shadcn

name	shadcn
purpose	準備する
description	Manages shadcn components and projects — adding, searching, fixing, debugging, styling, and composing UI, including chat interfaces. Provides project context, component docs, and usage examples. Applies when working with shadcn/ui, component registries, presets, --preset codes, or any project with a components.json file. Also triggers for 'shadcn init', 'create an app with --preset', or 'switch to --preset'.
user-invocable	false
allowed-tools	Bash(npx shadcn@latest *), Bash(pnpm dlx shadcn@latest *), Bash(bunx --bun shadcn@latest *)

前後工程

• 前工程: なし
• 後工程: なし
• 委譲先: なし

成果物

• 書き込む: なし
• 読み込む: components.json

shadcn/ui

A framework for building ui, components and design systems. Components are added as source code to the user's project via the CLI.

IMPORTANT: Run all CLI commands using the project's package runner: npx shadcn@latest, pnpm dlx shadcn@latest, or bunx --bun shadcn@latest — based on the project's packageManager. Examples below use npx shadcn@latest but substitute the correct runner for the project.

Current Project Context

!`npx shadcn@latest info --json`

The JSON above contains the project config and installed components. Use npx shadcn@latest docs <component> to get documentation and example URLs for any component.

Principles

1. Use existing components first. Use npx shadcn@latest search to check registries before writing custom UI. Check community registries too.
2. Compose, don't reinvent. Settings page = Tabs + Card + form controls. Dashboard = Sidebar + Card + Chart + Table.
3. Use built-in variants before custom styles. variant="outline", size="sm", etc.
4. Use semantic colors. bg-primary, text-muted-foreground — never raw values like bg-blue-500.

Critical Rules

These rules are always enforced. Each links to a file with Incorrect/Correct code pairs.

Styling & Tailwind → styling.md

• className for layout, not styling. Never override component colors or typography.
• No space-x-* or space-y-*. Use flex with gap-*. For vertical stacks, flex flex-col gap-*.
• Use size-* when width and height are equal. size-10 not w-10 h-10.
• Use truncate shorthand. Not overflow-hidden text-ellipsis whitespace-nowrap.
• No manual dark: color overrides. Use semantic tokens (bg-background, text-muted-foreground).
• Use cn() for conditional classes. Don't write manual template literal ternaries.
• No manual z-index on overlay components. Dialog, Sheet, Popover, etc. handle their own stacking.

Forms & Inputs → forms.md

• Forms use FieldGroup + Field. Never use raw div with space-y-* or grid gap-* for form layout.
• InputGroup uses InputGroupInput/InputGroupTextarea. Never raw Input/Textarea inside InputGroup.
• Buttons inside inputs use InputGroup + InputGroupAddon.
• Option sets (2–7 choices) use ToggleGroup. Don't loop Button with manual active state.
• FieldSet + FieldLegend for grouping related checkboxes/radios. Don't use a div with a heading.
• Field validation uses data-invalid + aria-invalid. data-invalid on Field, aria-invalid on the control. For disabled: data-disabled on Field, disabled on the control.

Component Structure → composition.md

• Items always inside their Group. SelectItem → SelectGroup. DropdownMenuItem → DropdownMenuGroup. CommandItem → CommandGroup.
• Use asChild (radix) or render (base) for custom triggers. Check base field from npx shadcn@latest info. → base-vs-radix.md
• Dialog, Sheet, and Drawer always need a Title. DialogTitle, SheetTitle, DrawerTitle required for accessibility. Use className="sr-only" if visually hidden.
• Use full Card composition. CardHeader/CardTitle/CardDescription/CardContent/CardFooter. Don't dump everything in CardContent.
• Button has no isPending/isLoading. Compose with Spinner + data-icon + disabled.
• TabsTrigger must be inside TabsList. Never render triggers directly in Tabs.
• Avatar always needs AvatarFallback. For when the image fails to load.

Use Components, Not Custom Markup → composition.md

• Use existing components before custom markup. Check if a component exists before writing a styled div.
• Callouts use Alert. Don't build custom styled divs.
• Empty states use Empty. Don't build custom empty state markup.
• Toast via sonner. Use toast() from sonner.
• Use Separator instead of <hr> or <div className="border-t">.
• Use Skeleton for loading placeholders. No custom animate-pulse divs.
• Use Badge instead of custom styled spans.

Icons → icons.md

• Icons in Button use data-icon. data-icon="inline-start" or data-icon="inline-end" on the icon.
• No sizing classes on icons inside components. Components handle icon sizing via CSS. No size-4 or w-4 h-4.
• Pass icons as objects, not string keys. icon={CheckIcon}, not a string lookup.

Chat & Messaging → chat.md

• Chat UI composes the chat primitives. Conversations use MessageScroller, rows use Message, surfaces use Bubble. Never hand-rolled bubble divs or a raw scroll container.
• MessageScroller owns scroll behavior. Streaming follow, anchoring, and jump-to-latest (MessageScrollerButton) are built in. Don't write a useStickToBottom/ResizeObserver hook.
• Attachments use Attachment; system notes and dividers use Marker. Not Item cards or Separator + a label.

