# Proposal: Design System & Component Library

Status: approved
Authors: Design Team, Accessibility Team
Owners: Design Lead, Accessibility Lead, Mobile Lead, Web Lead
Created: 2025-11-17
Scope: spec
Related: openspec/specs/architecture.md, openspec/specs/accessibility.md

Summary
- Build a unified design system and component library for Android, iOS, and Web that ensures platform parity, accessibility (WCAG 2.2 AA+), and consistent brand identity.

Motivation
- Accelerate feature development with reusable, accessible components.
- Ensure consistent UX and visual language across all platforms.
- Embed accessibility best practices at the component level.
- Support theming for future customization (light/dark mode, high contrast).

Goals / Non-Goals
- Goals: component library (buttons, inputs, cards, modals, navigation), design tokens (colors, typography, spacing), accessibility built-in, platform adapters, documentation/Storybook, versioning.
- Non-Goals: final brand identity (can be iterated); advanced animations (keep simple initially); custom illustrations (use placeholders).

User Stories
- As a developer, I can import pre-built, accessible components to build features quickly.
- As a user with low vision, I can enable high contrast mode and components adapt automatically.
- As a user, I experience consistent visual design whether I'm on mobile or web.
- As a designer, I have a single source of truth for design tokens and component specs.

Requirements

Functional
- Core components: Button, Input (text, email, password, textarea), Checkbox, Radio, Select/Dropdown, Card, Modal/Dialog, Toast/Snackbar, Tabs, Accordion, Navigation (app bar, bottom nav, sidebar), List (virtualized), Avatar, Badge, Chip/Tag, Spinner/Loading, Progress bar, Form (validation helpers), Link.
- Platform implementations: React Native components (mobile), Next.js/React components (web), with shared design tokens.
- Theming: light mode (default), dark mode, high contrast mode.
- Design tokens: colors (primary, secondary, background, text, error, success, etc.), typography (font families, sizes, weights, line heights), spacing (4px grid), border radius, shadows.

Accessibility (WCAG 2.2 AA+)
- All components support:
  - Keyboard navigation (tab order, focus indicators, enter/space activation).
  - Screen reader labels (accessible names, roles, states).
  - Color contrast: minimum 4.5:1 for text, 3:1 for UI components.
  - Dynamic type: components scale with user font size preferences.
  - Reduced motion: animations respect `prefers-reduced-motion`.
  - Touch targets: minimum 44x44pt (mobile), 44x44px (web).
- High contrast mode: boost contrast ratios to 7:1+.
- Focus management: modals trap focus, dismissible with Esc, return focus on close.

Design Tokens

Colors
- Primary: `#3B82F6` (blue, adjust for brand)
- Secondary: `#8B5CF6` (purple)
- Background: `#FFFFFF` (light), `#1F2937` (dark)
- Text: `#111827` (light mode), `#F9FAFB` (dark mode)
- Error: `#EF4444`
- Success: `#10B981`
- Warning: `#F59E0B`
- Border: `#D1D5DB` (light), `#4B5563` (dark)

Typography
- Font family: system fonts (SF Pro for iOS, Roboto for Android, Inter/system-ui for web)
- Font sizes: 12px, 14px, 16px (base), 18px, 20px, 24px, 32px, 48px
- Font weights: 400 (normal), 600 (semibold), 700 (bold)
- Line heights: 1.5 (body), 1.25 (headings)

Spacing
- Base unit: 4px
- Scale: 0 (0px), 1 (4px), 2 (8px), 3 (12px), 4 (16px), 5 (20px), 6 (24px), 8 (32px), 10 (40px), 12 (48px), 16 (64px), 20 (80px)

Border Radius
- sm: 4px
- md: 8px
- lg: 12px
- full: 9999px (pills/circles)

Shadows
- sm: `0 1px 2px rgba(0,0,0,0.05)`
- md: `0 4px 6px rgba(0,0,0,0.1)`
- lg: `0 10px 15px rgba(0,0,0,0.15)`

