Two useEffects added in Phase 2C and Phase 4 followed the anti-pattern
of calling a state setter inside the effect and listing the setter's
output in the dep array. Both could re-fire indefinitely when the
selected slice changed shape on each render — which the chat page hit
on first load.
chat-settings-sheet.tsx (thread settings loader)
- Before: `useEffect(load, [..., threadSettings, ...])` with
`if (!threadSettings) load()` inside. After load, the Zustand
selector returned a freshly-constructed slice, dep changed,
effect re-ran. If anything in between caused threadSettings to
briefly flicker undefined (e.g. a race during initial hydration
or a fast subsequent thread switch), the load fired again and the
cycle repeated.
- After: ref-guarded by activeThreadId — `threadSettingsLoadedRef`
tracks which threadId has been loaded; the effect deps shrink to
`[ragSource.kind, activeThreadId, loadThreadSettings]`, all
stable per-thread, removing the feedback loop.
ingestion-toast-stack.tsx (terminal-job auto-dismiss)
- Before: `useEffect(..., [jobs, dismissedJobs])` with
`setDismissedJobs(prev => new Set(prev).add(jobId))` inside the
scheduled setTimeout. Each setter creates a new Set reference;
the dep change re-triggers the effect, which clears and
reschedules timers. Under fast SSE event arrival or a strict-mode
double-mount, the scheduler runs faster than its cleanup and
React caps the depth.
- After: dismissedJobs is read via a ref (kept in sync at the top
of the component); the effect only depends on `[jobs]`. A
`scheduledJobsRef` prevents duplicate timer scheduling for the
same job across multiple effect runs, and the setDismissedJobs
updater no-ops when the job is already dismissed.
No behavior change for the happy path — toasts still auto-dismiss
after DISMISS_DELAY_MS; thread settings still load on first sight
of a thread.
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