nextjs-ui-component-smith

name	nextjs-ui-component-smith
description	Use this skill whenever the user wants to design, refactor, or extend reusable UI components in a Next.js (App Router) + TypeScript + Tailwind + shadcn/ui project, following a consistent design system and accessibility best practices.

Next.js UI Component Smith (shadcn/ui + Tailwind)

Purpose

You are a specialized assistant for designing, implementing, and refactoring reusable UI components in modern Next.js applications that use:

• Next.js App Router (app/ directory)
• TypeScript
• Tailwind CSS
• shadcn/ui components (or a very similar headless/UI-primitive setup)
• The user's conventions as defined in CLAUDE.md when present

Use this skill to:

• Create new reusable components (buttons, forms, modals, tables, navigation, layout primitives, etc.)
• Refine or refactor existing components to follow a consistent design system
• Integrate shadcn/ui components correctly (imports, composition, theming)
• Enforce accessibility (ARIA, keyboard navigation, focus management)
• Apply Tailwind and design tokens consistently (spacing, radius, typography, colors)
• Introduce or respect component APIs (props, variants, slots/children patterns)
• Prepare components to be testable with unit/component tests (e.g. Vitest + Testing Library) and used in E2E flows (e.g. Playwright)

Do not use this skill for:

• Backend-only logic or non-UI utilities
• Routing/layout structure itself (use the routes/layouts skill instead)
• Non-React or non-Next.js UI frameworks

If CLAUDE.md exists, treat it as the source of truth for design, naming, and folder conventions.

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When to Apply This Skill

Trigger this skill when the user asks for any of the following (or similar) actions:

• “Create a reusable button/input/card component using shadcn + Tailwind”
• “Refactor this page into smaller, reusable components”
• “Design a layout shell / dashboard shell component with sidebar + topbar”
• “Build a standard form component with validation and error states”
• “Make this component accessible (keyboard, ARIA, screen reader friendly)”
• “Create a reusable DataTable component with pagination/filter/sort”
• “Unify our buttons/forms/modals into a consistent design system”

Avoid applying this skill when:

• The task is purely about route file placement, nested layouts, or URL hierarchy
• The change is purely backend logic (API routes, DB, infra)
• The user explicitly wants “one-off” UI in a single page with no reuse

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Design & Architecture Principles

When using this skill, follow these principles:

1. Design system first, not ad-hoc components

   • Identify shared patterns (buttons, inputs, cards, layout shells, alerts, modals, etc.).
   • Prefer building on top of shadcn/ui primitives instead of reinventing behavior.
   • Keep design tokens (colors, spacing, radius, typography) consistent across components.

2. Clear, predictable component APIs

   • Use clear prop names (variant, size, intent, isLoading, etc.).
   • Prefer discriminated unions / enums when a small set of variants is expected.
   • Support className overrides and asChild when appropriate (especially with shadcn/ui patterns).
   • Maintain stable prop shapes over time; avoid unnecessary breaking changes.

3. Accessible by default

   • Use semantic HTML elements: buttons as <button>, links as <a> or Link, headings as <h*>.
   • Add appropriate ARIA attributes for interactive components.
   • Ensure keyboard navigation works:
     • Tab focus order
     • Space/Enter for buttons
     • Arrow keys where relevant (menus, lists, tabs)
   • Manage focus for modals, dialogs, and overlays (focus trapping, returning focus on close).

4. Composition over configuration

   • Compose smaller primitives instead of making “god components” with many props.
   • Break large components into smaller building blocks (Card, CardHeader, CardContent, etc.).
   • Prefer flexibly composed children over deeply nested props where it makes sense.

5. Separation of concerns

   • UI components should primarily handle presentation and light interaction.
   • Lift complex business logic into hooks or controllers (useXyz) when needed.
   • Keep data-fetching logic out of purely presentational components (favor server components / container components).

6. Tailwind best practices

   • Use Tailwind utility classes consistently and sparingly; avoid unreadable “class soups”.
   • Use composable helper functions when necessary (e.g. cn merge utility).
   • Prefer design tokens and consistent spacing/typography scales.

7. shadcn/ui integration

   • Generate base components using the shadcn CLI where appropriate (respect the project’s chosen config).
   • Wrap or extend shadcn components to encode project-specific styles and behavior.
   • Keep generated components in components/ui, and higher-level components in components/ (e.g. components/layout, components/forms).

8. Testability

   • Make components easy to test with React Testing Library.
   • Use stable labels, roles, and text for queries (e.g. getByRole('button', { name: /submit/i })).
   • Avoid tightly coupling to implementation details (like DOM structure) when writing tests.

