Course, chapter, lesson

Three levels, no more

A course is the sellable unit: title, description, cover. A chapter structures it; it is pure ordering and is never sold on its own. A lesson is the page your buyer actually looks at — text, video or both.

There is deliberately no deeper level. A fourth tier looks like order on paper and makes every navigation longer in practice.

Length computes itself

Course duration is the sum of all video durations, read out during processing. It exists nowhere as an input field — a typed number goes stale at the first re-cut, and a wrong length claim is a refund reason.

Order and rearranging

Chapters and lessons can be reordered without anyone losing progress: progress hangs off the lesson, not its position.