GEMINI.md for Next.js App Router Projects

# Project: [PROJECT NAME]
## Next.js 15 + App Router + TypeScript

## General Instructions
- Use Next.js App Router (not Pages Router)
- TypeScript strict mode is mandatory
- Use Server Components by default; only add "use client" when necessary
- Prefer Server Actions over API routes for mutations
- Use next/image for all images, next/font for fonts

## File Conventions
- `page.tsx` — route segments
- `layout.tsx` — shared layouts
- `loading.tsx` — loading UI (Suspense boundary)
- `error.tsx` — error boundary (must be "use client")
- `not-found.tsx` — 404 handling

## Data Fetching
- Fetch data in Server Components, not Client Components
- Use React cache() for request deduplication
- Set appropriate revalidate intervals or use `revalidatePath/revalidateTag`
- Never expose sensitive data (API keys, tokens) to Client Components

## Styling
- Use Tailwind CSS utility classes
- Use `cn()` utility for conditional classes (clsx + twMerge)
- Component-specific styles go in the component file
- Design tokens in tailwind.config.ts

## Performance
- Use dynamic imports for heavy Client Components
- Implement Suspense boundaries around slow data fetches
- Use `generateStaticParams` for known dynamic routes
- Set metadata in layout.tsx and page.tsx for SEO