Next.js App Router Architecture & File System Routing
Build layouts (layout.tsx), pages (page.tsx), loading boundaries (loading.tsx), and dynamic routes ([slug]/page.tsx).
App Router Directory Conventions
### Next.js App Router Conventions
- **`page.tsx`**: Exposes public route endpoints.
- **`layout.tsx`**: Wraps child routes while preserving state across page transitions.
- **`loading.tsx`**: Automatic React Suspense streaming fallback container.
- **`error.tsx`**: React Error Boundary fallback handling runtime exceptions.