Auth Scaffold

Auth Scaffold

Before generating any output, read config/defaults.md and adapt all patterns, imports, and code examples to the user's configured stack.

Generation Process

1. Determine auth requirements (providers, session strategy, RBAC)
2. Generate Auth.js configuration
3. Generate auth helper and route handler
4. Generate sign-in/sign-out components
5. Generate middleware for route protection

Auth.js Configuration

Create auth.ts at the project root:

import NextAuth from 'next-auth';
import Credentials from 'next-auth/providers/credentials';
import Google from 'next-auth/providers/google';
import GitHub from 'next-auth/providers/github';
import { PrismaAdapter } from '@auth/prisma-adapter';
import { prisma } from '@/lib/prisma';
import { z } from 'zod';
import bcrypt from 'bcryptjs';

const loginSchema = z.object({
  email: z.string().email(),
  password: z.string().min(8),
});

export const { handlers, auth, signIn, signOut } = NextAuth({
  adapter: PrismaAdapter(prisma),
  session: { strategy: 'jwt' },
  pages: {
    signIn: '/login',
  },
  providers: [
    Google({
      clientId: process.env.AUTH_GOOGLE_ID,
      clientSecret: process.env.AUTH_GOOGLE_SECRET,
    }),
    GitHub({
      clientId: process.env.AUTH_GITHUB_ID,
      clientSecret: process.env.AUTH_GITHUB_SECRET,
    }),
    Credentials({
      async authorize(credentials) {
        const parsed = loginSchema.safeParse(credentials);
        if (!parsed.success) return null;

        const user = await prisma.user.findUnique({
          where: { email: parsed.data.email },
        });

        if (!user?.hashedPassword) return null;

        const valid = await bcrypt.compare(parsed.data.password, user.hashedPassword);
        if (!valid) return null;

        return { id: user.id, name: user.name, email: user.email, role: user.role };
      },
    }),
  ],
  callbacks: {
    async jwt({ token, user }) {
      if (user) {
        token.role = user.role;
      }
      return token;
    },
    async session({ session, token }) {
      if (session.user) {
        session.user.id = token.sub!;
        session.user.role = token.role as string;
      }
      return session;
    },
  },
});

Prisma Schema Extension

Add these models required by Auth.js to prisma/schema.prisma:

enum Role {
  USER
  ADMIN
}

model User {
  id             String    @id @default(cuid())
  name           String?
  email          String?   @unique
  emailVerified  DateTime?
  image          String?
  hashedPassword String?
  role           Role      @default(USER)
  accounts       Account[]
  sessions       Session[]
  createdAt      DateTime  @default(now())
  updatedAt      DateTime  @updatedAt
}

model Account {
  id                String  @id @default(cuid())
  userId            String
  type              String
  provider          String
  providerAccountId String
  refresh_token     String? @db.Text
  access_token      String? @db.Text
  expires_at        Int?
  token_type        String?
  scope             String?
  id_token          String? @db.Text
  session_state     String?
  user              User    @relation(fields: [userId], references: [id], onDelete: Cascade)

  @@unique([provider, providerAccountId])
}

model Session {
  id           String   @id @default(cuid())
  sessionToken String   @unique
  userId       String
  expires      DateTime
  user         User     @relation(fields: [userId], references: [id], onDelete: Cascade)
}

model VerificationToken {
  identifier String
  token      String   @unique
  expires    DateTime

  @@unique([identifier, token])
}

Route Handler

Create app/api/auth/[...nextauth]/route.ts:

import { handlers } from '@/auth';

export const { GET, POST } = handlers;

Auth Helper

Create lib/auth.ts for convenient session access:

import { auth } from '@/auth';
import { redirect } from 'next/navigation';

export { auth } from '@/auth';

export async function requireAuth() {
  const session = await auth();
  if (!session?.user) {
    redirect('/login');
  }
  return session;
}

export async function requireRole(role: string) {
  const session = await requireAuth();
  if (session.user.role !== role) {
    redirect('/unauthorized');
  }
  return session;
}

Middleware Protection

Create middleware.ts at the project root:

import { auth } from '@/auth';
import { NextResponse } from 'next/server';

const protectedRoutes = ['/dashboard', '/settings', '/admin'];
const adminRoutes = ['/admin'];
const authRoutes = ['/login', '/register'];

export default auth((req) => {
  const { pathname } = req.nextUrl;
  const isLoggedIn = !!req.auth;
  const userRole = req.auth?.user?.role;

