temetro/.agents/skills/ai-elements/references/context.md

Context

A compound component system for displaying AI model context window usage, token consumption, and cost estimation.

The Context component provides a comprehensive view of AI model usage through a compound component system. It displays context window utilization, token consumption breakdown (input, output, reasoning, cache), and cost estimation in an interactive hover card interface.

See scripts/context.tsx for this example.

Installation

npx ai-elements@latest add context

Features

• Compound Component Architecture: Flexible composition of context display elements
• Visual Progress Indicator: Circular SVG progress ring showing context usage percentage
• Token Breakdown: Detailed view of input, output, reasoning, and cached tokens
• Cost Estimation: Real-time cost calculation using the tokenlens library
• Intelligent Formatting: Automatic token count formatting (K, M, B suffixes)
• Interactive Hover Card: Detailed information revealed on hover
• Context Provider Pattern: Clean data flow through React Context API
• TypeScript Support: Full type definitions for all components
• Accessible Design: Proper ARIA labels and semantic HTML
• Theme Integration: Uses currentColor for automatic theme adaptation

Props

<Context />

Prop	Type	Default	Description
maxTokens	number	-	The total context window size in tokens.
usedTokens	number	-	The number of tokens currently used.
usage	LanguageModelUsage	-	Detailed token usage breakdown from the AI SDK (input, output, reasoning, cached tokens).
modelId	ModelId	-	Model identifier for cost calculation (e.g.,
...props	ComponentProps<HoverCard>	-	Any other props are spread to the HoverCard component.

<ContextTrigger />

Prop	Type	Default	Description
children	React.ReactNode	-	Custom trigger element. If not provided, renders a default button with percentage and icon.
...props	ComponentProps<Button>	-	Props spread to the default button element.

<ContextContent />

Prop	Type	Default	Description
className	string	-	Additional CSS classes for the hover card content.
...props	ComponentProps<HoverCardContent>	-	Props spread to the HoverCardContent component.

<ContextContentHeader />

Prop	Type	Default	Description
children	React.ReactNode	-	Custom header content. If not provided, renders percentage and token count with progress bar.
...props	ComponentProps<div>	-	Props spread to the header div element.

<ContextContentBody />

Prop	Type	Default	Description
children	React.ReactNode	-	Body content, typically containing usage breakdown components.
...props	ComponentProps<div>	-	Props spread to the body div element.

<ContextContentFooter />

Prop	Type	Default	Description
children	React.ReactNode	-	Custom footer content. If not provided, renders total cost when modelId is provided.
...props	ComponentProps<div>	-	Props spread to the footer div element.

Usage Components

All usage components (ContextInputUsage, ContextOutputUsage, ContextReasoningUsage, ContextCacheUsage) share the same props:

Prop	Type	Default	Description
children	React.ReactNode	-	Custom content. If not provided, renders token count and cost for the respective usage type.
className	string	-	Additional CSS classes.
...props	ComponentProps<div>	-	Props spread to the div element.

Component Architecture

The Context component uses a compound component pattern with React Context for data sharing:

1. <Context> - Root provider component that holds all context data
2. <ContextTrigger> - Interactive trigger element (default: button with percentage)
3. <ContextContent> - Hover card content container
4. <ContextContentHeader> - Header section with progress visualization
5. <ContextContentBody> - Body section for usage breakdowns
6. <ContextContentFooter> - Footer section for total cost
7. Usage Components - Individual token usage displays (Input, Output, Reasoning, Cache)

Token Formatting

The component uses Intl.NumberFormat with compact notation for automatic formatting:

• Under 1,000: Shows exact count (e.g., "842")
• 1,000+: Shows with K suffix (e.g., "32K")
• 1,000,000+: Shows with M suffix (e.g., "1.5M")
• 1,000,000,000+: Shows with B suffix (e.g., "2.1B")

Cost Calculation

When a modelId is provided, the component automatically calculates costs using the tokenlens library:

• Input tokens: Cost based on model's input pricing
• Output tokens: Cost based on model's output pricing
• Reasoning tokens: Special pricing for reasoning-capable models
• Cached tokens: Reduced pricing for cached input tokens
• Total cost: Sum of all token type costs

Costs are formatted using Intl.NumberFormat with USD currency.

Styling

The component uses Tailwind CSS classes and follows your design system:

• Progress indicator uses currentColor for theme adaptation
• Hover card has customizable width and padding
• Footer has a secondary background for visual separation
• All text sizes use the text-xs class for consistency
• Muted foreground colors for secondary information