Agent skill
shadcn-components
Add or customize shadcn/ui components in the shared UI package. Use when adding new components from shadcn registry or updating existing component variants.
Install this agent skill to your Project
npx add-skill https://github.com/delorenj/skills/tree/main/shadcn-components
SKILL.md
shadcn/ui Components Skill
This skill helps you work with shadcn/ui components in packages/ui/.
When to Use This Skill
- Adding new shadcn/ui components to the shared UI library
- Customizing existing shadcn/ui component variants
- Updating component styling with Tailwind
- Finding and implementing component examples
- Debugging shadcn/ui component issues
- Managing component dependencies
shadcn/ui Overview
shadcn/ui is a collection of re-usable components built with Radix UI and Tailwind CSS. Components are copied into your codebase, giving you full control.
packages/ui/
├── src/
│ ├── components/ # shadcn/ui components
│ │ ├── badge.tsx
│ │ ├── button.tsx
│ │ ├── card.tsx
│ │ ├── dialog.tsx
│ │ └── ...
│ ├── lib/
│ │ └── utils.ts # cn() utility for class merging
│ └── styles/
│ └── globals.css # Global styles
├── components.json # shadcn/ui configuration
└── package.json
Discovery and Research
Search for Components
// Use MCP tool to search for components
mcp__shadcn__search_items_in_registries({
registries: ["@shadcn"],
query: "button"
})
mcp__shadcn__search_items_in_registries({
registries: ["@shadcn"],
query: "form input"
})
View Component Details
// Get component implementation details
mcp__shadcn__view_items_in_registries({
items: ["@shadcn/button", "@shadcn/card"]
})
Get Component Examples
// Find usage examples
mcp__shadcn__get_item_examples_from_registries({
registries: ["@shadcn"],
query: "button demo"
})
mcp__shadcn__get_item_examples_from_registries({
registries: ["@shadcn"],
query: "form example"
})
Get Add Command
// Get CLI command to add components
mcp__shadcn__get_add_command_for_items({
items: ["@shadcn/button", "@shadcn/dialog"]
})
Adding New Components
Step 1: Search and Research
# Use MCP tools to find the component
# Example: Adding a dropdown menu component
mcp__shadcn__search_items_in_registries({
registries: ["@shadcn"],
query: "dropdown menu"
})
Step 2: Get Add Command
mcp__shadcn__get_add_command_for_items({
items: ["@shadcn/dropdown-menu"]
})
// Returns: npx shadcn@latest add dropdown-menu
Step 3: Add Component
# Navigate to packages/ui
cd packages/ui
# Add component using CLI
npx shadcn@latest add dropdown-menu
# Or add multiple components at once
npx shadcn@latest add dropdown-menu select tabs
Step 4: Export Component
Update packages/ui/src/index.ts:
export {
DropdownMenu,
DropdownMenuTrigger,
DropdownMenuContent,
DropdownMenuItem,
DropdownMenuCheckboxItem,
DropdownMenuRadioItem,
DropdownMenuLabel,
DropdownMenuSeparator,
DropdownMenuShortcut,
DropdownMenuGroup,
DropdownMenuPortal,
DropdownMenuSub,
DropdownMenuSubContent,
DropdownMenuSubTrigger,
DropdownMenuRadioGroup,
} from "./components/dropdown-menu";
Step 5: Use in App
// In apps/web or apps/api
import {
DropdownMenu,
DropdownMenuTrigger,
DropdownMenuContent,
DropdownMenuItem,
} from "@sgcarstrends/ui";
export function UserMenu() {
return (
<DropdownMenu>
<DropdownMenuTrigger>Open</DropdownMenuTrigger>
<DropdownMenuContent>
<DropdownMenuItem>Profile</DropdownMenuItem>
<DropdownMenuItem>Settings</DropdownMenuItem>
<DropdownMenuItem>Logout</DropdownMenuItem>
</DropdownMenuContent>
</DropdownMenu>
);
}
Core Components
Button Component
// packages/ui/src/components/button.tsx
import { Button } from "@sgcarstrends/ui";
// Variants
<Button variant="default">Default</Button>
<Button variant="destructive">Destructive</Button>
<Button variant="outline">Outline</Button>
<Button variant="secondary">Secondary</Button>
<Button variant="ghost">Ghost</Button>
<Button variant="link">Link</Button>
// Sizes
<Button size="default">Default</Button>
<Button size="sm">Small</Button>
<Button size="lg">Large</Button>
<Button size="icon">Icon</Button>
Card Component
import {
Card,
CardHeader,
CardFooter,
CardTitle,
CardDescription,
CardContent,
} from "@sgcarstrends/ui";
export function InfoCard() {
return (
<Card>
<CardHeader>
<CardTitle>Card Title</CardTitle>
<CardDescription>Card description goes here</CardDescription>
</CardHeader>
<CardContent>
<p>Card content</p>
</CardContent>
<CardFooter>
<p>Card footer</p>
</CardFooter>
</Card>
);
}
Dialog Component
import {
Dialog,
DialogContent,
DialogDescription,
DialogHeader,
DialogTitle,
DialogTrigger,
} from "@sgcarstrends/ui";
export function ConfirmDialog() {
return (
<Dialog>
<DialogTrigger asChild>
<Button variant="outline">Open Dialog</Button>
</DialogTrigger>
<DialogContent>
<DialogHeader>
<DialogTitle>Are you sure?</DialogTitle>
<DialogDescription>
This action cannot be undone.
