Design System Architect

A design system is a single source of truth that brings consistency at scale.

Core Principle

Design systems are not just component libraries—they're the shared language between design and engineering. A good design system:

• Accelerates product development (reusable components)
• Ensures consistency across products (unified brand)
• Improves accessibility (baked into components)
• Enables scalability (compound growth, not linear)
• Reduces technical debt (centralized maintenance)

Goal: Build once, use everywhere. Maintain once, improve everywhere.

Phase 1: Design Tokens

What Are Design Tokens?

Design tokens are the atomic values of your design system. They're the smallest decisions (colors, spacing, typography) stored as data and consumed by all platforms.

Why Tokens Matter:

• Single source of truth (change once, update everywhere)
• Platform-agnostic (JSON → CSS, iOS, Android, etc.)
• Versioned and traceable (Git history for design decisions)
• Themeable (light/dark modes, brand variants)

Token Structure

// tokens/colors.json
{
  "color": {
    "brand": {
      "primary": {
        "50": { "value": "#eff6ff" },
        "100": { "value": "#dbeafe" },
        "200": { "value": "#bfdbfe" },
        "300": { "value": "#93c5fd" },
        "400": { "value": "#60a5fa" },
        "500": { "value": "#3b82f6" },
        "600": { "value": "#2563eb" },
        "700": { "value": "#1d4ed8" },
        "800": { "value": "#1e40af" },
        "900": { "value": "#1e3a8a" },
        "950": { "value": "#172554" }
      }
    },
    "semantic": {
      "background": {
        "primary": { "value": "{color.neutral.50}" },
        "secondary": { "value": "{color.neutral.100}" }
      },
      "text": {
        "primary": { "value": "{color.neutral.900}" },
        "secondary": { "value": "{color.neutral.600}" }
      },
      "feedback": {
        "success": { "value": "#10b981" },
        "warning": { "value": "#f59e0b" },
        "error": { "value": "#ef4444" },
        "info": { "value": "#3b82f6" }
      }
    }
  }
}

Token Categories

Primitive Tokens (Raw values):

{
  "color-blue-500": "#3b82f6",
  "space-4": "16px",
  "font-size-base": "16px"
}

Semantic Tokens (Named by purpose):

{
  "color-primary": "{color-blue-500}",
  "spacing-default": "{space-4}",
  "text-body": "{font-size-base}"
}

Component Tokens (Component-specific):

{
  "button-padding-x": "{spacing-default}",
  "button-background": "{color-primary}",
  "button-text": "{color-white}"
}

Token Architecture

tokens/
├── primitives/
│   ├── colors.json       # Raw color values
│   ├── spacing.json      # 4px, 8px, 16px...
│   ├── typography.json   # Font sizes, weights
│   ├── shadows.json      # Elevation system
│   └── radii.json        # Border radius values
├── semantic/
│   ├── colors.json       # background-primary, text-secondary
│   ├── spacing.json      # spacing-tight, spacing-comfortable
│   └── typography.json   # heading-xl, body-md
└── components/
    ├── button.json       # Button-specific tokens
    ├── input.json        # Input-specific tokens
    └── card.json         # Card-specific tokens

Token Transformation with Style Dictionary

Install Style Dictionary:

npm install --save-dev style-dictionary

config.json:

{
  "source": ["tokens/**/*.json"],
  "platforms": {
    "css": {
      "transformGroup": "css",
      "buildPath": "dist/css/",
      "files": [
        {
          "destination": "variables.css",
          "format": "css/variables"
        }
      ]
    },
    "js": {
      "transformGroup": "js",
      "buildPath": "dist/js/",
      "files": [
        {
          "destination": "tokens.js",
          "format": "javascript/es6"
        }
      ]
    }
  }
}

Build tokens:

npx style-dictionary build

Output (variables.css):

:root {
  --color-brand-primary-500: #3b82f6;
  --color-semantic-background-primary: #fafafa;
  --space-4: 16px;
  --font-size-base: 16px;
  --button-padding-x: 16px;
}

