web/src/api/useJob.test.tsx

@@ -14,7 +14,7 @@ function job(status: string, result: Draft | null, error: string | null = null)
 function renderJob(jobId: string | null) {
   const api = createApiClient(fakeLocation(), createNetworkStatus(window), createVerifiedSession(localStorage))
   const wrapper = ({ children }: { children: ReactNode }) => <ApiProvider client={api}>{children}</ApiProvider>
-  return renderHook(({ id }) => useJob<Draft>(id), { wrapper, initialProps: { id: jobId } })
+  return renderHook(({ id }) => useJob<Draft>('plan.draft', id), { wrapper, initialProps: { id: jobId } })
 }
 
 // advance runs the timers due in ms and lets the polls they start answer.
@@ -42,7 +42,7 @@ describe('useJob', () => {
       job('succeeded', { dinners: ['Tacos', 'Chili', 'Soup'] }),
     )
     const { result } = renderJob('j1')
-    expect(result.current).toEqual({ status: undefined, result: null, error: null })
+    expect(result.current).toMatchObject({ status: undefined, result: null, error: null })
 
     await advance(0)
     expect(result.current.status).toBe('queued')
@@ -51,7 +51,7 @@ describe('useJob', () => {
     await advance(499)
     expect(fetchMock).toHaveBeenCalledTimes(1)
     await advance(1)
-    expect(result.current).toEqual({ status: 'running', result: { dinners: ['Tacos'] }, error: null })
+    expect(result.current).toMatchObject({ status: 'running', result: { dinners: ['Tacos'] }, error: null })
 
     await advance(999)
     expect(fetchMock).toHaveBeenCalledTimes(2)
@@ -62,7 +62,7 @@ describe('useJob', () => {
     expect(fetchMock).toHaveBeenCalledTimes(4)
     await advance(2000)
     expect(fetchMock).toHaveBeenCalledTimes(5)
-    expect(result.current).toEqual({
+    expect(result.current).toMatchObject({
       status: 'succeeded',
       result: { dinners: ['Tacos', 'Chili', 'Soup'] },
       error: null,
@@ -106,10 +106,76 @@ describe('useJob', () => {
     expect(fetchMock).toHaveBeenCalledTimes(2)
     await advance(1)
     expect(fetchMock).toHaveBeenCalledTimes(3)
-    expect(result.current).toEqual({ status: 'succeeded', result: { dinners: ['Tacos', 'Chili'] }, error: null })
+    expect(result.current).toMatchObject({ status: 'succeeded', result: { dinners: ['Tacos', 'Chili'] }, error: null })
     expect(vi.getTimerCount()).toBe(0)
   })
 
