Feature 16: Google Calendar Sync (#130)

Co-authored-by: orchestrator-agent <20+orchestrator-agent@code.cubecraftcreations.com>

web/src/plan/PlanPage.module.css

@@ -258,9 +258,9 @@
   color: var(--color-neutral-700);
 }
 
-/* An action with nothing behind it yet (Push to Calendar until Feature 16,
-   the shopping list until Feature 17): it keeps focus, so hovering, tapping
-   or focusing it shows the tooltip. */
+/* An action with nothing behind it yet (the shopping list until Feature
+   17): it keeps focus, so hovering, tapping or focusing it shows the
+   tooltip. */
 .unavailable {
   position: relative;
   display: flex;
@@ -406,6 +406,21 @@
   color: var(--color-accent-2-800);
 }
 
+/* Under the Draft board's push button the line is centred and may wrap. */
+.mobileStatus {
+  flex: none;
+  justify-content: center;
+  white-space: normal;
+  text-align: center;
+}
+
+/* A push failure's way to the Google Calendar settings. */
+.settingsLink {
+  color: inherit;
+  font-weight: 800;
+  text-decoration: underline;
+}
+
 .actions {
   display: flex;
   flex-wrap: wrap;

web/src/plan/PlanPage.test.tsx

@@ -15,6 +15,7 @@ const THIS_WEEK = '/api/v1/plans/2026-10-05'
 const NEXT_WEEK = '/api/v1/plans/2026-10-12'
 const PREVIOUS_WEEK = '/api/v1/plans/2026-09-28'
 const DRAFT = `${THIS_WEEK}/draft`
+const PUSH = `${THIS_WEEK}/push-calendar`
 const JOB = '/api/v1/jobs/j1'
 
 const DAYS = ['2026-10-05', '2026-10-06', '2026-10-07', '2026-10-08', '2026-10-09', '2026-10-10', '2026-10-11']
@@ -50,6 +51,21 @@ function planBody(status: string, names = NAMES) {
   }
 }
 
+// syncedNow is the plan of the week of Oct 5 as a push answers it: synced
+// at the tests' noon.
+function syncedNow() {
+  return { ...planBody('synced'), calendar_synced_at: '2026-10-07T16:00:00Z' }
+}
+
+// deferred is a response the test sends when it chooses.
+function deferred() {
+  let send!: (response: Response) => void
+  const response = new Promise<Response>((resolve) => {
+    send = resolve
+  })
+  return { response, send }
+}
+
 // draftJob is job j1 drafting the week of Oct 5 into plan planId: a
 // redraft keeps the plan's id.
 function draftJob(status: string, error: string | null = null, planId = 'plan-1') {
@@ -225,17 +241,312 @@ describe('PlanPage', () => {
     expect(screen.queryByText('Draft')).not.toBeInTheDocument()
   })
 
-  it('offers Push to Calendar unavailable, with a tooltip saying why', async () => {
-    const fetchMock = stubServer({ [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')) })
+  it('pushes the plan to Calendar, showing progress, then the plan as synced', async () => {
+    const answer = deferred()
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')),
+      [`POST ${PUSH}`]: () => answer.response,
+    })
     await renderPage()
 
