routing

routing is a skill for Claude Code, Codex from CaseMark/casedotdev-starter-app. It costs 0 tokens per session (1,993 once invoked), scanned A, original, Apache-2.0.

A guide to routing in Next.js 15 and later, where folders and special files in an `app` directory define pages and shared layouts. Next.js is a framework for building web applications with React.

In plain words
What is it for?
Use it to create pages, nested routes, shared layouts, metadata, loading screens, error handling, not-found pages, and API routes.
Why use it?
It explains where routes, pages, layouts, loading states, errors, and API endpoints belong in a Next.js project.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create pages, nested routes, shared layouts, metadata, loading screens, error handling, not-found pages, and API routes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/casemark/casedotdev-starter-app/routing
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.

Any agent
npx skills add CaseMark/casedotdev-starter-app --skill routing
Clone the repo
git clone --depth 1 https://github.com/CaseMark/casedotdev-starter-app

Made for: Claude Code, Codex.

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 routing

README.md
[![agentmods](https://agentmods.dev/badge/skills/casemark/casedotdev-starter-app/routing.svg)](https://agentmods.dev/skills/casemark/casedotdev-starter-app/routing)
Your own site
<a href="https://agentmods.dev/skills/casemark/casedotdev-starter-app/routing"><img src="https://agentmods.dev/badge/skills/casemark/casedotdev-starter-app/routing.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,993 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00000 $0.01993
Opus 5 $0.00000 $0.00996
Sonnet 5 $0.00000 $0.00399
Haiku 4.5 $0.00000 $0.00199

Measured 7d ago against content hash 5b9b76c1e0f7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

routing 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 7d 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.

skills/routing/SKILL.md · 376 lines

How it starts

The opening of the file, as written. The whole thing — 376 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Routing Skill

Purpose

This skill covers the Next.js 15+ App Router, including pages, layouts, navigation, and route organization.

Key Concepts

  • App Router: Next.js 15+ uses the app/ directory for routing
  • File-based Routing: Folders define routes, special files define UI
  • Server Components: Default component type (no 'use client' needed)
  • Layouts: Shared UI that wraps pages

Special Files

  • page.tsx - Unique UI for a route, makes route publicly accessible
  • layout.tsx - Shared UI for a segment and its children
  • loading.tsx - Loading UI for a segment
  • error.tsx - Error UI for a segment
  • not-found.tsx - Not found UI
  • route.ts - API endpoint

Creating Pages

Basic Page

// app/about/page.tsx
export default function AboutPage() {
  return (
    <div>
      <h1>About</h1>
      <p>Welcome to our about page.</p>
    </div>
  );
}

Page with Metadata

// app/about/page.tsx
import type { Metadata } from 'next';

export const metadata: Metadata = {
  title: 'About Us',
  description: 'Learn more about our company',
};

export default function AboutPage() {
  return <div>{/* Content */}</div>;
}

Dynamic Routes

// app/cases/[id]/page.tsx
interface PageProps {
  params: Promise<{ id: string }>;
}

export default async function CasePage({ params }: PageProps) {
  const { id } = await params;
  
  return (
    <div>
      <h1>Case {id}</h1>
    </div>
  );
}

Multiple Dynamic Segments

// app/teams/[teamId]/cases/[caseId]/page.tsx
interface PageProps {
  params: Promise<{ 
    teamId: string; 
    caseId: string;
  }>;
}

export default async function TeamCasePage({ params }: PageProps) {
  const { teamId, caseId } = await params;
  
  return (
    <div>
      <h1>Team {teamId} - Case {caseId}</h1>
    </div>
  );
}

Layouts

Root Layout

// app/layout.tsx
import type { Metadata } from 'next';
import { Inter } from 'next/font/google';
import './globals.css';

const inter = Inter({ subsets: ['latin'] });

export const metadata: Metadata = {
  title: 'Create Legal App',
  description: 'Legal tech application',
};

export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <html lang="en">
      <body className={inter.className}>{children}</body>
    </html>
  );
}

Read the full file on GitHub · 376 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. 7d ago First seen · 376 lines · 0 tokens per session scan A 5b9b76c1e0f7

Subscribe to this mod's changes

routing is a skill published in the GitHub repository CaseMark/casedotdev-starter-app (2 stars, last pushed 2mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 1,993 tokens. 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.

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