</DialogDescription>
</DialogHeader>
<div className="flex justify-end gap-2">
<Button variant="outline">Cancel</Button>
<Button>Confirm</Button>
</div>
</DialogContent>
</Dialog>
);
}
Form Components
import { Label } from "@sgcarstrends/ui";
import { Input } from "@sgcarstrends/ui";
import { Textarea } from "@sgcarstrends/ui";
export function ContactForm() {
return (
<form className="space-y-4">
<div className="space-y-2">
<Label htmlFor="name">Name</Label>
<Input id="name" placeholder="Enter your name" />
</div>
<div className="space-y-2">
<Label htmlFor="message">Message</Label>
<Textarea id="message" placeholder="Enter your message" />
</div>
<Button type="submit">Submit</Button>
</form>
);
}
Badge Component
import { Badge } from "@sgcarstrends/ui";
export function StatusBadge({ status }: { status: string }) {
return (
<>
<Badge variant="default">Default</Badge>
<Badge variant="secondary">Secondary</Badge>
<Badge variant="destructive">Destructive</Badge>
<Badge variant="outline">Outline</Badge>
</>
);
}
Customization
Customizing Component Variants
Edit component file directly:
// packages/ui/src/components/button.tsx
const buttonVariants = cva(
"inline-flex items-center justify-center rounded-md text-sm font-medium",
{
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 hover:text-accent-foreground",
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",
// Add custom variant
success: "bg-green-500 text-white hover:bg-green-600",
},
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",
// Add custom size
xl: "h-14 rounded-md px-10 text-lg",
},
},
defaultVariants: {
variant: "default",
size: "default",
},
}
);
Creating Compound Components
// packages/ui/src/components/stat-card.tsx
import { Card, CardHeader, CardTitle, CardContent } from "./card";
import { cn } from "../lib/utils";
interface StatCardProps {
title: string;
value: string | number;
description?: string;
trend?: "up" | "down";
className?: string;
}
export function StatCard({
title,
value,
description,
trend,
className,
}: StatCardProps) {
return (
<Card className={cn("", className)}>
<CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
<CardTitle className="text-sm font-medium">{title}</CardTitle>
{trend && (
<span
className={cn(
"text-xs",
trend === "up" ? "text-green-500" : "text-red-500"
)}
>
{trend === "up" ? "↑" : "↓"}
</span>
)}
</CardHeader>
<CardContent>
<div className="text-2xl font-bold">{value}</div>
{description && (
<p className="text-xs text-muted-foreground">{description}</p>
)}
</CardContent>
</Card>
);
}
Export in packages/ui/src/index.ts:
export { StatCard } from "./components/stat-card";
Theming
Customizing Colors
Edit packages/ui/src/styles/globals.css:
@layer base {
:root {
--background: 0 0% 100%;
--foreground: 222.2 84% 4.9%;
--card: 0 0% 100%;
--card-foreground: 222.2 84% 4.9%;
--popover: 0 0% 100%;
--popover-foreground: 222.2 84% 4.9%;
--primary: 222.2 47.4% 11.2%;
--primary-foreground: 210 40% 98%;
--secondary: 210 40% 96.1%;
--secondary-foreground: 222.2 47.4% 11.2%;
--muted: 210 40% 96.1%;
--muted-foreground: 215.4 16.3% 46.9%;
--accent: 210 40% 96.1%;
--accent-foreground: 222.2 47.4% 11.2%;
--destructive: 0 84.2% 60.2%;
--destructive-foreground: 210 40% 98%;
--border: 214.3 31.8% 91.4%;
--input: 214.3 31.8% 91.4%;
--ring: 222.2 84% 4.9%;
--radius: 0.5rem;
}
.dark {
--background: 222.2 84% 4.9%;
--foreground: 210 40% 98%;
--card: 222.2 84% 4.9%;
--card-foreground: 210 40% 98%;
--popover: 222.2 84% 4.9%;
--popover-foreground: 210 40% 98%;
--primary: 210 40% 98%;
--primary-foreground: 222.2 47.4% 11.2%;
--secondary: 217.2 32.6% 17.5%;
--secondary-foreground: 210 40% 98%;
--muted: 217.2 32.6% 17.5%;
--muted-foreground: 215 20.2% 65.1%;
--accent: 217.2 32.6% 17.5%;
--accent-foreground: 210 40% 98%;
--destructive: 0 62.8% 30.6%;
--destructive-foreground: 210 40% 98%;
--border: 217.2 32.6% 17.5%;
--input: 217.2 32.6% 17.5%;
--ring: 212.7 26.8% 83.9%;
}
}
Component Configuration
components.json
{
"$schema": "https://ui.shadcn.com/schema.json",
"style": "default",
"rsc": true,
"tsx": true,
"tailwind": {
"config": "tailwind.config.ts",
