---
description: Accessibility guidelines for analytics charts and visualizations
globs:
  - "**/charts/**/*.tsx"
  - "**/analytics/**/*.tsx"
  - "**/dashboard/**/*.tsx"
  - "**/visualization/**/*.tsx"
alwaysApply: false
---

# Chart Accessibility Guidelines

Ensure analytics visualizations are accessible to all users.

## Color Contrast

### Don't Rely on Color Alone

```typescript
// ✅ Good - use patterns or labels in addition to color
dataLabels: {
  enabled: true,
  format: "{point.name}: {point.y}",
}

// ✅ Good - include values in legend
legend: {
  labelFormatter: function() {
    return `${this.name}: ${this.y}`;
  }
}
```

### Maintain Sufficient Contrast

```typescript
// ✅ Good - high contrast colors from design system
import { COLORS } from "@/lib/chart-constants";

// The COLORS palette is designed with WCAG AA contrast ratios
series: [{
  color: COLORS.greenPrimary, // Tested for contrast
}]
```

## Screen Reader Support

### Add Chart Descriptions

```typescript
// ✅ Good - describe the chart purpose
accessibility: {
  enabled: true,
  description: "Pie chart showing distribution of user intents: 45% Write Code, 28% Ask Questions, 17% Planning, 10% Automation",
}
```

### Provide Data Table Alternative

```tsx
// ✅ Good - offer table view for screen readers
<div role="region" aria-label="User activity chart">
  <HighchartsReact options={options} />
  <details className="sr-only">
    <summary>View as table</summary>
    <table>
      <caption>User Activity Data</caption>
      <thead>
        <tr>
          <th scope="col">Category</th>
          <th scope="col">Count</th>
        </tr>
      </thead>
      <tbody>
        {data.map(item => (
          <tr key={item.category}>
            <td>{item.category}</td>
            <td>{item.count}</td>
          </tr>
        ))}
      </tbody>
    </table>
  </details>
</div>
```

## Keyboard Navigation

### Enable Keyboard Support

```typescript
// ✅ Good - enable keyboard navigation
accessibility: {
  keyboardNavigation: {
    enabled: true,
  }
}
```

## Focus Indicators

### Ensure Visible Focus States

```typescript
// ✅ Good - visible focus on interactive elements
plotOptions: {
  series: {
    states: {
      hover: {
        enabled: true,
        brightness: 0.1,
      },
      select: {
        enabled: true,
        color: COLORS.bluePrimary,
      }
    }
  }
}
```

## Semantic Labels

### Use Descriptive Titles

```typescript
// ✅ Good - descriptive, not generic
title: {
  text: "Monthly Revenue by Product Category",
}

// ❌ Bad - vague title
title: {
  text: "Chart 1",
}
```

### Label Axes Clearly

```typescript
// ✅ Good - clear axis labels
xAxis: {
  title: {
    text: "Date",
  },
  accessibility: {
    description: "Dates from January to December 2024",
  }
},
yAxis: {
  title: {
    text: "Revenue (USD)",
  },
  accessibility: {
    description: "Revenue in US dollars, ranging from $0 to $100,000",
  }
}
```

## Animation Considerations

### Respect Reduced Motion Preferences

```typescript
// ✅ Good - disable animation for accessibility
chart: {
  animation: false,
},
plotOptions: {
  series: {
    animation: false,
  }
}

// Or detect user preference
const prefersReducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

chart: {
  animation: !prefersReducedMotion,
}
```

## Text Sizing

### Use Readable Font Sizes

```typescript
// ✅ Good - minimum 11px for labels
dataLabels: {
  style: {
    fontSize: "11px", // Minimum readable size
  }
},
legend: {
  itemStyle: {
    fontSize: "12px",
  }
}

// ❌ Bad - too small to read
dataLabels: {
  style: {
    fontSize: "8px",
  }
}
```

## Alternative Formats

### Offer Download Options

```tsx
// ✅ Good - allow data export
<ChartContainer>
  <HighchartsReact options={options} />
  <button
    onClick={() => downloadAsCSV(data)}
    aria-label="Download chart data as CSV file"
  >
    Download Data
  </button>
</ChartContainer>
```