-    const push = await screen.findByRole('button', { name: 'Looks good — push to Calendar' })
-    expect(push).toHaveAttribute('aria-disabled', 'true')
-    expect(push).toHaveAccessibleDescription('Push to Calendar arrives once Google Calendar can be connected.')
-    expect(screen.getByRole('tooltip', { hidden: true })).toHaveTextContent('Push to Calendar arrives once Google Calendar can be connected.')
+    expect(await screen.findByText('Not pushed to Google Calendar yet')).toBeInTheDocument()
+    const push = screen.getByRole('button', { name: 'Looks good — push to Calendar' })
     expect(declaredStyle(push).minHeight).toBe('50px')
     fireEvent.click(push)
-    expect(posts(fetchMock)).toEqual([])
+    await waitFor(() => expect(posts(fetchMock)).toEqual([`${PUSH} undefined`]))
+    const call = fetchMock.mock.calls.find(([, init]) => init?.method === 'POST')!
+    expect(new Headers(call[1]?.headers).get('X-MealQuest-CSRF')).toBe(ME.csrfToken)
+
+    // In progress: the button says so and is disabled, as is Rebuild week,
+    // and no day can be swapped.
+    const pushing = await screen.findByRole('button', { name: 'Pushing to Calendar…' })
+    expect(pushing).toBeDisabled()
+    expect(pushing).toHaveAttribute('aria-busy', 'true')
+    expect(screen.getByRole('button', { name: 'Rebuild week' })).toBeDisabled()
+    fireEvent.click(within(tile('MON')).getByRole('button'))
+    expect(screen.queryByRole('dialog')).not.toBeInTheDocument()
+
+    answer.send(jsonResponse(200, syncedNow()))
+    const status = await screen.findByText('Synced to Google Calendar just now')
+    expect(declaredStyle(status).color).toBe('var(--color-accent-2-800)')
+    expect(status.querySelector('svg')).not.toBeNull()
+    expect(screen.getByText('Synced')).toBeInTheDocument()
+    expect(screen.queryByText('Draft')).not.toBeInTheDocument()
+    expect(screen.getByRole('button', { name: 'Looks good — push to Calendar' })).toBeEnabled()
+    expect(screen.queryByRole('alert')).not.toBeInTheDocument()
+    // The plan shown is the one the push answered with: no second read.
+    expect(planReads(fetchMock)).toBe(1)
+  })
+
+  it('says a synced plan is on Google Calendar, and how long ago it was pushed', async () => {
+    stubServer({ [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('synced')) })
+    await renderPage()
+
+    const status = await screen.findByText('Synced to Google Calendar 2 min ago')
+    expect(declaredStyle(status).color).toBe('var(--color-accent-2-800)')
+    expect(status.querySelector('svg')).not.toBeNull()
+  })
+
+  it('says changes to a pushed plan are not pushed, and pushes them', async () => {
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('changed')),
+      [`POST ${PUSH}`]: () => jsonResponse(200, syncedNow()),
+    })
+    await renderPage()
+
+    expect(await screen.findByText('Changes not pushed')).toBeInTheDocument()
+    const status = screen.getByText('Changes not pushed to Google Calendar')
+    expect(declaredStyle(status).color).toBe('var(--color-neutral-700)')
+    fireEvent.click(screen.getByRole('button', { name: 'Looks good — push to Calendar' }))
+    expect(await screen.findByText('Synced to Google Calendar just now')).toBeInTheDocument()
+    expect(screen.queryByText('Changes not pushed')).not.toBeInTheDocument()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`])
+  })
+
+  it.each([
+    ['google_reconnect_required', 'Google access was revoked or expired.', 'Reconnect Google Calendar'],
+    ['no_calendar', 'No calendar is chosen for dinners yet.', 'Choose a calendar in Settings'],
+    ['not_connected', 'Google Calendar is not connected.', 'Connect Google Calendar'],
+    ['calendar_unavailable', 'The chosen calendar was deleted or MealQuest can no longer add dinners to it.', 'Choose another calendar'],
+  ])('sends a %s push failure to the Google Calendar settings', async (code, reason, fix) => {
+    stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')),
+      [`POST ${PUSH}`]: () => errorResponse(409, code),
+    })
+    await renderPage()
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Looks good — push to Calendar' }))
+    const alert = await screen.findByRole('alert')
+    expect(alert).toHaveTextContent(`Couldn't push to Calendar. ${reason} ${fix}`)
+    expect(within(alert).getByRole('link', { name: fix })).toHaveAttribute('href', '/settings/calendar')
+    expect(within(alert).queryByRole('button', { name: 'Retry' })).not.toBeInTheDocument()
+    // The plan is as it was: not synced.
+    expect(screen.getByText('Draft')).toBeInTheDocument()
+    expect(screen.getByText('Not pushed to Google Calendar yet')).toBeInTheDocument()
+    expect(screen.getByRole('button', { name: 'Looks good — push to Calendar' })).toBeEnabled()
+  })
+
+  it('marks the Google Calendar connection to be read again when Google refused the grant', async () => {
+    const connection = { status: 'connected', calendar_id: 'c1', calendar_name: 'Dinners', connected_at: null, last_sync_error: null }
+    const api = createApiClient(fakeLocation('/plan'), createNetworkStatus(window), createVerifiedSession(localStorage))
+    const queryClient = createQueryClient()
+    queryClient.setQueryData(['integrations', 'google'], connection)
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')),
+      [`POST ${PUSH}`]: () => errorResponse(409, 'google_reconnect_required'),
+    })
+    await api.loadMe()
+    render(
+      <ApiProvider client={api}>
+        <QueryClientProvider client={queryClient}>
+          <MemoryRouter initialEntries={['/plan']}>
+            <PlanPage />
+          </MemoryRouter>
+        </QueryClientProvider>
+      </ApiProvider>,
+    )
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Looks good — push to Calendar' }))
+    expect(await screen.findByRole('link', { name: 'Reconnect Google Calendar' })).toBeInTheDocument()
+    // The settings screen reads it again as it opens: it is now reconnect
+    // required.
+    expect(queryClient.getQueryState(['integrations', 'google'])?.isInvalidated).toBe(true)
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`])
+  })
+
+  it('says why any other push failed, and pushes again on Retry', async () => {
+    let push = () => errorResponse(502, 'google_failed')
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')),
+      [`POST ${PUSH}`]: () => push(),
+    })
+    await renderPage()
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Looks good — push to Calendar' }))
+    const alert = await screen.findByRole('alert')
+    expect(alert).toHaveTextContent("Couldn't push to Calendar. google_failed message")