"css": "src/styles/globals.css",
"baseColor": "slate",
"cssVariables": true
},
"aliases": {
"components": "@/components",
"utils": "@/lib/utils"
}
}
Utility Functions
cn() Utility
// packages/ui/src/lib/utils.ts
import { clsx, type ClassValue } from "clsx";
import { twMerge } from "tailwind-merge";
export function cn(...inputs: ClassValue[]) {
return twMerge(clsx(inputs));
}
Usage:
import { cn } from "@sgcarstrends/ui/lib/utils";
export function MyComponent({ className }: { className?: string }) {
return (
<div className={cn("base-classes", "conditional-classes", className)}>
Content
</div>
);
}
Testing Components
// packages/ui/src/components/__tests__/button.test.tsx
import { render, screen } from "@testing-library/react";
import { Button } from "../button";
describe("Button", () => {
it("renders correctly", () => {
render(<Button>Click me</Button>);
expect(screen.getByText("Click me")).toBeInTheDocument();
});
it("applies variant styles", () => {
render(<Button variant="destructive">Delete</Button>);
const button = screen.getByText("Delete");
expect(button).toHaveClass("bg-destructive");
});
it("handles click events", () => {
const handleClick = vi.fn();
render(<Button onClick={handleClick}>Click me</Button>);
screen.getByText("Click me").click();
expect(handleClick).toHaveBeenCalledOnce();
});
});
Run tests:
pnpm -F @sgcarstrends/ui test
Common Patterns
Responsive Components
import { Button } from "@sgcarstrends/ui";
export function ResponsiveButton() {
return (
<Button className="w-full md:w-auto">
Responsive Button
</Button>
);
}
Composition
import { Card, CardHeader, CardTitle, CardContent } from "@sgcarstrends/ui";
import { Button } from "@sgcarstrends/ui";
export function ActionCard({ title, children, onAction }: Props) {
return (
<Card>
<CardHeader>
<CardTitle>{title}</CardTitle>
</CardHeader>
<CardContent className="space-y-4">
{children}
<Button onClick={onAction} className="w-full">
Take Action
</Button>
</CardContent>
</Card>
);
}
Troubleshooting
Component Not Found
Problem: Import error when using component Solution:
- Check component is exported in
packages/ui/src/index.ts - Verify component file exists in
packages/ui/src/components/ - Run
pnpm installto update dependencies
Styling Issues
Problem: Tailwind classes not applying Solution:
- Check
packages/ui/tailwind.config.tsincludes correct content paths - Verify CSS variables are defined in
globals.css - Ensure parent app imports UI package's global CSS
TypeScript Errors
Problem: Type errors when using components Solution:
- Check component props are properly typed
- Run
pnpm buildin packages/ui - Restart TypeScript server in IDE
Updating Components
When shadcn/ui updates:
cd packages/ui
# Update specific component
npx shadcn@latest add button --overwrite
# Update multiple components
npx shadcn@latest add button card dialog --overwrite
References
- shadcn/ui Documentation: https://ui.shadcn.com
- Radix UI: https://www.radix-ui.com
- Related files:
packages/ui/src/components/- All UI componentspackages/ui/components.json- shadcn/ui configpackages/ui/CLAUDE.md- UI package documentation
Best Practices
- Use MCP Tools: Search before adding to avoid duplicates
- Export Components: Always export in index.ts
- Naming: Follow shadcn/ui naming conventions
- Testing: Write tests for custom variants
- Documentation: Document custom components
- Versioning: Keep shadcn/ui components updated
- Customization: Extend, don't modify core components
- Type Safety: Leverage TypeScript for props
- Size Utility: Use
size-*instead ofh-* w-*for equal dimensions (Tailwind v3.4+)
Size Utility Convention
When styling shadcn/ui components with equal height and width, use the size-* utility:
// ✅ Good - Use size-* for equal dimensions
<Button size="icon" className="size-10">
<Icon className="size-4" />
</Button>
<Avatar className="size-8">
<AvatarImage src={imageUrl} />
</Avatar>
// ❌ Avoid - Redundant h-* and w-*
<Button size="icon" className="h-10 w-10">
<Icon className="h-4 w-4" />
</Button>
<Avatar className="h-8 w-8">
<AvatarImage src={imageUrl} />
</Avatar>
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