Mern Scaffold

Purpose

Create a fully working MERN repo (Next.js + TypeScript + pnpm workspaces + Turborepo) with tooling configured and runnable immediately.

Arguments

• app-name — Project folder name (default: "app"). Use . to scaffold in the current directory (must be empty or near-empty).
• --github — Create GitHub repo and push (requires gh auth)
• --public — Make GitHub repo public (default: private)
• --org <n> — Create under org instead of personal account
• --repo <n> — Override repo name (default: app-name)
• --no-push — Create repo and commit but don't push

Template-first rule

Copy files from templates/ into the project. If a template doesn't exist, generate equivalent content.

Templates provide:

• Root configs (eslint, prettier, turbo, .prettierignore)
• Test configs (vitest.config.ts with jsdom + coverage, playwright.config.ts)
• Test setup (src/tests/setup.tsx with React mocks for next/image, next/navigation, matchMedia, localStorage)
• Server utilities (env validation, response helpers, rate limiting, sanitization)
• Shared package structure (Zod schemas)
• CLAUDE.md for the new repo
• VS Code workspace settings and extension recommendations

What gets created

<app-name>/
├── apps/web/                 # Next.js app (app router + Tailwind)
│   ├── e2e/                  # Playwright e2e tests
│   │   └── health.spec.ts   # Health check e2e test
│   └── src/
│       ├── app/api/health/   # Health check endpoint (app router)
│       │   └── route.ts
│       ├── __tests__/        # Test setup + smoke tests
│       │   ├── setup.tsx
│       │   └── smoke.test.ts
│       └── server/           # Server utilities from templates
├── packages/shared/          # Zod schemas + types
│   ├── package.json
│   └── src/
├── docs/                     # Documentation
│   └── PRD-TEMPLATE.md       # Product requirements template for Ralph
├── .vscode/                  # VS Code workspace config (from templates)
│   ├── settings.json
│   └── extensions.json
├── .github/                  # GitHub config (from templates)
│   ├── workflows/
│   │   ├── ci.yml            # CI pipeline (lint, format, typecheck, test, build, e2e)
│   │   ├── security.yml      # Dependency review + TruffleHog
│   │   └── pr-check.yml      # PR size labeler, commitlint, WIP check
│   ├── dependabot.yml        # Automated dependency updates
│   ├── CODEOWNERS            # Required reviewers by path
│   ├── SECURITY.md           # Security policy
│   └── pull_request_template.md  # PR template with checklist
├── .env.local                # Local env (gitignored)
├── .env.example              # Env template (committed)
├── CLAUDE.md                 # Repo context for Claude Code
└── (root configs)            # eslint, prettier, turbo, pnpm-workspace

Scaffold steps

1. Create root package.json

{
  "name": "<app-name>",
  "private": true,
  "packageManager": "pnpm@10.5.2",
  "scripts": {
    "dev": "turbo run dev",
    "build": "turbo run build",
    "lint": "eslint .",
    "lint:fix": "eslint . --fix",
    "format": "prettier --check .",
    "format:write": "prettier --write .",
    "test": "turbo run test",
    "test:e2e": "turbo run test:e2e",
    "typecheck": "turbo run typecheck"
  },
  "pnpm": {
    "onlyBuiltDependencies": ["husky"]
  }
}

2. Copy root configs from templates

• pnpm-workspace.yaml
• turbo.json
• eslint.config.mjs (uses eslint-plugin-import-x for flat config)
• prettier.config.cjs
• .prettierignore
• README.md
• CLAUDE.md

2a. Copy VS Code config from templates

• .vscode/settings.json
• .vscode/extensions.json

3. Run create-next-app

mkdir -p apps
pnpm dlx create-next-app@latest "$(pwd)/apps/web" --ts --tailwind --eslint --app --src-dir --import-alias "@/*" --use-pnpm --yes --disable-git

Important: Use absolute path for the target directory. CNA will not create parent directories and fails with "not writable" if apps/ doesn't exist.

Flags explained:

• --yes skips all interactive prompts (React Compiler, etc.)
• --disable-git prevents CNA from running git init (we handle git ourselves)

4. Post-CNA cleanup

Remove CNA artifacts (root config handles linting; monorepo has its own lockfile):

rm -f apps/web/eslint.config.mjs apps/web/pnpm-lock.yaml apps/web/pnpm-workspace.yaml

Update apps/web/package.json scripts:

• Replace "lint": "next lint" with "lint": "eslint ." (Next.js 16 removed next lint; root eslint handles it anyway)
• Add test scripts:

  {
    "scripts": {
      "dev": "next dev",
      "build": "next build",
      "start": "next start",
      "lint": "eslint .",
      "test": "vitest run",
      "test:watch": "vitest",
      "test:e2e": "playwright test",
      "typecheck": "tsc --noEmit"
    }
  }
  

