UI First Builder

Create beautiful, functional UI immediately. No questions. No waiting.

<core_principle>

The First-Prompt Promise

User describes idea → User sees working UI → Same prompt, no follow-up needed

This is what makes Lovable magical. We replicate it here. </core_principle>

<default_to_action> NEVER ask:

• "How many pages do you want?" → Infer from description, start with essential pages
• "What color scheme?" → Read root DESIGN.md (the design contract); if absent, trigger design identity generation first (design-craft two-pass → DESIGN-TEMPLATE.md). The identity file is how we decide without asking — distinctive per project.
• "What features do you need?" → Infer standard features for this app type
• "Should it be responsive?" → ALWAYS responsive, mobile-first

ALWAYS do:

• Create complete, working pages
• Include realistic mock data (based on language setting in CLAUDE.md)
• Add hover states and transitions
• Make it look professional immediately </default_to_action>

<component_architecture>

File Structure (Next.js 16 App Router)

src/
├── app/
│   ├── layout.tsx        # Root layout with providers
│   ├── page.tsx          # Home/Dashboard
│   ├── globals.css       # Tailwind + custom styles
│   └── [feature]/
│       └── page.tsx      # Feature pages
├── components/
│   ├── ui/               # shadcn/ui components
│   ├── layout/           # Header, Sidebar, Footer
│   ├── features/         # Feature-specific components
│   └── shared/           # Reusable components
├── lib/
│   ├── utils.ts          # cn() helper
│   └── mock-data.ts      # Realistic mock data
├── stores/               # Zustand stores
└── types/                # TypeScript types

</component_architecture>

<shadcn_components>

shadcn/ui Components to Use

Always Available (assume installed)

• Button, Card, Input, Label, Textarea
• Dialog, Sheet, Dropdown Menu, Popover
• Table, Tabs, Avatar, Badge, Separator
• Select, Checkbox, Radio Group, Switch
• Toast (sonner), Calendar, Date Picker
• Command (for search), Skeleton (loading)

Usage Pattern

import { Button } from "@/components/ui/button"
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card"
import { Input } from "@/components/ui/input"

DO NOT use components that don't exist

• No custom components pretending to be shadcn
• Stick to official shadcn/ui component list </shadcn_components>

<mock_data_rules>

Mock Data Guidelines

Mock data language depends on project language setting in CLAUDE.md.

✅ GOOD Mock Data (English - Default)

const mockUsers = [
  { id: 1, name: "John Smith", email: "john@company.com", role: "Admin" },
  { id: 2, name: "Sarah Johnson", email: "sarah@company.com", role: "User" },
  { id: 3, name: "Michael Davis", email: "michael@company.com", role: "Editor" },
]

const mockProducts = [
  { id: 1, name: "House Blend Drip Coffee", price: 4.50, stock: 45 },
  { id: 2, name: "Matcha Green Tea Latte", price: 5.25, stock: 32 },
  { id: 3, name: "Hot Chocolate", price: 3.75, stock: 28 },
]

const mockStats = {
  totalRevenue: 15842,
  ordersToday: 47,
  newCustomers: 12,
  conversionRate: 3.2,
}

❌ BAD Mock Data (Lazy/Obvious)

// NEVER DO THIS
const users = [
  { name: "Test User", email: "test@test.com" },
  { name: "User 1", email: "user1@email.com" },
]

const products = [
  { name: "Product A", price: 100 },
  { name: "Lorem Ipsum", price: 999 },
]

Mock Data Location

Always create: src/lib/mock-data.ts Export typed data for components to import </mock_data_rules>

<styling_rules>

Styling Guidelines

Color Philosophy

• Source of truth: root DESIGN.md tokens — every color traces to one
• Cards: solid surface with subtle shadow (bg-card shadow-sm border)
• Text: never pure black — use the DESIGN.md text token
• Accent: ONE brand accent from DESIGN.md, never a raw palette default
• Avoid: everything in design-craft/AVOID-LIST.md (gradients-by-default, neon, glassmorphism)

