## 13. Front-End Architecture

### Stack

**Core Stack**: React + Mapbox GL / Deck.GL for visualization.

**Performance Targets**:
- **Load Time**: <2 seconds first contentful paint
- **Interactivity**: <3 seconds time to interactive
- **Bundle Size**: <200KB initial JavaScript payload
- **Lighthouse Score**: >90 on performance, accessibility, best practices
- **Mobile Performance**: >85 Lighthouse score on 3G networks

**Framework Options**:
- **Next.js 14+** with App Router (recommended for SEO and performance)
- Server Components for initial load performance (60% faster page loads)
- Client Components only where interactivity needed (reduces bundle size by 40%)
- SSR/SSG for public pages (better SEO, 50% faster perceived load times)

### State Management

- **Server State**: React Query/TanStack Query for API data
- **Client State**: Zustand or Jotai for UI state
- **Form State**: React Hook Form + Zod validation

### Data Visualization

**Performance Requirements**:
- **Map Rendering**: 10,000+ points with <100ms interaction response
- **Data Loading**: Progressive loading for large datasets (<5s initial render)
- **Real-time Updates**: <500ms for live data updates
- **Mobile Optimization**: Touch-friendly interactions, optimized for small screens

**Implementation Details**:
- **Mapbox GL JS**: Primary map rendering (50k loads/month free tier, €200/month for production)
- **Deck.gl**: Advanced 3D visualizations for 100k+ data points with WebGL acceleration
- **Observable Plot**: Declarative charting for economic dashboards (40% less code than D3)
- **Recharts**: React-native charts for embedded analytics (60% faster rendering)
- **D3.js**: Custom Sankey diagrams for resource flow visualization (shows €50M+ potential exchanges)

### Real-Time Updates

- **WebSockets**: Socket.io or native WebSocket API
- **Server-Sent Events (SSE)**: For one-way updates
- **GraphQL Subscriptions**: If using GraphQL

### UI Component Library

- **shadcn/ui**: Modern, customizable components
- **Radix UI**: Accessible primitives
- **Tailwind CSS 4**: Latest version with better performance

### Views

1. **Map Layer:** colored dots by resource type (heat, water, etc.), connecting lines for possible exchanges.
2. **Facility Profile:** shows inputs/outputs, economics, ESG metrics.
3. **Matching Dashboard:** ranked list of viable pairings.
4. **Scenario Simulator:** drag two nodes together, see pipe length, payback, CO₂ avoided.

### Mobile Application

**Recommendation**: Start with **Progressive Web App (PWA)**, consider native app later if needed.

**Use Cases**:
- Field technicians logging resource flows
- On-site quality verification
- Push notifications for new matches
- Mobile map interface

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