[microbit-matt-hillsdon]

Adds axe scans to the Playwright suite. Scenarios call app.expectNoNewAccessibilityViolations() on the states they reach, and a new block in accessibility.test.ts covers the menus and dialogs that the page object's helpers click straight through. 22 scans in total.

Existing violations are not fixed here. They are recorded in knownViolations in src/e2e/axe.ts as a rule id, a CSS selector and a reason, and a scan fails only on violations that aren't listed. Fixing one means deleting its entry.

Each entry also records its WCAG level, taken from axe's tags for the rule, to help prioritise fixes. Currently known:

Level A

• 4.1.2: CodeMirror content has no accessible name (main editor and documentation code examples)
• 4.1.2: Simulator range sensor threshold marks use aria-label on a div with no role
• 1.1.1: Sidebar header logos and simulator sensor icons are role="img" with no label

Level AA

• 1.4.3: Editor line numbers are 2.02:1 contrast
• 1.4.3: Unselected sidebar tab labels are 4.3:1 contrast

axe best practice (not required by WCAG)

• API documentation entries skip to h4
• No level-one heading
• Resize handles and the simulator's sensor controls are outside landmarks

Theme

The known list is recorded against the Foundation's private theme, which is what CI and the deployed editor use. Without the theme package installed (forks, or a checkout without it) the color-contrast rule is skipped, as the open source default colours fail in different places. All other rules still run. This is noted in src/e2e/axe.ts and AGENTS.md.

Notes for review

• The only non-test change is data-testid="simulator" on the simulator container, so one known-violation entry can cover its sensor controls.
• The simulator iframe is excluded from scans. It is a separate deployment, and its h1 otherwise hides our missing one.
• The role-img-alt and heading-order entries are broad (div[role="img"], h4), so they would also hide a new instance of the same mistake.
• Nothing detects a known entry that no longer matches anything.
• The scans add about 13s to the Playwright step in CI (3m36s here against 3m23s on main).

[github-actions]

Preview build will be at
https://review-python.microbit.org/axe-e2e/

[microbit-matt-hillsdon]

The simulator iframe is excluded from scans. It is a separate deployment, and its h1 otherwise hides our missing one.

But almost certainly worth adding its own scan now we have e2e there.

[microbit-matt-hillsdon]

CC @microbit-grace as I'm going to do this everywhere in fairly short order.

[microbit-robert]

LGTM

[microbit-matt-hillsdon]

Just holding off merging until I have an ml-trainer version of the same in case I hit issues that suggest a change of approach or it seems shared code is worthwhile.