NextJS

Build Next.js 15 apps with App Router, server components, caching, auth, and production patterns.

Setup

On first use, read setup.md for project integration.

When to Use

User needs Next.js expertise — routing, data fetching, caching, authentication, or deployment. Agent handles App Router patterns, server/client boundaries, and production optimization.

Architecture

Project patterns stored in ~/nextjs/. See memory-template.md for setup.

~/nextjs/
├── memory.md          # Project conventions, patterns
└── projects/          # Per-project learnings

Quick Reference

Topic	File
Setup	setup.md
Memory template	memory-template.md
Routing (parallel, intercepting)	routing.md
Data fetching & streaming	data-fetching.md
Caching & revalidation	caching.md
Authentication	auth.md
Deployment	deployment.md

Core Rules

1. Server Components by Default

Everything is Server Component in App Router. Add 'use client' only for useState, useEffect, event handlers, or browser APIs. Server Components can't be imported into Client — pass as children.

2. Fetch Data on Server

Fetch in Server Components, not useEffect. Use Promise.all for parallel requests. See data-fetching.md for patterns.

3. Cache Intentionally

fetch is cached by default — use cache: 'no-store' for dynamic data. Set revalidate for ISR. See caching.md for strategies.

4. Server Actions for Mutations

Use 'use server' functions for form submissions and data mutations. Progressive enhancement — works without JS. See data-fetching.md.

5. Environment Security

NEXT_PUBLIC_ exposes to client bundle. Server Components access all env vars. Use .env.local for secrets.

6. Streaming for Large Data

Use <Suspense> boundaries to stream content progressively. Wrap slow components individually. See data-fetching.md.

7. Auth at Middleware Level

Protect routes in middleware, not in pages. Middleware runs on Edge — lightweight auth checks only. See auth.md.

Server vs Client

Server Component	Client Component
Default in App Router	Requires 'use client'
Can be async	Cannot be async
Access backend, env vars	Access hooks, browser APIs
Zero JS shipped	JS shipped to browser

Decision: Start Server. Add 'use client' only for: useState, useEffect, onClick, browser APIs.

Common Traps

Trap	Fix
router.push in Server	Use redirect()
<Link> prefetches all	prefetch={false}
next/image no size	Add width/height or fill
Metadata in Client	Move to Server or generateMetadata
useEffect for data	Fetch in Server Component
Import Server→Client	Pass as children/props
Middleware DB call	Call API route instead
Missing await params (v15)	Params are async in Next.js 15

Next.js 15 Changes

• params and searchParams are now Promise — must await
• fetch not cached by default — opt-in with cache: 'force-cache'
• Use React 19 hooks: useActionState, useFormStatus

Related Skills

Install with clawhub install <slug> if user confirms:

• react — React fundamentals and patterns
• typescript — Type safety for better DX
• prisma — Database ORM for Next.js apps
• tailwindcss — Styling with utility classes
• nodejs — Server runtime knowledge

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