Module
Use case: mark a lesson as complete. Validates the lesson exists and then writes through the ProgressTracker port. In v1 the tracker is in-memory and ephemeral; the use case contract is unchanged when persistence arrives.
ProgressTracker
Use case: mark a lesson as complete. Validates the lesson exists and then writes through the
ProgressTrackerport. In v1 the tracker is in-memory and ephemeral; the use case contract is unchanged when persistence arrives.