lifecycle

2 questions

AI

Which hook event should I use? The full list, ranked.

Claude Code exposes 28 hook events across five categories: lifecycle, tool execution, turn control, agent teams, and context management. Exit code 2 blocks the action on blocking events. Non-blocking events show stderr but cannot prevent what already happened.
AI

Setup or SessionStart hook for my install script?

SessionStart fires on every session start, resume, `/clear`, and post-compaction, so it has to be fast. Setup fires only on explicit `claude --init-only`, `claude -p --init`, or `claude -p --maintenance`, which makes it the right home for slow one-time work like dependency installs or scheduled cleanup. Neither hook can block Claude from starting; for hard preconditions, gate the `claude` binary, not the hook.