+  it.each([
+    ['an unknown status', { id: 'j1', kind: 'plan.draft', status: 'stuck', result: null, error: null }],
+    ['another job', { id: 'j2', kind: 'plan.draft', status: 'running', result: null, error: null }],
+    ['another kind', { id: 'j1', kind: 'suggestion_batch', status: 'running', result: null, error: null }],
+    ['no result', { id: 'j1', kind: 'plan.draft', status: 'running', error: null }],
+    ['an error that is not text', { id: 'j1', kind: 'plan.draft', status: 'failed', result: null, error: 500 }],
+    ['not a job', ['j1']],
+  ])('exposes an answer with %s as the error and stops, keeping the last status', async (_, body) => {
+    const fetchMock = stubFetch(job('running', { dinners: ['Tacos'] }), jsonResponse(200, body))
+    const { result } = renderJob('j1')
+
+    await advance(0)
+    await advance(500)
+    expect(fetchMock).toHaveBeenCalledTimes(2)
+    expect(result.current).toMatchObject({ status: 'running', result: { dinners: ['Tacos'] } })
+    expect(result.current.error?.message).toBe('GET /api/v1/jobs/j1: response is not the plan.draft job j1')
+    expect(vi.getTimerCount()).toBe(0)
+    await advance(10_000)
+    expect(fetchMock).toHaveBeenCalledTimes(2)
+  })
+
+  it('polls again at once on poll after stopping on an answer that is not the job, then keeps polling', async () => {
+    const fetchMock = stubFetch(
+      jsonResponse(200, { id: 'j1', kind: 'plan.draft', status: 'stuck', result: null, error: null }),
+      job('running', { dinners: ['Tacos'] }),
+      job('succeeded', { dinners: ['Tacos', 'Chili'] }),
+    )
+    const { result } = renderJob('j1')
+    await advance(0)
+    expect(result.current.error).not.toBeNull()
+    expect(vi.getTimerCount()).toBe(0)
+
+    act(() => result.current.poll())
+    await advance(0)
+    expect(fetchMock).toHaveBeenCalledTimes(2)
+    expect(result.current).toMatchObject({ status: 'running', result: { dinners: ['Tacos'] }, error: null })
+    await advance(500)
+    expect(fetchMock).toHaveBeenCalledTimes(3)
+    expect(result.current).toMatchObject({ status: 'succeeded', error: null })
+  })
+
+  it('polls at once on poll during the backoff after a failed poll, starting the backoff again', async () => {
+    const fetchMock = stubFetch(
+      job('running', null),
+      errorResponse(503, 'unavailable', true),
+      errorResponse(503, 'unavailable', true),
+      job('running', { dinners: ['Tacos'] }),
+      job('succeeded', { dinners: ['Tacos'] }),
+    )
+    const { result } = renderJob('j1')
+    await advance(0)
+    await advance(500)
+    await advance(1000)
+    expect(fetchMock).toHaveBeenCalledTimes(3)
+
+    // The next poll was due 2 s later; poll asks now.
+    act(() => result.current.poll())
+    await advance(0)
+    expect(fetchMock).toHaveBeenCalledTimes(4)
+    expect(result.current).toMatchObject({ status: 'running', result: { dinners: ['Tacos'] }, error: null })
+    expect(vi.getTimerCount()).toBe(1)
+    await advance(500)
+    expect(fetchMock).toHaveBeenCalledTimes(5)
+    expect(result.current.status).toBe('succeeded')
+  })
+
   it('stops polling on unmount after a failed poll', async () => {
     const fetchMock = stubFetch(errorResponse(503, 'unavailable', true))
     const { result, unmount } = renderJob('j1')
@@ -125,12 +191,15 @@ describe('useJob', () => {
   })
 
   it('stops polling the old job when the job id changes', async () => {
-    const fetchMock = stubFetch(job('running', null), job('running', null))
+    const fetchMock = stubFetch(
+      job('running', null),
+      jsonResponse(200, { id: 'j2', kind: 'plan.draft', status: 'running', result: null, error: null }),
+    )
     const { result, rerender } = renderJob('j1')
 
     await advance(0)
     rerender({ id: 'j2' })
-    expect(result.current).toEqual({ status: undefined, result: null, error: null })
+    expect(result.current).toMatchObject({ status: undefined, result: null, error: null })
     await advance(0)
     expect(request(fetchMock, 1).path).toBe('/api/v1/jobs/j2')
     expect(vi.getTimerCount()).toBe(1)
@@ -165,6 +234,6 @@ describe('useJob', () => {
     const { result } = renderJob(null)
     await advance(5000)
     expect(fetchMock).not.toHaveBeenCalled()
-    expect(result.current).toEqual({ status: undefined, result: null, error: null })
+    expect(result.current).toMatchObject({ status: undefined, result: null, error: null })
   })
 })

web/src/api/useJob.ts

@@ -1,8 +1,11 @@
-import { useEffect, useState } from 'react'
+import { useCallback, useEffect, useState } from 'react'
 import { useApi } from './ApiContext.tsx'
+import { isRecord } from './errors.ts'
 
 export type JobStatus = 'queued' | 'running' | 'succeeded' | 'failed'
 
