---

name: ui-component-builder description: Build, convert, and optimize React/Vue/Svelte UI components with TypeScript, advanced patterns, animations, and accessibility. Updated for React 19, Next.js 16, and modern 2025 standards. allowed-tools:

• Read
• Write
• Edit
• Bash
• Glob
• Grep
• Task

---

UI Component Builder

Expert skill for building production-ready UI components for component libraries. Specializes in React 19, Vue 3.5, and Svelte 5 with TypeScript 5.9, implementing advanced patterns, animations with Motion 12, and ensuring accessibility and performance.

Technology Stack (2025)

Core Technologies

• React 19.2 - Latest with React Compiler, use API, Server Components
• Next.js 16 - Turbopack stable, Cache Components, PPR
• TypeScript 5.9 - Latest stable with enhanced type inference
• Tailwind CSS 4.0 - CSS-first config, cascade layers, 100x faster incremental builds
• Motion 12 (formerly Framer Motion) - Hybrid engine, GPU-accelerated animations

Build & Testing

• Vitest 4.0 - Browser Mode stable, Visual Regression testing
• Vite 6 - Lightning fast HMR
• Storybook 9 - Component development platform

Utilities

• class-variance-authority (cva) - Variant management
• clsx/tailwind-merge - Conditional className composition
• Zod 4 - Runtime validation
• React Hook Form 8 - Form state management

Core Capabilities

1. Component Creation

• Create new components from scratch with TypeScript
• Implement compound components pattern
• Build components with render props
• Create custom hooks with the new use API (React 19)
• Support for polymorphic components (as prop pattern)
• Generic component types for maximum reusability
• Server Components support (Next.js 16)

2. Framework Conversion

Convert components seamlessly between frameworks:

• React 19 → Vue 3.5: JSX to template/composition API
• React 19 → Svelte 5: Hooks to runes ($state, $derived, $effect)
• Vue 3.5 → React 19: Template to JSX, composables to hooks
• Svelte 5 → React 19: Runes to useState/use

3. Advanced Patterns Implementation

Compound Components

Copy<Select>
  <Select.Trigger />
  <Select.Content>
    <Select.Item value="1">Option 1</Select.Item>
  </Select.Content>
</Select>

React 19 use API

Copyfunction Comments({ commentsPromise }: { commentsPromise: Promise<Comments[]> }) {
  const comments = use(commentsPromise)
  return comments.map(c => <Comment key={c.id} data={c} />)
}

Server Components (Next.js 16)

Copy// Server Component - runs on server only
async function ProductList() {
  const products = await db.products.findMany()
  return <ProductGrid products={products} />
}

// Client Component
'use client'
function AddToCart({ productId }: { productId: string }) {
  const [pending, startTransition] = useTransition()
}

4. Animation Integration (Motion 12)

Copyimport { motion, AnimatePresence } from 'motion/react'

export function Modal({ isOpen, onClose, children }: ModalProps) {
  return (
    <AnimatePresence>
      {isOpen && (
        <>
          <motion.div
            initial={{ opacity: 0 }}
            animate={{ opacity: 1 }}
            exit={{ opacity: 0 }}
            onClick={onClose}
            className="fixed inset-0 bg-black/50"
          />
          <motion.div
            initial={{ opacity: 0, scale: 0.95, y: 20 }}
            animate={{ opacity: 1, scale: 1, y: 0 }}
            exit={{ opacity: 0, scale: 0.95, y: 20 }}
            transition={{ type: 'spring', duration: 0.3 }}
            className="fixed inset-0 flex items-center justify-center"
          >
            {children}
          </motion.div>
        </>
      )}
    </AnimatePresence>
  )
}

5. TypeScript 5.9 Excellence

• Strict type safety with proper generic constraints
• Discriminated unions for component variants
• satisfies operator for better inference
• const type parameters
• Proper typing for refs, events, and children

6. Accessibility (a11y) First

• Semantic HTML elements
• ARIA attributes when needed
• Keyboard navigation (Tab, Enter, Escape, Arrow keys)
• Focus management and focus trapping
• Screen reader announcements
• WCAG 2.1 AA/AAA compliance
• prefers-reduced-motion support

7. Performance Optimization

• React Compiler automatic memoization
• Server Components for zero client JS
• Virtual scrolling for large lists
• Code splitting and lazy loading
• Streaming and Suspense

Component Patterns

Button Component (React 19 + Tailwind 4)

