Better Auth

Better Auth Skill

Authentication patterns and best practices for this Next.js application using Better Auth.

Architecture Overview

core/lib/
├── auth.ts                   # Better Auth configuration
├── auth-client.ts            # Client-side auth utilities
└── api/auth/
    ├── dual-auth.ts          # Dual authentication (API Key + Session)
    ├── index.ts              # API key validation
    └── scopes.ts             # Permission scopes

app/hooks/
└── useAuth.ts                # Client-side auth hook

app/(auth)/
├── login/                    # Login page
├── register/                 # Registration page
├── verify-email/             # Email verification
└── forgot-password/          # Password reset

When to Use This Skill

• Implementing authentication flows (login, register, logout)
• Adding API key authentication to endpoints
• Implementing role-based access control
• Setting up OAuth providers
• Testing authentication flows
• Securing API endpoints with dual auth

Authentication Methods

1. Session Authentication (Dashboard)

Used for authenticated users in the dashboard UI.

// Server-side session check
import { auth } from '@/core/lib/auth'

const session = await auth.api.getSession({
  headers: request.headers
})

if (!session?.user) {
  return redirect('/login')
}

// Client-side with useAuth hook
import { useAuth } from '@/app/hooks/useAuth'

function Dashboard() {
  const { user, session, isLoading, isAuthenticated } = useAuth()

  if (isLoading) return <Loading />
  if (!isAuthenticated) return redirect('/login')

  return <div>Welcome, {user.name}</div>
}

2. API Key Authentication (External APIs)

Used for external integrations and programmatic access.

// API Key headers
// Option 1: Authorization header
Authorization: Bearer sk_live_xxxxxxxxxxxxx

// Option 2: x-api-key header
x-api-key: sk_live_xxxxxxxxxxxxx

// CRITICAL: Always include team context
x-team-id: team-tmt-001

3. Dual Authentication (Unified Endpoints)

All /api/v1/ endpoints support both authentication methods.

import { authenticateRequest } from '@/core/lib/api/auth/dual-auth'

export async function GET(request: NextRequest) {
  // Tries API Key first, then Session
  const authResult = await authenticateRequest(request)

  if (!authResult.success) {
    return createAuthError('Unauthorized', 401)
  }

  // authResult contains:
  // - type: 'api-key' | 'session'
  // - user: { id, email, role, defaultTeamId }
  // - scopes: string[] (for API keys) or ['all'] (for sessions)
}

User Roles vs Team Roles

CRITICAL: Two Separate Role Systems

This application has two completely separate role systems:

User Roles (App-Level, FIXED)

// 3 fixed system roles - CANNOT be extended by themes
type UserRole = 'member' | 'superadmin' | 'developer'

Check user role:

import { roleHelpers } from '@/core/lib/role-helpers'

// CORRECT: Use roleHelpers for user roles
if (roleHelpers.isDeveloper(user.role)) {
  // Access to /devtools/*
}
if (roleHelpers.isSuperAdmin(user.role)) {
  // Access to /superadmin/*, bypass team checks
}

// WRONG: Don't check user roles like team roles
if (membership.hasRole('superadmin')) {} // Wrong context!

Team Roles (Team-Level, EXTENSIBLE)

// Core team roles (protected, always available)
type CoreTeamRole = 'owner' | 'admin' | 'member' | 'viewer'

// Theme can add custom roles
type TeamRole = CoreTeamRole | 'editor' | 'contributor' | string

*Custom roles defined in permissions.config.ts

Check team role:

import { MembershipService } from '@/core/lib/services'

// Get membership context
const membership = await MembershipService.get(userId, teamId)

// Check team role
if (membership.hasRole('admin')) {
  // Can manage team members
}

// Check specific permission
if (membership.can('products.create')) {
  // Can create products in this team
}

Why Two Systems?

User Metadata (users_metas)

User metadata is stored in a separate table (users_metas) using the standard entity meta pattern.