Component Specifications

Button
- Variants: primary, secondary, ghost, danger
- Sizes: sm, md, lg
- States: default, hover, active, disabled, loading
- Accessibility: role="button", aria-label if icon-only, keyboard enter/space, focus ring
- Touch target: min 44x44

Input
- Types: text, email, password, textarea, number
- States: default, focus, error, disabled
- Accessibility: label (visible or aria-label), aria-describedby for errors, role="textbox" for textarea
- Validation: inline error messages with icon, clear error state styling

Card
- Variants: elevated (shadow), outlined (border), flat
- Structure: header (optional), body, footer (optional)
- Accessibility: semantic sectioning (article/section), focus ring if interactive

Modal
- Structure: overlay (backdrop), dialog container, close button
- Accessibility: role="dialog", aria-modal="true", trap focus, Esc to close, return focus on close, aria-labelledby for title
- Animations: respect prefers-reduced-motion

Navigation
- Mobile: bottom tab bar, app bar (top), drawer (side)
- Web: top nav, sidebar (collapsible), breadcrumbs
- Accessibility: role="navigation", aria-current for active route, keyboard nav (arrow keys for tabs)

Platform-Specific Considerations
- iOS: use SF Symbols for icons, native haptics for interactions, iOS navigation patterns (back swipe).
- Android: use Material icons, ripple effects, Android navigation patterns (drawer, bottom nav).
- Web: use accessible HTML (semantic tags), focus-visible CSS, responsive breakpoints.

Observability & Telemetry
- Component usage analytics (opt-in): track which components are most used to prioritize improvements.
- Accessibility metrics: track high contrast mode adoption, screen reader usage (if detectable).

Test Plan
- Unit tests: component prop variations, state changes, event handlers.
- Accessibility tests:
  - Automated: axe (web), react-native-a11y linters (mobile).
  - Manual: VoiceOver (iOS), TalkBack (Android), NVDA/JAWS (web), keyboard-only nav.
- Visual regression: screenshot tests for all component variants (light/dark/high contrast).
- Cross-platform parity: ensure components look consistent on Android, iOS, Web.

Migration / Rollout Plan
- Phase 1: Design tokens + core components (Button, Input, Card, Modal).
- Phase 2: Navigation, Form helpers, List.
- Phase 3: Advanced components (Tabs, Accordion, etc.).
- Versioning: semantic versioning (1.0.0), changelog for breaking changes.
- Migration guide for existing components (if any from early development).

Risks & Mitigations
- Platform drift → enforce design review for all component changes; automated visual regression tests.
- Accessibility regressions → CI gates for a11y linters; manual audits per release.
- Over-engineering → start with MVP components; add complexity only when needed.

Alternatives Considered
- Custom vs existing design system (Material, Chakra, Ant Design) → choosing custom for brand control and accessibility customization, but borrowing patterns from established systems.
- Shared components vs platform-specific → choosing shared design tokens with platform-specific implementations for best native UX.

Work Breakdown
1. Define design tokens (colors, typography, spacing) in config files
2. Build core components: Button, Input, Card, Modal
3. Platform adapters: React Native (mobile), Next.js/React (web)
4. Accessibility audit and fixes
5. Documentation: Storybook (web), example app (mobile)
6. Visual regression test setup
7. Versioning and release process
8. Design review and feedback iteration
9. Theming implementation (light/dark/high contrast)
10. Rollout to first feature (e.g., Forum MVP)

Acceptance Criteria
- Core components implemented and documented.
- All components pass WCAG 2.2 AA automated checks (axe).
- Manual accessibility audit completed with VoiceOver, TalkBack, NVDA.
- Visual regression tests passing for all variants.
- Design tokens consistent across mobile and web.
- Documentation (Storybook/example app) published.
- At least one feature (e.g., Forum MVP) uses design system components.

Open Questions
- Final brand colors and logo (can use placeholders initially)?
- Icon library choice (SF Symbols for iOS, Material for Android, custom SVG for web)?
- Animation library (Framer Motion for web, Reanimated for mobile)?

Slash Commands
- `/review areas=mobile,web,accessibility,design`
- `/apply spec=openspec/specs/architecture.md`
- `/archive link=<PR>`