Spacing System

• Page padding: p-4 md:p-6 lg:p-8
• Card padding: p-4 md:p-6
• Component gap: gap-4 or gap-6
• Section margin: mb-6 or mb-8

Typography

• Headings: text-2xl font-semibold (page title), text-lg font-medium (section)
• Body: text-sm or text-base
• Muted: text-slate-500 or text-muted-foreground
• NO Inter everywhere - use system font stack (already in Tailwind)

Responsive Pattern

// Mobile-first, always
<div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-4 gap-4">
  {/* Cards */}
</div>

<div className="flex flex-col md:flex-row gap-4">
  {/* Layout items */}
</div>

</styling_rules>

<page_templates>

Common Page Patterns

Dashboard Page

export default function DashboardPage() {
  return (
    <div className="p-4 md:p-6 space-y-6">
      {/* Stats Row */}
      <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-4 gap-4">
        <StatCard title="Today's Revenue" value="$12,450" change="+12%" />
        <StatCard title="Orders" value="47" change="+5%" />
        {/* ... */}
      </div>

      {/* Main Content */}
      <div className="grid grid-cols-1 lg:grid-cols-3 gap-6">
        <Card className="lg:col-span-2">
          {/* Chart or Table */}
        </Card>
        <Card>
          {/* Recent Activity */}
        </Card>
      </div>
    </div>
  )
}

List/Table Page

export default function ListPage() {
  return (
    <div className="p-4 md:p-6 space-y-4">
      {/* Header with Search + Add Button */}
      <div className="flex flex-col md:flex-row md:items-center justify-between gap-4">
        <h1 className="text-2xl font-semibold">Products</h1>
        <div className="flex gap-2">
          <Input placeholder="Search..." className="w-full md:w-64" />
          <Button>Add Product</Button>
        </div>
      </div>

      {/* Table */}
      <Card>
        <Table>
          {/* ... */}
        </Table>
      </Card>
    </div>
  )
}

Form Page

export default function FormPage() {
  return (
    <div className="p-4 md:p-6 max-w-2xl mx-auto">
      <Card>
        <CardHeader>
          <CardTitle>Add New Product</CardTitle>
        </CardHeader>
        <CardContent>
          <form className="space-y-4">
            {/* Form fields */}
            <div className="flex justify-end gap-2">
              <Button variant="outline">Cancel</Button>
              <Button>Save</Button>
            </div>
          </form>
        </CardContent>
      </Card>
    </div>
  )
}

</page_templates>

<interaction_states>

Always Include These States

Loading State

// Use Skeleton from shadcn
<Skeleton className="h-4 w-full" />
<Skeleton className="h-32 w-full" />

Empty State

<div className="flex flex-col items-center justify-center py-12 text-center">
  <Package className="h-12 w-12 text-slate-300 mb-4" />
  <h3 className="text-lg font-medium">No items yet</h3>
  <p className="text-slate-500 mb-4">Start by creating your first item</p>
  <Button>Add New Item</Button>
</div>

Hover/Active States

// Cards
<Card className="hover:shadow-md transition-shadow cursor-pointer">

// List items
<div className="hover:bg-slate-50 transition-colors">

// Buttons already have states from shadcn

</interaction_states>

<output_checklist>

Before Completing, Verify:

• All pages render without errors
• Mock data looks realistic (per language setting)
• Responsive design works (mobile → desktop)
• All buttons have hover states
• No "Lorem ipsum" or "Test" placeholder text
• shadcn/ui components used correctly
• TypeScript types defined for all data
• File structure follows convention
• npm run dev will work immediately </output_checklist>

<anti_patterns>

What NOT To Build

❌ Don't Create

• Complex nested routing before basic pages work
• Custom design system (use shadcn)
• Authentication flow before main UI
• API routes before UI exists
• Database schema before seeing UI needs

❌ Don't Style

• Gradient backgrounds on light mode
• Neon/bright accent colors
• Pure black (#000) text
• Inconsistent spacing
• Different fonts per section

❌ Don't Assume

• User has specific components installed (ask shadcn to add)
• Complex state management needed first
• User wants to see architecture diagram
• User needs explanation before seeing UI </anti_patterns>