fix(settings): restore mounted flag on remount so auto-save can settle (MUL-4962)

[yyclaw]

What does this PR do?

Fixes the shared settings auto-save indicator getting stranded on "Saving…" forever, even though the save succeeded.

The useAutoSave mount effect (packages/views/settings/components/use-auto-save.ts) only cleared mountedRef in its cleanup and never re-set it to true on setup. Under React StrictMode (the Next.js dev default), the initial setup → cleanup → setup cycle leaves mountedRef.current pinned to false for the component's whole life. A successful save then never reaches its terminal branch (succeeded && mountedRef.current), so setStatus("saved") and onSuccess never fire — the indicator spins forever and no success toast appears, even though PATCH /api/workspaces/{id} returned 200.

The fix restores the invariant by setting mountedRef.current = true on every mount. This is the standard mounted-ref pattern and keeps the flag reflecting the live component across StrictMode's simulated remount (and any genuine remount).

Shared by all auto-saved settings surfaces (Repositories, GitHub, etc.), so this fixes the whole set.

Related Issue

Closes #5612

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Refactor / code improvement (no behavior change)
• Documentation update
• Tests (adding or improving test coverage)
• CI / infrastructure

Changes Made

• packages/views/settings/components/use-auto-save.ts: set mountedRef.current = true in the mount effect's setup so StrictMode's setup/cleanup/setup cycle no longer strands the flag at false.
• packages/views/settings/components/use-auto-save.test.tsx: add a StrictMode regression test asserting a successful save still transitions to success (onSuccess fires).

How to Test

1. Before the fix: run the web app in dev, go to Settings → Code repositories, add a repo URL and blur. The PATCH /api/workspaces/{id} returns 200 but the indicator stays on "Saving…" indefinitely.
2. After the fix: the indicator transitions to "Saved" and the success toast fires.
3. Automated: pnpm --filter @multica/views test -- use-auto-save. The added StrictMode test fails on the old code and passes with the fix.

Checklist

• I have included a thinking path that traces from project context to this change
• I have run tests locally and they pass
• I have added or updated tests where applicable
• If this change affects the UI, I have included before/after screenshots
• I have updated relevant documentation to reflect my changes
• If I added a new runtime / coding tool / UI tab, I synced the change to landing copy and relevant docs
• If this PR touches Chinese product copy, I checked it against conventions.zh.mdx
• I have considered and documented any risks above
• I will address all reviewer comments before requesting merge

AI Disclosure

AI tool used: Claude Code

Prompt / approach: Started from a user-reported "Saving… spins forever" bug with a screenshot. Traced the auto-save state machine end to end, confirmed via DevTools that the PATCH returned 200 (ruling out a hung request), then pinpointed the broken mounted-ref pattern that only misfires under StrictMode's double-invoked mount. Wrote a failing StrictMode regression test first, verified it fails on the old code and passes with the one-line invariant fix.

[vercel]

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[Bohan-J]

Thanks for the great fix, @yyclaw! 🙏

The root-cause analysis was spot on: mountedRef initialized to true with a cleanup-only mount effect gets pinned to false by StrictMode's setup → cleanup → setup cycle, so the terminal succeeded && mountedRef.current branch never fires and the indicator spins forever despite a 200. Restoring the flag in the effect's setup is exactly the right, minimal fix, and the StrictMode regression test (which fails on the old code and passes on the new) is a nice touch that will keep this from regressing.

Merging now. Thanks again for the clear write-up and for catching this — it improves every auto-saved settings surface. 🎉

Minor non-blocking follow-up (no action needed): the pnpm --filter @multica/views test -- use-auto-save command in the description runs the whole @multica/views suite rather than just this file under the current Vitest arg parsing — pnpm --filter @multica/views exec vitest run settings/components/use-auto-save.test.tsx targets it directly. Doesn't affect the code or this merge.