CLI

• Never decode preset codes or build preset URLs manually. Use npx shadcn@latest preset decode <code>, preset url <code>, or preset open <code>. For project-aware preset detection, use npx shadcn@latest preset resolve.
• Apply preset codes directly with the CLI. Use npx shadcn@latest apply <code> for existing projects, or npx shadcn@latest init --preset <code> when initializing.

Key Patterns

These are the most common patterns that differentiate correct shadcn/ui code. For edge cases, see the linked rule files above.

// Form layout: FieldGroup + Field, not div + Label.
<FieldGroup>
  <Field>
    <FieldLabel htmlFor="email">Email</FieldLabel>
    <Input id="email" />
  </Field>
</FieldGroup>

// Validation: data-invalid on Field, aria-invalid on the control.
<Field data-invalid>
  <FieldLabel>Email</FieldLabel>
  <Input aria-invalid />
  <FieldDescription>Invalid email.</FieldDescription>
</Field>

// Icons in buttons: data-icon, no sizing classes.
<Button>
  <SearchIcon data-icon="inline-start" />
  Search
</Button>

// Spacing: gap-*, not space-y-*.
<div className="flex flex-col gap-4">  // correct
<div className="space-y-4">           // wrong

// Equal dimensions: size-*, not w-* h-*.
<Avatar className="size-10">   // correct
<Avatar className="w-10 h-10"> // wrong

// Status colors: Badge variants or semantic tokens, not raw colors.
<Badge variant="secondary">+20.1%</Badge>    // correct
<span className="text-emerald-600">+20.1%</span> // wrong

Component Selection

Need	Use
Button/action	Button with appropriate variant
Form inputs	Input, Select, Combobox, Switch, Checkbox, RadioGroup, Textarea, InputOTP, Slider
Toggle between 2–5 options	ToggleGroup + ToggleGroupItem
Data display	Table, Card, Badge, Avatar
Navigation	Sidebar, NavigationMenu, Breadcrumb, Tabs, Pagination
Overlays	Dialog (modal), Sheet (side panel), Drawer (bottom sheet), AlertDialog (confirmation)
Feedback	sonner (toast), Alert, Progress, Skeleton, Spinner
Command palette	Command inside Dialog
Charts	Chart (wraps Recharts)
Layout	Card, Separator, Resizable, ScrollArea, Accordion, Collapsible
Empty states	Empty
Menus	DropdownMenu, ContextMenu, Menubar
Tooltips/info	Tooltip, HoverCard, Popover
Chat / conversation UI	MessageScroller, , , ,

Key Fields

The injected project context contains these key fields:

• aliases → use the actual alias prefix for imports (e.g. @/, ~/), never hardcode.
• isRSC → when true, components using useState, useEffect, event handlers, or browser APIs need "use client" at the top of the file. Always reference this field when advising on the directive.
• tailwindVersion → "v4" uses @theme inline blocks; "v3" uses tailwind.config.js.
• tailwindCssFile → the global CSS file where custom CSS variables are defined. Always edit this file, never create a new one.
• style → component visual treatment (e.g. nova, vega).
• base → primitive library (radix or base). Affects component APIs and available props.
• iconLibrary → determines icon imports. Use lucide-react for lucide, @tabler/icons-react for tabler, etc. Never assume lucide-react.
• resolvedPaths → exact file-system destinations for components, utils, hooks, etc.
• framework → routing and file conventions (e.g. Next.js App Router vs Vite SPA).
• packageManager → use this for any non-shadcn dependency installs (e.g. pnpm add date-fns vs npm install date-fns).
• preset → resolved preset code and values for the current project. Use npx shadcn@latest preset resolve --json when you only need preset information.

See cli.md — info command for the full field reference.

Component Docs, Examples, and Usage

Run npx shadcn@latest docs <component> to get the URLs for a component's documentation, examples, and API reference. Fetch these URLs to get the actual content.

npx shadcn@latest docs button dialog select

When creating, fixing, debugging, or using a component, always run npx shadcn@latest docs and fetch the URLs first. This ensures you're working with the correct API and usage patterns rather than guessing.

