Setup Pre Commit

Setup Pre-Commit

Install Husky pre-commit hooks with Prettier formatting, type checking, and test automation.

Arguments: $ARGUMENTS - --no-tests to skip test hook, --no-typecheck to skip typecheck hook

Behavior

1. Detect Package Manager

if [ -f "bun.lockb" ]; then PM="bun"
elif [ -f "pnpm-lock.yaml" ]; then PM="pnpm"
elif [ -f "yarn.lock" ]; then PM="yarn"
elif [ -f "package-lock.json" ]; then PM="npm"
else PM="npm"  # default
fi
echo "Package manager: $PM"

2. Check Existing Setup

# Early exit if already configured
if [ -f ".husky/pre-commit" ] && [ -f ".lintstagedrc" ]; then
  echo "Pre-commit hooks already configured. Show current config?"
  cat .husky/pre-commit
  exit 0
fi

# Check for existing Prettier config
ls .prettierrc .prettierrc.js .prettierrc.json .prettier.config.js 2>/dev/null || MISSING_PRETTIER=true

3. Install Dependencies

case "$PM" in
  bun)  bun add -d husky lint-staged prettier ;;
  pnpm) pnpm add -D husky lint-staged prettier ;;
  yarn) yarn add -D husky lint-staged prettier ;;
  npm)  npm install --save-dev husky lint-staged prettier ;;
esac

4. Initialize Husky

npx husky init
# Husky v9+ doesn't need shebangs in hook files

5. Create Pre-Commit Hook

cat > .husky/pre-commit << 'EOF'
npx lint-staged

EOF

# Add typecheck if script exists and not opted out
if [ "$ARGUMENTS" != *"--no-typecheck"* ] && \
   node -e "const p=require('./package.json'); process.exit(p.scripts?.typecheck ? 0 : 1)" 2>/dev/null; then
  echo 'npm run typecheck --if-present' >> .husky/pre-commit
fi

# Add tests if script exists and not opted out
if [ "$ARGUMENTS" != *"--no-tests"* ] && \
   node -e "const p=require('./package.json'); process.exit(p.scripts?.test ? 0 : 1)" 2>/dev/null; then
  echo 'npm run test --if-present' >> .husky/pre-commit
fi

6. Create lint-staged Config

cat > .lintstagedrc << 'EOF'
{
  "*": "prettier --write --ignore-unknown"
}
EOF
# prettier --ignore-unknown skips files Prettier can't parse

7. Create Prettier Config (if missing)

if [ "$MISSING_PRETTIER" = true ]; then
  cat > .prettierrc << 'EOF'
{
  "semi": true,
  "singleQuote": true,
  "tabWidth": 2,
  "trailingComma": "es5",
  "printWidth": 100
}
EOF
fi

8. Verify

# Verify all files exist
ls -la .husky/pre-commit .lintstagedrc

# Test lint-staged (dry run against staged files)
git add -N . 2>/dev/null || true
echo "Run 'npx lint-staged' to test against staged files."

9. Report

Pre-commit hooks installed:
  .husky/pre-commit    — runs lint-staged [+ typecheck] [+ tests]
  .lintstagedrc        — Prettier on all staged files
  .prettierrc          — default formatting config [if created]

Package manager: pnpm
Hooks active: lint-staged, typecheck, test

Test it: git add <file> && git commit -m "test"

Examples

/setup-pre-commit
/setup-pre-commit --no-tests
/setup-pre-commit --no-typecheck

Edge Cases

• No package.json: Reports "not a Node.js project" and exits
• Husky already installed: Shows current config and offers to update
• No typecheck/test scripts: Skips those hooks silently (uses --if-present)
• Monorepo: Detects workspace root and installs at root level

Token Optimization

Expected range: 300–600 tokens

Early exit: Returns immediately if .husky/pre-commit and .lintstagedrc already exist.

Bash for detection: Package manager and existing config detected via filesystem checks — no file reads.

Patterns used: Early exit, Bash for system queries, template-based generation