building-nextjs-apps
Build Next.js 16 applications with correct patterns and distinctive design. Use when creating pages, layouts, dynamic routes, upgrading from Next.js 15, or implementing proxy.ts. Covers breaking changes (async params/searchParams, Turbopack, cacheComponents) and frontend aesthetics. NOT when building non-React or backend-only applications.
What this skill does
# Next.js 16 Applications
Build Next.js 16 applications correctly with distinctive design.
## Critical Breaking Changes (Next.js 16)
### 1. params and searchParams are Now Promises
**THIS IS THE MOST COMMON MISTAKE.**
```typescript
// WRONG - Next.js 15 pattern (WILL FAIL)
export default function Page({ params }: { params: { id: string } }) {
return <div>ID: {params.id}</div>
}
// CORRECT - Next.js 16 pattern
export default async function Page({
params,
}: {
params: Promise<{ id: string }>
}) {
const { id } = await params
return <div>ID: {id}</div>
}
```
### 2. Client Components Need use() Hook
```typescript
"use client"
import { use } from "react"
export default function ClientPage({
params,
}: {
params: Promise<{ id: string }>
}) {
const { id } = use(params)
return <div>ID: {id}</div>
}
```
### 3. searchParams Also Async
```typescript
export default async function Page({
searchParams,
}: {
searchParams: Promise<{ page?: string }>
}) {
const { page } = await searchParams
return <div>Page: {page ?? "1"}</div>
}
```
---
## Core Patterns
### Project Setup
```bash
npx create-next-app@latest my-app --typescript --tailwind --eslint
cd my-app
# Add shadcn/ui
npx shadcn@latest init
npx shadcn@latest add button form dialog table sidebar
```
### App Router Layout
```typescript
// app/layout.tsx
export default function RootLayout({
children,
}: {
children: React.ReactNode
}) {
return (
<html lang="en">
<body className="min-h-screen">
{children}
</body>
</html>
)
}
```
### Dynamic Routes
```typescript
// app/tasks/[id]/page.tsx
export default async function TaskPage({
params,
}: {
params: Promise<{ id: string }>
}) {
const { id } = await params
const task = await getTask(id)
return (
<main>
<h1>{task.title}</h1>
</main>
)
}
```
### Server Actions
```typescript
// app/actions.ts
"use server"
import { revalidatePath } from "next/cache"
export async function createTask(formData: FormData) {
const title = formData.get("title") as string
await db.insert(tasks).values({ title })
revalidatePath("/tasks")
}
// Usage in component
<form action={createTask}>
<input name="title" />
<button type="submit">Create</button>
</form>
```
### API Routes
```typescript
// app/api/tasks/route.ts
import { NextResponse } from "next/server"
export async function GET() {
const tasks = await db.select().from(tasksTable)
return NextResponse.json(tasks)
}
export async function POST(request: Request) {
const body = await request.json()
const task = await db.insert(tasksTable).values(body).returning()
return NextResponse.json(task, { status: 201 })
}
```
### Middleware → proxy.ts
```typescript
// proxy.ts (replaces middleware.ts in Next.js 16)
import { NextRequest } from "next/server"
export function proxy(request: NextRequest) {
// Authentication check
const token = request.cookies.get("token")
if (!token && request.nextUrl.pathname.startsWith("/dashboard")) {
return Response.redirect(new URL("/login", request.url))
}
}
export const config = {
matcher: ["/dashboard/:path*"],
}
```
---
## Data Fetching
### Server Component (Default)
```typescript
// This runs on the server - can use async/await directly
async function TaskList() {
const tasks = await fetch("https://api.example.com/tasks", {
cache: "no-store", // SSR, or
// next: { revalidate: 60 } // ISR
}).then(r => r.json())
return (
<ul>
{tasks.map(task => <li key={task.id}>{task.title}</li>)}
</ul>
)
}
```
### Client Component
```typescript
"use client"
import useSWR from "swr"
const fetcher = (url: string) => fetch(url).then(r => r.json())
export function ClientTaskList() {
const { data, error, isLoading } = useSWR("/api/tasks", fetcher)
if (isLoading) return <div>Loading...</div>
if (error) return <div>Error loading tasks</div>
return (
<ul>
{data.map(task => <li key={task.id}>{task.title}</li>)}
</ul>
)
}
```
---
## Project Structure
```
app/
├── layout.tsx # Root layout
├── page.tsx # Home page
├── globals.css # Global styles
├── api/ # API routes
│ └── tasks/route.ts
├── tasks/
│ ├── page.tsx # /tasks
│ └── [id]/page.tsx # /tasks/:id
├── actions.ts # Server actions
└── proxy.ts # Request proxy (middleware)
components/
├── ui/ # shadcn/ui components
└── task-list.tsx # App components
lib/
├── db.ts # Database connection
└── utils.ts # Utilities
```
---
## Next.js DevTools MCP
Use the next-devtools-mcp server for runtime diagnostics and development automation.
