You can start and use Codex TUI to verify changes.
Important notes:
Start interactively. Always set RUST_LOG="trace" when starting the process. Pass -c log_dir=<some_temp_dir> argument to have logs written to a specific directory to help with debugging. When sending a test message programmatically, send text first, then send Enter in a separate write (do not send text + Enter in one burst). Use just codex target to run - just codex -c ...