feat(host): guard codex resume against an active session

[tanlethanh]

Summary

• Resuming a codex session that is open in another terminal failed with already has an active writer and exited immediately; codex holds an exclusive writer lock per thread for the session's whole life and has no force flag.
• zedra <slug> <args> now dispatches to an agent's own CLI wrapper via AgentActor::run_wrapped (default None); codex is the only implementation, since "already running" means something different per agent.
• zedra codex resume probes the lock first and offers kill / fork / cancel, then execs the real CLI. Everything else forwards unchanged.
• resume_launch_command routes through the wrapper, so the app shows the prompt instead of a dead terminal.

Notes

• y (default) sends SIGTERM, polls the lock for 3s, escalates to SIGKILL. f rewrites resume to fork, dropping --include-non-interactive, which ForkCommand does not accept.
• Prompt is laid out for a phone-width terminal: longest line is 35 chars at 40 columns.
• A custom agents.overrides.codex.resume_cmd keeps the guard by keeping the zedra codex prefix.
• Verified end to end against real codex processes: cancel leaves the holder alive, fork creates a new session and leaves the holder alive, kill terminates it and resumes, a free lock skips the prompt.

🤖 Generated with Claude Code

https://claude.ai/code/session_01VQXVaJtBFwALs97XDrh53W