Hooks and the SDKLesson 17 of 18

Another Useful Hook

Chaining Multiple Hooks for Layered Protection

Real-world projects benefit from multiple hooks working together. You can chain pre-hooks for security and post-hooks for quality, creating a comprehensive safety net that catches issues at every stage of Claude's tool use.

jsonMultiple hooks for layered security and quality
// .claude/settings.local.json
{
  "hooks": {
    "preToolUse": [
      {
        "matcher": "read|grep",
        "command": "node ./hooks/block_secrets.js"
      },
      {
        "matcher": "bash",
        "command": "node ./hooks/validate_commands.js"
      }
    ],
    "postToolUse": [
      {
        "matcher": "edit|write",
        "command": "node ./hooks/type_check.js"
      },
      {
        "matcher": "edit",
        "command": "node ./hooks/dedup_check.js"
      }
    ]
  }
}
LayerHook TypePurposeTools Watched
SecurityPre-hookBlock access to secrets and sensitive filesread, grep
SafetyPre-hookValidate shell commands before executionbash
Type SafetyPost-hookCatch type errors after every editedit, write
Code QualityPost-hookDetect duplicate code in critical dirsedit

A complete hook stack for production projects

Start Simple, Add Gradually

Don't implement all hooks at once. Start with the type checker hook (highest value, lowest cost), then add the .env guard, then consider deduplication for critical directories. Each hook adds latency, so find the right balance for your workflow.

Key Takeaways

  • Chain multiple pre-hooks (security) and post-hooks (quality) for layered protection
  • Pre-hooks guard: block secret access, validate commands before execution
  • Post-hooks enforce: type checking after edits, duplicate detection in critical directories
  • Start with the type checker hook (highest value), then add more as needed
  • Each hook adds latency -- balance coverage with development speed

Check Your Understanding

Test what you learned in this lesson.

Q1.In a layered hook setup, what is the recommended order to add hooks to your project?

Q2.Which combination provides the most comprehensive hook protection?

Q3.Why do hooks add latency to Claude Code?