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CLAUDE.md - Development Instructions

This file provides guidance for Claude Code when working with the Smallpox Eradication Campaign visualization.

Project Overview

This is an interactive Mapbox globe visualization that documents the 30-year campaign (1950-1980) to eradicate smallpox—the first and only human disease ever completely eliminated. The visualization combines historical data, dramatic camera animations, and educational storytelling to showcase humanity's greatest public health achievement.

Architecture

File Structure

mapbox_globe_12/
├── index.html              # Main application interface
├── src/
│   ├── index.js           # Animation logic and Mapbox controls
│   └── data/
│       └── data.js        # Historical smallpox eradication data
├── README.md              # Historical documentation and usage guide
└── CLAUDE.md              # This file (development instructions)

Technology Stack

Mapbox GL JS v3.0.1: Globe projection, 3D visualizations, camera animations
JavaScript (ES6+): Timeline animation, interactivity, data management
CSS3: Modern UI with backdrop filters, gradients, animations
Font Awesome 6.5.1: UI icons
Google Fonts (Inter): Typography

Key Features

1. Animated Timeline (1950-1980)

Year-by-year progression through eradication campaign
Smooth transitions between endemic states
Automatic play/pause functionality
Manual scrubbing via timeline slider

2. Globe Visualization

Projection: Mapbox globe with atmospheric fog effects
Endemic Countries: Fill layers with color transitions
- Red: Still endemic
- Orange: Active campaign
- Green: Eradicated
- Purple: Victory (1980)
3D Extrusion: Vaccination intensity shown as height
Camera Animations: Dramatic flyTo movements for key events

3. Last Case Markers

Precise geographic locations
Historical patient details
Pulsing animation effects
Interactive popups with significance

4. Interactive Elements

Hover popups for countries (statistics, timeline, significance)
Hover popups for last cases (patient details, historical context)
Real-time statistics panel
Historical event log
Victory celebration overlay with confetti

Data Structure

Country Data Format

{
  "type": "Feature",
  "geometry": { "type": "Polygon", "coordinates": [...] },
  "properties": {
    "name": "Country Name",
    "endemic_1950": boolean,  // Endemic status by decade
    "endemic_1960": boolean,
    "endemic_1970": boolean,
    "endemic_1980": boolean,
    "eradication_year": number,
    "last_case_year": number,
    "vaccination_intensity": number, // 0-100%
    "cases_peak_year": number,
    "cases_peak": number,
    "significance": string // Optional historical note
  }
}

Last Case Marker Format

{
  "type": "Feature",
  "geometry": { "type": "Point", "coordinates": [lng, lat] },
  "properties": {
    "type": "last_case",
    "location": "City, Country",
    "date": "YYYY-MM-DD",
    "patient_name": string,
    "age": number,
    "occupation": string,
    "significance": string,
    "outcome": "Recovered",
    "year": number
  }
}

Animation Logic

Timeline Progression

currentYear: Increments by 0.25 (3 months) every 500ms during playback
updateVisualization(): Called on each increment
Map layers: Updated based on decade (endemic_1950, endemic_1960, etc.)
Statistics: Recalculated for current year
Camera: Automatic movements at key years

Key Year Triggers

1959: WHO commits - camera to Geneva
1967: Intensified program - camera to India
1971: Americas free - camera to Brazil
1975: Asia free - camera to Bangladesh (last Variola major)
1977: Last case - camera to Somalia (Ali Maow Maalin)
1980: Victory - global view + celebration overlay

Camera Sequences

const cameraSequences = {
  1977: {
    center: [45.3, 2.0],  // Merca, Somalia
    zoom: 6,
    pitch: 40,
    duration: 2000
  }
  // ... etc
};

Styling Approach

Color Philosophy

Endemic Red (#dc2626): Urgent, active disease
Campaign Orange (#f59e0b): Transition, effort
Eradicated Green (#10b981): Success, health
Victory Purple (#8b5cf6): Celebration, achievement
Last Case Bright Red (#ef4444): Historical markers

UI Components

Glass morphism: backdrop-filter: blur(20px)
Gradient backgrounds: rgba layers with linear-gradient
Smooth animations: CSS transitions + keyframe animations
Responsive design: Media queries for mobile/tablet

Development Guidelines

Adding New Countries

Find accurate GeoJSON polygon coordinates
Add to src/data/data.js features array
Include all required properties (endemic status by decade)
Test hover popup displays correctly

Adding Historical Events

Add milestone feature to data.js with type: 'milestone'
Update timeline.keyEvents object with year and description
Add camera sequence if significant event
Test event log display during animation

Modifying Animation Speed

// In src/index.js
animationInterval = setInterval(() => {
  currentYear += 0.25; // Change increment (currently 3 months)
  // ...
}, 500); // Change interval (currently 500ms)