+    expect(within(alert).queryByRole('link')).not.toBeInTheDocument()
+
+    push = () => jsonResponse(200, syncedNow())
+    fireEvent.click(within(alert).getByRole('button', { name: 'Retry' }))
+    expect(await screen.findByText('Synced to Google Calendar just now')).toBeInTheDocument()
+    expect(screen.queryByRole('alert')).not.toBeInTheDocument()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`, `${PUSH} undefined`])
+  })
+
+  it('reads the plan again when it changed while being pushed', async () => {
+    let plan = planBody('draft')
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, plan),
+      [`POST ${PUSH}`]: () => errorResponse(409, 'plan_changed'),
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    plan = planBody('draft', ['Lasagna', ...NAMES.slice(1)])
+    fireEvent.click(screen.getByRole('button', { name: 'Looks good — push to Calendar' }))
+    expect(await screen.findByRole('alert')).toHaveTextContent(
+      "Couldn't push to Calendar. The plan changed while it was being pushed; push it again.",
+    )
+    expect(await screen.findByText('Lasagna')).toBeInTheDocument()
+    expect(planReads(fetchMock)).toBe(2)
+  })
+
+  it('pushes nothing again until the changed plan is read and shown', async () => {
+    let read: () => Response | Promise<Response> = () => jsonResponse(200, planBody('draft'))
+    let push = () => errorResponse(409, 'plan_changed')
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => read(),
+      [`POST ${PUSH}`]: () => push(),
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    const reread = deferred()
+    read = () => reread.response
+    const pushButton = screen.getByRole('button', { name: 'Looks good — push to Calendar' })
+    fireEvent.click(pushButton)
+    await waitFor(() => expect(planReads(fetchMock)).toBe(2))
+    // While the changed plan is read, the push stays busy: neither Push
+    // nor Retry sends it again.
+    expect(screen.getByRole('button', { name: 'Pushing to Calendar…' })).toBeDisabled()
+    expect(screen.queryByRole('button', { name: 'Retry' })).not.toBeInTheDocument()
+    fireEvent.click(screen.getByRole('button', { name: 'Pushing to Calendar…' }))
+    expect(screen.getByText('Beef tacos')).toBeInTheDocument()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`])
+
+    reread.send(jsonResponse(200, planBody('draft', ['Lasagna', ...NAMES.slice(1)])))
+    const alert = await screen.findByRole('alert')
+    expect(alert).toHaveTextContent("Couldn't push to Calendar. The plan changed while it was being pushed; push it again.")
+    expect(screen.getByText('Lasagna')).toBeInTheDocument()
+    expect(screen.getByRole('button', { name: 'Looks good — push to Calendar' })).toBeEnabled()
+
+    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('pushes nothing again until the changed plan is shown, even after leaving the week and coming back', async () => {
+    let read: () => Response | Promise<Response> = () => jsonResponse(200, planBody('draft'))
+    let push = () => errorResponse(409, 'plan_changed')
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => read(),
+      [`GET ${NEXT_WEEK}`]: () => errorResponse(404, 'not_found'),
+      [`POST ${PUSH}`]: () => push(),
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    const reread = deferred()
+    read = () => reread.response
+    fireEvent.click(screen.getByRole('button', { name: 'Looks good — push to Calendar' }))
+    await waitFor(() => expect(planReads(fetchMock)).toBe(2))
+
+    // Leaving the week and coming back while the changed plan is read
+    // remounts the board: the push is still busy, and sends nothing again.
+    fireEvent.click(screen.getByRole('button', { name: 'Next week' }))
+    expect(await screen.findByRole('button', { name: 'Draft this week' })).toBeInTheDocument()
+    fireEvent.click(screen.getByRole('button', { name: 'Previous week' }))
+    await screen.findByText('Beef tacos')
+    expect(screen.getByRole('button', { name: 'Pushing to Calendar…' })).toBeDisabled()
+    expect(screen.queryByRole('button', { name: 'Retry' })).not.toBeInTheDocument()
+    fireEvent.click(screen.getByRole('button', { name: 'Pushing to Calendar…' }))
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`])
+
+    await act(async () => reread.send(jsonResponse(200, planBody('draft', ['Lasagna', ...NAMES.slice(1)]))))
+    const alert = await screen.findByRole('alert')
+    expect(alert).toHaveTextContent("Couldn't push to Calendar. The plan changed while it was being pushed; push it again.")
+    expect(screen.getByText('Lasagna')).toBeInTheDocument()
+    expect(screen.getByRole('button', { name: 'Looks good — push to Calendar' })).toBeEnabled()
+
+    push = () => jsonResponse(200, syncedNow())
+    fireEvent.click(within(alert).getByRole('button', { name: 'Retry' }))
+    expect(await screen.findByText('Synced to Google Calendar just now')).toBeInTheDocument()
+    expect(screen.queryByRole('alert')).not.toBeInTheDocument()
+    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')
+    const fetchMock = stubServer({
+      [`GET ${THIS_WEEK}`]: () => read(),
+      [`GET ${NEXT_WEEK}`]: () => errorResponse(404, 'not_found'),
+      [`POST ${PUSH}`]: () => push(),
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    const reread = deferred()
+    read = () => reread.response
+    fireEvent.click(screen.getByRole('button', { name: 'Looks good — push to Calendar' }))
+    await waitFor(() => expect(planReads(fetchMock)).toBe(2))
+    fireEvent.click(screen.getByRole('button', { name: 'Next week' }))
+    expect(await screen.findByRole('button', { name: 'Draft this week' })).toBeInTheDocument()
+    await act(async () => reread.send(jsonResponse(200, planBody('draft', ['Lasagna', ...NAMES.slice(1)]))))
+    read = () => jsonResponse(200, planBody('draft', ['Lasagna', ...NAMES.slice(1)]))
+    fireEvent.click(screen.getByRole('button', { name: 'Previous week' }))
+
+    // The board comes back on the changed plan: Push sends that one.
+    expect(await screen.findByText('Lasagna')).toBeInTheDocument()
+    expect(screen.queryByText('Beef tacos')).not.toBeInTheDocument()
+    expect(screen.getByRole('alert')).toHaveTextContent('The plan changed while it was being pushed; push it again.')
+    push = () => jsonResponse(200, syncedNow())
+    fireEvent.click(screen.getByRole('button', { name: 'Looks good — push to Calendar' }))
+    expect(await screen.findByText('Synced to Google Calendar just now')).toBeInTheDocument()
+    expect(posts(fetchMock)).toEqual([`${PUSH} undefined`, `${PUSH} undefined`])
   })
 
