Startup Hook Skill for Claude Code

Create SessionStart hooks that install dependencies so tests and linters work in Claude Code sessions (CLI, web, or API).

Hook Basics

Input (via stdin)

{
  "session_id": "abc123",
  "source": "startup|resume|clear|compact",
  "transcript_path": "/path/to/transcript.jsonl",
  "permission_mode": "default",
  "hook_event_name": "SessionStart",
  "cwd": "/workspace/repo"
}

Async Mode