api}>
+        <QueryClientProvider client={queryClient}>{children}</QueryClientProvider>
+      </ApiProvider>
+    )
+    const hook = renderHook(
+      ({ week }) => ({ plan: usePlan(week), swap: useSwapDay(week), push: usePushToCalendar(week) }),
+      { wrapper, initialProps: { week: WEEK } },
+    )
+    await waitFor(() => expect(hook.result.current.plan.isSuccess).toBe(true))
+
+    // A swap and a push of the week settle: both stay while it is shown,
+    // the push's failure speaking for the week.
+    act(() => hook.result.current.swap.mutate(ORZO))
+    await waitFor(() => expect(hook.result.current.swap.pending).toBe(false))
+    act(() => hook.result.current.push.mutate())
+    await waitFor(() => expect(hook.result.current.push.error).not.toBeNull())
+    expect(weekMutations(queryClient, WEEK)).toEqual(['swap success', 'push error'])
+
+    // Another week shown leaves them behind; a push sent there stays
+    // pending across showing a third week.
+    hook.rerender({ week: NEXT })
+    await waitFor(() => expect(hook.result.current.plan.isSuccess).toBe(true))
+    expect(weekMutations(queryClient, WEEK)).toEqual([])
+    act(() => hook.result.current.push.mutate())
+    hook.rerender({ week: LATER })
+    await waitFor(() => expect(hook.result.current.plan.isSuccess).toBe(true))
+    expect(weekMutations(queryClient, NEXT)).toEqual(['push pending'])
+    hook.rerender({ week: NEXT })
+    expect(hook.result.current.push.pending).toBe(true)
+
+    // Once it settles, it stays while its week is shown and is left behind
+    // once another is.
+    await act(async () => nextPush.send(errorResponse(500, 'internal')))
+    await waitFor(() => expect(hook.result.current.push.error).not.toBeNull())
+    expect(weekMutations(queryClient, NEXT)).toEqual(['push error'])
+    hook.rerender({ week: LATER })
+    expect(weekMutations(queryClient, NEXT)).toEqual([])
+  })
+})

web/src/plan/api.ts

@@ -1,3 +1,4 @@
+import { useEffect } from 'react'
 import { useMutation, useMutationState, useQuery, useQueryClient } from '@tanstack/react-query'
 import { ApiError, useApi, type ApiRead } from '../api/index.ts'
 import { isRecord } from '../api/errors.ts'
@@ -177,6 +178,30 @@ function sameDay(a: PlanDay, b: PlanDay): boolean {
   )
 }
 
+// WeekMutation is a kind of mutation of a week the mutation cache keeps for
+// it: its swaps and its pushes.
+type WeekMutation = 'swap' | 'push'
+
+// useWeekMutationsKept bounds the mutations of kind the cache keeps. When a
+// week is shown, the settled ones of every other week are removed, unless
+// that week still has one pending: a pending one, and those an earlier
+// pending one must see, stay across leaving its week and coming back. The
+// cache holds at most the week shown's and those of weeks left pending.
+function useWeekMutationsKept(weekStart: string, kind: WeekMutation) {
+  const queryClient = useQueryClient()
+  useEffect(() => {
+    const mutations = queryClient.getMutationCache()
+    const left = mutations.findAll({
+      predicate: ({ options: { mutationKey: key } }) =>
+        key !== undefined && key.length === 3 && key[0] === 'plans' && key[1] !== weekStart && key[2] === kind,
+    })
+    const pending = new Set(left.filter((m) => m.state.status === 'pending').map((m) => m.options.mutationKey![1]))
+    for (const mutation of left) {
+      if (!pending.has(mutation.options.mutationKey![1])) mutations.remove(mutation)
+    }
+  }, [queryClient, weekStart, kind])
+}
+
 // swapKey keys the swaps of the week starting on weekStart in the mutation
 // cache, where they outlive the Draft board that sent them.
 function swapKey(weekStart: string) {
@@ -206,10 +231,12 @@ export type SwapDay = {
 // earlier one is answered with is not written over a later one, and its
 // failure is not the week's. dismiss leaves settled swaps behind; it is
 // refused while one is pending, so a later swap is always in the cache for
-// an earlier, pending one to see.
+// an earlier, pending one to see. Settled swaps of a week no longer shown
+// are left behind too (useWeekMutationsKept).
 export function useSwapDay(weekStart: string): SwapDay {
   const { apiFetch } = useApi()
   const queryClient = useQueryClient()
+  useWeekMutationsKept(weekStart, 'swap')
   const key = planKey(weekStart)
   const mutationKey = swapKey(weekStart)
   const mutations = queryClient.getMutationCache()
@@ -225,7 +252,8 @@ export function useSwapDay(weekStart: string): SwapDay {
     const isLatest = () => mutations.findAll({ mutationKey }).every((other) => other.mutationId <= mutation.mutationId)
     const mutation = mutations.build<Plan, Error, Swap, { previous: PlanDay; swapped: PlanDay }>(queryClient, {
       mutationKey,
-      // Kept until dismissed: a later swap must stay in the cache while an
+      // Kept until dismissed or its week is left settled
+      // (useWeekMutationsKept): a later swap must stay in the cache while an
       // earlier one is pending.
       gcTime: Infinity,
       mutationFn: async ({ date, dinner }) => {
@@ -302,10 +330,13 @@ export type PushToCalendar = {
 //
 // The week's pushes live in the mutation cache, not in the component, as its
 // swaps do, so leaving the week and coming back keeps one pending. reset
-// leaves settled pushes behind; it is refused while one is pending.
+// leaves settled pushes behind; it is refused while one is pending. Settled
+// pushes of a week no longer shown are left behind too
+// (useWeekMutationsKept).
 export function usePushToCalendar(weekStart: string): PushToCalendar {
   const { apiFetch } = useApi()
   const queryClient = useQueryClient()
+  useWeekMutationsKept(weekStart, 'push')
   const key = planKey(weekStart)
   const mutationKey = pushKey(weekStart)
   const mutations = queryClient.getMutationCache()
@@ -319,8 +350,9 @@ export function usePushToCalendar(weekStart: string): PushToCalendar {
   function mutate() {
     const mutation = mutations.build<Plan, Error, void, unknown>(queryClient, {
       mutationKey,
-      // Kept until reset: a push pending in a week left must still be found
+      // Kept until reset or its week is left settled (useWeekMutationsKept):
-      // when it is shown again.
+      // a push pending in a week left must still be found when it is shown
+      // again.
       gcTime: Infinity,
       mutationFn: async () => {
         const path = `${planPath(weekStart)}/push-calendar`