Dark Mode with Tokens

// tokens/semantic/colors-light.json
{
  "background": {
    "primary": { "value": "#ffffff" },
    "secondary": { "value": "#f9fafb" }
  },
  "text": {
    "primary": { "value": "#111827" },
    "secondary": { "value": "#6b7280" }
  }
}

// tokens/semantic/colors-dark.json
{
  "background": {
    "primary": { "value": "#111827" },
    "secondary": { "value": "#1f2937" }
  },
  "text": {
    "primary": { "value": "#f9fafb" },
    "secondary": { "value": "#d1d5db" }
  }
}

CSS Output:

:root {
  --background-primary: #ffffff;
  --text-primary: #111827;
}

[data-theme='dark'] {
  --background-primary: #111827;
  --text-primary: #f9fafb;
}

Phase 2: Component Architecture

Atomic Design Methodology

Atoms → Molecules → Organisms → Templates → Pages

atoms/
├── Button/
├── Input/
├── Label/
├── Icon/
└── Text/

molecules/
├── FormField/         # Label + Input + Error
├── SearchBar/         # Input + Icon + Button
└── Card/              # Container + Text + Button

organisms/
├── Header/            # Logo + Nav + SearchBar
├── LoginForm/         # FormFields + Button
└── ProductCard/       # Card + Image + Price + CTA

templates/
├── DashboardLayout/   # Header + Sidebar + Content
└── MarketingLayout/   # Header + Hero + Features + Footer

pages/
├── HomePage/          # MarketingLayout + specific content
└── DashboardPage/     # DashboardLayout + widgets

Component Structure

components/
└── Button/
    ├── Button.tsx           # Component implementation
    ├── Button.module.css    # Scoped styles
    ├── Button.stories.tsx   # Storybook stories
    ├── Button.test.tsx      # Unit tests
    ├── Button.types.ts      # TypeScript types
    ├── index.ts             # Public exports
    └── README.md            # Component docs

Button Component (Atomic Example)

Button.types.ts:

export type ButtonVariant = 'primary' | 'secondary' | 'tertiary' | 'danger'
export type ButtonSize = 'sm' | 'md' | 'lg'

export interface ButtonProps extends React.ButtonHTMLAttributes<HTMLButtonElement> {
  variant?: ButtonVariant
  size?: ButtonSize
  isLoading?: boolean
  leftIcon?: React.ReactNode
  rightIcon?: React.ReactNode
  fullWidth?: boolean
  children: React.ReactNode
}

Button.tsx:

import React from 'react'
import styles from './Button.module.css'
import { ButtonProps } from './Button.types'

export function Button({
  variant = 'primary',
  size = 'md',
  isLoading = false,
  leftIcon,
  rightIcon,
  fullWidth = false,
  disabled,
  children,
  className,
  ...props
}: ButtonProps) {
  const classes = [
    styles.button,
    styles[variant],
    styles[size],
    fullWidth && styles.fullWidth,
    isLoading && styles.loading,
    className
  ].filter(Boolean).join(' ')

  return (
    <button
      className={classes}
      disabled={disabled || isLoading}
      aria-busy={isLoading}
      {...props}
    >
      {leftIcon && <span className={styles.iconLeft}>{leftIcon}</span>}
      <span className={styles.content}>{children}</span>
      {rightIcon && <span className={styles.iconRight}>{rightIcon}</span>}
      {isLoading && (
        <span className={styles.spinner} aria-label="Loading">
          <svg className={styles.spinnerIcon} viewBox="0 0 24 24">
            <circle cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" fill="none" opacity="0.25" />
            <path d="M12 2a10 10 0 0 1 10 10" stroke="currentColor" strokeWidth="4" fill="none" strokeLinecap="round" />
          </svg>
        </span>
      )}
    </button>
  )
}

Button.module.css:

.button {
  /* Base */
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-base);
  font-weight: 500;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 150ms ease;
  user-select: none;

  /* Accessibility */
  outline-offset: 2px;
}

.button:focus-visible {
  outline: 2px solid var(--color-focus);
}

.button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* Variants */
.primary {
  background: var(--button-primary-background);
  color: var(--button-primary-text);
}