Schema

-- core/migrations/003_user_metas.sql
CREATE TABLE "users_metas" (
  id TEXT PRIMARY KEY,
  "userId" TEXT NOT NULL REFERENCES "users"(id) ON DELETE CASCADE,
  "metaKey" TEXT NOT NULL,
  "metaValue" JSONB NOT NULL DEFAULT '{}',
  "dataType" TEXT,              -- 'string' | 'number' | 'boolean' | 'json'
  "isPublic" BOOLEAN DEFAULT FALSE,
  "isSearchable" BOOLEAN DEFAULT FALSE,
  CONSTRAINT users_metas_unique_key UNIQUE ("userId", "metaKey")
);

Common Meta Keys

Usage

import { MetaService } from '@/core/lib/services'

// Get user meta
const theme = await MetaService.get('users', userId, 'preferences.theme')

// Set user meta
await MetaService.set('users', userId, 'preferences.theme', 'dark')

// Get multiple metas
const prefs = await MetaService.getMany('users', userId, [
  'preferences.theme',
  'preferences.language'
])

// Delete meta
await MetaService.delete('users', userId, 'onboarding.step')

Client-Side Hook

import { useUserSettings } from '@/core/hooks/useUserSettings'

function SettingsPage() {
  const { settings, updateSetting, isLoading } = useUserSettings()

  const toggleTheme = () => {
    updateSetting('preferences.theme', settings.theme === 'dark' ? 'light' : 'dark')
  }

  return (
    <Button
      {settings.theme === 'dark' ? 'Light Mode' : 'Dark Mode'}
    </Button>
  )
}

RLS Policies

• Owner access: Users can read/write their own metas
• Admin access: Superadmins can read/write any user's metas
• Public read: Metas with isPublic = true are readable by anyone

API Key Scopes

// Scope format: {entity}:{action}
// Examples:
// - tasks:read     → Read tasks
// - tasks:write    → Create/update tasks
// - tasks:delete   → Delete tasks
// - tasks:*        → Full tasks access
// - *              → Superadmin full access

// Check scopes in API
const hasAccess = authResult.scopes?.includes('tasks:read') ||
                  authResult.scopes?.includes('tasks:*') ||
                  authResult.scopes?.includes('*')

Test Users

Theme Users (password: Test1234)

DEFAULT_THEME_USERS = {
  OWNER: 'carlos.mendoza@tmt.dev',      // Everpoint Labs (owner)
  ADMIN: 'james.wilson@tmt.dev',        // Everpoint Labs (admin)
  MEMBER: 'emily.johnson@tmt.dev',      // Everpoint Labs (member)
  EDITOR: 'diego.ramirez@tmt.dev',      // Everpoint Labs (editor)
  VIEWER: 'sarah.davis@tmt.dev',        // Ironvale Global (viewer)
}

Core Users (password: Pandora1234)

CORE_USERS = {
  SUPERADMIN: 'superadmin@tmt.dev',     // Global superadmin
  DEVELOPER: 'developer@tmt.dev',       // Global developer
}

Test Teams

Registration Control

Registration behavior is configurable at the theme level via auth in app.config.ts.

Registration Modes

Theme Configuration

// contents/themes/my-theme/config/app.config.ts

// Option 1: Open registration (default, no config needed)
auth: {
  registration: { mode: 'open' },
}

// Option 2: Only Google OAuth for specific domains (no email+password)
auth: {
  registration: {
    mode: 'domain-restricted',
    allowedDomains: ['nextspark.dev', 'mycompany.com'],
  },
}

// Option 3: Email+password AND Google OAuth, restricted to specific domains
auth: {
  registration: {
    mode: 'domain-open',
    allowedDomains: ['nextspark.dev', 'mycompany.com'],
  },
}

// Option 4: Invitation-only (integrates with single-tenant teams mode)
auth: {
  registration: { mode: 'invitation-only' },
}

Types

// packages/core/src/lib/config/types.ts
type RegistrationMode = 'open' | 'domain-restricted' | 'domain-open' | 'invitation-only'

interface AuthConfig {
  registration: {
    mode: RegistrationMode
    allowedDomains?: string[]  // For 'domain-restricted' and 'domain-open' modes
  }
  providers?: {
    google?: { enabled?: boolean }
  }
}