+const STATUSES: readonly string[] = ['queued', 'running', 'succeeded', 'failed'] satisfies JobStatus[]
+
 // Job is the GET /api/v1/jobs/{id} response. result may be set while the job
 // is running (a partial result); error is set only when it failed.
 export type Job<R> = {
@@ -18,28 +21,56 @@ export type JobState<R> = {
   status: JobStatus | undefined
   // The latest result, partial while the job runs.
   result: R | null
-  // The job's failure, or the latest polling request's own failure (cleared
+  // The job's failure, the latest polling request's own failure (cleared
-  // by the next poll that answers).
+  // by the next poll that answers), or an answer that is not this job.
   error: Error | null
+  // poll asks for the job now, starting the backoff again — also after
+  // polling stopped on an answer that is not this job.
+  poll: () => void
 }
 
 // Polling starts at FIRST_DELAY_MS and doubles up to MAX_DELAY_MS.
 export const FIRST_DELAY_MS = 500
 export const MAX_DELAY_MS = 2000
 
+type JobData<R> = Omit<JobState<R>, 'poll'>
+
 const idle = { status: undefined, result: null, error: null }
 
+// parseJob checks a GET /api/v1/jobs/{id} answer is the kind of job asked
+// for, with a known status. result is passed on unread for the caller to
+// check.
+function parseJob<R>(where: string, kind: string, jobId: string, body: unknown): Job<R> {
+  if (
+    !isRecord(body) ||
+    body.id !== jobId ||
+    body.kind !== kind ||
+    typeof body.status !== 'string' ||
+    !STATUSES.includes(body.status) ||
+    !('result' in body) ||
+    (body.error !== null && typeof body.error !== 'string')
+  ) {
+    throw new Error(`${where}: response is not the ${kind} job ${jobId}`)
+  }
+  return { id: jobId, kind, status: body.status as JobStatus, result: body.result as R | null, error: body.error as string | null }
+}
+
 function isTerminal(status: JobStatus): boolean {
   return status === 'succeeded' || status === 'failed'
 }
 
-// useJob polls GET /api/v1/jobs/{jobId} until the job succeeds or fails,
+// useJob polls GET /api/v1/jobs/{jobId}, a job of the given kind, until it
-// backing off from 500 ms to 2 s. A failed poll is exposed as the error and
+// succeeds or fails, backing off from 500 ms to 2 s. A failed poll is
-// polling continues. Polling stops only at a terminal status, when jobId
+// exposed as the error and polling continues. An answer that is not this
-// changes and on unmount. A null jobId polls nothing.
+// job is exposed as the error and stops polling until poll is called.
-export function useJob<R>(jobId: string | null): JobState<R> {
+// Polling also stops at a terminal status, when jobId changes and on
+// unmount. A null jobId polls nothing.
+export function useJob<R>(kind: string, jobId: string | null): JobState<R> {
   const { apiFetch } = useApi()
-  const [state, setState] = useState<{ jobId: string | null; job: JobState<R> }>({ jobId, job: idle })
+  const [state, setState] = useState<{ jobId: string | null; job: JobData<R> }>({ jobId, job: idle })
+  // Each poll call bumps round, which restarts the polling effect.
+  const [round, setRound] = useState(0)
+  const poll = useCallback(() => setRound((r) => r + 1), [])
 
   useEffect(() => {
     if (jobId === null) return
@@ -47,37 +78,51 @@ export function useJob<R>(jobId: string | null): JobState<R> {
     let timer: ReturnType<typeof setTimeout> | undefined
     let delay = FIRST_DELAY_MS
 
