auth-skill

name	auth-skill
description	Secure authentication using Better Auth on Next.js frontend and JWT verification in FastAPI backend with shared secret.

Auth Skill – Better Auth + FastAPI

Architecture Overview

• Frontend: Next.js + Better Auth (JavaScript)
• Backend: FastAPI (Python)
• Auth Method: JWT (Bearer Token)
• Auth State: Stateless (No backend sessions)

Authentication Flow

1. User Login (Frontend)

   • User signs in via Better Auth
   • Better Auth creates a session
   • JWT token is issued using shared secret

2. API Request (Frontend → Backend)

   • JWT token attached in request header:

     Authorization: Bearer <token>
     

3. JWT Verification (Backend)

   • FastAPI extracts token from header
   • Verifies signature using shared secret
   • Decodes token to get user_id, email

4. Authorization Enforcement

   • Backend matches decoded user_id
   • Filters all DB queries by authenticated user
   • Prevents cross-user data access

Required Component Changes

1. Better Auth Configuration (Frontend)

• Enable JWT plugin
• Set token expiry (e.g. 7 days)
• Use shared secret via environment variable

BETTER_AUTH_SECRET=super-secret-key