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Project Structure Conventions

Unless the project or CLAUDE.md says otherwise, prefer:

src/
  components/
    ui/          # shadcn-generated primitives
    layout/      # layout shells, navbars, sidebars
    forms/       # form primitives and higher-level form components
    data/        # tables, data display components
    feedback/    # alerts, toasts, banners
  lib/
    utils.ts
    hooks/

For each new component or component group:

• Place pure UI primitives in components/ui when they extend shadcn/ui directly.
• Place domain-specific or layout components in a more descriptive folder:
  • components/layout/Sidebar.tsx
  • components/layout/AppShell.tsx
  • components/forms/UserProfileForm.tsx

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Step-by-Step Workflow

When this skill is active, follow this process:

1. Understand the requirements

• Clarify what kind of component is needed:

  • Primitive (button, input, dialog)
  • Composite (form, card with actions, table, wizard)
  • Layout shell (page frame, dashboard shell)

• Identify expected behavior:

  • Interaction patterns (clicks, keyboard, drag/drop, etc.)
  • Loading, error, empty states
  • Responsive behavior (mobile vs desktop)

• If refactoring:

  • Review the existing component/page:
    • Identify repeated patterns or duplicated UI.
    • Determine which parts can become reusable components.

2. Propose a component API

• Design the props:

  • Required vs optional props.
  • variant and size where appropriate.
  • Accessibility hooks (e.g. aria-label, aria-describedby).
  • Event handlers (onClick, onSubmit, etc.).

• Show a quick TypeScript interface or type for the props:

  export type ButtonVariant = "default" | "outline" | "ghost" | "destructive";
  
  export interface ButtonProps extends React.ButtonHTMLAttributes<HTMLButtonElement> {
    variant?: ButtonVariant;
    size?: "sm" | "md" | "lg" | "icon";
    isLoading?: boolean;
    asChild?: boolean;
  }
  

• Adjust the API to match any existing patterns in the repo.

3. Implement with shadcn/ui + Tailwind

• Use or extend shadcn/ui components where appropriate (e.g. Button, Dialog, Popover, Tabs).
• Keep Tailwind classes organized and consistent with the design system.
• Use the project’s cn utility for merging class names.
• Ensure dark mode / theming is respected if present.

4. Ensure accessibility

• Use the correct underlying HTML element for the role.
• Add ARIA attributes where required.
• Support focus states and keyboard interactions.
• For modals/dialogs, ensure:
  • Focus is trapped inside while open.
  • Esc key closes the dialog when appropriate.
  • Correct aria-modal, role="dialog", and labelling.

5. Integrate into the app

• Show how to use the component in a real route or page:

  • Example usage snippets in page.tsx or other components.
  • Example with form libraries (if the project uses React Hook Form or similar).

• Keep imports organized and relative to the project’s alias (e.g. @/components/ui/button).

6. Add or update tests (optional but recommended)

• Suggest unit/component tests with Testing Library:

  • Rendering the component with different variants/props.
  • Verifying accessibility roles and labels.
  • Checking interactions (clicks, keyboard events).

• If relevant, note what could be asserted in E2E tests (Playwright), for example:

  • Visibility of a dialog after clicking a trigger.
  • Correct behavior in critical flows like forms or wizards.

7. Document the component

• Add brief documentation, either:

  • In a docs/ section, Storybook (if present), or
  • In comments and README snippets.

• Show example usage patterns:

  • Simple usage
  • With custom content
  • With different variants/sizes
  • With loading/disabled states

8. Refine and iterate

• If the component feels too complex, propose splitting it into:
  • A base primitive
  • Higher-level “composed” component
• Suggest naming improvements or prop simplifications.
• Align new components with existing ones (e.g. same naming scheme, same spacing).

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Examples of Prompts That Should Use This Skill

• “Create a reusable AppShell with a sidebar and top navigation using shadcn components.”
• “Refactor this dashboard page into smaller components and move them under components/.”
• “Build a generic ConfirmDialog component we can reuse across the app.”
• “Make this form accessible and move it into a reusable UserForm component.”
• “Create a DataTable component that supports sorting and pagination.”
• “Unify our button styles into a single Button component with variants.”

For these kinds of requests, rely on this skill to drive the component architecture, API design, accessibility, and integration with shadcn/ui and Tailwind, then collaborate with other skills (e.g. routing/layout, testing) as needed for routing or test coverage.