-    function next() {
+    async function fetchJob() {
-      timer = setTimeout(poll, delay)
+      const path = `/api/v1/jobs/${encodeURIComponent(jobId!)}`
-      delay = Math.min(delay * 2, MAX_DELAY_MS)
+      let body: unknown
-    }
-
-    async function poll() {
       try {
-        const job = await apiFetch<Job<R>>(`/api/v1/jobs/${encodeURIComponent(jobId!)}`)
+        body = await apiFetch<unknown>(path)
-        if (!active) return
-        const error = job.status === 'failed' ? new Error(job.error ?? `job ${job.id} failed without an error message`) : null
-        setState({ jobId, job: { status: job.status, result: job.result, error } })
-        if (isTerminal(job.status)) return
       } catch (error) {
         if (!active) return
         // A failed poll is not the job's end: keep the last known status and
         // result, expose the request's error, and poll again.
-        setState((prev) => ({
+        fail(error instanceof Error ? error : new Error(String(error)))
-          jobId,
-          job: { ...(prev.jobId === jobId ? prev.job : idle), error: error instanceof Error ? error : new Error(String(error)) },
-        }))
-      }
         next()
+        return
+      }
+      if (!active) return
+      let job: Job<R>
+      try {
+        job = parseJob<R>(`GET ${path}`, kind, jobId!, body)
+      } catch (error) {
+        // An answer that is not this job will not become one by asking
+        // again: expose it and stop.
+        fail(error as Error)
+        return
+      }
+      const error = job.status === 'failed' ? new Error(job.error ?? `job ${job.id} failed without an error message`) : null
+      setState({ jobId, job: { status: job.status, result: job.result, error } })
+      if (!isTerminal(job.status)) next()
     }
 
-    void poll()
+    // fail keeps the last known status and result, with error.
+    function fail(error: Error) {
+      setState((prev) => ({ jobId, job: { ...(prev.jobId === jobId ? prev.job : idle), error } }))
+    }
+
+    function next() {
+      timer = setTimeout(fetchJob, delay)
+      delay = Math.min(delay * 2, MAX_DELAY_MS)
+    }
+
+    void fetchJob()
     return () => {
       active = false
       clearTimeout(timer)
     }
-  }, [apiFetch, jobId])
+  }, [apiFetch, kind, jobId, round])
 
   // State left from a previous jobId is not this job's.
-  return state.jobId === jobId ? state.job : idle
+  return { ...(state.jobId === jobId ? state.job : idle), poll }
 }

web/src/discover/DiscoverPage.test.tsx

@@ -68,6 +68,11 @@ function sent(fetchMock: Mock<typeof fetch>) {
     .map(([input, init]) => `${init?.method} ${String(input)}`)
 }
 
+// jobPolls counts the GET /api/v1/jobs/j1 requests.
+function jobPolls(fetchMock: Mock<typeof fetch>) {
+  return fetchMock.mock.calls.filter(([input, init]) => (init?.method ?? 'GET') === 'GET' && String(input) === '/api/v1/jobs/j1').length
+}
+
 afterEach(() => {
   vi.unstubAllGlobals()
 })
@@ -419,11 +424,50 @@ describe('DiscoverPage', () => {
     expect(alert).toHaveTextContent("Couldn't check on new side quests.")
     expect(screen.getAllByTestId('skeleton-card')).toHaveLength(3)
 
