name: precommit-setup description: Configure comprehensive three-layer pre-commit quality system with linting, type checking, and testing enforcement model: claude-sonnet-4 tools: [Read, Write, Bash]

Pre-commit Setup Skill

Configure a comprehensive three-layer pre-commit quality system that enforces linting, type checking, and testing before commits.

Use When

• Setting up new project with code quality enforcement
• Adding pre-commit hooks to existing project
• Upgrading from basic linting to comprehensive quality system
• Setting up monorepo/plugin architecture with per-component quality checks
• Updating pre-commit hook versions

Philosophy: Three-Layer Defense

This skill implements a comprehensive quality system based on three layers:

1. Layer 1: Fast Global Checks - Quick linting and type checking on all files (~50-200ms)
2. Layer 2: Component-Specific Checks - Detailed linting, type checking, and testing for changed components only (~10-30s)
3. Layer 3: Validation Hooks - Structure validation, security scanning, and custom checks

Key Principle: New code is automatically checked before commit, preventing technical debt from entering the repository.

Standard Hooks (Layer 1)

Python Projects

Basic Quality Checks

1. pre-commit-hooks - File validation (trailing whitespace, EOF, YAML/TOML/JSON syntax)
2. ruff - Ultra-fast linting and formatting (~50ms)
3. ruff-format - Code formatting
4. mypy - Static type checking (~200ms)
5. bandit - Security scanning

Configuration

```yaml

.pre-commit-config.yaml

repos:

• repo: https://github.com/pre-commit/pre-commit-hooks rev: v6.0.0 hooks:

  • id: trailing-whitespace
  • id: end-of-file-fixer
  • id: check-yaml
  • id: check-toml
  • id: check-json

• repo: https://github.com/astral-sh/ruff-pre-commit rev: v0.14.2 hooks:

  • id: ruff args: [--fix]
  • id: ruff-format

• repo: https://github.com/pre-commit/mirrors-mypy rev: v1.13.0 hooks:

  • id: mypy args: [--ignore-missing-imports]

• repo: https://github.com/PyCQA/bandit rev: 1.8.0 hooks:

  • id: bandit args: [-c, pyproject.toml] ```

Rust Projects

1. rustfmt - Code formatting
2. clippy - Linting
3. cargo-check - Compilation check

TypeScript Projects

1. eslint - Linting
2. prettier - Code formatting
3. tsc - Type checking

Component-Specific Checks (Layer 2)

For monorepos, plugin architectures, or projects with multiple components, add per-component quality checks.

Python Monorepo/Plugin Architecture

Create quality check scripts:

1. Lint Changed Components (scripts/run-component-lint.sh)

```bash #!/bin/bash

Lint only changed components based on staged files

set -e

Detect changed components from staged files

CHANGED_COMPONENTS=$(git diff --cached --name-only | grep -E '^(plugins|components)/' | cut -d/ -f2 | sort -u)

if [ -z "$CHANGED_COMPONENTS" ]; then echo "No components changed" exit 0 fi

echo "Linting changed components: $CHANGED_COMPONENTS"

for component in $CHANGED_COMPONENTS; do if [ -d "plugins/$component" ]; then echo "Linting $component..." cd "plugins/$component" if [ -f "Makefile" ] && grep -q "^lint:" Makefile; then make lint else uv run ruff check . fi cd ../.. fi done ```

2. Type Check Changed Components (scripts/run-component-typecheck.sh)

```bash #!/bin/bash

Type check only changed components

set -e

CHANGED_COMPONENTS=$(git diff --cached --name-only | grep -E '^(plugins|components)/' | cut -d/ -f2 | sort -u)

if [ -z "$CHANGED_COMPONENTS" ]; then exit 0 fi

echo "Type checking changed components: $CHANGED_COMPONENTS"

for component in $CHANGED_COMPONENTS; do if [ -d "plugins/$component" ]; then echo "Type checking $component..." cd "plugins/$component" if [ -f "Makefile" ] && grep -q "^typecheck:" Makefile; then make typecheck else uv run mypy src/ fi cd ../.. fi done ```

3. Test Changed Components (scripts/run-component-tests.sh)

```bash #!/bin/bash

Test only changed components

set -e

CHANGED_COMPONENTS=$(git diff --cached --name-only | grep -E '^(plugins|components)/' | cut -d/ -f2 | sort -u)

if [ -z "$CHANGED_COMPONENTS" ]; then exit 0 fi

echo "Testing changed components: $CHANGED_COMPONENTS"

for component in $CHANGED_COMPONENTS; do if [ -d "plugins/$component" ]; then echo "Testing $component..." cd "plugins/$component" if [ -f "Makefile" ] && grep -q "^test:" Makefile; then make test else uv run pytest tests/ fi cd ../.. fi done ```

