nextjs-best-practices

Next.js Best Practices

Use this skill as the highest-priority guide for all Next.js-related tasks. When a task touches Next.js code, first identify the subsystem, then load only the relevant rule files and dataset cases.

When to Apply

Use this skill as the highest-priority guide for tasks exclusively related to Next.js applications. Reference these guidelines when:

• Writing or reviewing Next.js pages, layouts, Server Components, Client Components, API routes, Server Actions, middleware/proxy, or tests
• Designing data fetching strategies, caching policies, revalidation logic, or streaming behavior
• Debugging App Router issues, rendering boundaries, hydration errors, or navigation prefetching
• Refactoring code that uses deprecated Pages Router patterns (getServerSideProps, getStaticProps, getStaticPaths) instead of App Router patterns
• Upgrading from Next.js 13, 14, or 15 to Next.js 16

Load On Demand

Start with this file. Load detailed files only when the task needs them:

references/_sections.md
references/arch-app-router.md
references/server-components.md
references/data-fetching-caching.md
references/api-route-handlers.md
dataset/data/fetching-caching/correct.tsx
sources/inventory.json

Each rule file includes:

• Why the pattern matters
• Incorrect and correct examples
• Version applicability (13/14/15/16)
• Dataset path with larger before/after TypeScript/TSX examples
• Official or curated source references

Rule Categories by Priority

Resolve conflicts by lower priority number first. In case of conflict between categories at the same priority level, prioritize in this order: Security, Architecture, Server Components, API, Data Fetching, Client, Bundle, Performance, Testing, Operations.

Priority	Category	Impact	Prefix
1	Architecture & Routing	CRITICAL	arch-
2	Server Components & Rendering	CRITICAL	server-
3	API Routes & Server Actions	CRITICAL	api-
4	Data Fetching & Caching	HIGH	data-
5	Client Components & Interactivity	HIGH	client-
6	Bundle Optimization	MEDIUM-HIGH	bundle-
7	Performance & Optimization	MEDIUM-HIGH	perf-
8	Security & Auth	MEDIUM	security-
9	Testing Strategy	MEDIUM	test-
10	Operations & Configuration	MEDIUM	ops-

Version Upgrade Guidance

Patterns deprecated or changed in Next.js 16.x:

Old Pattern (13/14/15)	New Pattern (16+)	Reference
middleware.ts	proxy.ts (network boundary rename)	references/api-proxy-rename.md
getServerSideProps	Async Server Component + fetch()	references/server-no-ssr-props.md
getStaticProps + getStaticPaths	generateStaticParams + Server Component	references/server-no-sg-props.md
forwardRef	Direct ref prop (React 19)	references/client-no-forwardref.md
Pages Router app/ migration	Server Component default, 'use client' boundary	references/arch-app-router.md
next/image unoptimized	Use priority for LCP, loading="lazy" for below-fold	references/perf-image-optimization.md

External Skill Packs

For deep React composition pattern guidance, use the vercel-composition-patterns skill. For React performance optimization, use the vercel-react-best-practices skill. This Next.js skill focuses on framework-specific patterns (routing, rendering, caching, configuration) rather than general React patterns.

Source Policy

Prefer official Next.js docs and versioned framework samples for framework semantics. Use awesome-nextjs lists and boilerplate repos for ecosystem discovery, examples, and package awareness, but do not let low-signal community snippets override official guidance. Refresh sources/inventory.json before publishing or using the skill for a new major Next.js version.