Yep, that’s why I don’t like SuperProductivity, it’s hard to make proper sync on top of json/caldav(especially with proper conflict resolution). As far as I know, SuperProductivity building its own cloud sync protocol, but it’s plan to be a paid feature anytime.

As for mobile version - yep, I plan to add them too. It’s already support PWA, so you can install app as a bookmark (and it opens pretty fast btw!). But I want to have proper notifications in future and maybe widgets, so andriod/ios will be, but not sure when.

Thanks for the feedback!