Textarea

# Aster Component Implementation Prompt — Textarea

## 1. Component Purpose & Canonical Role
- **Component:** Textarea (`textarea`)
- **Category:** Form Controls
- **Native Element:** `<textarea>`
- **Summary:** A field for longer text across several lines.
- **When to Use:** When user input is expected to exceed a single line.
- **When Not to Use:** Single-line strings such as emails, slugs, or passwords (use Input).

## 2. Authoritative Repository Files
- **Component CSS:** `components/textarea/textarea.css`
- **Component Spec:** `docs/components/textarea.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-form-field">
  <label class="as-form-field__label" for="deploy-notes">Release Notes</label>
  <div class="as-textarea-box">
    <textarea class="as-textarea" id="deploy-notes" maxlength="300" placeholder="Enter notes..."></textarea>
    <div class="as-textarea__footer">
      <span class="as-textarea__counter">0 / 300</span>
    </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
```