## Why
DB-only listing and pagination failures must not look like exhausted history. This hardens the DB-only listing added in https://github.com/openai/codex/pull/18502 and page refilling added in https://github.com/openai/codex/pull/7509.
## What changed
- Return JSON-RPC error `-32603` when `useStateDbOnly: true` cannot query the local state database, including requests with an empty `cwd` array.
- Track all cursors encountered while filling a page and return `-32603` for repeated cursors, including on full pages.
- Document that callers can retry these errors; a successful response with `nextCursor: null` still indicates exhaustion. Default scan-and-repair requests retain their filesystem fallback.
## Testing
Add regression tests for missing or mismatched state databases versus healthy empty history, with active and archived listings and null or empty `cwd` filters. Cover repeated cursors during page refilling and on full pages using the in-memory thread store.
GitOrigin-RevId: 09653a84fc65f47316d8bbae9e4cf3dd8ce9948a
Brent Traut
406eb53c07