FileChanged Hook - Claude Code

FileChanged hooks react to external changes in the project - another editor saved a file, git pulled new commits, a build wrote an artifact.

What it does

You declare paths or patterns to watch. When Claude Code detects a change, the hook fires with the path and the kind of change. It can update the model's context, invalidate caches, or trigger a follow-up action. It's how Claude stays aware of what's happening outside its own edits.

When to use it

• Reacting to lockfile changes to suggest a reinstall.
• Reloading config when .env or settings files shift.
• Notifying Claude when a teammate pushed a fresh branch state.
• Building IDE-like responsiveness in CLI sessions.

Gotchas

• Watching too many paths causes noise. Start narrow.
• FileChanged events can fire during Claude's own edits - be careful not to loop.
• Debounce rapid-fire events (package managers that touch many files at once).

Official docs: https://code.claude.com/docs/en/hooks.md#filechanged