# Context Picker

> A bare token-driven context window size picker — a radiogroup of six options (4K, 16K, 32K, 128K, 256K, 1M tokens) where each option stacks miniature page bars that light up with the brand gradient when selected — themed by the AI Steppers design system in both light and dark.

- Category: Input
- Frameworks: Vanilla, React + CSS, React + Tailwind
- Design system: Runway
- Dark mode: yes
- Access: premium (Atheros AI Pass)
- Tags: radio
- Page: https://builder.atheros.ai/components/context-picker
- Preview: https://d17nmjscumqk5d.cloudfront.net/builder/templates/tpl_builder_context_picker/preview-25bc8e836209.webp

## Features

- Bare centered picker with a small on-brand title group — no panel card or extra chrome
- Six context window options (4K, 16K, 32K, 128K, 256K, 1M tokens) as one native radiogroup
- Each option stacks 1–4 tapered page bars that visualize the window size
- Selecting an option sweeps the brand two-color gradient across its page bars with a springy staggered fill
- Selected option gets a gradient border paint and a soft glow ring; its size label turns gradient
- Hovering an option brightens its page bars with a cascading delay
- A gentle pop animation replays on the page stack whenever the selection changes
- Visually-hidden live region announces the chosen window size to assistive technology
- Native radio semantics — arrow keys move the selection, labels toggle on click
- Dark and light themes flip the gradient (pink→blue light, violet→teal dark)
- Responsive layout that adapts down to 320px
- Fully respects `prefers-reduced-motion`

## Accessibility

- **Radiogroup semantics** — `role="radiogroup"` with `aria-label="Context window size"` on the picker
- **Option labels** — Every hidden radio input carries an explicit `aria-label` ("4K tokens" … "128K tokens")
- **Live readout** — Visually-hidden `role="status"` with `aria-live="polite"` announces the chosen window size
- **Decorative bars** — Page-bar stacks are `aria-hidden="true"` — size text carries the meaning
- **Keyboard navigation** — Native radio arrow-key navigation moves the selection within the group
- **Focus indicators** — `:focus-visible` on a hidden radio draws the `--ring` outline on its option label
- **Theme toggle** — `role="switch"` with `aria-checked` toggled by JS, Enter/Space activation
- **Reduced motion** — `prefers-reduced-motion: reduce` disables all animations

## Keyboard shortcuts

- `ArrowRight / ArrowDown` — Select the next context window option
- `ArrowLeft / ArrowUp` — Select the previous context window option
- `Enter` — Activate the theme toggle
- `Space` — Select the focused option or activate the theme toggle
- `Tab` — Move focus between the theme toggle and the picker

## Common questions

**Which frameworks is Context Picker available in?**

Context Picker ships as Vanilla, React + CSS and React + Tailwind — HTML, CSS, JS and React source you can copy, download or clone into Atheros AI Builder.

**Is the Context Picker input component free?**

Context Picker is a premium component. Anyone can preview it; the source, downloads and AI customisation are included with Atheros AI Pass.

**Does Context Picker support dark mode?**

Yes. Context Picker ships light and dark themes, both drawn from the Runway design system's tokens. Switch the preview to dark mode to compare them.

## Get the code

Preview Context Picker live, then sign in to copy or download the source, apply another design system, or ask the AI assistant to change it: https://builder.atheros.ai/components/context-picker

Every component on https://builder.atheros.ai is also reachable from Claude Code, Cursor and Codex through the Atheros MCP server (paid plans). Component index: https://builder.atheros.ai/llms-components.txt