.primary:hover:not(:disabled) {
  background: var(--button-primary-background-hover);
}

.secondary {
  background: transparent;
  color: var(--button-secondary-text);
  border: 1px solid var(--button-secondary-border);
}

.secondary:hover:not(:disabled) {
  background: var(--button-secondary-background-hover);
}

.tertiary {
  background: transparent;
  color: var(--button-tertiary-text);
}

.tertiary:hover:not(:disabled) {
  background: var(--button-tertiary-background-hover);
}

.danger {
  background: var(--color-error);
  color: var(--color-white);
}

.danger:hover:not(:disabled) {
  background: var(--color-error-dark);
}

/* Sizes */
.sm {
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-sm);
  height: 32px;
}

.md {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-base);
  height: 40px;
}

.lg {
  padding: var(--space-3) var(--space-6);
  font-size: var(--text-lg);
  height: 48px;
}

/* Modifiers */
.fullWidth {
  width: 100%;
}

.loading {
  color: transparent;
}

.spinner {
  position: absolute;
  display: flex;
  align-items: center;
  justify-content: center;
  inset: 0;
}

.spinnerIcon {
  width: 20px;
  height: 20px;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.iconLeft,
.iconRight {
  display: flex;
  align-items: center;
}

.content {
  display: flex;
  align-items: center;
}

FormField Component (Molecule Example)

FormField.tsx:

import React from 'react'
import styles from './FormField.module.css'

interface FormFieldProps {
  label: string
  error?: string
  hint?: string
  required?: boolean
  children: React.ReactNode
}

export function FormField({
  label,
  error,
  hint,
  required = false,
  children
}: FormFieldProps) {
  const inputId = React.useId()
  const errorId = `${inputId}-error`
  const hintId = `${inputId}-hint`

  // Clone child to pass accessibility props
  const childWithProps = React.cloneElement(
    children as React.ReactElement,
    {
      id: inputId,
      'aria-invalid': !!error,
      'aria-describedby': [
        hint ? hintId : null,
        error ? errorId : null
      ].filter(Boolean).join(' ') || undefined
    }
  )

  return (
    <div className={styles.field}>
      <label htmlFor={inputId} className={styles.label}>
        {label}
        {required && (
          <span className={styles.required} aria-label="required">
            *
          </span>
        )}
      </label>

      {hint && (
        <div id={hintId} className={styles.hint}>
          {hint}
        </div>
      )}

      {childWithProps}

      {error && (
        <div id={errorId} className={styles.error} role="alert">
          {error}
        </div>
      )}
    </div>
  )
}

Component API Design Principles

1. Sensible Defaults:

// ✅ Good: Works with minimal props
<Button>Click me</Button>

// ✅ Good: Customizable when needed
<Button variant="secondary" size="lg" fullWidth>
  Click me
</Button>

2. Composition Over Configuration:

// ❌ Bad: Too many props
<Modal
  title="Delete Account"
  body="Are you sure?"
  confirmText="Delete"
  cancelText="Cancel"
  onConfirm={handleDelete}
  onCancel={handleCancel}
/>

// ✅ Good: Composable
<Modal>
  <Modal.Header>Delete Account</Modal.Header>
  <Modal.Body>Are you sure?</Modal.Body>
  <Modal.Footer>
    <Button variant="danger" onClick={handleDelete}>Delete</Button>
    <Button variant="secondary" onClick={handleCancel}>Cancel</Button>
  </Modal.Footer>
</Modal>

3. Controlled & Uncontrolled Modes:

// Uncontrolled (internal state)
<Input defaultValue="hello" />

// Controlled (external state)
<Input value={value} onChange={setValue} />

4. Polymorphic Components:

interface ButtonProps<T extends React.ElementType = 'button'> {
  as?: T
  // ... other props
}