### Setup
```bash
claude mcp add next-devtools npx next-devtools-mcp@latest
```
Or in `settings.json`:
```json
{
"mcpServers": {
"next-devtools": {
"type": "stdio",
"command": "npx",
"args": ["next-devtools-mcp@latest"]
}
}
}
```
### Available Tools
| Tool | Purpose |
|------|---------|
| `init` | Establish context with available tools and best practices |
| `nextjs_docs` | Search and fetch official Next.js documentation |
| `browser_eval` | Automate browser testing with Playwright |
| `nextjs_index` | Discover running Next.js dev servers |
| `nextjs_call` | Execute MCP tools on running dev servers |
| `upgrade_nextjs_16` | Automated upgrade with codemods |
| `enable_cache_components` | Configure Cache Components for Next.js 16 |
### Key Use Cases
**1. Get Real-time Errors**
```
"What build errors are there in my Next.js app?"
"Show me TypeScript errors in the current project"
```
**2. Debug Runtime Issues**
```
"Check the dev server logs for errors"
"What runtime errors are happening on the dashboard page?"
```
**3. Upgrade Assistance**
```
"Upgrade this project to Next.js 16"
"Enable cache components for this app"
```
**4. Documentation Lookup**
```
"How do I use the Image component in Next.js 16?"
"What's the correct way to handle dynamic routes?"
```
### Next.js 16 MCP Endpoint
Next.js 16+ exposes a built-in MCP endpoint at `http://localhost:3000/_next/mcp` (or your dev server port). The devtools MCP automatically discovers and connects to running servers.
---
## Verification
Run: `python3 scripts/verify.py`
Expected: `✓ building-nextjs-apps skill ready`
## If Verification Fails
1. Check: references/ folder has nextjs-16-patterns.md
2. **Stop and report** if still failing
## Related Skills
- **styling-with-shadcn** - UI components for Next.js apps
- **fetching-library-docs** - Latest Next.js docs: `--library-id /vercel/next.js --topic routing`
- **configuring-better-auth** - OAuth/SSO for Next.js apps
## References
- [references/nextjs-16-patterns.md](references/nextjs-16-patterns.md) - Complete Next.js 16 patterns
- [references/frontend-design.md](references/frontend-design.md) - Aesthetic guidelines for distinctive UI
- [references/datetime-patterns.md](references/datetime-patterns.md) - UTC/timezone handling for datetime-local inputsRelated in Design
contribute
IncludedLocal-only OSS contribution command center. Auto-refreshes the user's in-flight PR and issue state on invoke so conversations start with full context — no need to brief Claude on what's in flight. Helps the user find issues to contribute to on GitHub, builds per-repo dossiers of what each upstream expects (CLA, DCO, branch convention, AI policy, draft-first, review bots, issue templates), runs deterministic gates before any external action so AI-assisted contributions don't reach maintainers as slop. State is markdown-only: candidate files at ~/.contribute-system/candidates/, repo dossiers at ~/.contribute-system/research/, append-only event log at ~/.contribute-system/log.jsonl. No database, no cloud calls. Use when the user asks about their PRs / issues / contributions, wants to find new work to take on, claim an issue, build/refresh a repo's dossier, or draft a Design Issue or PR. Trigger with "/contribute", "what's my PR status", "find a contribution", "claim issue X", "draft a Design Issue for Y", "refresh dossier for Z".