+    // Retry polls the job at once, well before the next poll is due; it
+    // does not ask for another batch.
     failPoll = false
+    const polls = jobPolls(server.fetchMock)
     fireEvent.click(within(alert).getByRole('button', { name: 'Retry' }))
+    await waitFor(() => expect(jobPolls(server.fetchMock)).toBe(polls + 1), { timeout: 200 })
     await screen.findByRole('article', { name: 'Korean beef bowls' })
     expect(screen.queryByRole('alert')).not.toBeInTheDocument()
-    expect(sent(server.fetchMock)).toEqual(['POST /api/v1/suggestions/batches', 'POST /api/v1/suggestions/batches'])
+    expect(sent(server.fetchMock)).toEqual(['POST /api/v1/suggestions/batches'])
+  })
+
+  it('shows a batch whose job answers with an unknown status as an error, and Retry polls the job again', async () => {
+    let status = 'stuck'
+    const server = stubServer([], {
+      'POST /api/v1/suggestions/batches': () =>
+        jsonResponse(202, { batch_id: 'b1', job_id: 'j1', trigger: 'manual', status: 'pending' }),
+      'GET /api/v1/jobs/j1': () => {
+        if (status === 'succeeded') server.deck = [BOWLS]
+        return jsonResponse(200, {
+          id: 'j1',
+          kind: 'suggestion_batch',
+          status,
+          result: { batch_id: 'b1', stage: 'done', suggestion_ids: ['s1'], dropped: 0 },
+          error: null,
+        })
+      },
+    })
+    await renderPage()
+    fireEvent.click(await screen.findByRole('button', { name: 'Get more now' }))
+
+    const alert = await screen.findByRole('alert')
+    expect(alert).toHaveTextContent(
+      "Couldn't check on new side quests. GET /api/v1/jobs/j1: response is not the suggestion_batch job j1",
+    )
+    // Polling has stopped: nothing more is asked until Retry.
+    await new Promise((resolve) => setTimeout(resolve, 700))
+    expect(jobPolls(server.fetchMock)).toBe(1)
+
+    status = 'succeeded'
+    fireEvent.click(within(alert).getByRole('button', { name: 'Retry' }))
+    await screen.findByRole('article', { name: 'Korean beef bowls' })
+    expect(jobPolls(server.fetchMock)).toBe(2)
+    expect(screen.queryByRole('alert')).not.toBeInTheDocument()
+    expect(sent(server.fetchMock)).toEqual(['POST /api/v1/suggestions/batches'])
   })
 
   it('shows a batch whose job result is unreadable with a retry', async () => {

web/src/discover/DiscoverPage.tsx

@@ -9,6 +9,7 @@ import { Icon } from '../ui/Icon.tsx'
 import { IconButton } from '../ui/IconButton.tsx'
 import { Skeleton } from '../ui/Skeleton.tsx'
 import {
+  BATCH_JOB_KIND,
   DECK_KEY,
   parseBatchResult,
   useDeck,
@@ -73,7 +74,7 @@ export function DiscoverPage() {
   const questLog = useQuestLog()
   const decision = useDecide()
   const startBatch = useStartBatch()
-  const job = useJob<unknown>(startBatch.data?.job_id ?? null)
+  const job = useJob<unknown>(BATCH_JOB_KIND, startBatch.data?.job_id ?? null)
 
   const top = deck.data?.[0]
   const busy = decision.isPending
@@ -89,7 +90,8 @@ export function DiscoverPage() {
       return { stored: 0, error: error as Error }
     }
   }, [job.result, startBatch.data?.job_id])
-  // The job's failure, the latest poll's failure, or an unreadable result.
+  // The job's failure, the latest poll's failure, an answer that is not the
+  // batch's job, or an unreadable result.
   const batchError = job.error ?? batch.error
 
   const { mutate: mutateDecision } = decision
@@ -147,7 +149,7 @@ export function DiscoverPage() {
         </div>
         {finding && <p className={styles.finding}>Finding new side quests…</p>}
         {jobRunning && batchError !== null && (
-          <ErrorBanner onRetry={() => startBatch.mutate()}>Couldn't check on new side quests. {batchError.message}</ErrorBanner>
+          <ErrorBanner onRetry={job.poll}>Couldn't check on new side quests. {batchError.message}</ErrorBanner>
         )}
       </section>
     )

web/src/discover/api.ts

@@ -29,6 +29,9 @@ export type Choice = 'try' | 'pass'
 // running it, which GET /api/v1/jobs/{id} reports on.
 export type Batch = { batch_id: string; job_id: string }
 
+// BATCH_JOB_KIND is the kind of the job running a suggestion batch.
+export const BATCH_JOB_KIND = 'suggestion_batch'
+
 // BatchResult is the suggestion batch job's result, published as it goes.
 export type BatchResult = { batch_id: string; stage: string; suggestion_ids: string[]; dropped: number }