## Summary

<!-- What changed, and why? Keep this focused on user/business impact. -->

## Scope

- [ ] UI / product behavior
- [ ] API / backend logic
- [ ] Settings / admin configuration
- [ ] Performance / caching
- [ ] Logging / security
- [ ] Documentation / CI / repository hygiene

## Required Verification

- [ ] `pnpm check:branch`
- [ ] `pnpm check:quality`
- [ ] `pnpm build`
- [ ] `AUTH_TRUST_HOST=true PORT=3001 pnpm dev`
- [ ] `SMOKE_BASE_URL=http://127.0.0.1:3001 pnpm smoke:routes`

If any required check was not run, explain why:

```text

```

## Release Readiness

- [ ] No real secrets, OAuth codes, cookies, Authorization headers, signed URLs, or `.env.local` values are included.
- [ ] No tracked local artifacts such as `.DS_Store`, swap files, `.claude/`, migration backups, or `tsconfig.tsbuildinfo`.
- [ ] No new public UI links point to `/classic` or `/chat/[id]`.
- [ ] `/api/chat` remains treated as an internal Canvas/Agent generation API unless this PR explicitly migrates callers.
- [ ] New or modified high-risk logging uses `createLogger` / `createClientLogger` and is covered by `pnpm check:logs` when applicable.

## Screenshots / Evidence

<!-- Add screenshots, route smoke output, CI links, or notes for reviewers. -->

## Follow-ups

<!-- List intentional non-blocking follow-ups, if any. -->