React Server Components Framework

Overview

React Server Components (RSC) enable server-first rendering with client-side interactivity. This skill covers Next.js 16 App Router patterns, Server Components, Server Actions, and streaming.

When to use this skill:

• Building Next.js 16+ applications with the App Router
• Designing component boundaries (Server vs Client Components)
• Implementing data fetching with caching and revalidation
• Creating mutations with Server Actions
• Optimizing performance with streaming and Suspense

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Quick Reference

Server vs Client Components

Feature	Server Component	Client Component
Directive	None (default)	'use client'
Async/await	Yes	No
Hooks	No	Yes
Browser APIs	No	Yes
Database access	Yes	No
Client JS bundle	Zero	Ships to client

Key Rule: Server Components can render Client Components, but Client Components cannot directly import Server Components (use children prop instead).

Data Fetching Quick Reference

Next.js 16 Cache Components (Recommended):

import { cacheLife, cacheTag } from 'next/cache'

// Cached component with duration
async function CachedProducts() {
  'use cache'
  cacheLife('hours')
  cacheTag('products')
  return await db.product.findMany()
}

// Invalidate cache
import { revalidateTag } from 'next/cache'
revalidateTag('products')

Legacy Fetch Options (Next.js 15):

// Static (cached indefinitely)
await fetch(url, { cache: 'force-cache' })

// Revalidate every 60 seconds
await fetch(url, { next: { revalidate: 60 } })

// Always fresh
await fetch(url, { cache: 'no-store' })

// Tag-based revalidation
await fetch(url, { next: { tags: ['posts'] } })

Server Actions Quick Reference

'use server'

export async function createPost(formData: FormData) {
  const title = formData.get('title') as string
  const post = await db.post.create({ data: { title } })
  revalidatePath('/posts')
  redirect("/posts/" + post.id)
}

Async Params/SearchParams (Next.js 16)

Route parameters and search parameters are now Promises that must be awaited:

// app/posts/[slug]/page.tsx
export default async function PostPage({
  params,
  searchParams,
}: {
  params: Promise<{ slug: string }>
  searchParams: Promise<{ page?: string }>
}) {
  const { slug } = await params
  const { page } = await searchParams
  return <Post slug={slug} page={page} />
}

Note: Also applies to layout.tsx, generateMetadata(), and route handlers. Load: Read("${CLAUDE_SKILL_DIR}/references/nextjs-16-upgrade.md") for complete migration guide.

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References

Load on demand with Read("${CLAUDE_SKILL_DIR}/references/<file>"):

File	Content
server-components.md	Async server components, data fetching patterns, route segment config, generateStaticParams, error handling
client-components.md	'use client' directive, React 19 patterns, interactivity, hydration, composition via children
streaming-patterns.md	Suspense boundaries, loading.tsx, parallel streaming, PPR, skeleton best practices
react-19-patterns.md	Function declarations, ref as prop, useActionState, useFormStatus, useOptimistic, Activity, useEffectEvent
server-actions.md	Progressive enhancement, useActionState forms, Zod validation, optimistic updates
routing-patterns.md	Parallel routes, intercepting routes, route groups, dynamic and catch-all routes
migration-guide.md	Pages Router to App Router migration, getServerSideProps/getStaticProps replacement
cache-components.md	"use cache" directive (replaces experimental_ppr), cacheLife, cacheTag, revalidateTag, PPR integration
nextjs-16-upgrade.md	Node.js 20.9+, breaking changes (async params, cookies, headers), proxy.ts migration, Turbopack, new caching APIs
tanstack-router-patterns.md	React 19 features without Next.js, route-based data fetching, client-rendered app patterns
capability-details.md	Keyword and problem-mapping metadata for all 12 RSC capabilities

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Best Practices Summary

Component Boundaries

• Keep Client Components at the edges (leaves) of the component tree
• Use Server Components by default
• Extract minimal interactive parts to Client Components
• Pass Server Components as children to Client Components

Data Fetching

• Fetch data in Server Components close to where it's used
• Use parallel fetching (Promise.all) for independent data
• Set appropriate cache and revalidate options
• Use generateStaticParams for static routes

Performance

• Use Suspense boundaries for streaming
• Implement loading.tsx for instant loading states
• Enable PPR for static/dynamic mix
• Use route segment config to control rendering mode

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Templates

• scripts/ServerComponent.tsx - Basic async Server Component with data fetching
• scripts/ClientComponent.tsx - Interactive Client Component with hooks
• scripts/ServerAction.tsx - Server Action with validation and revalidation

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Troubleshooting

Error	Fix
"You're importing a component that needs useState"	Add 'use client' directive
"async/await is not valid in non-async Server Components"	Add async to function declaration
"Cannot use Server Component inside Client Component"	Pass Server Component as children prop
"Hydration mismatch"	Use 'use client' for Date.now(), Math.random(), browser APIs
"params is not defined" or params returning Promise	Add await before params (Next.js 16 breaking change)
"experimental_ppr is not a valid export"	Use Cache Components with "use cache" directive instead
"cookies/headers is not a function"	Add await before cookies() or headers() (Next.js 16)

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Resources

• Next.js 16 Documentation
• React 19.2 Blog Post
• React Server Components RFC
• App Router Migration Guide

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Related Skills

After mastering React Server Components:

1. Streaming API Patterns - Real-time data patterns
2. Type Safety & Validation - tRPC integration
3. Edge Computing Patterns - Global deployment
4. Performance Optimization - Core Web Vitals

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Capability Details

Keyword and problem-mapping metadata for each RSC capability (react-19-patterns, use-hook-suspense, optimistic-updates-async, rsc-patterns, server-actions, data-fetching, streaming-ssr, caching, cache-components, tanstack-router-patterns, async-params, nextjs-16-upgrade).

Load full capability details: Read("${CLAUDE_SKILL_DIR}/references/capability-details.md")