// Render as button (default)
<Button onClick={handleClick}>Click</Button>

// Render as link
<Button as="a" href="/dashboard">Dashboard</Button>

// Render as Next.js Link
<Button as={Link} href="/about">About</Button>

Phase 3: Storybook Documentation

Storybook Setup

Install Storybook:

npx storybook@latest init

Button.stories.tsx:

import type { Meta, StoryObj } from '@storybook/react'
import { Button } from './Button'

const meta: Meta<typeof Button> = {
  title: 'Atoms/Button',
  component: Button,
  parameters: {
    layout: 'centered',
  },
  tags: ['autodocs'],
  argTypes: {
    variant: {
      control: 'select',
      options: ['primary', 'secondary', 'tertiary', 'danger'],
    },
    size: {
      control: 'select',
      options: ['sm', 'md', 'lg'],
    },
    isLoading: { control: 'boolean' },
    fullWidth: { control: 'boolean' },
    disabled: { control: 'boolean' },
  },
}

export default meta
type Story = StoryObj<typeof Button>

// Primary story
export const Primary: Story = {
  args: {
    variant: 'primary',
    children: 'Button',
  },
}

// All variants
export const AllVariants: Story = {
  render: () => (
    <div style={{ display: 'flex', gap: '1rem' }}>
      <Button variant="primary">Primary</Button>
      <Button variant="secondary">Secondary</Button>
      <Button variant="tertiary">Tertiary</Button>
      <Button variant="danger">Danger</Button>
    </div>
  ),
}

// All sizes
export const AllSizes: Story = {
  render: () => (
    <div style={{ display: 'flex', gap: '1rem', alignItems: 'center' }}>
      <Button size="sm">Small</Button>
      <Button size="md">Medium</Button>
      <Button size="lg">Large</Button>
    </div>
  ),
}

// With icons
export const WithIcons: Story = {
  render: () => (
    <div style={{ display: 'flex', gap: '1rem' }}>
      <Button leftIcon={<Icon name="plus" />}>Add Item</Button>
      <Button rightIcon={<Icon name="arrow-right" />}>Next</Button>
    </div>
  ),
}

// Loading state
export const Loading: Story = {
  args: {
    isLoading: true,
    children: 'Loading...',
  },
}

// Disabled state
export const Disabled: Story = {
  args: {
    disabled: true,
    children: 'Disabled',
  },
}

// Full width
export const FullWidth: Story = {
  args: {
    fullWidth: true,
    children: 'Full Width Button',
  },
}

MDX Documentation

Button.mdx:

````mdx import { Meta, Story, Canvas, Controls } from '@storybook/blocks' import * as ButtonStories from './Button.stories'

<Meta of={ButtonStories} />

Button

Buttons allow users to trigger actions and make choices with a single tap.

When to Use

• Primary actions (submit forms, complete workflows)
• Secondary actions (cancel, go back)
• Tertiary actions (view details, learn more)
• Dangerous actions (delete, remove)

Variants

<Canvas of={ButtonStories.AllVariants} />

Primary

Use for the main action on a page. Limit to one per screen.

Secondary

Use for less important actions. Can have multiple per screen.

Tertiary

Use for the least important actions, like "Learn more" links.

Danger

Use for destructive actions like deleting data.

Sizes

<Canvas of={ButtonStories.AllSizes} />

• Small: Dense UIs, table actions
• Medium: Default for most use cases
• Large: Hero CTAs, mobile-first designs

With Icons

<Canvas of={ButtonStories.WithIcons} />

Icons can clarify the button's purpose or indicate direction.

States

Loading

<Canvas of={ButtonStories.Loading} />

Show a loading spinner when an async action is in progress.

Disabled

<Canvas of={ButtonStories.Disabled} />

Disable buttons when an action is not currently available.

Accessibility

• ✅ Keyboard accessible (Tab, Enter/Space)
• ✅ Focus visible indicator
• ✅ ARIA attributes (aria-busy, aria-disabled)
• ✅ Loading state announced to screen readers

Props

<Controls />

Usage

import { Button } from '@/components/Button'

function MyComponent() {
  return (
    <Button variant="primary" onClick={handleClick}>
      Click me
    </Button>
  )
}

