## What changed
- Add `--codex-ui-plugin-process` to `codex-code-mode-host` and a typed protocol for initializing, invoking, and closing UI plugin isolates.
- Support persistent module state and string results from synchronous or promise-based exports across up to 32 isolates in one helper process.
- Require sandbox-enabled V8 with JIT disabled, restrict executable loading and globals, and enforce execution deadlines and per-instance queue, source, result, and promise limits.
- Close affected isolates on script failures, cancellation, or overload, and return bounded script diagnostics.
- Bump the helper handshake to version 3 and increase the maximum frame size to 1 MiB.
## Testing
Add wire-level integration tests and runtime unit tests covering promise settlement, cancellation, loading restrictions, diagnostics, failure isolation, capacity reuse, transport bounds, and watchdog synchronization. Add CLI tests for argument validation before helper startup.
GitOrigin-RevId: bad6a57c84d9197c1fd76a78cf060502c5bc8bb8
## What changed
- Move the V8 implementation into a dedicated `codex-code-mode-runtime` crate used by `codex-code-mode-host`, removing the embedded runtime fallback from the Codex process.
- Resolve the host executable from the active installation layout and check its availability before selecting tools.
- Fall back to direct tools with a one-time warning when optional code mode is unavailable. Keep `code_mode_only` and `disable_in_process_fallback` configurations fail-closed.
## Testing
- Cover host discovery for standalone and package layouts, including missing hosts and symlinks.
- Verify direct-tool fallback, one-time warnings, and fail-closed code-mode-only behavior.
GitOrigin-RevId: 5aa3c6f1db148b2231fc24089a2ee0e2b00dbddb
Joe Savona