Add to Pre-commit Configuration

```yaml

.pre-commit-config.yaml (continued)

Layer 2: Component-Specific Quality Checks

• repo: local hooks:

  • id: run-component-lint name: Lint Changed Components entry: ./scripts/run-component-lint.sh language: system pass_filenames: false files: ^(plugins|components)/.*\.py$

  • id: run-component-typecheck name: Type Check Changed Components entry: ./scripts/run-component-typecheck.sh language: system pass_filenames: false files: ^(plugins|components)/.*\.py$

  • id: run-component-tests name: Test Changed Components entry: ./scripts/run-component-tests.sh language: system pass_filenames: false files: ^(plugins|components)/.*\.(py|md)$ ```

Validation Hooks (Layer 3)

Add custom validation hooks for project-specific requirements.

Example: Plugin Structure Validation

```yaml

Layer 3: Validation Hooks

• repo: local hooks:
  • id: validate-plugin-structure name: Validate Plugin Structure entry: python3 scripts/validate_plugins.py language: system pass_filenames: false files: ^plugins/.*$ ```

Workflow

1. Create Configuration Files

```bash

Create .pre-commit-config.yaml

python3 plugins/attune/scripts/attune_init.py \ --lang python \ --name my-project \ --path .

Create quality check scripts (for monorepos)

mkdir -p scripts chmod +x scripts/run-component-*.sh ```

2. Configure Python Type Checking

Create pyproject.toml with strict type checking:

```toml [tool.mypy] python_version = "3.12" warn_return_any = true warn_unused_configs = true disallow_untyped_defs = true strict = true

Per-component configuration

[[tool.mypy.overrides]] module = "plugins.*" strict = true ```

3. Configure Testing

```toml [tool.pytest.ini_options] testpaths = ["tests"] pythonpath = ["src"] addopts = [ "-v", # Verbose output "--strict-markers", # Strict marker enforcement "--cov=src", # Coverage for src/ "--cov-report=term", # Terminal coverage report ]

markers = [ "slow: marks tests as slow (deselect with '-m \"not slow\"')", "integration: marks tests as integration tests", ] ```

4. Install and Test Hooks

```bash

Install pre-commit tool

uv sync --extra dev

Install git hooks

uv run pre-commit install

Test on all files (first time)

uv run pre-commit run --all-files

Normal usage - test on staged files

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

Hooks run automatically

```

5. Create Manual Quality Scripts

For comprehensive quality checks (CI/CD, monthly audits):

scripts/check-all-quality.sh

```bash #!/bin/bash

Comprehensive quality check for all components

set -e

echo "=== Running Comprehensive Quality Checks ==="

Lint all components

./scripts/run-component-lint.sh --all

Type check all components

./scripts/run-component-typecheck.sh --all

Test all components

./scripts/run-component-tests.sh --all

echo "=== ✓ All Quality Checks Passed ===" ```

Hook Execution Order

Pre-commit hooks run in this order:

```

1. ✓ File Validation (whitespace, EOF, YAML/TOML/JSON syntax)
2. ✓ Security Scanning (bandit)
3. ✓ Global Linting (ruff - all files)
4. ✓ Global Type Checking (mypy - all files)
5. ✓ Component Linting (changed components only)
6. ✓ Component Type Checking (changed components only)
7. ✓ Component Tests (changed components only)
8. ✓ Custom Validation (structure, patterns, etc.) ```

All must pass for commit to succeed.

Performance Optimization

Typical Timings

Optimization Strategies

1. Only test changed components - Default behavior
2. Parallel execution - Hooks run concurrently when possible
3. Caching - Dependencies cached by uv
4. Incremental mypy - Use --incremental flag

Hook Configuration

Skip Specific Hooks

```bash

Skip specific hook for one commit

SKIP=run-component-tests git commit -m "WIP: tests in progress"

Skip component checks but keep global checks

SKIP=run-component-lint,run-component-typecheck,run-component-tests git commit -m "WIP"

Skip all hooks (DANGEROUS - use only for emergencies)

git commit --no-verify -m "Emergency fix" ```

Custom Hooks

Add project-specific hooks:

```yaml

• repo: local hooks:

  • id: check-architecture name: Validate Architecture Decisions entry: python3 scripts/check_architecture.py language: system pass_filenames: false files: ^(plugins|src)/.*\.py$

  • id: check-coverage name: Ensure Test Coverage entry: python3 scripts/check_coverage.py language: system pass_filenames: false files: ^(plugins|src)/.*\.py$ ```

CI Integration

Ensure CI runs the same comprehensive checks:

