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next-best-practices

next-best-practices is a skill for Claude Code, Codex from fellipeutaka/leon. It costs 38 tokens per session (1,017 once invoked), scanned A, a copy of next-best-practices, MIT.

A set of rules for writing and reviewing Next.js applications, covering project files, server and client code, asynchronous APIs, errors, metadata, images, fonts, and bundling.

In plain words
What is it for?
Use it when creating or reviewing Next.js routes, components, server functions, metadata, error handling, runtime choices, and performance-related configuration.
Why use it?
It helps catch framework-specific mistakes, such as using server and browser code in the wrong place or relying on outdated asynchronous APIs.

Skill for Claude CodeCodex

Written for Claude Code and Codex: user-invocable in frontmatter, but also agents/openai.yaml present.

not rated 5repo 5d ago A scan 38 tokens copy · 100% MIT

Good fit Use it when creating or reviewing Next.js routes, components, server functions, metadata, error handling, runtime choices, and performance-related configuration.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fellipeutaka/leon/next-best-practices
View source ↗ fellipeutaka/leon
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 fellipeutaka/leon --skill next-best-practices
Clone the repo
git clone --depth 1 https://github.com/fellipeutaka/leon

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 next-best-practices

README.md
[![agentmods](https://agentmods.dev/badge/skills/fellipeutaka/leon/next-best-practices/github.svg)](https://agentmods.dev/skills/fellipeutaka/leon/next-best-practices)
Your own site
<a href="https://agentmods.dev/skills/fellipeutaka/leon/next-best-practices"><img src="https://agentmods.dev/badge/skills/fellipeutaka/leon/next-best-practices/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for next-best-practices

Your own site · 80×15
<a href="https://agentmods.dev/skills/fellipeutaka/leon/next-best-practices"><img src="https://agentmods.dev/badge/skills/fellipeutaka/leon/next-best-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,017 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 100% copy Near-identical to another mod 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 $0.00038 $0.01017
Opus 5 $0.00019 $0.00508
Sonnet 5 $0.00008 $0.00203
Haiku 4.5 $0.00004 $0.00102

Measured 9d ago against content hash c78f952d4e98, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

next-best-practices 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 9d 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.

Origin

This is a copy

100% identical to next-best-practices — 20 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/next-best-practices/SKILL.md · 154 lines

How it starts

The opening of the file, as written. The whole thing — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Next.js Best Practices

Apply these rules when writing or reviewing Next.js code.

File Conventions

See file-conventions.md for:

  • Project structure and special files
  • Route segments (dynamic, catch-all, groups)
  • Parallel and intercepting routes
  • Middleware rename in v16 (middleware → proxy)

RSC Boundaries

Detect invalid React Server Component patterns.

See rsc-boundaries.md for:

  • Async client component detection (invalid)
  • Non-serializable props detection
  • Server Action exceptions

Async Patterns

Next.js 15+ async API changes.

See async-patterns.md for:

  • Async params and searchParams
  • Async cookies() and headers()
  • Migration codemod

Runtime Selection

See runtime-selection.md for:

  • Default to Node.js runtime
  • When Edge runtime is appropriate

Directives

See directives.md for:

  • 'use client', 'use server' (React)
  • 'use cache' (Next.js)

Functions

See functions.md for:

  • Navigation hooks: useRouter, usePathname, useSearchParams, useParams
  • Server functions: cookies, headers, draftMode, after
  • Generate functions: generateStaticParams, generateMetadata

Error Handling

See error-handling.md for:

  • error.tsx, global-error.tsx, not-found.tsx
  • redirect, permanentRedirect, notFound
  • forbidden, unauthorized (auth errors)
  • unstable_rethrow for catch blocks

Data Patterns

See data-patterns.md for:

  • Server Components vs Server Actions vs Route Handlers
  • Avoiding data waterfalls (Promise.all, Suspense, preload)
  • Client component data fetching

Route Handlers

See route-handlers.md for:

  • route.ts basics
  • GET handler conflicts with page.tsx
  • Environment behavior (no React DOM)
  • When to use vs Server Actions

Metadata & OG Images

See metadata.md for:

  • Static and dynamic metadata
  • generateMetadata function
  • OG image generation with next/og
  • File-based metadata conventions

Read the full file on GitHub · 154 lines

Files

What ships with it

20 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 154 lines · 38 tokens per session scan A c78f952d4e98

Subscribe to this mod's changes

next-best-practices is a skill published in the GitHub repository fellipeutaka/leon (5 stars, last pushed 5d ago), licensed MIT. It adds 38 tokens to every session and 1,017 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to next-best-practices, differing in 20 lines, and is treated as a copy.

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