Copyimport { forwardRef, type ButtonHTMLAttributes } from 'react'
import { cva, type VariantProps } from 'class-variance-authority'
import { cn } from '@/lib/utils'

const buttonVariants = cva(
  'inline-flex items-center justify-center rounded-md font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 disabled:pointer-events-none disabled:opacity-50',
  {
    variants: {
      variant: {
        default: 'bg-primary text-primary-foreground hover:bg-primary/90',
        destructive: 'bg-destructive text-destructive-foreground hover:bg-destructive/90',
        outline: 'border border-input bg-background hover:bg-accent',
        secondary: 'bg-secondary text-secondary-foreground hover:bg-secondary/80',
        ghost: 'hover:bg-accent hover:text-accent-foreground',
        link: 'text-primary underline-offset-4 hover:underline',
      },
      size: {
        default: 'h-10 px-4 py-2',
        sm: 'h-9 rounded-md px-3',
        lg: 'h-11 rounded-md px-8',
        icon: 'h-10 w-10',
      },
    },
    defaultVariants: {
      variant: 'default',
      size: 'default',
    },
  }
)

interface ButtonProps
  extends ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof buttonVariants> {
  asChild?: boolean
}

const Button = forwardRef<HTMLButtonElement, ButtonProps>(
  ({ className, variant, size, ...props }, ref) => {
    return (
      <button
        ref={ref}
        className={cn(buttonVariants({ variant, size, className }))}
        {...props}
      />
    )
  }
)

Button.displayName = 'Button'
export { Button, buttonVariants }

Compound Component Pattern

Copyimport { createContext, useContext, useState, type ReactNode } from 'react'

interface TabsContextValue {
  activeTab: string
  setActiveTab: (tab: string) => void
}

const TabsContext = createContext<TabsContextValue | null>(null)

function useTabs() {
  const context = useContext(TabsContext)
  if (!context) throw new Error('Tabs components must be used within Tabs')
  return context
}

export function Tabs({ defaultValue, children }: { defaultValue: string; children: ReactNode }) {
  const [activeTab, setActiveTab] = useState(defaultValue)

  return (
    <TabsContext value={{ activeTab, setActiveTab }}>
      <div className="w-full">{children}</div>
    </TabsContext>
  )
}

export function TabsTrigger({ value, children }: { value: string; children: ReactNode }) {
  const { activeTab, setActiveTab } = useTabs()
  const isActive = activeTab === value

  return (
    <button
      role="tab"
      aria-selected={isActive}
      onClick={() => setActiveTab(value)}
      className={cn(
        'px-4 py-2 font-medium transition-colors',
        isActive ? 'border-b-2 border-primary text-primary' : 'text-muted-foreground'
      )}
    >
      {children}
    </button>
  )
}

export function TabsContent({ value, children }: { value: string; children: ReactNode }) {
  const { activeTab } = useTabs()
  if (activeTab !== value) return null
  return <div role="tabpanel" className="py-4">{children}</div>
}

Framework Conversion

React 19 to Svelte 5

Copy// REACT 19
function Counter() {
  const [count, setCount] = useState(0)
  const doubled = useMemo(() => count * 2, [count])
  return <button onClick={() => setCount(c => c + 1)}>{count}</button>
}

// SVELTE 5 (Runes)
<script lang="ts">
  let count = $state(0)
  let doubled = $derived(count * 2)
</script>

<button onclick={() => count++}>{count} ({doubled})</button>

React 19 to Vue 3.5

Copy// REACT 19
function Counter() {
  const [count, setCount] = useState(0)
  return <button onClick={() => setCount(c => c + 1)}>{count}</button>
}

// VUE 3.5
<script setup lang="ts">
import { ref } from 'vue'
const count = ref(0)
</script>

<template>
  <button @click="count++">{{ count }}</button>
</template>

Tailwind CSS 4.0 Configuration

Copy@import "tailwindcss";

@theme {
  --color-primary: oklch(0.7 0.15 250);
  --color-secondary: oklch(0.6 0.12 280);
  --font-sans: "Inter", system-ui, sans-serif;
  --radius-md: 0.5rem;
}

@media (prefers-color-scheme: dark) {
  @theme {
    --color-background: oklch(0.15 0.01 250);
    --color-foreground: oklch(0.95 0.01 250);
  }
}

Best Practices (2025)

Component Structure

Copycomponents/
  Button/
    Button.tsx           # Main component
    Button.types.ts      # Type definitions
    Button.test.tsx      # Vitest 4 tests
    Button.stories.tsx   # Storybook 9 stories
    index.ts             # Public exports

React 19 Best Practices

• Use React Compiler - no manual memoization needed
• Prefer Server Components when possible
• Use use API for data fetching in render
• Leverage Suspense for loading states
• Use useOptimistic for optimistic updates
• Use useFormStatus for form states

Performance Checklist

• Server Components for static content
• React Compiler enabled (auto-memoization)
• Lazy loading for heavy components
• Virtual scrolling for large lists

Accessibility Checklist

• Semantic HTML elements
• Keyboard navigation works
• ARIA attributes where needed
• WCAG AA color contrast (4.5:1)
• prefers-reduced-motion support

When to Use This Skill

Activate when you need to:

• Create new UI components
• Convert components between React/Vue/Svelte
• Implement advanced component patterns
• Add animations with Motion 12
• Optimize component performance
• Improve accessibility
• Build Server Components (Next.js 16)

Output Format

Provide:

1. Complete Component Code: Fully typed and production-ready
2. Usage Example: How to use the component
3. Props Documentation: All props with types
4. Accessibility Notes: Keyboard shortcuts and ARIA
5. Performance Tips: React Compiler, Server Components

Always follow React 19, Next.js 16, and TypeScript 5.9 conventions.