   it('rebuilds a draft at once, showing skeleton tiles until the new plan is read', async () => {
@@ -715,20 +1026,19 @@ describe.each([
     expect(screen.getByRole('button', { name: 'Next week' })).toBeInTheDocument()
     expect(screen.queryByRole('button', { name: 'This week' }) !== null).toBe(layout === 'desktop')
 
-    // Actions: the shopping list and Push to Calendar unavailable, saying
-    // why; Rebuild week outlined and working.
+    // Actions: the shopping list unavailable, saying why; Rebuild week
+    // outlined and Push to Calendar primary, both working.
     const shopping = screen.getByRole('button', { name: 'Shopping list' })
     expect(shopping).toHaveAttribute('aria-disabled', 'true')
     expect(shopping).toHaveAccessibleDescription('The shopping list arrives once the Supply run is built.')
     const push = screen.getByRole('button', { name: 'Push to Calendar' })
-    expect(push).toHaveAttribute('aria-disabled', 'true')
-    expect(push).toHaveAccessibleDescription('Push to Calendar arrives once Google Calendar can be connected.')
+    expect(push).toBeEnabled()
+    expect(push).not.toHaveAttribute('aria-disabled')
     expect(declaredStyle(push).background).toBe('var(--color-accent)')
     const rebuild = screen.getByRole('button', { name: 'Rebuild week' })
     expect(rebuild).toBeEnabled()
     expect(declaredStyle(rebuild).borderColor).toBe('var(--color-neutral-300)')
     fireEvent.click(shopping)
-    fireEvent.click(push)
     expect(posts(fetchMock)).toEqual([])
     // Mobile's own pieces are not shown.
     expect(screen.queryByRole('button', { name: 'Looks good — push to Calendar' })).not.toBeInTheDocument()
@@ -795,6 +1105,43 @@ describe.each([
     expect(await screen.findByText('Changes not pushed to Google Calendar')).toBeInTheDocument()
   })
 
+  it('pushes the plan from the header, showing progress, then the plan as synced', async () => {
+    const answer = deferred()
+    stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('changed')),
+      [`POST ${PUSH}`]: () => answer.response,
+      ...lists,
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    fireEvent.click(screen.getByRole('button', { name: 'Push to Calendar' }))
+    const pushing = await screen.findByRole('button', { name: 'Pushing…' })
+    expect(pushing).toBeDisabled()
+    expect(pushing).toHaveAttribute('aria-busy', 'true')
+    expect(screen.getByRole('button', { name: 'Rebuild week' })).toBeDisabled()
+
+    answer.send(jsonResponse(200, syncedNow()))
+    const status = await screen.findByText('Synced to Google Calendar just now')
+    expect(declaredStyle(status).color).toBe('var(--color-accent-2-800)')
+    expect(screen.getByRole('button', { name: 'Push to Calendar' })).toBeEnabled()
+  })
+
+  it('links a google_reconnect_required push failure to the Google Calendar settings', async () => {
+    stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('synced')),
+      [`POST ${PUSH}`]: () => errorResponse(409, 'google_reconnect_required'),
+      ...lists,
+    })
+    await renderPage()
+
+    await screen.findByText('Beef tacos')
+    fireEvent.click(screen.getByRole('button', { name: 'Push to Calendar' }))
+    const alert = await screen.findByRole('alert')
+    expect(within(alert).getByRole('link', { name: 'Reconnect Google Calendar' })).toHaveAttribute('href', '/settings/calendar')
+    expect(screen.getByText('Synced to Google Calendar 2 min ago')).toBeInTheDocument()
+  })
+
   if (layout === 'desktop') {
     it('shows the Quest log and Regulars in the 290 px right panel', async () => {
       stubServer({ [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')), ...lists })

web/src/plan/PlanPage.tsx

@@ -1,7 +1,8 @@
 import { useQueryClient } from '@tanstack/react-query'
 import { CalendarDays, Check, ChevronLeft, ChevronRight, Plus, RefreshCw, ShoppingCart } from 'lucide-react'
 import { useEffect, useId, useMemo, useState, type ReactNode } from 'react'
-import { useJob } from '../api/index.ts'
+import { Link } from 'react-router'
+import { ApiError, useJob } from '../api/index.ts'
 import { QUEST_LOG_KEY } from '../discover/api.ts'
 import { Confirm } from '../settings/LeaveGuard.tsx'
 import { methodLabels } from '../settings/RegularsSettingsPage.tsx'
@@ -20,6 +21,7 @@ import {
   parseDraftResult,
   planKey,
   usePlan,
+  usePushToCalendar,
   useStartDraft,
   useSwapDay,
   type DraftResult,
@@ -62,9 +64,20 @@ const draftFailures: Record<string, string> = {
   internal_error: 'Something went wrong on the server.',
 }
 
-// PUSH_HINT is why Push to Calendar is unavailable.
-// TODO(Feature 16): connect Push to Calendar once Google Calendar is.
-const PUSH_HINT = 'Push to Calendar arrives once Google Calendar can be connected.'
+// CALENDAR_SETTINGS is the Google Calendar settings screen.
+const CALENDAR_SETTINGS = '/settings/calendar'
+
+// settingsFailures says why a push failed, by its API error code, for the
+// failures only the Google Calendar settings can fix, and what to do there.
+const settingsFailures: Record<string, { reason: string; fix: string }> = {
+  google_reconnect_required: { reason: 'Google access was revoked or expired.', fix: 'Reconnect Google Calendar' },
+  not_connected: { reason: 'Google Calendar is not connected.', fix: 'Connect Google Calendar' },
+  no_calendar: { reason: 'No calendar is chosen for dinners yet.', fix: 'Choose a calendar in Settings' },
+  calendar_unavailable: {
+    reason: 'The chosen calendar was deleted or MealQuest can no longer add dinners to it.',
+    fix: 'Choose another calendar',
+  },
+}
 
