## What changed
- Make `TimeProvider::current_time` and `CodexThread::current_time` synchronous, with clock reads required to avoid yielding or calling back into the session.
- Remove the experimental `currentTime/read` app-server request and its client-backed clock and sleep polling implementation.
- Require a host-provided `TimeProvider` for external clocks. App-server thread startup now fails when `features.current_time_reminder.clock_source = "external"` has no provider.
## Testing
Add coverage for external provider selection and rejection of app-server thread startup without an external provider.
GitOrigin-RevId: 09479d6eb28453b343dee78b3673092e73ae5d73
Move channel notification formatting into `PostPreview::notification_text()` and use it in the local message-board host. Preserve the notification fields, preview text, and `read_post` hint for truncated posts.
GitOrigin-RevId: fd3596c45194c958817a24f8fc35a886f766a84b
## Why
Core tests depend on `codex-app-server` to install and clean up agent message boards. A dedicated host crate lets them use this functionality without depending on the app server.
## What changed
Move the existing host implementation into `codex-agent-message-board-host` and update core test helpers and scenarios to use it directly. Keep the installation and deletion functions re-exported from `codex-app-server`.
GitOrigin-RevId: 9ed62d50a5f31c70550d70ba3c583399e869168a
Ruslan Nigmatullin