````

````

Storybook Addons

# Accessibility testing
npm install --save-dev @storybook/addon-a11y

# Component interactions
npm install --save-dev @storybook/addon-interactions

# Design tokens addon
npm install --save-dev storybook-addon-designs
````

**.storybook/main.ts:**

import type { StorybookConfig } from '@storybook/react-vite'

const config: StorybookConfig = { stories: ['../src/**/*.stories.@(js|jsx|ts|tsx|mdx)'], addons: [ '@storybook/addon-links', '@storybook/addon-essentials', '@storybook/addon-interactions', '@storybook/addon-a11y', 'storybook-addon-designs' ], framework: '@storybook/react-vite' }

export default config

---

## Phase 4: Theming & Customization

### CSS Variables Approach

**tokens.css:**

:root { / Primitives / --color-blue-500: #3b82f6; --color-red-500: #ef4444; --space-4: 16px;

/ Semantic (can be overridden) / --color-primary: var(--color-blue-500); --color-danger: var(--color-red-500); --spacing-default: var(--space-4);

/ Component tokens / --button-primary-background: var(--color-primary); --button-primary-text: white; --button-padding: var(--spacing-default); }

/ Theme override / [data-theme='brand-red'] { --color-primary: #dc2626; }

[data-theme='dark'] { --color-primary: #60a5fa; --button-primary-background: var(--color-primary); }

### Theme Provider (React)

**ThemeProvider.tsx:**

import React, { createContext, useContext, useEffect, useState } from 'react'

type Theme = 'light' | 'dark' | 'auto'

interface ThemeContextValue { theme: Theme setTheme: (theme: Theme) => void resolvedTheme: 'light' | 'dark' }

const ThemeContext = createContext<ThemeContextValue | undefined>(undefined)

export function ThemeProvider({ children }: { children: React.ReactNode }) { const [theme, setTheme] = useState<Theme>('auto') const [resolvedTheme, setResolvedTheme] = useState<'light' | 'dark'>('light')

useEffect(() => { // Load saved theme const saved = localStorage.getItem('theme') as Theme if (saved) setTheme(saved) }, [])

useEffect(() => { // Save theme localStorage.setItem('theme', theme)

// Resolve theme if (theme === 'auto') { const isDark = window.matchMedia('(prefers-color-scheme: dark)').matches setResolvedTheme(isDark ? 'dark' : 'light') } else { setResolvedTheme(theme) } }, [theme])

useEffect(() => { // Apply theme to DOM document.documentElement.setAttribute('data-theme', resolvedTheme) }, [resolvedTheme])

return ( <ThemeContext.Provider value={{ theme, setTheme, resolvedTheme }}> {children} </ThemeContext.Provider> ) }

export function useTheme() { const context = useContext(ThemeContext) if (!context) { throw new Error('useTheme must be used within ThemeProvider') } return context }

### Multi-Brand Theming

// themes/acme.ts export const acmeTheme = { colors: { primary: '#3b82f6', secondary: '#8b5cf6' }, typography: { fontFamily: 'Inter, sans-serif' }, spacing: { unit: 8 } }

// themes/contoso.ts export const contosoTheme = { colors: { primary: '#dc2626', secondary: '#f59e0b' }, typography: { fontFamily: 'Roboto, sans-serif' }, spacing: { unit: 4 } }

**Theme Application:**

function applyTheme(theme: Theme) { Object.entries(theme.colors).forEach(([key, value]) => { document.documentElement.style.setProperty(--color-${key}, value) })

document.documentElement.style.setProperty('--font-base', theme.typography.fontFamily)

document.documentElement.style.setProperty('--space-unit', ${theme.spacing.unit}px) }

---

## Phase 5: Versioning & Governance

### Semantic Versioning

**MAJOR.MINOR.PATCH**

- **MAJOR:** Breaking changes (v1.0.0 → v2.0.0)
  - Removed props
  - Changed prop types
  - Changed default behavior

- **MINOR:** New features, backwards-compatible (v1.0.0 → v1.1.0)
  - New props
  - New components
  - New variants

