Build Next.js 16 applications with correct patterns and distinctive design. Use when creating pages, layouts, dynamic routes, upgrading from Next.js 15, or implementing proxy.ts. Covers breaking changes (async params/searchParams, Turbopack, cacheComponents) and frontend aesthetics. NOT when building non-React or backend-only applications.
Build AI chat interfaces with custom backends, authentication, and context injection. Use when integrating chat UI with AI agents, adding auth to chat, injecting user/page context, or implementing httpOnly cookie proxies. Covers ChatKitServer, useChatKit, and MCP auth patterns. NOT when building simple chatbots without persistence or custom agent integration.