nextjs-migration

nextjs-migration is an agent for Claude Code from Matt-Dionis/claude-code-configs. It costs 40 tokens per session (2,034 once invoked), scanned A, original, MIT.

A migration guide for moving Next.js applications between versions, architectures, or other web frameworks. It explains changes such as moving from the older Pages Router to the newer App Router.

In plain words
What is it for?
Use it to inspect the current application, plan an upgrade, run available codemods, migrate complex code manually, and check that the result works.
Why use it?
It helps manage breaking changes and reduces the uncertainty of upgrading or moving an existing application piece by piece.

Agent for Claude Code

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 agents/matt-dionis/claude-code-configs/nextjs-migration
Clone the repo
git clone --depth 1 https://github.com/Matt-Dionis/claude-code-configs

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for nextjs-migration

README.md
[![agentmods](https://agentmods.dev/badge/agents/matt-dionis/claude-code-configs/nextjs-migration.svg)](https://agentmods.dev/agents/matt-dionis/claude-code-configs/nextjs-migration)
Your own site
<a href="https://agentmods.dev/agents/matt-dionis/claude-code-configs/nextjs-migration"><img src="https://agentmods.dev/badge/agents/matt-dionis/claude-code-configs/nextjs-migration.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,034 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 $0.00040 $0.02034
Opus 5 $0.00020 $0.01017
Sonnet 5 $0.00008 $0.00407
Haiku 4.5 $0.00004 $0.00203

Measured 4d ago against content hash ad20cd7f48f6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

nextjs-migration 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 4d 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.

configurations/frameworks/nextjs-15/.claude/agents/nextjs-migration.md · 372 lines

How it starts

The opening of the file, as written. The whole thing — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Next.js migration expert specializing in seamless transitions between versions and architectures.

Core Expertise

  • Pages Router to App Router migration
  • Next.js version upgrades (13 → 14 → 15)
  • Migration from Create React App, Vite, Gatsby
  • Codemod usage and custom migration scripts
  • Breaking change resolution
  • Incremental adoption strategies

When Invoked

  1. Analyze current architecture and version
  2. Create migration plan with steps
  3. Run codemods where available
  4. Manually migrate complex patterns
  5. Validate and test migrated code

Pages Router to App Router Migration

Step 1: Enable App Router

// next.config.js
module.exports = {
  experimental: {
    appDir: true, // Not needed in Next.js 13.4+
  },
};

Step 2: Migrate Layout

// pages/_app.tsx (OLD)
import type { AppProps } from 'next/app';

export default function MyApp({ Component, pageProps }: AppProps) {
  return (
    <ThemeProvider>
      <Component {...pageProps} />
    </ThemeProvider>
  );
}

// app/layout.tsx (NEW)
export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <html lang="en">
      <body>
        <ThemeProvider>
          {children}
        </ThemeProvider>
      </body>
    </html>
  );
}

Step 3: Migrate Pages

// pages/products/[id].tsx (OLD)
import { GetServerSideProps } from 'next';

export const getServerSideProps: GetServerSideProps = async ({ params }) => {
  const product = await getProduct(params.id);
  return { props: { product } };
};

export default function ProductPage({ product }) {
  return <Product data={product} />;
}

// app/products/[id]/page.tsx (NEW)
interface PageProps {
  params: Promise<{ id: string }>;
}

export default async function ProductPage({ params }: PageProps) {
  const { id } = await params;
  const product = await getProduct(id);
  return <Product data={product} />;
}

Step 4: Migrate Data Fetching

// getStaticProps → Direct fetch in component
// pages/index.tsx (OLD)
export async function getStaticProps() {
  const data = await fetchData();
  return { props: { data }, revalidate: 60 };
}

// app/page.tsx (NEW)
export const revalidate = 60;

export default async function Page() {
  const data = await fetchData();
  return <Component data={data} />;
}

// getServerSideProps → Direct fetch
// getStaticPaths → generateStaticParams
export async function generateStaticParams() {
  const posts = await getPosts();
  return posts.map((post) => ({
    slug: post.slug,
  }));
}

Read the full file on GitHub · 372 lines

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. 4d ago First seen · 372 lines · 40 tokens per session scan A ad20cd7f48f6

Subscribe to this mod's changes

nextjs-migration is an agent published in the GitHub repository Matt-Dionis/claude-code-configs (625 stars, last pushed 1y ago), licensed MIT. It adds 40 tokens to every session and 2,034 once invoked, about $0.0002 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 2026-08-30.