5. Install root dependencies

pnpm add -D eslint @eslint/js@^9 globals typescript-eslint @next/eslint-plugin-next eslint-plugin-react-hooks eslint-plugin-react-refresh eslint-plugin-import-x eslint-plugin-unused-imports vitest @vitest/coverage-v8 turbo prettier -w

6. Copy test configs to apps/web from templates

• apps/web/vitest.config.ts
• apps/web/src/__tests__/setup.tsx
• apps/web/playwright.config.ts

7. Install web app testing dependencies

pnpm --filter web add -D @testing-library/react @testing-library/jest-dom @testing-library/user-event jsdom @playwright/test vitest @vitest/coverage-v8

8. Install Playwright browsers

pnpm --filter web exec playwright install chromium

Note: Playwright is installed in the web workspace, not root. Use --filter web to run from the correct scope.

9. Copy server utilities from templates to apps/web/src/server/

• env.ts
• http/response.ts
• http/rateLimit.ts
• http/validate.ts
• http/securityHeaders.ts
• db/sanitize.ts
• db/mongoose.ts

10. Install web app server dependencies

pnpm --filter web add zod mongoose

11. Create packages/shared

Create packages/shared/package.json:

{
  "name": "@repo/shared",
  "version": "0.0.0",
  "private": true,
  "main": "./src/index.ts",
  "types": "./src/index.ts",
  "scripts": {
    "lint": "eslint .",
    "test": "vitest run --passWithNoTests",
    "typecheck": "tsc --noEmit"
  }
}

Create packages/shared/tsconfig.json:

{
  "compilerOptions": {
    "target": "ES2022",
    "lib": ["ES2022"],
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "noEmit": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "resolveJsonModule": true,
    "isolatedModules": true,
    "declaration": true,
    "declarationMap": true
  },
  "include": ["src/**/*.ts"],
  "exclude": ["node_modules"]
}

Copy shared source files from templates:

• packages/shared/src/index.ts
• packages/shared/src/schemas/example.ts

Install shared dependencies:

pnpm --filter @repo/shared add zod
pnpm --filter @repo/shared add -D typescript vitest

Add workspace reference in web app:

pnpm --filter web add '@repo/shared@workspace:*'

Note: Single quotes required — zsh expands unquoted * as a glob.

12. Create docs/

Copy docs/PRD-TEMPLATE.md from templates.

13. Create health check endpoint

Create apps/web/src/app/api/health/route.ts:

import { NextResponse } from "next/server";

export async function GET() {
  return NextResponse.json({ ok: true, data: { status: "ok" } });
}

14. Create smoke test

Create apps/web/src/__tests__/smoke.test.ts:

import { describe, it, expect } from "vitest";

describe("smoke test", () => {
  it("should pass a basic assertion", () => {
    expect(1 + 1).toBe(2);
  });
});

15. Create e2e test

Create apps/web/e2e/health.spec.ts:

import { test, expect } from "@playwright/test";

test("health endpoint returns ok", async ({ request }) => {
  const response = await request.get("/api/health");
  expect(response.ok()).toBeTruthy();
  const body = await response.json();
  expect(body).toEqual({ ok: true, data: { status: "ok" } });
});

16. Create environment files

.env.local (gitignored):

MONGODB_URI=mongodb://localhost:27017/hello-mern

.env.example (committed):

MONGODB_URI=mongodb://localhost:27017/myapp

17. Create .gitignore

node_modules
.next
dist
build
out
coverage
.turbo
.env.local
.env.test
*.tsbuildinfo
playwright-report
test-results

18. Create GitHub config files

Copy all .github/ files from templates. Replace __GITHUB_USER__ in dependabot.yml and CODEOWNERS with the GitHub username (from gh api user or the --org argument). Replace __APP_NAME__ in ci.yml with the project name.

19. Run pnpm install

pnpm install

20. Run quality gates (must all pass before done)

pnpm lint
pnpm format
pnpm typecheck
pnpm test
pnpm build
pnpm test:e2e

Fix any failures and re-run until all pass.

21. git init

git init

This prepares the repo for the github-hooks step.

GitHub setup (if --github)

• Requires gh auth status to succeed
• Creates repo: gh repo create <owner>/<repo> --<visibility> --source . --remote origin
• Commits and pushes unless --no-push

Post-scaffold: GitHub security (recommended)

After scaffolding, run these skills to complete GitHub security setup:

1. /github-hooks --platform mern — Install local Git hooks

   • Husky + lint-staged for pre-commit validation
   • Commit message enforcement (conventional commits)
   • Secret scanning (gitleaks)
   • Pre-push test runs

2. /github-secure (if --github was used) — Configure repo security via GitHub API

   • Branch protection rules
   • Dependabot alerts + security updates
   • Auto-merge enablement
   • (Files already created by scaffold — github-secure skips existing files)

These are invoked automatically by /mern-kit.

Output

Summarize: structure created, commands available, what tooling is included, GitHub status if applicable, and remind to run github-hooks/github-secure if not using mern-kit.

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