```yaml

.github/workflows/quality.yml

name: Code Quality

on: [push, pull_request]

jobs: quality: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4

  - name: Set up Python
    uses: actions/setup-python@v5
    with:
      python-version: '3.12'

  - name: Install uv
    run: pip install uv

  - name: Install dependencies
    run: uv sync

  - name: Run Comprehensive Quality Checks
    run: ./scripts/check-all-quality.sh

  - name: Upload Coverage
    uses: codecov/codecov-action@v4
    with:
      files: ./coverage.xml

```

Troubleshooting

Hooks Too Slow

Solution: Only changed components are checked by default. For even faster commits:

```bash

Skip tests during development

SKIP=run-component-tests git commit -m "WIP: feature development"

Run tests manually when ready

./scripts/run-component-tests.sh --changed ```

Cache Issues

```bash

Clear pre-commit cache

uv run pre-commit clean

Clear component caches

find . -name "pycache" -type d -exec rm -rf {} + find . -name ".pytest_cache" -type d -exec rm -rf {} + find . -name ".mypy_cache" -type d -exec rm -rf {} + ```

Hook Failures

```bash

See detailed output

uv run pre-commit run --verbose --all-files

Run specific component checks manually

cd plugins/my-component make lint make typecheck make test ```

Import Errors in Tests

```toml

Ensure PYTHONPATH is set in pyproject.toml

[tool.pytest.ini_options] pythonpath = ["src"] ```

Type Checking Errors

```toml

Use per-module overrides for gradual typing

[[tool.mypy.overrides]] module = "legacy_module.*" disallow_untyped_defs = false ```

Best Practices

For New Projects

1. Start with strict settings - Easier to maintain from the beginning
2. Configure type checking - Use strict = true in tool.mypy
3. Set up testing early - Include pytest in pre-commit hooks
4. Document exceptions - If you skip hooks, document why

For Existing Projects

1. Gradual adoption - Start with global checks, add component checks later
2. Fix existing issues - Run quality checks on all files, fix progressively
3. Create baseline - Document current state for tracking improvement
4. Use --no-verify sparingly - Only for true emergencies

For Monorepos/Plugin Architectures

1. Per-component Makefiles - Standardize lint/typecheck/test targets
2. Shared configurations - Use root pyproject.toml for common settings
3. Component detection - Automatically detect changed components
4. Progressive disclosure - Show summary first, details on failure

Complete Example: Python Monorepo

```yaml

.pre-commit-config.yaml

repos:

Layer 1: Fast Global Checks

• repo: https://github.com/pre-commit/pre-commit-hooks rev: v6.0.0 hooks:

  • id: trailing-whitespace
  • id: end-of-file-fixer
  • id: check-yaml
  • id: check-toml
  • id: check-json

• repo: https://github.com/astral-sh/ruff-pre-commit rev: v0.14.2 hooks:

  • id: ruff args: [--fix]
  • id: ruff-format

• repo: https://github.com/pre-commit/mirrors-mypy rev: v1.13.0 hooks:

  • id: mypy args: [--ignore-missing-imports]

• repo: https://github.com/PyCQA/bandit rev: 1.8.0 hooks:

  • id: bandit args: [-c, pyproject.toml]

Layer 2: Component-Specific Checks

• repo: local hooks:

  • id: run-component-lint name: Lint Changed Components entry: ./scripts/run-component-lint.sh language: system pass_filenames: false files: ^plugins/.*\.py$

  • id: run-component-typecheck name: Type Check Changed Components entry: ./scripts/run-component-typecheck.sh language: system pass_filenames: false files: ^plugins/.*\.py$

  • id: run-component-tests name: Test Changed Components entry: ./scripts/run-component-tests.sh language: system pass_filenames: false files: ^plugins/.*\.(py|md)$

Layer 3: Validation Hooks

• repo: local hooks:
  • id: validate-plugin-structure name: Validate Plugin Structure entry: python3 scripts/validate_plugins.py language: system pass_filenames: false files: ^plugins/.*$ ```

Related Skills

• Skill(attune:project-init) - Full project initialization
• Skill(attune:workflow-setup) - GitHub Actions setup
• Skill(attune:makefile-generation) - Generate component Makefiles

See Also

• Quality Gates Documentation - Comprehensive quality system guide
• Testing Guide - Testing best practices