nextjs-react19

A set of patterns for building Next.js applications with React 19 using the App Router, Next.js’s file-based routing system. It covers server-rendered components, data loading, routes, forms, and loading or error states.

In plain words
What is it for?
Use it when creating pages and layouts, fetching data, defining API routes, handling dynamic or modal routes, and building form actions.
Why use it?
It helps keep newer Next.js and React code organized and avoids mixing server-side and browser-side responsibilities incorrectly.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/usrrname/cursorrules/nextjs
Any agent
npx skills add usrrname/cursorrules --skill nextjs
Clone the repo
git clone --depth 1 https://github.com/usrrname/cursorrules

Made for: Claude Code, Codex.

Per session 14 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 414 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00014 $0.00414
Opus 5 $0.00007 $0.00207
Sonnet 5 $0.00003 $0.00083
Haiku 4.5 $0.00001 $0.00041

Measured 2d ago against content hash 2aea92026abc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

nextjs-react19 scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/nextjs/SKILL.md · 81 lines

What it actually says

Next.js React 19 Skill

Build modern Next.js applications with App Router and React 19 features.

When to Use

  • Creating Next.js pages and layouts
  • Working with Server Components
  • Implementing data fetching
  • Setting up API routes

Critical Rules

App Router

  • Use Server Components by default
  • Mark Client Components with 'use client'
  • Keep Client Components small and focused
  • Use async/await in Server Components

Data Fetching

  • Fetch directly in Server Components
  • Use React.cache for deduplication
  • Implement proper error boundaries
  • Use loading.js for suspense states

Routing

  • Use file-based routing in app/
  • Implement parallel routes with @folder
  • Use intercepting routes for modals
  • Handle dynamic segments with [param]

React 19 Features

  • Use Actions for form mutations
  • Leverage useOptimistic for UI updates
  • Implement useFormStatus for pending states
  • Use Server Actions for mutations

Examples

Good

// Server Component
async function BlogPage() {
  const posts = await getPosts();
  
  return (
    <main>
      {posts.map(post => (
        <PostCard key={post.id} post={post} />
      ))}
    </main>
  );
}

// Client Component
'use client';

function LikeButton({ postId }: { postId: string }) {
  const [optimisticLikes, addOptimisticLike] = useOptimistic(
    likes,
    (state) => state + 1
  );
  
  return <button>{optimisticLikes} likes</button>;
}
  • /react - React TypeScript patterns
  • /typescript - TypeScript fundamentals
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 81 lines · 14 tokens per session scan A 2aea92026abc

Subscribe to this mod's changes

nextjs-react19 is a skill published in the GitHub repository usrrname/cursorrules (10 stars, last pushed 4mo ago), licensed ISC. It adds 14 tokens to every session and 414 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.