 // SHOPPING_HINT is why the shopping list is unavailable.
 // TODO(Feature 17): open the Supply run, with its count, once it is built.
@@ -204,9 +217,13 @@ function SkeletonTiles({ label, layout, children }: { label: string; layout: Bre
 // the plan is read again. Rebuilding a plan pushed to Calendar asks first,
 // and sends confirm. A failed draft is shown with Retry; no plan is made up.
 //
-// From tablet up it is the plan manager (mocks 2c, 2d): Rebuild week and the
-// unavailable Shopping list and Push to Calendar are actions in the header,
+// From tablet up it is the plan manager (mocks 2c, 2d): Rebuild week, Push to
+// Calendar and the unavailable Shopping list are actions in the header,
 // over the plan's sync status and the 7-column grid.
+//
+// Push to Calendar, on either layout, sends the plan shown and shows it as
+// synced once the server answers; a failure says why, linking to the Google
+// Calendar settings when only they can fix it.
 function WeekBoard({
   weekStart,
   timezone,
@@ -225,6 +242,8 @@ function WeekBoard({
   const job = useJob<unknown>(DRAFT_JOB_KIND, jobId)
   const [confirming, setConfirming] = useState(false)
   const swap = useSwapDay(weekStart)
+  const push = usePushToCalendar(weekStart)
+  const pushing = push.pending
   // The date of the day being swapped, while the swap sheet is open.
   const [swappingDate, setSwappingDate] = useState<string | null>(null)
   const label = weekLabel(weekStart)
@@ -282,13 +301,28 @@ function WeekBoard({
 
   const drafting = startDraft.isPending || (jobId !== null && job.status !== 'failed' && resultError === null)
 
+  // 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. Nor does it send a plan from this device's cache,
+  // 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()
+    push.reset()
+    push.mutate()
+  }
+
   const { mutate } = startDraft
   function start(confirm: boolean) {
     setConfirming(false)
-    // A draft asked for again leaves the last one's failure, and a failed
-    // swap's, behind.
+    // A draft asked for again leaves the last one's failure, a failed
+    // swap's and a failed push's behind.
     setJobId(null)
     swap.dismiss()
+    push.reset()
     mutate(
       { weekStart, confirm },
       {
@@ -302,12 +336,14 @@ function WeekBoard({
   // It waits for a swap of the week still pending, which may yet fail: the
   // Rebuild week tile is disabled meanwhile.
   function rebuild() {
-    if (swap.pending) return
+    if (swap.pending || pushing) return
     if (plan.data && pushedToCalendar(plan.data.status)) setConfirming(true)
     else start(false)
   }
 
-  const failure = swap.failed !== null ? (
+  const failure = push.error !== null ? (
+    <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}
     </ErrorBanner>
@@ -328,6 +364,7 @@ function WeekBoard({
   // swapIn sends the swap chosen in the sheet and closes it.
   function swapIn(chosen: Swap) {
     setSwappingDate(null)
+    push.reset()
     swap.mutate(chosen)
   }
   // dropIn swaps in a dinner dragged onto a day. A drag is not picked up,
@@ -338,9 +375,10 @@ function WeekBoard({
   }
   // openSwap opens the swap sheet on a day. One swap of the week is sent at
   // a time, even across leaving the week and coming back: the plan the
-  // server answers it with must not overwrite another still pending.
+  // server answers it with must not overwrite another still pending. Nor is
+  // one sent while the week is being pushed to Calendar.
   function openSwap(date: string) {
-    if (swap.pending) return
+    if (swap.pending || pushing) return
     swap.dismiss()
     setSwappingDate(date)
   }
@@ -379,7 +417,7 @@ function WeekBoard({
     body =
       layout !== 'mobile' ? (
         <>
-          <DropBoard days={days} pending={swap.pending} drop={dropIn} />
+          <DropBoard days={days} pending={swap.pending || pushing} drop={dropIn} />
           <ul className={`${styles.week} ${styles[layout]}`} aria-label="Dinners this week">
             {days.map((day) => (
               <DayColumn
@@ -414,15 +452,16 @@ function WeekBoard({
               />
             ))}
             <li className={styles.rebuildCell}>
-              <button type="button" className={styles.rebuild} onClick={rebuild} disabled={swap.pending}>
+              <button type="button" className={styles.rebuild} onClick={rebuild} disabled={swap.pending || pushing}>
                 <Icon icon={Plus} size="inline" />
                 Rebuild week
               </button>
             </li>
           </ul>
-          <Unavailable hint={PUSH_HINT} className={styles.pushButton}>
-            Looks good — push to Calendar
-          </Unavailable>
+          <Button className={styles.pushButton} onClick={pushToCalendar} disabled={!canPush} aria-busy={pushing}>
+            {pushing ? 'Pushing to Calendar…' : 'Looks good — push to Calendar'}
+          </Button>
+          <SyncStatus plan={plan.data} className={styles.mobileStatus} />
           {sheet}
         </>
       )
@@ -458,14 +497,19 @@ function WeekBoard({
               <Icon icon={ShoppingCart} size="inline" />
               Shopping list
             </Unavailable>
-            <Button variant="outline" className={styles.action} onClick={rebuild} disabled={swap.pending || drafting || !plan.isSuccess}>
+            <Button
+              variant="outline"
+              className={styles.action}
+              onClick={rebuild}
+              disabled={swap.pending || pushing || drafting || !plan.isSuccess}
+            >
               <Icon icon={RefreshCw} size="inline" />
               Rebuild week
             </Button>
-            <Unavailable hint={PUSH_HINT} below className={styles.action}>
+            <Button className={styles.action} onClick={pushToCalendar} disabled={!canPush} aria-busy={pushing}>
               <Icon icon={CalendarDays} size="inline" />
-              Push to Calendar
-            </Unavailable>
+              {pushing ? 'Pushing…' : 'Push to Calendar'}
+            </Button>
           </div>
         </div>
       </header>
@@ -507,10 +551,11 @@ function WeekBoard({
   )
 }
 
