Design System Architecture

Design System Architecture

Purpose

Design a token-based design system architecture, including primitive → semantic → component token hierarchy, theming strategy (dark/light mode), and cross-platform implementation plan.

Inputs

• Existing styling approach (Tailwind, CSS modules, styled-components, etc.)
• Target platforms (web, iOS, Android, cross-platform)
• Brand guidelines or existing color palette
• Current component inventory
• Theming requirements (dark mode, high contrast, brand variations)

Process

Step 1: Audit Current State

Review the existing styling approach:

• How are colors, spacing, and typography defined today?
• Are there hardcoded values scattered across components?
• Is there an existing design system or component library?
• What CSS methodology is used (utility-first, BEM, CSS-in-JS)?

Step 2: Define Primitive Tokens

Establish the raw values that form the foundation:

• Color primitives: Named palette (blue-50 through blue-900, gray scale, semantic colors)
• Spacing scale: 4px base unit → 0, 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64
• Type scale: Size ramp with corresponding line heights and letter spacing
• Border radius: Small (4px), medium (8px), large (16px), full (9999px)
• Shadow/elevation: Subtle, medium, prominent
• Duration: Fast (100ms), normal (200ms), slow (300ms)

Step 3: Define Semantic Tokens

Map primitives to semantic meaning:

• Surface: surface-primary, surface-secondary, surface-elevated
• Text: text-primary, text-secondary, text-muted, text-inverse
• Border: border-default, border-strong, border-focus
• Interactive: interactive-primary, interactive-hover, interactive-pressed
• Status: status-success, status-warning, status-error, status-info
• Spacing: space-xs, space-sm, space-md, space-lg, space-xl

Step 4: Define Component Tokens

Map semantic tokens to component-specific values:

• Button: button-bg, button-text, button-border, button-radius
• Input: input-bg, input-border, input-focus-ring, input-text
• Card: card-bg, card-border, card-shadow, card-radius, card-padding

Step 5: Design Theme Architecture

Define how themes override token values:

• Light theme: Default token assignments
• Dark theme: Which semantic tokens change, which stay the same
• High contrast: Increased border widths, higher contrast ratios
• Implementation: CSS custom properties, Tailwind config, or platform-specific theming

Step 6: Cross-Platform Strategy

If multiple platforms:

• Token format: Use Style Dictionary or similar to generate platform-specific output
• Web: CSS custom properties or Tailwind theme config
• iOS: Swift color/spacing constants or asset catalogs
• Android: XML resources or Compose theme
• Shared source of truth: JSON or YAML token definitions

Output Format

# Design System Architecture

## Token Hierarchy

### Primitive Tokens
| Category | Token | Value |
|----------|-------|-------|
| Color | blue-500 | #3B82F6 |
| Spacing | space-4 | 16px |
| Type | text-base | 16px/24px |

### Semantic Tokens
| Token | Light | Dark | Usage |
|-------|-------|------|-------|
| surface-primary | white | gray-900 | Main background |
| text-primary | gray-900 | gray-50 | Body text |
| interactive-primary | blue-500 | blue-400 | Buttons, links |

### Component Tokens
| Component | Token | Maps To |
|-----------|-------|---------|
| Button (primary) | button-bg | interactive-primary |
| Button (primary) | button-text | text-inverse |

## Theme Switching
[Implementation approach — CSS class, media query, user preference]

## File Structure

tokens/ primitives.json semantic-light.json semantic-dark.json components.json

## Migration Plan
[Steps to migrate from current approach to token-based system]

Quality Checks

• All existing hardcoded values can be mapped to tokens
• Semantic tokens cover all current UI needs without gaps
• Dark mode token overrides maintain WCAG AA contrast
• Token naming is consistent and predictable
• The migration path doesn't require a big-bang rewrite
• Cross-platform strategy has a single source of truth

Evolution Notes

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