Prevent AI coding assistants from writing deprecated React 18 patterns or obsolete Next.js router code by placing a `.cursorrules` file in your project root:
markdown
# Architecture Guidelines - Next.js 15 App Router, React 19 Server Components by default. - Always use 'use client' ONLY at leaf interactive components. - Never import 'next/router'; use 'next/navigation' (useRouter, usePathname, useSearchParams). - Use Tailwind CSS v4 utility classes. Prefer semantic color tokens. - In Server Components, fetch directly via Prisma or native fetch. Never use useEffect for initial data load. - Ensure strict TypeScript compliance with zero 'any' types.
This simple 1KB file stops 95% of hallucinated imports and obsolete lifecycle methods.