-// SyncStatus is the plan manager's status line: whether the plan is on
-// Google Calendar and, once synced, how long ago it was pushed, kept current
-// minute by minute.
-function SyncStatus({ plan }: { plan: Plan }) {
+// SyncStatus is the plan's status line, in the plan manager's header and
+// under the Draft board's push button: whether the plan is on Google
+// Calendar and, once synced, how long ago it was pushed, kept current minute
+// by minute.
+function SyncStatus({ plan, className }: { plan: Plan; className?: string }) {
   const { status, calendar_synced_at: syncedAt } = plan
   const [now, setNow] = useState(() => new Date())
   useEffect(() => {
@@ -518,7 +563,7 @@ function SyncStatus({ plan }: { plan: Plan }) {
     return () => clearInterval(timer)
   }, [])
   return (
-    <p className={[styles.status, status === 'synced' && styles.synced].filter(Boolean).join(' ')}>
+    <p className={[styles.status, status === 'synced' && styles.synced, className].filter(Boolean).join(' ')}>
       {status === 'synced' && <Icon icon={Check} size="inline" />}
       {syncStatuses[status]}
       {status === 'synced' && syncedAt !== null && ` ${ago(syncedAt, now)}`}
@@ -526,9 +571,38 @@ function SyncStatus({ plan }: { plan: Plan }) {
   )
 }
 
-// Unavailable is an action with nothing behind it yet (Push to Calendar, the
-// shopping list): it stays focusable, so a tap or focus shows the tooltip
-// saying why, above it or, at the top of the page, below.
+// PushFailure says why Push to Calendar failed. A failure only the Google
+// Calendar settings can fix links there; any other offers to push again,
+// 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) {
+    return (
+      <ErrorBanner>
+        Couldn't push to Calendar. {settings.reason}{' '}
+        <Link to={CALENDAR_SETTINGS} className={styles.settingsLink}>
+          {settings.fix}
+        </Link>
+      </ErrorBanner>
+    )
+  }
+  return (
+    <ErrorBanner onRetry={onRetry}>
+      Couldn't push to Calendar.{' '}
+      {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>
+  )
+}
+
+// Unavailable is an action with nothing behind it yet (the shopping list):
+// it stays focusable, so a tap or focus shows the tooltip saying why, above
+// it or, at the top of the page, below.
 function Unavailable({
   hint,
   variant = 'primary',

web/src/plan/api.test.tsx

@@ -1,11 +1,12 @@
 import { QueryClientProvider, type QueryClient } from '@tanstack/react-query'
-import { act, renderHook, waitFor } from '@testing-library/react'
+import { act, render, renderHook, waitFor } from '@testing-library/react'
 import type { ReactNode } from 'react'
+import { MemoryRouter, Route, Routes, useNavigate, type NavigateFunction } 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 { errorResponse, fakeLocation, jsonResponse, ME } from '../test/fetchStub.ts'
-import { planKey, usePlan, useSwapDay, type Plan } from './api.ts'
+import { planKey, usePlan, usePushToCalendar, useSwapDay, type Plan, type PushToCalendar, type SwapDay } from './api.ts'
 
