Function
The catalog and the learner's state
The featured course, the other enrolled courses and the available ones
Each enrolled course's progress comes from courseOverviewProgress with that course's own record as the last opened video — the same reading the course overview makes — so every screen names the same next video. Records of courses the learner is not enrolled in are ignored.
Sorts the catalog into the course to lead with, the learner's other courses and the courses still available to them. A learner enrolled in nothing is led by the first level course, as a recommendation — never a reference course.