By name: a11y-check description: "Accessibility audit against WCAG 2.1 AA. Checks semantic HTML, ARIA, keyboard navigation, color contrast, screen reader compatibility." metadata: instruction_budget: "26" framework_dependency: "mycelium" framework_dependency_note: "This skill is designed to run within the Mycelium framework (https://github.com/haabe/mycelium). Standalone use will skip the canvas state, theory gates, and harness behavior the skill assumes. Install: /plugin install mycelium@haabe/mycelium."
Accessibility Audit
Evaluate user-facing work against WCAG 2.1 AA. Accessibility is a design constraint, not a polish step (Downe Principle 11).
WCAG 2.1 AA Checklist by Principle
1. Perceivable
- All images have meaningful alt text (or alt="" for decorative)
- Video has captions; audio has transcripts
- Color is never the sole indicator of meaning
- Color contrast: 4.5:1 normal text, 3:1 large text
- Content is readable at 200% zoom without horizontal scroll
- Text spacing can be adjusted without loss of content
2. Operable
- All interactive elements reachable via keyboard (Tab/Shift+Tab)
- Visible focus indicators on all focusable elements
- No keyboard traps (can always Tab away)
- Skip navigation link for repetitive content
- Page titles are descriptive and unique
- Focus order matches visual order
- Touch targets are at least 44x44 CSS pixels
3. Understandable
- Language of page is declared (lang attribute)
- Form inputs have associated labels
- Error messages identify the field and describe the fix
- Instructions don't rely solely on sensory characteristics
- Navigation is consistent across pages
4. Robust
- Valid HTML (no duplicate IDs, proper nesting)
- ARIA used correctly (roles, states, properties)
- Custom components expose name, role, value to assistive tech
- Status messages use aria-live regions
Automated Testing Tools (by stack)
| Stack | Tool | Command |
|---|---|---|
| React/Web | axe-core | npx axe <url> or axe-core in tests |
| Any web | Lighthouse | npx lighthouse <url> --only-categories=accessibility |
| Any web | pa11y | npx pa11y <url> |
| CI/CD | axe-linter | Add to CI pipeline |
Common Violations and Fixes
| Violation | Fix |
|---|---|
| Missing alt text | Add descriptive alt or alt="" for decorative |
| Low color contrast | Increase contrast ratio to 4.5:1 minimum |
| Missing form labels | Add <label for="id"> or aria-label |
| No focus indicator | Add :focus-visible styles, never outline: none |
| Non-semantic buttons | Use <button> not <div onclick> |
| Missing heading hierarchy | Use h1-h6 in order, don't skip levels |
| Auto-playing media | Add pause/stop controls, respect prefers-reduced-motion |
When to Run
- During development: after every UI component
- Before PR: full automated scan
- Before release: manual screen reader test of critical journeys
- After design changes: re-audit affected components
Sensitive Context Note
For products handling sensitive user contexts (health, finance, domestic violence, government services), also review trauma-informed design principles in ${CLAUDE_PLUGIN_ROOT}/domains/quality/CLAUDE.md. Source: Hussain (Chayn), built on SAMHSA's 6 Principles (2014).
Neurodiversity Considerations
For information-dense or learning-oriented products, supplement WCAG with the Neurodiversity Design System (neurodiversity.design, Soward). Its 8 principle categories with neurotype-to-UI-element matrix address cognitive accessibility needs that WCAG does not fully cover (e.g., font shapes for dyslexia, number formatting for dyscalculia, animation controls for ADHD).