Nextjs 16

Documents the critical v15→v16 breaking changes: proxy.ts replacing middleware.ts, Turbopack-only builds, use cache replacing Partial Prerendering, required React 19, and async params/searchParams. This skill covers core framework APIs only — for assembling a full production stack (Prisma, Better Auth, shadcn/ui, Zustand together) use nextjs-stack instead; for a pure React SPA without next.config.* use the react-expert skills instead.

Next.js 16 Expert

Production-ready React framework with Server Components, streaming, and Turbopack.

Agent Workflow (MANDATORY)

Before ANY implementation, use TeamCreate to spawn 3 agents:

1. explore-codebase - Analyze existing routes, components, and patterns
2. research-expert - Verify latest Next.js 16 docs via Context7/Exa
3. mcp__context7__query-docs - Check breaking changes v15→v16

After implementation, run sniper for validation.

Overview

When to Use

• Building new React applications with server-first architecture
• Need Server Components for optimal performance and SEO
• Implementing streaming and progressive rendering
• Migrating from Next.js 14/15 to version 16
• Using proxy.ts for route protection (replaces middleware)
• Leveraging Turbopack for faster development builds

Why Next.js 16

Breaking Changes from v15

Critical Migration Points

1. proxy.ts replaces middleware.ts - Full Node.js runtime, not Edge
2. Turbopack ONLY - Webpack completely deprecated and removed
3. use cache directive - Replaces Partial Prerendering (PPR)
4. React 19 required - New hooks and View Transitions API
5. Async params/searchParams - Must await dynamic route params

SOLID Architecture

Module-Based Structure

Pages are thin entry points importing from feature modules:

• app/page.tsx → imports from modules/public/home/
• app/dashboard/page.tsx → imports from modules/auth/dashboard/
• modules/cores/ → Shared services, utilities, configurations

File Conventions

• page.tsx - Route UI component
• layout.tsx - Shared UI wrapper
• loading.tsx - Suspense loading state
• error.tsx - Error boundary
• not-found.tsx - 404 handling

Core Concepts

Server Components (Default)

All components are Server Components by default. Use 'use client' directive only when needed for interactivity, hooks, or browser APIs.

Caching Strategy

• use cache - Mark async functions for caching
• cacheTag() - Tag cached data for targeted revalidation
• cacheLife() - Control cache duration (stale, revalidate, expire)
• revalidateTag() - Invalidate cached data on-demand

Data Fetching

Server Components fetch data directly. Use fetch() with native caching or database queries. No need for getServerSideProps or getStaticProps.

Reference Guide

Best Practices

1. Server Components first - Only add 'use client' when necessary
2. Colocate data fetching - Fetch data where it's used
3. Streaming with Suspense - Wrap slow components in Suspense
4. proxy.ts over middleware - Full Node.js runtime for auth
5. Cache explicitly - Use use cache for expensive operations
6. Parallel routes - Load independent UI sections simultaneously

Performance

Build Optimization

• Turbopack - Incremental compilation, instant HMR
• React Compiler - Automatic memoization
• Tree shaking - Unused code elimination
• Code splitting - Automatic route-based splitting

Runtime Optimization

• Streaming - Progressive HTML rendering
• Partial hydration - Only hydrate interactive components
• Image optimization - Automatic WebP/AVIF conversion
• Font optimization - Zero layout shift with next/font