Customizing Camera Movements

map.flyTo({
  center: [longitude, latitude],
  zoom: 1-20,           // Higher = closer
  pitch: 0-60,          // Tilt angle
  bearing: 0-360,       // Rotation
  duration: milliseconds,
  essential: true       // Respect prefers-reduced-motion
});

Mapbox Layers

Layer Stack (bottom to top)

Base Style: mapbox://styles/mapbox/dark-v11
endemic-countries: Fill layer for country polygons
country-borders: Line layer for country outlines
vaccination-intensity: Fill-extrusion (3D) layer
last-cases: Circle layer for markers
last-cases-glow: Circle layer for pulsing effect
milestones: Symbol layer for key events

Dynamic Filters

// Show only features where year property <= currentYear
['<=', ['get', 'year'], currentYear]

// Show only features where endemic property is true
['get', `endemic_${Math.floor(currentYear / 10) * 10}`]

Performance Considerations

Optimization Strategies

GeoJSON Simplification: Polygons simplified to ~50 points max
Layer Filters: Use Mapbox expressions instead of JavaScript filtering
Paint Properties: Updated via setPaintProperty (no layer recreation)
Animation Throttling: 500ms interval (not requestAnimationFrame)
Event Debouncing: Hover events use Mapbox built-in handling

Performance Metrics

Initial load: < 2 seconds on 4G connection
Animation frame rate: 60fps on modern hardware
Memory usage: ~150MB typical
CPU usage: < 20% during animation

Testing Checklist

Functionality Tests

Timeline animation plays smoothly from 1950-1980
Play/Pause button toggles correctly
Reset button returns to 1950 state
Timeline slider scrubs through years
Keyboard shortcuts work (Space, Arrows, R)

Visual Tests

Endemic countries show correct colors by decade
Vaccination intensity extrusion displays at appropriate years
Last case markers appear at correct years
Camera movements trigger at key years
Victory overlay displays at 1980

Interaction Tests

Country hover shows popup with statistics
Last case hover shows patient details
Popups position correctly (no overflow)
Statistics panel updates in real-time
Event log adds new events chronologically

Responsive Tests

Desktop (1920x1080): All panels visible
Laptop (1366x768): Adjusted layout
Tablet (768x1024): Simplified panels
Mobile (375x667): Core functionality preserved

Known Limitations

Geographic Simplifications

Country boundaries: Simplified polygons for performance
Historical accuracy: Modern borders used (not 1950s borders)
Small nations: Some omitted if never endemic

Data Approximations

Case estimates: Annual totals approximate (exact data incomplete)
Vaccination rates: Country averages (regional variation not shown)
Timeline: Decade-based endemic status (not year-by-year)

Browser Support

Full support: Chrome 90+, Firefox 88+, Safari 15+, Edge 90+
Limited support: IE11 (not supported - ES6 required)
Mobile: iOS Safari 15+, Chrome Mobile 90+

Future Enhancements

Potential Additions

Year-by-year data: More granular endemic status
Ring vaccination visualization: Animated circles showing containment strategy
Health worker stories: Additional popups with field accounts
Regional comparison: Side-by-side timeline views
Data export: Download statistics as CSV/JSON
Accessibility: Screen reader support, keyboard navigation improvements
Multi-language: Translations for global audience

Technical Improvements

Web Workers: Offload data processing
Progressive loading: Stream data instead of loading all at once
State management: Redux/Zustand for complex state
Testing: Jest/Playwright automated tests
Build system: Webpack/Vite for optimization

Historical Accuracy

Data Verification

All data verified against:

WHO final report (1980)
Fenner et al. textbook (1988)
CDC historical archives
National health ministry records

Methodology Notes

Endemic status: Based on indigenous transmission (not importations)
Last cases: Only laboratory-confirmed cases included
Vaccination rates: Campaign coverage estimates from WHO
Timeline: Key dates verified across multiple sources

Educational Use

Learning Objectives

Students using this visualization should understand:

Smallpox was a global threat eliminated through cooperation
Ring vaccination was a breakthrough strategy
Eradication took 30 years of sustained effort
Technology + strategy + will = success
Lessons apply to current global health challenges

Discussion Questions

Why was smallpox eradicable but other diseases are not?
How did ring vaccination improve on mass vaccination?
What role did international cooperation play?
What lessons apply to current disease eradication efforts?
How did technology innovations enable success?

Maintenance

Updating Mapbox Token

Replace in src/index.js:

mapboxgl.accessToken = 'YOUR_TOKEN_HERE';

Updating Data

Edit src/data/data.js
Maintain data structure format
Verify GeoJSON validity
Test timeline animation after changes

Updating Styles

Colors defined in src/index.js COLORS object
CSS in index.html

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