Lefthook Configuration

Lefthook manages git hooks for automated quality checks.

Configuration File

The lefthook.yml defines hooks:

pre-commit:
  parallel: true
  commands:
    lint:
      glob: "*.{ts,tsx,js,jsx,json}"
      run: bun run lint
    typecheck:
      glob: "*.{ts,tsx}"
      run: bun run typecheck

commit-msg:
  commands:
    commitlint:
      run: bunx commitlint --edit {1}

Hooks

Pre-commit

Runs before each commit:

Check	Command	Glob Pattern	Purpose
lint	bun run lint	*.{ts,tsx,js,jsx,json}	Code quality
typecheck	bun run typecheck	*.{ts,tsx}	Type safety

Both checks run in parallel for speed. Hooks only trigger when matching files are staged.

Commit-msg

Validates commit message format:

• Uses Conventional Commits
• Configured in commitlint.config.ts

Valid formats:

feat: add new feature
fix: resolve bug
docs: update readme
chore: update dependencies

Installation

Lefthook installs automatically via the prepare script:

{
  "scripts": {
    "prepare": "lefthook install"
  }
}

After bun install, hooks are ready.

Bypassing Hooks

In emergencies (not recommended):

git commit --no-verify -m "emergency fix"

Customization

Adding Tests to Pre-commit

pre-commit:
  parallel: true
  commands:
    lint:
      glob: "*.{ts,tsx,js,jsx,json}"
      run: bun run lint
    typecheck:
      glob: "*.{ts,tsx}"
      run: bun run typecheck
    test:
      glob: "*.{ts,tsx}"
      run: bun run test

Adding Pre-push Hook

pre-push:
  commands:
    test:
      run: vitest run

Commitlint Custom Rules

The template includes a custom rule to prevent bare @mentions:

// commitlint.config.ts
plugins: [
  {
    rules: {
      "no-at-mentions": ({ body, subject }) => {
        // Blocks @username but allows `@param`
      },
    },
  },
];