better-auth

Better Auth in TypeScript — setting up the auth instance, picking adapters, wiring framework route handlers, configuring sessions and cookies, adding plugins (2FA, organization, admin, magicLink, JWT), or porting from NextAuth/Auth.js, Clerk, Auth0, or Supabase Auth. Covers Next.js, SvelteKit, Hono, Express, Nuxt, Astro, and React/Vue/Svelte clients. Trigger when writing, reviewing, or migrating Better Auth code — and even when the user doesn't explicitly mention Better Auth but is working on TypeScript authentication, session cookies, OAuth providers, or auth-library migration. Contains 42 rules organized by impact across 8 categories.