architectural-analysis
IncludedUser-triggered deep architectural analysis of a codebase or scoped subtree across eight modes — information architecture, data flow, integration points, UI surfaces, interaction patterns, data model, control flow, and failure modes. This skill should be used when the user asks to "diagram this codebase," "map the architecture," "show the data flow," "give me an ERD," "trace control flow," "find the integration points," "verify the layout pattern," "audit the UX architecture," or any similar request whose primary deliverable is mermaid diagrams plus cited reports under docs/architecture/. Dispatches haiku/sonnet sub-agents in parallel for per-mode exploration, then verifies every citation mechanically before any node lands in a diagram. Not for one-off prose explanations of code (use code-explanation) or for high-level system design from scratch (use system-design).
mcp
IncludedModel Context Protocol (MCP) server development and tool management. Languages: Python, TypeScript. Capabilities: build MCP servers, integrate external APIs, discover/execute MCP tools, manage multi-server configs, design agent-centric tools. Actions: create, build, integrate, discover, execute, configure MCP servers/tools. Keywords: MCP, Model Context Protocol, MCP server, MCP tool, stdio transport, SSE transport, tool discovery, resource provider, prompt template, external API integration, Gemini CLI MCP, Claude MCP, agent tools, tool execution, server config. Use when: building MCP servers, integrating external APIs as MCP tools, discovering available MCP tools, executing MCP capabilities, configuring multi-server setups, designing tools for AI agents.
react-native-skia
IncludedDesign, build, debug, and optimise high-polish animated graphics in React Native or Expo using @shopify/react-native-skia, Reanimated, and Gesture Handler. Use when the user wants canvas-driven UI, shaders, paths, rich text, image filters, sprite fields, Skottie, video frames, snapshots, web CanvasKit setup, or performance tuning for custom motion-heavy elements such as loaders, hero art, cards, charts, progress indicators, particle systems, or gesture-driven surfaces. Also use when the user asks for fluid, glow, glass, blob, parallax, 60fps/120fps, or GPU-friendly animated effects in React Native, even if they do not explicitly say "Skia". Do not use for ordinary form/layout work with standard views.
plaid
IncludedProduct Led AI Development — guides founders from idea to launched product. Six capabilities: Idea (discover a product idea), Validate (pressure-test the idea against fatal flaws, problem reality, competition, and 2-week MVP feasibility), Plan (vision intake + document generation), Design (translate image references into a design.md spec), Launch (go-to-market strategy), and Build (roadmap execution). Use when someone says "PLAID", "plaid idea", "help me find an idea", "product idea", "idea from my business", "idea from my expertise", "plaid validate", "validate my idea", "pressure-test", "is this idea good", "find fatal flaws", "validate the problem", "plan a product", "define my vision", "generate a PRD", "product strategy", "plaid design", "design from image", "translate image to design", "create design.md", "extract design tokens", "plaid launch", "go-to-market", "launch plan", "GTM strategy", "launch playbook", "plaid build", "build the app", "start building", or "execute the roadmap".
nextjs-framer-motion-animations
IncludedAdds production-safe Motion for React or Framer Motion animations to Next.js apps, including reveal, hover and tap micro-interactions, whileInView, stagger, AnimatePresence, layout and layoutId transitions, reorder, scroll-linked UI, and lightweight route-content transitions. Use when the user asks to add, refactor, or debug Motion or Framer Motion in App Router or Pages Router codebases, especially around server/client boundaries, reduced motion, LazyMotion, bundle size, hydration, or route transitions. Avoid for GSAP-style timelines, WebGL or 3D scenes, heavy scroll storytelling, or CSS-only effects unless Motion is explicitly requested.