Workflow

1. Get project context — already injected above. Run npx shadcn@latest info again if you need to refresh.
2. Check installed components first — before running add, always check the components list from project context or list the resolvedPaths.ui directory. Don't import components that haven't been added, and don't re-add ones already installed.
3. Find components — npx shadcn@latest search.
4. Get docs and examples — run npx shadcn@latest docs <component> to get URLs, then fetch them. Use npx shadcn@latest view to browse registry items you haven't installed. To preview changes to installed components, use npx shadcn@latest add --diff.
5. Install or update — npx shadcn@latest add. When updating existing components, use --dry-run and --diff to preview changes first (see Updating Components below).
6. Fix imports in third-party components — After adding components from community registries (e.g. @bundui, @magicui), check the added non-UI files for hardcoded import paths like @/components/ui/.... These won't match the project's actual aliases. Use npx shadcn@latest info to get the correct ui alias (e.g. @workspace/ui/components) and rewrite the imports accordingly. The CLI rewrites imports for its own UI files, but third-party registry components may use default paths that don't match the project.
7. Review added components — After adding a component or block from any registry, always read the added files and verify they are correct. Check for missing sub-components (e.g. SelectItem without SelectGroup), missing imports, incorrect composition, or violations of the Critical Rules. Also replace any icon imports with the project's iconLibrary from the project context (e.g. if the registry item uses lucide-react but the project uses hugeicons, swap the imports and icon names accordingly). Fix all issues before moving on.
8. Registry must be explicit — When the user asks to add a block or component, do not guess the registry. If no registry is specified (e.g. user says "add a login block" without specifying , , , etc.), ask which registry to use. Never default to a registry on behalf of the user.

Updating Components

When the user asks to update a component from upstream while keeping their local changes, use --dry-run and --diff to intelligently merge. NEVER fetch raw files from GitHub manually — always use the CLI.

1. Run npx shadcn@latest add <component> --dry-run to see all files that would be affected.
2. For each file, run npx shadcn@latest add <component> --diff <file> to see what changed upstream vs local.
3. Decide per file based on the diff:
   • No local changes → safe to overwrite.
   • Has local changes → read the local file, analyze the diff, and apply upstream updates while preserving local modifications.
   • User says "just update everything" → use --overwrite, but confirm first.
4. Never use --overwrite without the user's explicit approval.

Quick Reference

# Create a new project.
npx shadcn@latest init --name my-app --preset base-nova
npx shadcn@latest init --name my-app --preset a2r6bw --template vite

# Create a monorepo project.
npx shadcn@latest init --name my-app --preset base-nova --monorepo
npx shadcn@latest init --name my-app --preset base-nova --template next --monorepo

# Initialize existing project.
npx shadcn@latest init --preset base-nova
npx shadcn@latest init --defaults  # shortcut: --template=next --preset=nova (base style implied)

# Apply a preset to an existing project.
npx shadcn@latest apply a2r6bw
npx shadcn@latest apply a2r6bw --only theme
npx shadcn@latest apply a2r6bw --only font
npx shadcn@latest apply a2r6bw --only theme,font

# Inspect preset codes and project preset state.
npx shadcn@latest preset decode a2r6bw
npx shadcn@latest preset url a2r6bw
npx shadcn@latest preset open a2r6bw
npx shadcn@latest preset resolve
npx shadcn@latest preset resolve --json

# Add components.
npx shadcn@latest add button card dialog
npx shadcn@latest add @magicui/shimmer-button
npx shadcn@latest add owner/repo/item
npx shadcn@latest add --all

# Preview changes before adding/updating.
npx shadcn@latest add button --dry-run
npx shadcn@latest add button --diff button.tsx
npx shadcn@latest add @acme/form --view button.tsx
npx shadcn@latest add owner/repo/item --dry-run

# Search registries.
npx shadcn@latest search @shadcn -q "sidebar"
npx shadcn@latest search @tailark -q "stats"
npx shadcn@latest search owner/repo -q "login"
npx shadcn@latest search                          # all configured registries
npx shadcn@latest search @shadcn -q "menu" -t ui  # filter by item type

# Get component docs and example URLs.
npx shadcn@latest docs button dialog select

# View registry item details (for items not yet installed).
npx shadcn@latest view @shadcn/button
npx shadcn@latest view owner/repo/item

Named presets: nova, vega, maia, lyra, mira, luma Templates: next, vite, start, react-router, astro (all support --monorepo) and laravel (not supported for monorepo) Preset codes: Version-prefixed base62 strings (e.g. a2r6bw or b0), from ui.shadcn.com.

Detailed References

• rules/forms.md — FieldGroup, Field, InputGroup, ToggleGroup, FieldSet, validation states
• rules/composition.md — Groups, overlays, Card, Tabs, Avatar, Alert, Empty, Toast, Separator, Skeleton, Badge, Button loading
• rules/chat.md — MessageScroller, Message, Bubble, Attachment, Marker; streaming, anchoring, jump-to-latest
• rules/icons.md — data-icon, icon sizing, passing icons as objects
• rules/styling.md — Semantic colors, variants, className, spacing, size, truncate, dark mode, cn(), z-index
• rules/base-vs-radix.md — asChild vs render, Select, ToggleGroup, Slider, Accordion
• cli.md — Commands, flags, presets, templates
• registry.md — Authoring source registries, include, item definitions, dependencies, GitHub registry rules
• customization.md — Theming, CSS variables, extending components