frontend-builder

Frontend Builder

Overview

Builds maintainable, performant React and Next.js frontends using a server-first architecture. Covers component design, state management, data fetching, forms, styling, and performance optimization. Not for backend API design, database schema, or deployment infrastructure.

Quick Reference

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

References

• 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