Hook Development

Claude Code hooks are event-driven triggers that execute custom automation during workflow events like PreToolUse or SessionStart, allowing you to run prompt-based reasoning or deterministic bash scripts to validate and control AI actions.

To create a PreToolUse hook for file write safety, configure a command hook or prompt-based hook that intercepts write actions, validates file paths against security rules, and blocks execution if sensitive files are targeted.

Command hooks execute deterministic bash scripts for specific tasks, providing consistent results, while prompt-based hooks leverage LLM reasoning to perform context-aware validation and make dynamic decisions within your automation workflow.

Yes, you can implement a Stop hook to ensure tests are run before an agent stops. This event-driven automation triggers when the session ends, executing validation scripts to verify all required test suites have completed successfully.

Prevent prompt injection and ensure path safety by implementing security best practices in your hook configuration, validating all inputs strictly, sanitizing environment variables, and enforcing deterministic path checks before executing commands.

Bash command hooks provide deterministic execution but lack context-aware reasoning, meaning they cannot evaluate complex semantic inputs like prompt-based hooks, requiring explicit environment variable parsing and strict input output format handling.