feat: Subprocess/child process exec (shell passthrough, timeouts, kill grandchildren)

[buihongduc132]

Summary

• Provide robust subprocess execution: shell passthrough, streaming output, per-command timeouts, and cleanup of child/descendant processes.

Motivation

• Match Claude Code Bash/tool behavior and ensure reliable exec for long-running or nested processes.

Scope

• Shell passthrough command prefix (e.g., ! cmd) from TUI/CLI.
• Exec policy: working dir, env, per-profile PATH; soft/hard timeouts; SIGINT/SIGTERM escalations; kill grandchildren.
• Output: live tail, size limits, truncation messaging; exit codes.
• Config: exec_timeout_ms, per-profile overrides.

References

• Docs (Claude Bash tool): https://docs.anthropic.com/en/docs/agents-and-tools/tool-use/bash-tool
• Related base PRs:
  • Kill grandchildren on timeout: ``openai/codex PR 1852
  • Shell passthrough ! commands: ``openai/codex PR 2471
  • Customizable exec timeout: ``openai/codex PR 2416
  • MCP timeout fixes: ``openai/codex PR 2968

Acceptance Criteria

• Commands run with streaming output, respect timeouts, and terminate all descendants.
• Clear UX on termination and errors; tests cover nested processes.\n\nNote: Links to base PRs are defanged to avoid cross-repo noise. Open locally via:\n- gh pr view openai/codex#<PR_NUMBER> -w\n

[buihongduc132]

Parking this for later

Deferring subprocess/child-process passthrough and process-group handling. We will revisit with a concrete design for:

• opt-in passthrough mode
• timeouts and output capture policies
• kill-grandchildren handling across platforms
• sandbox interactions and approval policy

Closing for now to reduce noise; will reopen or file a new issue when ready to implement.

[buihongduc132]

Closing for now; will revisit when ready to implement. See prior comment for scope.

[shepting]

The --timeout argument in particular could be handled by openai#3750 if it looks reasonable.