Right now, track progress is saved every 3 seconds when the app is backgrounded. This means stopping the lesson and then returning to it may result in a short progress loss. It's not a huge deal, and it can actually be kind of nice to get a few extra seconds of context when you come back to the track, but it would be better to implement this context deliberately instead of relying on a 'luck of the draw' based on when the progress was last saved.
An explicit stop or pause request from the notification should save the current progress immediately.
Right now, track progress is saved every 3 seconds when the app is backgrounded. This means stopping the lesson and then returning to it may result in a short progress loss. It's not a huge deal, and it can actually be kind of nice to get a few extra seconds of context when you come back to the track, but it would be better to implement this context deliberately instead of relying on a 'luck of the draw' based on when the progress was last saved.
An explicit stop or pause request from the notification should save the current progress immediately.