Create a durable, visual teaching artifact — plus an optional check-in (predict-then-reveal for diffs, corrected exercises) that makes it stick — for something worth learning: a concept, a diff, an idea, or a window of your own recent work. Use when the user wants to be taught, wants a deep explainer, wants to understand a substantial change, or wants a work recap built for retention. Not for ordinary Q&A, brief 'why?' follow-ups, operational diagnosis, status updates, or a concise trade-off answer that belongs inline in chat. For learning, not repo docs or verdicts.