Helper Functions

import {
  isRegistrationOpen,
  isDomainAllowed,
  isGoogleAuthEnabled,
  shouldBlockSignup,
  getPublicAuthConfig,
} from '@/core/lib/auth/registration-helpers'

Enforcement Points

1. Route handler (app/api/auth/[...all]/route.ts): Blocks email signup for domain-restricted and invitation-only modes
2. Database hook (auth.ts → databaseHooks.user.create.before): Validates email domain for domain-restricted and domain-open modes; blocks signup in invitation-only mode when team exists
3. Session hook (auth.ts → databaseHooks.session.create.before): Validates email domain on every login for domain-restricted and domain-open modes
4. Signup page (app/(auth)/signup/page.tsx): Redirects to /login for domain-restricted and invitation-only
5. LoginForm: Hides Google OAuth button and signup link based on mode
6. SignupForm: Hides Google button when disabled

Client-Side Config

Use PUBLIC_AUTH_CONFIG (from config-sync.ts) in client components. This strips allowedDomains for security.

import { PUBLIC_AUTH_CONFIG } from '@/core/lib/config/config-sync'

// PUBLIC_AUTH_CONFIG.registration.mode → 'open' | 'domain-restricted' | 'domain-open' | 'invitation-only'
// PUBLIC_AUTH_CONFIG.providers.google.enabled → boolean

Authentication Flows

Email/Password Registration

1. User submits registration form
2. Validate email format and password strength
3. Create user with emailVerified = false
4. Send verification email with token
5. User clicks verification link
6. Set emailVerified = true
7. Redirect to login

Email/Password Login

1. User submits login form
2. Validate credentials
3. Check emailVerified = true
4. Create session
5. Set HttpOnly cookie
6. Redirect to dashboard

Google OAuth

1. User clicks "Sign in with Google"
2. Redirect to Google OAuth
3. Google returns profile data
4. Map profile to user (mapProfileToUser)
5. Create/update user record
6. Create session
7. Redirect to dashboard

Password Reset

1. User requests password reset
2. Generate reset token (1-hour expiry)
3. Send reset email
4. User clicks reset link
5. Validate token
6. User enters new password
7. Update password hash (bcrypt)
8. Invalidate token
9. Redirect to login

Security Rules

Password Requirements

// Minimum requirements
const passwordSchema = z.string()
  .min(8, 'Password must be at least 8 characters')
  .max(128, 'Password cannot exceed 128 characters')
  .regex(/[A-Z]/, 'Password must contain uppercase letter')
  .regex(/[0-9]/, 'Password must contain a number')

Session Configuration

// Session settings
const sessionConfig = {
  expiresIn: 60 * 60 * 24 * 7,  // 7 days
  updateAge: 60 * 60 * 24,      // Update every day
  cookieOptions: {
    httpOnly: true,
    secure: process.env.NODE_ENV === 'production',
    sameSite: 'lax'
  }
}

Rate Limiting

Token Expiration

useAuth Hook

import { useAuth } from '@/app/hooks/useAuth'

function Component() {
  const {
    // State
    user,             // Current user object
    session,          // Session data
    isLoading,        // Loading state
    isAuthenticated,  // Boolean auth status

    // Actions
    signIn,           // (email, password) => Promise
    signUp,           // (email, password, name) => Promise
    signOut,          // () => Promise
    resetPassword,    // (email) => Promise
    updateProfile,    // (data) => Promise
  } = useAuth()

  // Example: Sign in
  const handleLogin = async () => {
    try {
      await signIn(email, password)
      router.push('/dashboard')
    } catch (error) {
      setError(error.message)
    }
  }
}

Protected Routes

Middleware Protection

// middleware.ts
export { auth as middleware } from "@/core/lib/auth"

export const config = {
  matcher: [
    '/dashboard/:path*',
    '/profile/:path*',
    '/api/user/:path*'
  ]
}

