Validation and accessibility checks

Broken or inaccessible courses shouldn't be discoverable only after they're in front of learners. Tessera checks on every build: structural validation plus accessibility checks run automatically, and a deeper audit is one command away.

Validation, always on

Every preview session and every export validates the course first: page syntax, course configuration, quiz setup (a multiple-choice question with no correct answer marked, say), and broken references to images or media. Errors stop the build and say what's wrong, so a broken package can't reach your LMS. Between builds, pnpm validate <course> gives the same answer in seconds.

Accessibility checks on every build

Alongside validation, every build checks for the accessibility basics:

• Images have alt text (or are explicitly marked decorative)
• Video and audio have titles and captions or a transcript
• Questions have proper labels
• Headings don't skip levels
• Your brand colour has sufficient contrast
• The course declares its language correctly

The serious ones (a missing alt, an untitled video) block the export; the rest warn. Because your assistant sees these diagnostics as it works, most problems get fixed before you ever see them.

The deep audit

pnpm check <course> runs validation and then the full audit: it builds the course, renders every page in a headless browser (including pages behind quiz gates), and runs axe-core, the same engine behind most professional accessibility tooling. That catches what static checks can't: real rendered contrast, focus order, computed ARIA. You get a report and a clear pass/fail against the severity threshold you choose, checked against the WCAG ruleset you configure (2.0 A, 2.0 AA, or 2.1 AA).

Accessible by construction

The built-in components come keyboard-navigable with correct ARIA semantics out of the box; the drag-and-drop sorting question, for instance, also works click-to-place. Courses start from a compliant baseline instead of earning one later.

What remains yours

No tool can make content accessible by itself. Tessera can prove an alt attribute exists, not that it describes the image well; it can require captions, not write accurate ones. Plain language, sensible reading order, and captions that match the audio are still authorship, yours and your assistant's.