nextjs-auth

# Next.js Auth Skill

Patterns for implementing authentication with NextAuth.js / Auth.js.

## Setup

### Basic Configuration

```typescript
// app/api/auth/[...nextauth]/route.ts
import NextAuth from 'next-auth'
import { authOptions } from '@/lib/auth'

const handler = NextAuth(authOptions)
export { handler as GET, handler as POST }
```

```typescript
// lib/auth.ts
import { NextAuthOptions } from 'next-auth'
import CredentialsProvider from 'next-auth/providers/credentials'
import GoogleProvider from 'next-auth/providers/google'

export const authOptions: NextAuthOptions = {
  providers: [
    GoogleProvider({
      clientId: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    }),
    CredentialsProvider({
      name: 'Credentials',
      credentials: {
        email: { label: 'Email', type: 'email' },
        password: { label: 'Password', type: 'password' },
      },
      async authorize(credentials) {
        const user = await verifyCredentials(
          credentials?.email,
          credentials?.password
        )
        if (user) return user
        return null
      },
    }),
  ],
  pages: {
    signIn: '/auth/signin',
    signOut: '/auth/signout',
    error: '/auth/error',
  },
  callbacks: {
    async jwt({ token, user }) {
      if (user) {
        token.id = user.id
        token.role = user.role
      }
      return token
    },
    async session({ session, token }) {
      session.user.id = token.id as string
      session.user.role = token.role as string
      return session
    },
  },
  session: {
    strategy: 'jwt',
  },
}
```

### Type Extensions

```typescript
// types/next-auth.d.ts
import { DefaultSession } from 'next-auth'

declare module 'next-auth' {
  interface Session {
    user: {
      id: string
      role: string
    } & DefaultSession['user']
  }

  interface User {
    role: string
  }
}

declare module 'next-auth/jwt' {
  interface JWT {
    id: string
    role: string
  }
}
```

## Server-