Popover

# Aster Component Implementation Prompt — Popover

## 1. Component Purpose & Canonical Role
- **Component:** Popover (`popover`)
- **Category:** Overlays & Dialogs
- **Native Element:** `<div role="dialog">`
- **Summary:** A small floating card attached to a button.
- **When to Use:** Quick inline filter cards, contextual metadata inspectors, or setting callouts.
- **When Not to Use:** Plain text labels without interactive controls (use Tooltip).

## 2. Authoritative Repository Files
- **Component CSS:** `components/popover/popover.css`
- **Component Spec:** `docs/components/popover.md`
- **Agent Contract:** `skills/using-aster-components/SKILL.md`
- **Compiled Bundle:** `dist/css/aster.css` and `dist/js/aster.js`

## 3. Canonical HTML Structure & Classes
```html
<div class="as-popover-anchor">
  <button type="button" class="as-button as-button--secondary as-popover-trigger" id="pop-btn" aria-haspopup="dialog" aria-expanded="false">
    <span class="as-button__label">Filter Pods</span>
  </button>
  <div class="as-popover" role="dialog" aria-labelledby="pop-btn" hidden>
    <div class="as-popover__header">
      <h4 class="as-popover__title">Filter Preferences</h4>
      <button type="button" class="as-popover__close" data-popover-close aria-label="Close popover"></button>
    </div>
    <div class="as-popover__body">Display healthy worker instances only.</div>
  </div>
</div>
```

## 4. Measured Geometry
Measured from the rendered component when this page loads.

## 5. Non-Negotiable Aster Constraints
1. **Zero Primitive Color Leaks:** Bind colors strictly to `--as-semantic-color-*` custom properties. Never use `--as-color-primitive-*` or hardcoded hex values in component usage.
2. **Minimum 4px Radius Policy:** Never use `2px` border-radius. Use `--as-radius-sm` (`4px`), `--as-radius-md` (`8px`), `--as-radius-lg` (`12px`), or `--as-radius-full` (`9999px`).
3. **Single Standard Density Mode:** Compact mode (`data-density="compact"` / `.as-*--compact`) is permanently retired. Do not emit compact classes or attributes.
4. **WCAG 2.2 AA Accessibility:** Maintain >= 4.5:1 text contrast, >= 3:1 UI/border contrast, >= 24x24px interactive hit targets, and full keyboard operability (`Tab`, `Enter`, `Space`, `Escape`, Arrow keys).

## 6. Verification Commands
```bash
npm run test:components
npm run test:contrast
npm run test:browser
```