# Web Next Best Practices

> Next.js best practices - file conventions, RSC boundaries, data patterns, async APIs, metadata, error handling, route handlers, image/font optimization, bundling. Use this skill when writing or reviewing Next.js code to ensure it follows established best practices for performance, maintainability, and correctness. Refer to the linked reference docs for detailed rules and examples in each area.

- Skill: `majiayu000/web-next-best-practices` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/web-next-best-practices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/web-next-best-practices/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/web-next-best-practices

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# Next.js Best Practices

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

## File Conventions

See [file-conventions.md](./references/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](./references/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](./references/async-patterns.md) for:
- Async `params` and `searchParams`
- Async `cookies()` and `headers()`
- Migration codemod

## Runtime Selection

See [runtime-selection.md](./references/runtime-selection.md) for:
- Default to Node.js runtime
- When Edge runtime is appropriate

## Directives

See [directives.md](./references/directives.md) for:
- `'use client'`, `'use server'` (React)
- `'use cache'` (Next.js)

## Functions

See [functions.md](./references/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](./references/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](./references/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](./references/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](./references/metadata.md) for:
- Static and dynamic metadata
- `generateMetadata` function
- OG image generation with `next/og`
- File-based metadata conventions

## Image Optimization

See [image.md](./references/image.md) for:
- Always use `next/image` over `<img>`
- Remote images configuration
- Responsive `sizes` attribute
- Blur placeholders
- Priority loading for LCP

## Font Optimization

See [font.md](./references/font.md) for:
- `next/font` setup
- Google Fonts, local fonts
- Tailwind CSS integration
- Preloading subsets

## Bundling

See [bundling.md](./references/bundling.md) for:
- Server-incompatible packages
- CSS imports (not link tags)
- Polyfills (already included)
- ESM/CommonJS issues
- Bundle analysis

## Scripts

See [scripts.md](./references/scripts.md) for:
- `next/script` vs native script tags
- Inline scripts need `id`
- Loading strategies
- Google Analytics with `@next/third-parties`

## Hydration Errors

See [hydration-error.md](./references/hydration-error.md) for:
- Common causes (browser APIs, dates, invalid HTML)
- Debugging with error overlay
- Fixes for each cause

## Suspense Boundaries

See [suspense-boundaries.md](./references/suspense-boundaries.md) for:
- CSR bailout with `useSearchParams` and `usePathname`
- Which hooks require Suspense boundaries

## Parallel & Intercepting Routes

See [parallel-routes.md](./references/parallel-routes.md) for:
- Modal patterns with `@slot` and `(.)` interceptors
- `default.tsx` for fallbacks
- Closing modals correctly with `router.back()`

## Self-Hosting

See [self-hosting.md](./references/self-hosting.md) for:
- `output: 'standalone'` for Docker
- Cache handlers for multi-instance ISR
- What works vs needs extra setup

## Debug Tricks

See [debug-tricks.md](./references/debug-tricks.md) for:
- MCP endpoint for AI-assisted debugging
- Rebuild specific routes with `--debug-build-paths`