This is a tricky one. I would consider doing the following - comments / suggestions welcome:
- Publish a classic build to the candidate channel only
- Publish a strict build to the stable channel, which has a zenity / yad / dialog popup which pops up before the application launches to explain you’re now classic confined, and to tell people to
snap refresh termius --candidate(and omit the--classicso they get to read the message that pops up when they try to refresh to the classic snap) - Monitor the snap metrics for your snap to see how many have moved from stable to candidate. Be accepting of the fact not everyone will, as not everyone will start your application and see the popup
- Once a chunk of users have moved over, promote the classic build to the stable channel and close the candidate channel
I can’t think of a better way to do it.