 const WEEK = '2026-10-05'
 const PLAN = `/api/v1/plans/${WEEK}`
@@ -203,3 +204,198 @@ describe('useSwapDay', () => {
     await act(async () => friday.send(jsonResponse(200, planBody())))
   })
 })
+
+describe('week mutations', () => {
+  const NEXT = '2026-10-12'
+  const LATER = '2026-10-19'
+
+  // weekMutations lists the swaps and pushes the mutation cache holds for
+  // the week starting on weekStart, with their status.
+  function weekMutations(queryClient: QueryClient, weekStart: string) {
+    return queryClient
+      .getMutationCache()
+      .findAll({ mutationKey: ['plans', weekStart] })
+      .map((mutation) => `${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([])
+  })
+
+  it('leaves behind what settles in a week no longer shown, unless that week still has one pending or it is the failure that speaks for it', async () => {
+    const friday = deferred()
+    const monday = deferred()
+    const nextPush = deferred()
+    const laterPush = deferred()
+    stubServer({
+      [`GET ${PLAN}`]: () => jsonResponse(200, planBody()),
+      [`PUT ${FRIDAY}`]: () => friday.reply,
+      [`PUT ${MONDAY}`]: () => monday.reply,
+      [`GET /api/v1/plans/${NEXT}`]: () => errorResponse(404, 'not_found'),
+      [`POST /api/v1/plans/${NEXT}/push-calendar`]: () => nextPush.reply,
+      [`GET /api/v1/plans/${LATER}`]: () => errorResponse(404, 'not_found'),
+      [`POST /api/v1/plans/${LATER}/push-calendar`]: () => laterPush.reply,
+    })
+    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))
+
+    // Two swaps of the week and a push of the next are left pending, and a
+    // third week is shown.
+    act(() => hook.result.current.swap.mutate(ORZO))
+    act(() => hook.result.current.swap.mutate(FISH))
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual(['swap pending', 'swap pending']))
+    hook.rerender({ week: NEXT })
+    await waitFor(() => expect(hook.result.current.plan.isSuccess).toBe(true))
+    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'])
+
+    // The later swap settles first: the earlier, still pending, must see it,
+    // so both stay.
+    await act(async () => monday.send(jsonResponse(200, planBody({ 0: { id: 'r1', name: 'Fish tacos' } }))))
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual(['swap pending', 'swap success']))
+
+    // The push succeeds while the third week is shown: it is left behind,
+    // and the week's pending swap is not.
+    await act(async () => nextPush.send(jsonResponse(200, { ...planBody(), week_start: NEXT })))
+    await waitFor(() => expect(weekMutations(queryClient, NEXT)).toEqual([]))
+    expect(weekMutations(queryClient, WEEK)).toEqual(['swap pending', 'swap success'])
+
+    // Once the earlier swap fails, the week has none pending: both are left
+    // behind, the failure not being the week's latest.
+    await act(async () => friday.send(errorResponse(409, 'dinner_not_plannable')))
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual([]))
+
+    // A push of the third week fails once another is shown: it stays, to be
+    // shown on coming back, until yet another week is.
+    act(() => hook.result.current.push.mutate())
+    hook.rerender({ week: NEXT })
+    await waitFor(() => expect(hook.result.current.plan.isSuccess).toBe(true))
+    await act(async () => laterPush.send(errorResponse(500, 'internal')))
+    await waitFor(() => expect(weekMutations(queryClient, LATER)).toEqual(['push error']))
+    hook.rerender({ week: WEEK })
+    expect(weekMutations(queryClient, LATER)).toEqual([])
+  })
+
+  it('leaves behind what settles once Plan is left for another route, and keeps what is pending', async () => {
+    const friday = deferred()
+    const monday = deferred()
+    const push = deferred()
+    stubServer({
+      [`GET ${PLAN}`]: () => jsonResponse(200, planBody()),
+      [`PUT ${FRIDAY}`]: () => friday.reply,
+      [`PUT ${MONDAY}`]: () => monday.reply,
+      [`POST ${PLAN}/push-calendar`]: () => push.reply,
+    })
+    const api = createApiClient(fakeLocation('/plan'), createNetworkStatus(window), createVerifiedSession(localStorage))
+    await api.loadMe()
+    const queryClient = createQueryClient()
+    let week!: { plan: ReturnType<typeof usePlan>; swap: SwapDay; push: PushToCalendar }
+    let navigate!: NavigateFunction
+    function Week() {
+      week = { plan: usePlan(WEEK), swap: useSwapDay(WEEK), push: usePushToCalendar(WEEK) }
+      return null
+    }
+    function Navigator() {
+      navigate = useNavigate()
+      return null
+    }
+    render(
+      <ApiProvider client={api}>
+        <QueryClientProvider client={queryClient}>
+          <MemoryRouter initialEntries={['/plan']}>
+            <Navigator />
+            <Routes>
+              <Route path="/plan" element={<Week />} />
+              <Route path="/settings" element={null} />
+            </Routes>
+          </MemoryRouter>
+        </QueryClientProvider>
+      </ApiProvider>,
+    )
+    await waitFor(() => expect(week.plan.isSuccess).toBe(true))
+
+    // Two swaps and a push of the week are left pending, and Settings is
+    // shown.
+    act(() => week.swap.mutate(ORZO))
+    act(() => week.swap.mutate(FISH))
+    act(() => week.push.mutate())
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual(['swap pending', 'swap pending', 'push pending']))
+    act(() => void navigate('/settings'))
+
+    // The swaps settle: once neither is pending they are left behind, and
+    // the push still pending is not.
+    await act(async () => monday.send(jsonResponse(200, planBody({ 0: { id: 'r1', name: 'Fish tacos' } }))))
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual(['swap pending', 'swap success', 'push pending']))
+    await act(async () => friday.send(jsonResponse(200, planBody({ 0: { id: 'r1', name: 'Fish tacos' }, 4: { id: 'q1', name: 'Lemon orzo', is_new: true } }))))
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual(['push pending']))
+
+    // The push succeeds: the plan as synced is recorded, and the push is
+    // left behind.
+    const synced = { ...planBody(), status: 'synced', calendar_synced_at: '2026-10-08T06:00:00Z' }
+    await act(async () => push.send(jsonResponse(200, synced)))
+    await waitFor(() => expect(weekMutations(queryClient, WEEK)).toEqual([]))
+    expect(queryClient.getQueryData<Plan>(planKey(WEEK))).toMatchObject({ status: 'synced', calendar_synced_at: new Date('2026-10-08T06:00:00Z') })
+  })
+})

web/src/plan/api.ts

@@ -1,8 +1,10 @@
-import { useMutation, useMutationState, useQuery, useQueryClient } from '@tanstack/react-query'
+import { useEffect } from 'react'
+import { useMutation, useMutationState, useQuery, useQueryClient, type Mutation, type QueryClient } from '@tanstack/react-query'
 import { ApiError, useApi, type ApiRead } from '../api/index.ts'
 import { isRecord } from '../api/errors.ts'
 import { METHODS, oneOf, photoId, type Method } from '../dinners/api.ts'
 import { QUEST_LOG_KEY } from '../discover/api.ts'
+import { noteGoogleFailure } from '../settings/calendarApi.ts'
 
 export const PLANS_PATH = '/api/v1/plans'
 
