luiz tanure

Posted on Aug 11 • Originally published at letanure.dev

Claude Code: Part 8 - Hooks for Automated Quality Checks

#claudecode #hooks #automation #qualityassurance

Claude Code: Part 8 - Hooks for Automated Quality Checks

The Problem

Every time Claude edits a TypeScript file, you find yourself typing the same commands:

"Now run pnpm type:check to make sure there are no errors"
"Don't forget to run the linter"

"Can you test this change?"

It's like having a talented developer who consistently forgets the basic quality checks. They do great work, but you're constantly reminding them about the fundamentals: compile, lint, test, repeat.

The Solution

Hooks automatically run quality checks at specific points in your workflow. Think of them as training your AI teammate to follow your development standards automatically - like a senior developer who runs tests before every commit without being reminded.

What Are Hooks?

Hooks are shell commands that trigger automatically when certain events happen:

Example: Automatically run pnpm type:check after Claude edits any TypeScript file
Example: Validate security rules before Claude accesses authentication files
Example: Auto-format code after Claude writes new files

Common Hook Events

PostToolUse - After Claude uses a tool

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit:*",
        "hooks": [
          {
            "type": "command",
            "command": "pnpm type:check"
          }
        ]
      }
    ]
  }
}

PreToolUse - Before Claude uses a tool
UserPromptSubmit - When you submit a prompt
SessionStart - When Claude starts

Simple Example: Auto Type-Check

Create this in your Claude settings:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit:*.ts|Edit:*.tsx",
        "hooks": [
          {
            "type": "command",
            "command": "pnpm type:check --noEmit"
          }
        ]
      }
    ]
  }
}

What happens:

Claude edits a TypeScript file
Hook automatically runs type checking
You see results immediately

Practical Hook Patterns

Code Quality Enforcement

{
  "matcher": "Write|Edit",
  "hooks": [
    {
      "type": "command",
      "command": "pnpm lint --fix"
    }
  ]
}

Security Validation

{
  "matcher": "Read:src/auth/*|Edit:src/auth/*",
  "hooks": [
    {
      "type": "command",
      "command": "./scripts/security-check.sh"
    }
  ]
}

Test Runner

{
  "matcher": "Edit:*.test.*",
  "hooks": [
    {
      "type": "command",
      "command": "npm test -- --related"
    }
  ]
}

Communication Improvements

Stop Claude from saying "You are right" repeatedly:

{
  "UserPromptSubmit": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "echo 'Skip acknowledgments - focus on the solution'"
        }
      ]
    }
  ]
}

This hook reminds Claude to be more direct and action-focused in responses.

Hook Configuration Locations

Project-level: .claude/settings.json

{
  "hooks": {
    // Project-specific hooks here
  }
}

Personal: ~/.claude/settings.json

{
  "hooks": {
    // Your personal hooks across all projects
  }
}

Hook Scripts Best Practices

Create focused scripts:

#!/bin/bash
# scripts/validate-auth.sh
echo "Validating authentication code..."
if grep -r "console.log" src/auth/; then
  echo "❌ Found console.log in auth code"
  exit 1
fi
echo "✅ Auth validation passed"

Make them fast:

Use specific file patterns
Avoid running heavy operations on every edit
Cache results when possible

Security Considerations

⚠️ Important: Hooks execute shell commands. Only use hooks you trust.

Best practices:

Review hook commands before adding them
Use absolute paths for scripts
Test hooks in safe environments first
Avoid hooks from untrusted sources

When Hooks Are Useful

Perfect for:

Code quality enforcement (linting, type checking)
Running relevant tests after changes
Security validation for sensitive files
Custom workflow automation

Avoid for:

Complex logic (keep hooks simple)
Slow operations that interrupt workflow
Operations that require user input

Troubleshooting Hooks

Hook not running?

Check JSON syntax in settings
Verify command exists and is executable
Test command manually first

Hook causing problems?

Check exit codes (non-zero stops Claude)
Review hook output for errors
Temporarily disable to isolate issues

Background Command Execution

New in Claude Code 1.0.71: Run bash commands in the background without interrupting your Claude conversation.

Shortcut: Ctrl+b

Example:

Press Ctrl+b
Type: npm run build
Command runs in background
Continue working with Claude while build runs
See results when complete

Perfect for:

Long-running builds or tests
File watching processes
Background monitoring tasks

Getting Started

Start simple - One hook for type checking
Test thoroughly - Run commands manually first
Add gradually - Don't overwhelm your workflow
Monitor impact - Ensure hooks help, don't hinder

Example starter hook:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit:*.ts|Edit:*.tsx",
        "hooks": [
          {
            "type": "command",
            "command": "echo 'TypeScript file edited'"
          }
        ]
      }
    ]
  }
}