Pre-Commit Hooks

PromptKit uses pre-commit hooks to maintain code quality. The hooks run automatically before each commit and only check changed code, making them fast and developer-friendly.

Quick Setup

# Install required tools
brew install golangci-lint gosec
pip3 install diff-cover

# Enable the hook (one-time)
chmod +x .git/hooks/pre-commit

Or use the installation script:

./scripts/install-hooks.sh

What Gets Checked

The pre-commit hook runs four checks:

1. Linting - Only on changed Go files using golangci-lint --new-from-rev=HEAD
2. Security - Security scanning with gosec on changed code (if installed)
3. Tests - Only for packages with changes
4. Coverage - Requires ≥80% test coverage on changed lines only (via diff-cover)

Speed: Typically 15-35 seconds (vs. 2-4 minutes for full repo checks)

Usage

Normal Workflow

Just commit as usual - the hook runs automatically:

git add .
git commit -m "feat: add new feature"

Skipping the Hook

For emergencies or work-in-progress commits, include [skip-pre-commit] in your message:

git commit -m "wip: experimental changes [skip-pre-commit]"

Note: CI will still run full checks on your PR.

Manual Verification

Run the same checks manually before pushing:

make verify                 # Run all checks (recommended)
make lint-diff              # Lint changed files only
make test-coverage-diff     # Check coverage on changes

How It Works

The pre-commit system only checks code you’ve changed:

• Linting: Uses --new-from-rev=HEAD to only report issues in new/modified lines
• Coverage: Uses diff-cover to calculate coverage percentage for changed lines only

This means:

• ✅ You’re never blocked by legacy code issues
• ✅ All new code must pass quality checks
• ✅ Coverage improves gradually over time

CI Integration

GitHub Actions runs the same checks in the verify job:

• Downloads coverage from the test job
• Runs diff-cover against the PR base branch
• Posts results as a PR comment
• Fails the PR if coverage on changed lines is below 80%

Troubleshooting

Hook Not Running

chmod +x .git/hooks/pre-commit

Missing Tools

# golangci-lint
brew install golangci-lint

# gosec (security scanner)
brew install gosec

# diff-cover
pip3 install diff-cover

Coverage Check Fails

The hook shows which lines need test coverage. Options:

1. Add tests for the changed lines (recommended)
2. Use [skip-pre-commit] if the code is truly not testable
3. Run make test-coverage-diff to see a detailed report

Configuration

Changing Coverage Threshold

Edit the --fail-under value in:

• Makefile (test-coverage-diff target)
• .git/hooks/pre-commit
• .github/workflows/ci.yml (verify job)

Disabling Specific Linters

Edit .golangci.yml to disable linters that don’t fit your workflow.