Code Formatter Installer

---
name: code-formatter-installer
description: Installs and configures Prettier, ESLint, EditorConfig, and other code quality tools to enforce consistent code style across the team. Generates config files, npm scripts, editor settings recommendations, and CI integration suggestions. Use when users request "setup prettier", "add eslint", "configure code formatting", or "enforce code style".
---

# Code Formatter & Linter Installer

Establish consistent code formatting and linting across your project.

## Core Workflow

1. **Detect stack**: Identify language/framework (JS/TS, Python, Go, Rust)
2. **Choose tools**: Select appropriate formatters and linters
3. **Generate configs**: Create config files with best-practice rules
4. **Add scripts**: Include npm/package scripts for format/lint
5. **Configure editor**: Provide VS Code, IntelliJ, Vim settings
6. **Setup pre-commit**: Add git hooks for automatic formatting
7. **CI integration**: Suggest GitHub Actions or CI config

## Tool Selection by Stack

### JavaScript/TypeScript

- **Formatter**: Prettier
- **Linter**: ESLint + typescript-eslint
- **Editor**: EditorConfig
- **Hooks**: Husky + lint-staged

### Python

- **Formatter**: Black + isort
- **Linter**: Ruff or Flake8 + mypy
- **Hooks**: pre-commit

### Go

- **Formatter**: gofmt + goimports
- **Linter**: golangci-lint

### Rust

- **Formatter**: rustfmt
- **Linter**: clippy

## Configuration Templates

### Prettier (.prettierrc.json)

```json
{
  "semi": true,
  "trailingComma": "es5",
  "singleQuote": true,
  "printWidth": 100,
  "tabWidth": 2,
  "arrowParens": "avoid"
}
```

### ESLint (.eslintrc.json)

```json
{
  "extends": [
    "eslint:recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:react/recommended",
    "prettier"
  ],
  "rules": {
    "no-console": "warn",
    "@typescript-eslint/no-unused-vars": "error"
  }
}
```

### EditorConfig (.editorconfig)

```ini
root = true

[*]
indent_style = space
indent_size = 2
end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true

[*.py]
indent_size = 4

[*.md]
trim_trailing_whitespace = false
```

### Python (pyproject.toml)

```toml
[tool.black]
line-length = 100
target-version = ['py311']

[tool.isort]
profile = "black"
line_length = 100

[tool.mypy]
strict = true
warn_return_any = true
```

## Package Scripts

### JavaScript/TypeScript (package.json)

```json
{
  "scripts": {
    "format": "prettier --write .",
    "format:check": "prettier --check .",
    "lint": "eslint . --ext .ts,.tsx,.js,.jsx",
    "lint:fix": "eslint . --ext .ts,.tsx,.js,.jsx --fix",
    "typecheck": "tsc --noEmit"
  }
}
```

### Python

```bash
# Makefile or scripts
format:
	black .
	isort .

lint:
	ruff check .
	mypy .

format-check:
	black --check .
	isort --check .
```

## Git Hooks Setup

### Husky + lint-staged (Node.js)

1. Install dependencies:

```bash
npm install --save-dev husky lint-staged
npx husky init
```

2. Configure lint-staged (.lintstagedrc.json):

```json
{
  "*.{ts,tsx,js,jsx}": ["eslint --fix", "prettier --write"],
  "*.{json,md,yml}": ["prettier --write"]
}
```

3. Add pre-commit hook (.husky/pre-commit):

```bash
#!/bin/sh
npx lint-staged
```

### pre-commit (Python)

1. Create .pre-commit-config.yaml:

```yaml
repos:
  - repo: https://github.com/psf/black
    rev: 24.1.1
    hooks:
      - id: black

  - repo: https://github.com/pycqa/isort
    rev: 5.13.2
    hooks:
      - id: isort

  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.2.0
    hooks:
      - id: ruff
        args: [--fix]

  - repo: https://github.com/pre-commit/mirrors-mypy
    rev: v1.8.0
    hooks:
      - id: mypy
```

2. Install:

```bash
pip install pre-commit
pre-commit install
```

## Editor Configuration

### VS Code (settings.json)

```json
{
  "editor.defaultFormatter": "esbenp.prettier-vscode",
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": true
  },
  "[python]": {
    "editor.defaultFormatter": "ms-python.black-formatter"
  }
}
```

### VS Code Extensions (.vscode/extensions.json)

```json
{
  "recommendations": [
    "esbenp.prettier-vscode",
    "dbaeumer.vscode-eslint",
    "editorconfig.editorconfig",
    "ms-python.black-formatter"
  ]
}
```

### IntelliJ/WebStorm

- Enable: Settings → Languages & Frameworks → JavaScript → Prettier → On save
- Enable: Settings → Tools → Actions on Save → Reformat code

## CI Integration

### GitHub Actions (.github/workflows/lint.yml)

```yaml
name: Lint

on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
      - run: npm ci
      - run: npm run format:check
      - run: npm run lint
      - run: npm run typecheck
```

### Pre-merge checks

```yaml
# .github/workflows/pr-checks.yml
- name: Check formatting
  run: |
    npm run format:check || {
      echo "Code is not formatted. Run 'npm run format' locally."
      exit 1
    }
```

## Installation Checklist

For every setup, provide:

- [ ] Config files (.prettierrc, .eslintrc, .editorconfig, etc.)
- [ ] Ignore files (.prettierignore, .eslintignore)
- [ ] Package scripts (format, lint, format:check, lint:fix)
- [ ] Git hooks (husky/pre-commit)
- [ ] Editor settings (.vscode/settings.json)
- [ ] CI workflow (.github/workflows/lint.yml)
- [ ] Documentation (README section on running lint/format)

## Best Practices

1. **Run formatter last**: Prettier should override other formatting rules
2. **Extend configs**: Use popular presets (Airbnb, Standard, etc.)
3. **Ignore generated files**: Add build outputs to ignore files
4. **Make hooks skippable**: Allow `git commit --no-verify` for emergencies
5. **Document process**: Add "Code Style" section to CONTRIBUTING.md
6. **Test on clean install**: Ensure configs work without local editor setup
7. **Keep rules minimal**: Start strict, relax if needed

## Common Configurations

See `assets/configs/` for ready-to-use config files:

- Next.js + TypeScript
- React + TypeScript
- Node.js + TypeScript
- Python FastAPI
- Python Django

## Bypass Instructions (Emergencies)

```bash
# Skip pre-commit hooks
git commit --no-verify

# Skip CI checks (not recommended)
git push --no-verify
```

Document when bypass is acceptable (hotfixes, emergencies only).