  // Redirect logged-in users away from auth pages
  if (isLoggedIn && authRoutes.some((route) => pathname.startsWith(route))) {
    return NextResponse.redirect(new URL('/dashboard', req.url));
  }

  // Protect authenticated routes
  if (!isLoggedIn && protectedRoutes.some((route) => pathname.startsWith(route))) {
    const callbackUrl = encodeURIComponent(pathname);
    return NextResponse.redirect(new URL(`/login?callbackUrl=${callbackUrl}`, req.url));
  }

  // Protect admin routes
  if (adminRoutes.some((route) => pathname.startsWith(route)) && userRole !== 'ADMIN') {
    return NextResponse.redirect(new URL('/unauthorized', req.url));
  }

  return NextResponse.next();
});

export const config = {
  matcher: ['/((?!api/auth|_next/static|_next/image|favicon.ico).*)'],
};

Sign-In / Sign-Out Components

Sign-In Button (Client Component)

'use client';

import { signIn } from 'next-auth/react';

interface SignInButtonProps {
  provider: 'google' | 'github' | 'credentials';
  children: React.ReactNode;
  className?: string;
}

export function SignInButton({ provider, children, className }: SignInButtonProps) {
  return (
    <button
      => signIn(provider, { callbackUrl: '/dashboard' })}
      className={className}
    >
      {children}
    </button>
  );
}

Sign-Out Button (Client Component)

'use client';

import { signOut } from 'next-auth/react';

interface SignOutButtonProps {
  children?: React.ReactNode;
  className?: string;
}

export function SignOutButton({ children = 'Sign out', className }: SignOutButtonProps) {
  return (
    <button
      => signOut({ callbackUrl: '/' })}
      className={className}
    >
      {children}
    </button>
  );
}

Session Provider (Layout)

Wrap the root layout to enable useSession in client components:

import { SessionProvider } from 'next-auth/react';

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <body>
        <SessionProvider>{children}</SessionProvider>
      </body>
    </html>
  );
}

Session Access Patterns

Server Component

import { auth } from '@/lib/auth';

export default async function ProfilePage() {
  const session = await auth();
  if (!session?.user) return <p>Not authenticated</p>;

  return <p>Welcome, {session.user.name}</p>;
}

Client Component

'use client';

import { useSession } from 'next-auth/react';

export function UserMenu() {
  const { data: session, status } = useSession();

  if (status === 'loading') return <span aria-busy="true">Loading...</span>;
  if (!session) return null;

  return <span>{session.user?.name}</span>;
}

API Route

import { auth } from '@/auth';
import { NextResponse } from 'next/server';

export async function GET() {
  const session = await auth();
  if (!session) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  return NextResponse.json({ user: session.user });
}

Server Action

'use server';

import { auth } from '@/auth';

export async function updateProfile(formData: FormData) {
  const session = await auth();
  if (!session?.user) throw new Error('Unauthorized');

  // Proceed with update
}

Environment Variables

Add to .env.local:

AUTH_SECRET=          # Generate with: npx auth secret
AUTH_GOOGLE_ID=       # Google OAuth client ID
AUTH_GOOGLE_SECRET=   # Google OAuth client secret
AUTH_GITHUB_ID=       # GitHub OAuth client ID
AUTH_GITHUB_SECRET=   # GitHub OAuth client secret

Type Extension

Extend the Auth.js types in types/next-auth.d.ts:

import { DefaultSession } from 'next-auth';

declare module 'next-auth' {
  interface User {
    role?: string;
  }

  interface Session {
    user: {
      id: string;
      role: string;
    } & DefaultSession['user'];
  }
}

declare module 'next-auth/jwt' {
  interface JWT {
    role?: string;
  }
}

Integration Check

After generating the auth scaffold, verify that: the Prisma schema includes all four Auth.js models (User, Account, Session, VerificationToken), the route handler exports GET and POST from handlers, the middleware matcher excludes api/auth routes, the JWT callback passes the role to the session, and AUTH_SECRET is listed in .env.local. If using RBAC, verify the requireRole helper is used in protected server components and API routes.

Asset

See assets/auth-config/auth.ts for a minimal starter Auth.js configuration.