---
description: Highcharts chart patterns and best practices for analytics visualizations
globs:
  - "**/charts/**/*.tsx"
  - "**/charts/**/*.ts"
  - "**/analytics/**/*.tsx"
  - "**/dashboard/**/*.tsx"
  - "**/visualization/**/*.tsx"
alwaysApply: false
---

# Highcharts Best Practices

When building analytics charts with Highcharts, follow these patterns for consistency and quality.

## Chart Configuration

### Always Use Transparent Backgrounds

```typescript
// ✅ Good - inherits page/card background
chart: {
  backgroundColor: "transparent",
}

// ❌ Bad - hardcoded background
chart: {
  backgroundColor: "#ffffff",
}
```

### Disable Animation in Production

```typescript
// ✅ Good - better performance
chart: {
  animation: false,
},
plotOptions: {
  series: {
    animation: false,
  },
}
```

### Disable Credits

```typescript
// ✅ Good - always disable Highcharts branding
credits: { enabled: false }
```

## Color Usage

### Use Design System Colors

```typescript
import { COLORS, COLOR_ARRAY } from "@/lib/chart-constants";

// ✅ Good - use predefined palette
series: [{
  color: COLORS.greenPrimary,
}]

// ✅ Good - auto-assign from array
plotOptions: {
  bar: {
    colorByPoint: true,
    colors: COLOR_ARRAY,
  }
}

// ❌ Bad - hardcoded arbitrary colors
series: [{
  color: "#ff0000",
}]
```

### Use Semantic Colors for Meaningful Data

```typescript
import { COMPLEXITY_COLORS, INTENT_COLORS } from "@/lib/chart-constants";

// ✅ Good - complexity data uses semantic colors
const color = COMPLEXITY_COLORS[dataItem.complexity] || COLORS.neutralPrimary;

// ❌ Bad - arbitrary colors for semantic data
const color = COLOR_ARRAY[index];
```

## Styling

### Use CSS Variables for Theme Support

```typescript
// ✅ Good - supports light/dark themes
style: {
  color: "var(--color-theme-text-secondary)",
}

// ❌ Bad - hardcoded colors break themes
style: {
  color: "#666666",
}
```

### Use Shared Style Constants

```typescript
import { CHART_STYLES, COMMON_CHART_OPTIONS } from "@/lib/chart-constants";

// ✅ Good - consistent styling
xAxis: {
  labels: {
    style: CHART_STYLES.text.tertiary,
  },
},
yAxis: COMMON_CHART_OPTIONS.yAxis("Count"),
tooltip: COMMON_CHART_OPTIONS.tooltip,
```

## Data Handling

### Filter Low-Percentage Outliers

```typescript
import { filterLowPercentage } from "@/lib/data-utils";

// ✅ Good - remove noise from LLM classification data
const filteredData = filterLowPercentage(data, 1); // Remove items under 1%
```

### Limit Categories for Readability

```typescript
// ✅ Good - limit to top N categories
const topCategories = sortedData.slice(0, 7);
const otherCount = sortedData.slice(7).reduce((sum, d) => sum + d.count, 0);
if (otherCount > 0) {
  topCategories.push({ category: "Other", count: otherCount });
}

// ❌ Bad - show all 50 categories
const allCategories = sortedData; // Creates unreadable chart
```

### Sort Data Appropriately

```typescript
// ✅ Good - sort by value for rankings
const sorted = [...data].sort((a, b) => b.count - a.count);

// ✅ Good - sort chronologically for time series
const sorted = [...data].sort((a, b) => new Date(a.date) - new Date(b.date));
```

## Pie Charts

### Use Donut Style with Inner Size

```typescript
plotOptions: {
  pie: {
    innerSize: "50%", // Creates donut effect
    borderWidth: 2,
    borderColor: "var(--color-theme-bg)",
  }
}
```

### Limit to 7 Categories Maximum

If you have more than 7 categories, aggregate smaller ones into "Other" or switch to a bar chart.

## Bar Charts

### Use Horizontal Bars for Long Labels

```typescript
// ✅ Good for long category names
chart: {
  type: "bar", // Horizontal bars
}

// Consider vertical column only for short labels
chart: {
  type: "column", // Vertical bars
}
```

### Calculate Dynamic Height

```typescript
// ✅ Good - height scales with data
chart: {
  height: Math.max(300, data.length * 28),
}
```

## Time Series Charts

### Use Stacked Area for Composition Over Time

```typescript
plotOptions: {
  area: {
    stacking: "normal",
    lineWidth: 1,
    lineColor: "transparent",
    marker: { enabled: false },
  }
}
```

### Format Date Labels Consistently

```typescript
import { formatDateLabel } from "@/lib/data-utils";

xAxis: {
  categories: dates.map(formatDateLabel), // "Dec 8", "Dec 9", etc.
}
```

## Tooltips

### Use Shared Tooltips for Multi-Series Charts

```typescript
tooltip: {
  ...COMMON_CHART_OPTIONS.tooltip,
  shared: true,
}
```

### Show Percentages in Tooltips

```typescript
tooltip: {
  pointFormat: "{series.name}: <b>{point.y} ({point.percentage:.1f}%)</b>",
}
```

## Accessibility

### Provide Meaningful Descriptions

```typescript
accessibility: {
  description: "Bar chart showing user activity by category over the past 30 days",
}
```

## Empty States

### Always Handle No Data

```typescript
if (!data || data.length === 0) {
  return (
    <Card>
      <DashboardEmptyState
        title="No Data Available"
        description="No data found for the selected date range."
      />
    </Card>
  );
}
```