I’ve looked around GNOME’s app settings and the Warehouse app for Flatpak, and noticed that they have statistics on the data usage of (sandboxed) applications, while KDE seemingly doesn’t. Discover lets you delete the data of uninstalled apps, but you can’t really do that if you don’t know that an app is uninstalled and still using disk space (unless you go into ~/.var/app/ manually, of course).
This is why I think it would be nice to add a System Settings page for managing (sandboxed) application data. It would (imo) consist of a list of apps (including uninstalled ones), where you can go through each one and look at how much is spent by the app, how much of that is cache, and clear cache or, alternatively, trash all data related to the app.
One other feature that would be nice to have (and that I’ve implemented in the PoC) is app data snapshotting - this is lifted from Warehouse, but there they’re more managed - I would think it would be cool to make it possible to just snapshot into a file (just archiving the data directory) and then apply it later, making it possible to transfer flatpak data across machines. (You could also include the application’s master secret in the snapshot, so that transferring even encrypted data across machines could work, but I have no idea whether that’s worth the possible drawbacks of people getting told to snapshot their data and send it to scammers…)
As I’ve said, I’ve made a PoC of this (with a lot of code lifted from the Flatpak/App Permissions KCM), and here’s a small collection of photos of what I’ve implemented in it (I would upload a video, but it seems this forum doesn’t allow them). The design is… horrible, but I mostly just want to get feedback on the core idea.
(I also tried a design with a pie chart, but it didn’t seem to make much sense.)
