Nextjs Patterns

--- name: nextjs-patterns type: reference description: "Comprehensive Next.js development patterns for App Router, Server Components, TypeScript, and Tailwind CSS. Covers foundational principles, data fetching, routing, performance, and an 8-phase development workflow. Also includes Server Actions and Metadata patterns." paths: ["/*.tsx", "/.jsx", "**/next.config.", "/app//.ts", "**/tailwind.config."] when_to_use: "Building or optimizing Next.js 14+ / 15+ applications with App Router, Server Components, streaming, or Server Actions." allowed-tools: Read, Glob, Grep, Write, Edit, Bash user-invocable: true effort: 3

Next.js Development Patterns

Comprehensive patterns and best practices for Next.js 14+ / 15+ App Router architecture, Server Components, and modern full-stack React development.

1. Foundational Principles

Server vs Client Components

• Server (Default): Use for data fetching, layouts, and static content.
• Client ('use client'): Use for interactivity (useState, useEffect), event handlers, and browser-only APIs.
• Decision Rule: Stay on the server as long as possible. Split components so the interactive "leaf nodes" are client-side while the data-heavy "branch nodes" remain on the server.

Routing & Organization

• App Router: Use the app/ directory for file-based routing.
• Route Groups: (group-name) for organization without affecting URL structure.
• Special Files: page.tsx, layout.tsx, loading.tsx, error.tsx, not-found.tsx.
• Advanced Routing: Parallel routes (@slot) and Intercepting routes ((.)).

2. Data Fetching & Caching

Strategy Matrix

Patterns

• Server Fetching: Fetch data directly in Server Components using async/await.
• Streaming: Use Suspense and loading.tsx to stream UI to the client.
• Server Actions: Perform mutations with use server functions. Validate with Zod.

3. 8-Phase Development Workflow

Phase 1: Project Setup

Scaffold with @app-builder, configure TypeScript, and set up ESLint/Prettier.

Phase 2: Component Architecture

Design hierarchy and implement base layout components using @frontend-developer and @react-patterns.

Phase 3: Styling & Design

Configure Tailwind CSS v4 and design tokens using @tailwind-patterns and @frontend-design.

Phase 4: Data Fetching

Implement Server Component data fetching and set up React Query/SWR if client-side fetching is needed.

Phase 5: Routing & Navigation

Set up file-based routing, dynamic routes, and handle redirects/guards.

Phase 6: Forms & Validation

Use React Hook Form and Zod for robust, type-safe data entry.

Phase 7: Testing

Write unit/integration tests with Vitest and E2E flows with @playwright-skill.

Phase 8: Optimization & Deploy

Analyze bundle size, optimize images with next/image, and deploy to Vercel/similar.

4. Performance & Metadata

• Images: Always use next/image. Set priority for LCP elements.
• Dynamic Imports: Use for heavy client-side libraries.
• Metadata API: Use generateMetadata for dynamic SEO tags per route.

Resources & Anti-Patterns

• implementation-playbook.md: Detailed code examples for every pattern.
• Anti-Pattern: Using 'use client' at the top level of every file.
• Anti-Pattern: Fetching data inside useEffect for information available on first load.

Guidance: If you need deeper walkthroughs, refer to the resources/ folder within this skill.