- **PATCH:** Bug fixes (v1.0.0 → v1.0.1)
  - CSS fixes
  - Accessibility improvements
  - TypeScript fixes

### Changelog

**CHANGELOG.md:**

````markdown
# Changelog

## [2.0.0] - 2024-01-15

### Breaking Changes

- **Button:** Renamed `type` prop to `variant`
- **Input:** Removed `error` prop (use FormField wrapper instead)

### Migration Guide

// Before <Button type="primary">Click</Button>

// After <Button variant="primary">Click</Button>

````

## [1.5.0] - 2024-01-10

### Added

- **Button:** New `isLoading` prop
- **Input:** New `leftIcon` and `rightIcon` props
- **Card:** New component

### Fixed

- **Button:** Focus outline now visible on all browsers
- **Input:** Placeholder color now meets WCAG contrast requirements

## [1.4.1] - 2024-01-05

### Fixed

- **Button:** Loading spinner now centered correctly
- **Modal:** Fixed backdrop z-index issue

````

### Component Lifecycle

**P0 (Must Have):**
- Button, Input, Label, Text, Icon
- FormField, Card, Modal

**P1 (Should Have):**
- Select, Checkbox, Radio, Switch, Textarea
- Tabs, Accordion, Dropdown, Tooltip

**P2 (Nice to Have):**
- DatePicker, Combobox, Slider, Toggle
- Toast, Drawer, Popover

**P3 (Future):**
- DataTable, Calendar, FileUpload
- Charts, Timeline, Stepper

### Deprecation Strategy

**1. Announce deprecation:**

/** @deprecated Use variant prop instead. Will be removed in v3.0.0. / export interface ButtonProps { type?: 'primary' | 'secondary' // Deprecated variant?: 'primary' | 'secondary' // New } ````

2. Support both (with warning):

export function Button({ type, variant, ...props }: ButtonProps) {
  if (type) {
    console.warn('Button: `type` prop is deprecated. Use `variant` instead.')
  }

  const finalVariant = variant || type || 'primary'
  // ...
}

3. Remove in next major version:

// v3.0.0 - type prop removed entirely
export interface ButtonProps {
  variant?: 'primary' | 'secondary'
}

Design System Governance

Design System Team:

• Owner: Overall vision and roadmap
• Designers: Visual design, UX patterns
• Engineers: Implementation, tooling
• Contributors: Product teams building components

Contribution Flow:

1. Proposal → GitHub issue
2. Design Review → Figma mockup
3. API Design → TypeScript interface
4. Implementation → PR with tests + stories
5. Documentation → README + Storybook
6. Release → Semantic versioning + changelog

Proposal Template:

````markdown

Component Name

Problem: What user need does this solve?

Usage: When should this be used?

API Proposal:

interface ComponentProps {
  // ...
}

````

Design Mockup: [Link to Figma]

Accessibility: How will this be accessible?

Alternatives Considered: What else did we explore?

````

Testing Design Systems

Visual Regression Testing

Chromatic (Storybook integration):