Page-Level Protection

// app/dashboard/page.tsx
import { auth } from '@/core/lib/auth'
import { redirect } from 'next/navigation'

export default async function DashboardPage() {
  const session = await auth.api.getSession({
    headers: headers()
  })

  if (!session) {
    redirect('/login')
  }

  return <Dashboard user={session.user} />
}

Error Codes

Testing Authentication

Cypress Session Pattern

describe('Authenticated Tests', () => {
  beforeEach(() => {
    cy.session('owner-session', () => {
      cy.visit('/login')
      cy.get('[data-cy="email-input"]').type('carlos.mendoza@tmt.dev')
      cy.get('[data-cy="password-input"]').type('Test1234')
      cy.get('[data-cy="login-submit"]').click()
      cy.url().should('include', '/dashboard')
    }, {
      validate: () => {
        cy.visit('/dashboard')
        cy.url().should('include', '/dashboard')
      }
    })
  })

  it('should access protected page', () => {
    cy.visit('/dashboard/tasks')
    cy.get('[data-cy="tasks-table"]').should('exist')
  })
})

API Test Pattern

describe('API Auth Tests', () => {
  const API_KEY = Cypress.env('SUPERADMIN_API_KEY')
  const TEAM_ID = 'team-tmt-001'

  it('should authenticate with API key', () => {
    cy.request({
      method: 'GET',
      url: '/api/v1/tasks',
      headers: {
        'Authorization': `Bearer ${API_KEY}`,
        'x-team-id': TEAM_ID
      }
    }).then((response) => {
      expect(response.status).to.eq(200)
    })
  })

  it('should reject without API key', () => {
    cy.request({
      method: 'GET',
      url: '/api/v1/tasks',
      failOnStatusCode: false
    }).then((response) => {
      expect(response.status).to.eq(401)
    })
  })
})

OAuth Configuration

Google OAuth

// core/lib/auth.ts
socialProviders: {
  google: {
    clientId: process.env.GOOGLE_CLIENT_ID!,
    clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    mapProfileToUser: (profile) => ({
      email: profile.email,
      name: profile.name,
      image: profile.picture,
      emailVerified: profile.email_verified
    })
  }
}

Environment Variables

# Better Auth
BETTER_AUTH_SECRET=your-secret-key
NEXT_PUBLIC_APP_URL=http://localhost:5173

# Google OAuth
GOOGLE_CLIENT_ID=your-client-id
GOOGLE_CLIENT_SECRET=your-client-secret

# Email (Resend)
RESEND_API_KEY=your-resend-key
RESEND_FROM_EMAIL=noreply@yourdomain.com

Anti-Patterns

// NEVER: Store passwords in plain text
user.password = 'plain-text-password'

// CORRECT: Use bcrypt via Better Auth
await auth.api.signUp({ email, password, name })

// NEVER: Skip email verification
if (!user.emailVerified) {
  // Allow access anyway... WRONG!
}

// CORRECT: Require verification
if (!user.emailVerified) {
  redirect('/verify-email')
}

// NEVER: Expose API keys in client code
const API_KEY = 'sk_live_xxxxx' // In browser!

// CORRECT: Use environment variables (server-side only)
const API_KEY = process.env.API_KEY // Server only

// NEVER: Skip team context for entity operations
// Missing x-team-id header

// CORRECT: Always include team context
headers: { 'x-team-id': teamId }

// NEVER: Trust client-provided user data
const userId = request.body.userId // User can fake this!

// CORRECT: Get user from authenticated session
const { user } = await authenticateRequest(request)

Checklist

Before finalizing authentication code:

• Uses Better Auth for all auth operations
• Sessions use HttpOnly, Secure cookies
• Email verification required for email/password
• Password meets minimum requirements (8+ chars)
• API endpoints use dual auth pattern
• Protected routes redirect unauthenticated users
• Error responses use proper status codes
• Rate limiting implemented for sensitive endpoints
• OAuth profile mapping configured correctly
• Test users documented and working

Related Skills

• cypress-e2e - UAT testing with session authentication
• cypress-api - API testing with API key authentication
• nextjs-api-development - API route patterns