🔑 Skill: auth-expert (v2.0.0)

🌟 Overview & Vision 2026

This skill provides a deep-dive into Auth.js v5, the successor to NextAuth.js. It is specifically optimized for the Next.js 16.1.1 App Router, React 19.2 Server Actions, and Edge Runtime constraints.

In 2026, authentication is no longer just about a login form; it's about a unified session architecture that works across Server Components, Client Components, Middleware, and Server Actions without performance trade-offs.

📚 Table of Contents

1. Core Architecture: The Dual-Config Pattern
2. Quick Start: The 5-Minute Setup
3. Universal Auth: The auth() Protocol
4. Route Protection & Middleware
5. React 19 Server Actions & Authentication
6. The "Do Not" List (Common Pitfalls)
7. Security Hardening Checklist
8. Advanced Patterns: Types & Extensibility
9. Deep Dives (References)