Accessibility

Accessibility Requirements (NON-NEGOTIABLE):

Keyboard Navigation:
- Tab: Move focus to button
- Enter/Space: Activate button
- Focus visible: 2px outline, --color-focus-ring
- Focus trap: NO (button must allow tab-through)

Screen Readers:
- aria-label: [When button text isn't descriptive]
- aria-busy="true": [During loading state]
- aria-disabled="true": [When disabled, NOT just disabled attribute]
- Role: "button" (explicit, even on <button> element)

Loading State (Screen Reader):
- Announce: "Loading" (use aria-live="polite" region)
- Original text: aria-label preserves it while visual shows spinner

Disabled State:
- NEVER use disabled on buttons that need explanation
- Use aria-disabled="true" + pointer-events: none
- Add tooltip explaining WHY disabled

Color Contrast:
- WCAG AA minimum: 4.5:1 (text), 3:1 (interactive elements)
- Test with: All color modes (light/dark/high contrast)
- Tool: Include contrast ratio check in component tests

Touch Targets (Mobile):
- Minimum: 44x44px (actual tappable area, NOT visual size)
- Implementation: Use padding to expand hitbox if visual smaller

Testing Requirements:
- Run jest-axe on all variants
- Test keyboard-only navigation (no mouse)
- Test with VoiceOver (Mac) or NVDA (Windows)
- If ANY axe violation, fix before marking complete

❌ DON'T let AI do this:
- <div onClick> without role="button" and keyboard handlers
- disabled without aria-disabled
- Icon-only buttons without aria-label
- Focus styles that are "outline: none" only

✅ DO enforce this:
- Semantic HTML (<button>, not <div>)
- Both disabled AND aria-disabled="true"
- aria-label on all icon-only buttons
- Visible focus indicator (never remove without replacement)