accessibility-check

Use when a task changes any screen, form, dialog, menu or control - Lighthouse/axe scan of the changed screens, a keyboard walk, and the thresholds that fail a task

SKILL.md

GitHub

Accessibility Check

Thresholds

The same bar the frontend developer builds to (accessibility-basics, ui-quality-floor, responsive-mobile-first) — QA and developer share one bar, not a separate QA opinion:

  • labels on every control, aria-label on icon-only buttons;
  • visible focus on every interactive element;
  • contrast ≥4.5:1 body text / ≥3:1 large text;
  • touch targets ≥44px phone / ≥24px desktop;
  • <input> font ≥16px on phone;
  • exactly one <h1>, lang set on <html>, no user-scalable=no;
  • a dialog traps focus while open, Escape closes it, focus returns to the trigger;
  • submitting with errors moves focus to the first invalid field, which carries aria-invalid.

Scan (public pages)

QA=${TMPDIR:-/tmp}/tt-<task-key>/qa; mkdir -p "$QA"; node -v   # lighthouse@13 needs Node >=22, else lighthouse@12
CHROME_PATH="$CHROME_BIN" npx -y lighthouse@13 "http://localhost:5173/settings" \
  --only-categories=accessibility,best-practices --form-factor=mobile \
  --screenEmulation.mobile --screenEmulation.width=360 --screenEmulation.height=800 --screenEmulation.deviceScaleFactor=2 \
  --chrome-flags="--headless=new" --output=json --output-path="$QA/lh-settings-360.json" --quiet
jq -r '.audits|to_entries[]|select(.value.score==0)|"\(.key)\t\(.value.title)"' "$QA/lh-settings-360.json"  # no jq: node -e 'for (const [k,v] of Object.entries(require(process.argv[1]).audits)) if (v.score===0) console.log(k+"\t"+v.title)' "$QA/lh-settings-360.json"

Run with run_terminal timeout_seconds: 300. errors-in-console in the output doubles as the console check for page load.

Full axe (pages behind login, or when Lighthouse flags something)

Install playwright-core + @axe-core/playwright into $QA, never the workspace:

cd "$QA" && [ -d node_modules/@axe-core/playwright ] || npm i --no-audit --no-fund --silent playwright-core@1.63 @axe-core/playwright@4.13
cat > axe.cjs <<'EOF'
const { chromium } = require('playwright-core');
const { AxeBuilder } = require('@axe-core/playwright');
(async () => {
  const [url, width = '360'] = process.argv.slice(2);
  const browser = await chromium.launch({ executablePath: process.env.CHROME_BIN });
  const page = await browser.newPage({ viewport: { width: Number(width), height: 800 } });
  await page.goto(url);
  const { violations } = await new AxeBuilder({ page })
    .withTags(['wcag2a', 'wcag2aa', 'wcag21a', 'wcag21aa', 'wcag22aa']).analyze();
  for (const v of violations) console.log(`${v.impact}\t${v.id}\t${v.nodes.length}\t${v.nodes[0].target.join(' ')}`);
  console.log(`violations=${violations.length}`);
  await browser.close();
})();
EOF
node axe.cjs http://localhost:5173/settings 360

For a page behind login, add page.fill/page.click lines before the scan.

Keyboard walk (playwright-cli)

cd "$QA"; PW="npx -y @playwright/cli@0.1"; $PW --help | head -5
$PW open --browser=chrome http://localhost:5173/settings
$PW press Tab; $PW --raw eval "(() => { const a = document.activeElement; return a.tagName + '|' + (a.getAttribute('aria-label') || a.textContent.trim().slice(0, 40)) + '|outline=' + getComputedStyle(a).outlineStyle })()"

Repeat Tab through every changed control; order must follow visual order, with no outline=none and no box-shadow silently replacing it. Open the dialog, press Escape, eval activeElement = the trigger.

Verdict and recording

  • A critical or serious violation whose target is inside a changed screen → fail the task (qa-criterion-verdicts rubric).
  • A violation outside the changed screen → a pre-existing-defect note (in_qa), not a fail.
  • Moderate/minor → a note, not a fail.
  • Record as a test case with category: visual and a title prefix a11y: — the category enum has no accessibility value of its own.

Red Flags

  • Quoting the Lighthouse score instead of the failing audits by name.
  • Scanning a page you did not change and failing the task for what it finds there.
  • "Keyboard OK" written with no Tab walk actually run.