Feature request: expose hook/plugin system for third-party monitoring tools

The ask

Add a hook or plugin system so third-party apps like AgentPeek can monitor Command Code sessions. AgentPeek currently supports 25 coding agents (Claude Code, Codex, Cursor, OpenCode, etc.) but cannot integrate with Command Code because there is no hook or plugin API to tap into.

What other agents provide

• Claude Code — hook events surfaced through ~/.claude/settings.json. Hooks fire for tool calls, permission prompts, sub-agents, etc.
• OpenCode — a plugin system at ~/.config/opencode/plugins/, where AgentPeek drops a JS file to receive session events.
• Others — at minimum, structured session/transcript/usage data stored on disk in a readable format (JSON, JSONL, SQLite) that tools can tail.

What Command Code would need to expose

At minimum:

1. Session lifecycle events — session start/end, project path, model, state (thinking, executing, waiting, idle)
2. Activity events — tool calls, files touched, diffs, commands run
3. Permission prompts — the command/file/diff being proposed, so tools can surface them in their UI
4. Usage data — token counts, cost, rate-limit windows (readable from disk or an events stream)

The ideal path is a hook system similar to Claude Code, or a plugin directory like OpenCode. Even just documenting where session data lives on disk would be a good first step.

Use case

Tools like AgentPeek let you monitor all your coding agents from the Mac notch/menu bar — answer permission prompts without finding the terminal, track usage across agents, view session transcripts, etc. Command Code users would benefit from the same visibility.

该 issue 未指定任何文件、测试或入口点。首先定位 Command Code 生成会话、活动、权限和使用情况数据的位置，然后检查 hook、plugin 或可读事件流如何公开这些数据。完成的标准是：有一条文档化的集成路径，使第三方监控器能够消费所需的事件。