Reported by a user who spent over an hour and a half on the onboarding
syncing step, on two devices, without ever getting into the app.
## What was happening
When Enable Banking rate limits a connection, `SyncBankingConnectionJob`
records the error and backs off, but leaves the connection **Active with
`last_synced_at` still NULL** — the exact shape `syncStatus` treated as
"still syncing". The step polled that endpoint forever, and there was no
deadline or escape on the client.
Confirmed in production for the reporter: a Trade Republic connection
returned `429` on every scheduled sync for two days straight. They
unblocked themselves by deleting the connection — `onboarded_at` was set
four seconds later. Three other users are in the same state right now,
one of them from today.
## What changed
- **`syncStatus` no longer waits on a connection that already failed**,
and reports it as `failed` separately from `pending`.
- **The step says so instead of pretending it worked.** Advancing
silently dropped the user on a "You are all set!" screen with an empty
dashboard and no way to find out why. Now they get a short explanation
and a Continue button.
- **Client deadline raised to 5 minutes** — the previous 2 was under the
worst case of a healthy first sync (3 attempts of a 120s job, 30s apart)
— and the status request now has a timeout, so a hanging poll can't
stall the step either. A failing status check keeps polling until the
deadline rather than skipping the user ahead.
- **`AccountMappingController` clears the stale error** when it
reactivates a connection, so a genuine sync in flight isn't reported as
failed.
## Testing
- Feature tests for the rate-limited case, for a healthy connection
syncing alongside a failed one, and for the failed flag; a
`rateLimited()` factory state replaces the hand-rolled attributes.
- Vitest coverage for the three client branches: failed, deadline
reached, and the normal advance.
- Browser QA against the real app, reproducing the production state: the
honest screen appears instead of the spinner, Continue moves on, the
user completes onboarding and reaches the app; and a genuinely pending
sync still spins and then advances by itself once the connection syncs.
No console errors.
## Demo
https://github.com/user-attachments/assets/e54e029d-db7a-47b0-8b93-0da5569aa363
<!-- PLACEHOLDER: drag the QA video here -->
## Not in this PR
`settings/connections.tsx` has the same `active && !last_synced_at` =
"syncing" heuristic, so a rate-limited connection shows a permanent
green "Syncing" badge there and its error is never rendered (the error
block is gated on `status === 'error'`). Same bug class, separate
surface — worth a follow-up.
a3eafecf60