Pattern	Approach	Key Points
Framework	Next.js App Router (default), React + Vite (SPAs)	Server-first rendering, file-based routing
Components	Page, Feature, UI, Layout types	Single responsibility, typed props, composition
Server vs Client	Server Components default, `'use client'` at leaf nodes	Push interactivity to edges of component tree
State (local)	`useState`, props, lift to parent	Keep state close to where it is consumed
State (global)	Context API (theme, auth), Zustand (complex)	Avoid Context for frequently changing values
Data fetching	Server Components (server), TanStack Query (client)	Server Actions for mutations, `revalidatePath` for cache
Forms	React Hook Form + Zod, or Server Actions + `useActionState`	Schema validation, optimistic updates with `useOptimistic`
Styling	Tailwind CSS v4 + shadcn/ui	CSS-first config with `@theme`, OKLCH colors
Performance	Suspense streaming, code splitting, memoization	`React.lazy()`, `next/dynamic`, selective `memo()`
Error handling	Error boundaries, `error.tsx` per route	Wrap feature sections, not individual components

Common Mistakes

Mistake	Correct Pattern
Adding `'use client'` to every component	Default to Server Components; add `'use client'` only for interactivity
Giant multi-responsibility component	Break into focused sub-components with single purposes
Placing all state at the top of the component tree	Keep state as close to where it is consumed as possible
Using `useEffect` to compute derived data	Use `useMemo` for derived values; reserve `useEffect` for side effects
Missing error boundaries around feature sections	Wrap feature areas with error boundaries to prevent full-page crashes
Creating API routes for simple mutations	Use Server Actions with `'use server'` for form submissions and mutations
Passing non-serializable props to Client Components	Props crossing server/client boundary must be serializable (no functions, classes)
Using `tailwind.config.js` with Tailwind v4	Use CSS-first configuration with `@theme` directive in CSS file
Fetching data in Client Components when Server Components suffice	Fetch in Server Components by default; use TanStack Query only when client-side caching is needed

Delegation

When building frontends, delegate to specialized skills:

react-patterns -- React hooks, rendering patterns, and performance optimization
nextjs -- Next.js routing, middleware, and deployment configuration
tanstack-query -- Client-side data fetching, caching, and mutations
tanstack-form -- Complex form handling and field-level validation
tailwind -- Tailwind CSS utility patterns and responsive design
design-system -- Token hierarchy and component architecture
performance-optimizer -- Profiling, bundle analysis, and Core Web Vitals

Component Architecture -- Component types, folder structure, TypeScript patterns, and composition
Server Components -- Server/client boundary, Server Actions, Suspense streaming, and data flow
State Management -- useState, Context API, Zustand, and URL state patterns
Data Fetching -- TanStack Query, Server Components data, and cache revalidation
Forms and Validation -- React Hook Form, Zod schemas, Server Actions, and useActionState
Styling -- Tailwind CSS v4, shadcn/ui, CSS-first config, and responsive patterns
Performance and Errors -- Memoization, code splitting, Suspense streaming, and error boundaries