Function
The lessons whose tickets should be recorded
Idempotent and quiet: ids already held are skipped, and when nothing is new nothing is sent and no subscriber is notified. Callers can therefore hand it every complete lesson they know about on each render without looping.
The tickets show at once and are saved for the learner in one request; a refused save withdraws them.
Deliberately not a hook — the lesson page calls it from an effect when it sees a lesson become complete, and the Achievements page calls it for the lessons that were complete before tickets were stored.
Records a ticket for every lesson that has not earned one yet.