@@ -176,6 +178,82 @@ function sameDay(a: PlanDay, b: PlanDay): boolean {
   )
 }
 
+// weekMutation is the kind and week of a swap or push of a week the mutation
+// cache keeps for it, or null for any other mutation.
+function weekMutation(mutation: Mutation): { kind: 'swap' | 'push'; week: string } | null {
+  const key = mutation.options.mutationKey
+  if (key === undefined || key.length !== 3 || key[0] !== 'plans' || (key[2] !== 'swap' && key[2] !== 'push')) return null
+  return { kind: key[2], week: String(key[1]) }
+}
+
+// WeeksShown is what keepWeekMutations is told of the weeks shown: show
+// marks a week shown until the function it returns is called.
+type WeeksShown = { show: (weekStart: string) => () => void }
+
+const weeksShown = new WeakMap<QueryClient, WeeksShown>()
+
+// keepWeekMutations bounds the swaps and pushes the mutation cache of
+// queryClient keeps, for as long as the query client lives, whatever is
+// shown: it is installed on the client's own mutation cache once, the first
+// time a week is shown, and is never removed, so a swap or push that settles
+// after its Draft board, or the whole Plan, is gone is still collected.
+//
+// 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. When one settles, the same is done, except that a week's latest,
+// when it failed, stays until a week is next shown, so that coming straight
+// back to it shows the failure. The cache holds at most the weeks shown's,
+// those of weeks left pending, and one failure of each week whose last
+// pending one settled since a week was last shown.
+function keepWeekMutations(queryClient: QueryClient): WeeksShown {
+  const kept = weeksShown.get(queryClient)
+  if (kept !== undefined) return kept
+  const mutations = queryClient.getMutationCache()
+  // How many times each week is shown at once.
+  const shown = new Map<string, number>()
+  function sweep(settled: boolean) {
+    // The mutations of each kind of each week not shown, in the order sent.
+    const left = new Map<string, Mutation[]>()
+    for (const mutation of mutations.getAll()) {
+      const of = weekMutation(mutation)
+      if (of === null || shown.has(of.week)) continue
+      const id = `${of.kind} ${of.week}`
+      left.set(id, [...(left.get(id) ?? []), mutation])
+    }
+    for (const week of left.values()) {
+      if (week.some((mutation) => mutation.state.status === 'pending')) continue
+      const latest = week.at(-1)
+      for (const mutation of week) {
+        if (settled && mutation === latest && mutation.state.status === 'error') continue
+        mutations.remove(mutation)
+      }
+    }
+  }
+  mutations.subscribe((event) => {
+    if (event.type === 'updated' && weekMutation(event.mutation) !== null && event.mutation.state.status !== 'pending') sweep(true)
+  })
+  const show = (weekStart: string) => {
+    shown.set(weekStart, (shown.get(weekStart) ?? 0) + 1)
+    sweep(false)
+    return () => {
+      const times = shown.get(weekStart)! - 1
+      if (times === 0) shown.delete(weekStart)
+      else shown.set(weekStart, times)
+    }
+  }
+  const keeping = { show }
+  weeksShown.set(queryClient, keeping)
+  return keeping
+}
+
+// useWeekShown marks the week starting on weekStart shown while the
+// component is mounted (keepWeekMutations).
+function useWeekShown(weekStart: string) {
+  const queryClient = useQueryClient()
+  useEffect(() => keepWeekMutations(queryClient).show(weekStart), [queryClient, weekStart])
+}
+
 // 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) {
@@ -205,10 +283,12 @@ 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 (keepWeekMutations).
 export function useSwapDay(weekStart: string): SwapDay {
   const { apiFetch } = useApi()
   const queryClient = useQueryClient()
+  useWeekShown(weekStart)
   const key = planKey(weekStart)
   const mutationKey = swapKey(weekStart)
   const mutations = queryClient.getMutationCache()
@@ -224,7 +304,8 @@ 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 settled in a week not shown
+      // (keepWeekMutations): a later swap must stay in the cache while an
       // earlier one is pending.
       gcTime: Infinity,
       mutationFn: async ({ date, dinner }) => {
@@ -274,3 +355,85 @@ export function useSwapDay(weekStart: string): SwapDay {
     dismiss,
   }
 }
+
+// pushKey keys the pushes of the week starting on weekStart in the mutation
+// cache, where they outlive the Draft board that sent them.
+function pushKey(weekStart: string) {
+  return ['plans', weekStart, 'push'] as const
+}
+
+// PushToCalendar is the push of one week, as the mutation cache holds it:
+// whether it is pending, and why the latest failed, if it failed.
+export type PushToCalendar = {
+  pending: boolean
+  error: Error | null
+  mutate: () => void
+  reset: () => void
+}
+
+// usePushToCalendar pushes the plan of the week starting on weekStart to the
+// chosen Google calendar (POST /api/v1/plans/{weekStart}/push-calendar). The
+// server answers with the plan as synced, which replaces the one shown, as a
+// swap's answer does. A push refused because the plan changed meanwhile
+// reads the plan again, whether or not the week is shown, and stays pending
+// until that read lands: nothing is pushed again before the changed plan is
+// the one shown. One Google refused the grant for reads the Google Calendar
+// connection again, which is now reconnect required.
+//
+// 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. Settled
+// pushes of a week no longer shown are left behind too
+// (keepWeekMutations).
+export function usePushToCalendar(weekStart: string): PushToCalendar {
+  const { apiFetch } = useApi()
+  const queryClient = useQueryClient()
+  useWeekShown(weekStart)
+  const key = planKey(weekStart)
+  const mutationKey = pushKey(weekStart)
+  const mutations = queryClient.getMutationCache()
+  // The week's pushes, in the order sent.
+  const pushes = useMutationState({
+    filters: { mutationKey },
+    select: (mutation) => ({ status: mutation.state.status, error: mutation.state.error }),
+  })
+  const latest = pushes.at(-1)
+
+  function mutate() {
+    const mutation = mutations.build<Plan, Error, void, unknown>(queryClient, {
+      mutationKey,
+      // Kept until reset or settled in a week not shown (keepWeekMutations):
+      // 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`
+        return parsePlan(`POST ${path}`, weekStart, await apiFetch<unknown>(path, { method: 'POST' }), false)
+      },
+      onSuccess: (plan) => queryClient.setQueryData<Plan>(key, plan),
+      onError: async (error) => {
+        noteGoogleFailure(queryClient, error)
+        if (error instanceof ApiError && error.code === 'plan_changed') {
+          await queryClient.invalidateQueries({ queryKey: key, refetchType: 'all' })
+        }
+      },
+    })
+    // A failure is the mutation's state, which error reports.
+    mutation.execute().catch(() => undefined)
+  }
+
+  function reset() {
+    const week = mutations.findAll({ mutationKey })
+    if (week.some((mutation) => mutation.state.status === 'pending')) {
+      throw new Error(`The week of ${weekStart} has a push pending, which cannot be reset.`)
+    }
+    for (const mutation of week) mutations.remove(mutation)
+  }
+
+  return {
+    pending: pushes.some((push) => push.status === 'pending'),
+    error: latest?.status === 'error' ? latest.error! : null,
+    mutate,
+    reset,
+  }
+}