setup-ts-pre-commit

name	setup-ts-pre-commit
description	Set up Husky pre-commit hooks with lint-staged using Biome, plus type checking and tests. Use when user wants to add pre-commit hooks, set up Husky, configure lint-staged, or add commit-time

Setup Pre-Commit Hooks with Biome

What This Sets Up

• Husky pre-commit hook
• lint-staged running Biome on staged files
• typecheck and test scripts in the pre-commit hook, if present
• Biome config if missing

Do not add Prettier. Biome owns formatting and linting.

Steps

1. Detect package manager

Check for lockfiles:

• pnpm-lock.yaml → pnpm
• package-lock.json → npm
• yarn.lock → yarn
• bun.lockb → bun

Use whichever is present. Default to npm if unclear.

Command equivalents:

Package manager	Add dev deps	Run binary
npm	npm install -D ...	npx ...
pnpm	pnpm add -D ...	pnpm exec ...
yarn	yarn add -D ...	yarn ...
bun	bun add -d ...	bunx ...

2. Inspect existing scripts

Read package.json.

Look for:

• lint
• format
• typecheck
• test

Prefer existing scripts over inventing new ones.

If the repo already has a CI script such as check, check:ci, or ci, note what it runs. Do not blindly put the whole CI command in pre-commit if it includes slow builds or integration tests.

3. Install dependencies

Install as devDependencies:

husky lint-staged @biomejs/biome

Skip @biomejs/biome if already installed.

4. Initialize Husky

Use the detected package manager:

  npx husky init

or:

  pnpm exec husky init

or equivalent.

This creates .husky/ and usually adds this script to package.json:

  {
    "scripts": {
      "prepare": "husky"
    }
  }

If prepare already exists, preserve existing behavior and append Husky safely, for example:

  {
    "scripts": {
      "prepare": "husky"
    }
  }

If unsure, ask before overwriting a non-Husky prepare script.

5. Create .husky/pre-commit

Write this file. No shebang needed for Husky v9+.

For pnpm:

  pnpm exec lint-staged
  pnpm typecheck
  pnpm test

Adapt commands for the detected package manager.

Rules:

• Include typecheck only if package.json has a typecheck script.
• Include test only if package.json has a test script.
• If either script is missing, omit it and tell the user.
• Do not run build by default. CI should usually own build verification.

Examples:

npm:

  npx lint-staged
  npm run typecheck
  npm run test

pnpm:

  pnpm exec lint-staged
  pnpm typecheck
  pnpm test

yarn:

  yarn lint-staged
  yarn typecheck
  yarn test

bun:

  bunx lint-staged
  bun run typecheck
  bun run test

6. Create lint-staged config

Prefer .lintstagedrc.json.

Use Biome, not Prettier:

  {
    "*.{js,jsx,ts,tsx,json,jsonc,css,graphql,md,mdx,yml,yaml}": "biome check --write --no-errors-on-unmatched"
  }

If the repo’s biome.json restricts included files, align the lint-staged globs with that config.

If the repo has unsupported file types, remove them from the glob.

7. Create biome.json if missing

Only create this file if no Biome config exists.

Use:

  {
    "$schema": "https://biomejs.dev/schemas/2.0.0/schema.json",
    "formatter": {
      "enabled": true,
      "indentStyle": "space",
      "indentWidth": 2,
      "lineWidth": 100
    },
    "javascript": {
      "formatter": {
        "semicolons": "always",
        "quoteStyle": "double"
      }
    },
    "linter": {
      "enabled": true,
      "rules": {
        "recommended": true
      }
    }
  }

If the project already has formatting conventions, match them instead of using these defaults.

8. Ensure package scripts exist

If missing, add only scripts that make sense for the repo.

Common defaults:

  {
    "scripts": {
      "format": "biome format --write .",
      "format:check": "biome format .",
      "lint": "biome check ."
    }
  }

Do not add typecheck unless TypeScript is configured.

Do not add test unless the test runner is already installed or the user asked to set one up.

9. Verify

Check:

• .husky/pre-commit exists
• .husky/pre-commit is executable
• .lintstagedrc.json exists
• prepare script in package.json runs husky
• biome.json exists or the repo already had Biome config
• package.json contains needed devDependencies

Run:

  npx lint-staged

or package-manager equivalent.

Then run any hook commands directly:

  npm run typecheck
  npm run test

Adapt for package manager.

Notes:

• Husky runs Git hooks.
• lint-staged limits formatting/linting to staged files.
• Biome owns formatting and linting.
• CI remains the source of truth.
• Keep pre-commit fast. Avoid full builds unless the user explicitly wants slower commits.