## What changed
- Emit a `codex_thread_hint_status` analytics event for each native history-notes thread hint attempt.
- Report whether retrieval was successful or failed along with thread context and timing, without including hint contents.
- Treat valid empty responses as successful retrievals while continuing to omit them from the context window.
## Testing
- Extend the app-server history-notes tests to verify success, empty-result success, and backend failure statuses.
GitOrigin-RevId: b9462f312847e8c871ed2be0c8cf8df0928a7fdd
