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:

1. Claude edits a TypeScript file
2. Hook automatically runs type checking
3. 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?

1. Check JSON syntax in settings
2. Verify command exists and is executable
3. Test command manually first

Hook causing problems?

1. Check exit codes (non-zero stops Claude)
2. Review hook output for errors
3. 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:

1. Press Ctrl+b
2. Type: npm run build
3. Command runs in background
4. Continue working with Claude while build runs
5. See results when complete

Perfect for:

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

Getting Started

1. Start simple - One hook for type checking
2. Test thoroughly - Run commands manually first
3. Add gradually - Don't overwhelm your workflow
4. 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'"
          }
        ]
      }
    ]
  }
}

Hooks turn Claude into a more integrated part of your development environment, automatically handling the routine tasks you'd normally do manually.

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Claude Code Blog Series

Previous: Part 7 - IDE Integration with VS Code and JetBrains Next: Part 9 - Complete Development Workflows

Full Series:

1. Part 1 - Getting Started and Installation
2. Part 2 - CLAUDE.md Configuration Files
3. Part 3 - Conversation Management and Context
4. Part 4 - Slash Commands and Custom Commands
5. Part 5 - MCP Servers and Tool Integration
6. Part 6 - Subagents and Task Delegation
7. Part 7 - IDE Integration with VS Code and JetBrains
8. Part 8 - Hooks for Automated Quality Checks (this post)
9. Part 9 - Complete Development Workflows
10. Part 10 - Power User CLI Options and Scripting
11. Part 11 - Troubleshooting and Recovery