Use when building Next.js 14/15 applications with the App Router. Invoke for routing, layouts, Server Components, Client Components, Server Actions, Route Handlers, authentication, middleware, data fetching, caching, revalidation, streaming, Suspense, loading states, error boundaries, dynamic routes, parallel routes, intercepting routes, or any Next.js architecture question.
Initial release — senior-level Next.js 14/15 App Router knowledge base and coding skill. - Covers advanced routing, layouts, Server/Client Components, authentication, middleware, data fetching, and more. - Provides detailed file/folder conventions, lifecycle, and hands-on TypeScript-first code examples. - Usage triggers include App Router, Server Actions, Route Handlers, NextAuth, metadata, streaming, and error boundaries. - Emphasizes core Next.js 15 principles: server-first, minimal `'use client'`, async params, colocation, and strict typing. - Output optimized for practical, implementation-ready code.