configure-accessibility - SKILL.md Agent Skill

name: configure-accessibility description: Use when making a frontend accessible — turns on a11y linting (Biome a11y rules for React/JSX, eslint-plugin-vuejs-accessibility for Vue templates), establishes semantic-HTML/focus/reduced-motion conventions, and adds axe checks to the test stack so accessibility regressions fail CI.

Configure Accessibility

1. Audit current state

grep -E '"(eslint-plugin-vuejs-accessibility|vitest-axe|@axe-core/playwright|axe-core)"' package.json 2>/dev/null
grep -rn "skip.*main\|role=\"main\"\|<main" src/ 2>/dev/null | head

Detect a11y lint, axe in tests, and whether a skip link / landmarks exist. Prerequisites: configure-linting (Biome) and configure-test-stack (axe plugs into Vitest/Playwright).

2. Decide what to do

Nothing → full setup (lint + conventions + axe tests).
Lint on but no axe tests → add axe (step 6).
Both present → confirm the conventions in a11y-rules.md and the keyboard pass.

3. Detect framework

React/JSX → Biome's a11y rules cover it. Vue → Biome lints <script> only, so add eslint-plugin-vuejs-accessibility for templates (the same Biome-doesn't-do-Vue-templates gap as configure-linting).

4. Lint for accessibility

Biome's recommended set (from configure-linting) already enables the core a11y rules — keep them at error, don't downgrade:

useAltText, useButtonType, useKeyWithClickEvents, useValidAnchor, noSvgWithoutTitle, useAriaPropsForRole, noAutofocus, …

Vue templates (Biome gap)

pnpm add -D eslint eslint-plugin-vuejs-accessibility

Run it over .vue files only (templates); let Biome keep <script>/TS. See a11y-rules.md.

5. App conventions (the part lint can't check)

Apply the rules in a11y-rules.md:

Landmarks + one <h1>: <header>/<nav>/<main>/<footer>; logical heading order.
Skip link: first focusable element jumps to #main.
Focus-visible: never strip the outline without a focus-visible:ring replacement (your design-system primitives already include one).
Focus management: move focus to the heading on route change; trap focus in modals/dialogs via a headless lib (Radix/Ark/Headless UI), never hand-rolled.
Reduced motion: gate non-essential animation behind motion-safe: / prefers-reduced-motion.

// skip link (render first inside <body>)
<a href="#main" className="sr-only focus:not-sr-only focus:absolute focus:p-2">Skip to content</a>
...
<main id="main">…</main>

6. Test with axe (fail CI on regressions)

Component-level (React, tests/ui): pnpm add -D vitest-axe, register the matcher once in a setup file, then assert:

// tests/setup/axe.ts (add to the ui project's setupFiles)
import { expect } from 'vitest';
import { toHaveNoViolations } from 'vitest-axe';
expect.extend(toHaveNoViolations);
// in a test: expect(await axe(container)).toHaveNoViolations();

End-to-end (any framework, tests/e2e):

pnpm add -D @axe-core/playwright

// tests/e2e/a11y.spec.ts
import { test, expect } from '@playwright/test';
import AxeBuilder from '@axe-core/playwright';

test('home page has no detectable a11y violations', async ({ page }) => {
  await page.goto('/');
  const { violations } = await new AxeBuilder({ page }).analyze();
  expect(violations).toEqual([]);
});

axe catches ~a third of issues automatically — pair it with a manual keyboard pass (Tab through every interactive element; nothing is reachable only by mouse).

7. Verify

pnpm biome check          # a11y lint rules pass
pnpm test:e2e             # axe spec passes

Plus a keyboard-only walk of the main flow.

References

./a11y-rules.md — semantic HTML, focus, reduced motion, contrast, the lint-vs-axe-vs-manual split, Vue template linting.
../_shared/conventions.md — atoms (primitives carry focus rings), @/ alias.