npm install --save-dev chromatic

# Run visual tests
npx chromatic --project-token=YOUR_TOKEN
````

**package.json:**

{ "scripts": { "chromatic": "chromatic --exit-zero-on-changes" } }

### Component Testing

import { render, screen } from '@testing-library/react' import userEvent from '@testing-library/user-event' import { Button } from './Button'

describe('Button', () => { it('renders children', () => { render(<Button>Click me</Button>) expect(screen.getByRole('button', { name: 'Click me' })).toBeInTheDocument() })

it('calls onClick when clicked', async () => { const user = userEvent.setup() const handleClick = jest.fn()

render(<Button onClick={handleClick}>Click me</Button>) await user.click(screen.getByRole('button'))

expect(handleClick).toHaveBeenCalledTimes(1) })

it('disables button when loading', () => { render(<Button isLoading>Click me</Button>) expect(screen.getByRole('button')).toBeDisabled() expect(screen.getByLabelText('Loading')).toBeInTheDocument() })

it('applies variant classes', () => { render(<Button variant="danger">Delete</Button>) expect(screen.getByRole('button')).toHaveClass('danger') }) })

### Accessibility Testing

import { axe, toHaveNoViolations } from 'jest-axe' expect.extend(toHaveNoViolations)

it('has no accessibility violations', async () => { const { container } = render(<Button>Click me</Button>) const results = await axe(container) expect(results).toHaveNoViolations() })

---

## Publishing & Distribution

### NPM Package Setup

**package.json:**

{ "name": "@company/design-system", "version": "1.0.0", "description": "Company design system", "main": "dist/index.js", "module": "dist/index.esm.js", "types": "dist/index.d.ts", "files": ["dist", "README.md"], "scripts": { "build": "rollup -c", "prepublishOnly": "npm run build" }, "peerDependencies": { "react": "^18.0.0", "react-dom": "^18.0.0" }, "publishConfig": { "access": "public" } }

**rollup.config.js:**

import typescript from '@rollup/plugin-typescript' import postcss from 'rollup-plugin-postcss'

export default { input: 'src/index.ts', output: [ { file: 'dist/index.js', format: 'cjs', sourcemap: true }, { file: 'dist/index.esm.js', format: 'esm', sourcemap: true } ], plugins: [ typescript({ tsconfig: './tsconfig.json' }), postcss({ modules: true, extract: 'styles.css' }) ], external: ['react', 'react-dom'] }

**Publish:**

npm login npm version patch # or minor, major npm publish

### Consumption

npm install @company/design-system

import { Button, Input, Card } from '@company/design-system' import '@company/design-system/dist/styles.css'

function App() { return ( <Card> <Input placeholder="Email" /> <Button variant="primary">Submit</Button> </Card> ) }

---

## Design System Checklist

### Foundation

- [ ] Design tokens (colors, spacing, typography, shadows, radii)
- [ ] Token transformation pipeline (Style Dictionary)
- [ ] Dark mode support
- [ ] Documentation site (Storybook)

### Components

- [ ] Atomic design structure (atoms → organisms)
- [ ] Component API guidelines (sensible defaults, composition)
- [ ] TypeScript types for all components
- [ ] CSS modules or styled-components
- [ ] Accessibility baked in (WCAG 2.1 AA)

### Documentation

- [ ] Storybook stories for all components
- [ ] MDX docs with usage examples
- [ ] Props table (auto-generated)
- [ ] Design guidelines (when to use, when not to use)
- [ ] Code examples

### Testing

- [ ] Unit tests (70%+ coverage)
- [ ] Accessibility tests (jest-axe)
- [ ] Visual regression tests (Chromatic)
- [ ] Manual testing checklist

### Governance

- [ ] Semantic versioning
- [ ] Changelog maintained
- [ ] Contribution guidelines
- [ ] Component lifecycle (P0 → P3)
- [ ] Deprecation strategy

### Distribution

- [ ] NPM package published
- [ ] Storybook deployed
- [ ] Installation guide
- [ ] Migration guides for breaking changes

---

## Tools & Resources

**Token Management:**

- Style Dictionary (token transformation)
- Figma Tokens (sync Figma → code)

**Component Development:**

- Storybook (documentation)
- Chromatic (visual testing)
- React + TypeScript

**Testing:**

- Jest + React Testing Library
- jest-axe (accessibility)
- Playwright (E2E)

**Build & Distribution:**

- Rollup or tsup (bundling)
- NPM (distribution)
- Changesets (versioning)

**Inspiration:**

- [Radix UI](https://www.radix-ui.com/) (accessible primitives)
- [Chakra UI](https://chakra-ui.com/) (themeable components)
- [Material UI](https://mui.com/) (comprehensive system)
- [Ant Design](https://ant.design/) (enterprise-grade)

---

## Related Skills

- `visual-designer` - Design foundations (color, typography, spacing)
- `accessibility-engineer` - WCAG compliance
- `frontend-builder` - React component patterns
- `testing-strategist` - Component testing strategies

---

**A design system is never done—it evolves with your product.** 🎨