Allow system backup

[Mynacol]

I recently moved to a new phone and used the system backup/restore solution Seedvault to migrate my data. Unfortunately, this app opts-out of system backups.

First off: apps can require client side encryption for system backups, so you can preserve privacy.

Next, you can define arbitrary files/folders to include or exclude. So you can avoid saving articles which could/should be just fetched again from the server. But settings and maybe credentials could be saved and would ease backup management for us users.

Finally, News uses a system account and seedvault currently doesn't support backing that up. This should not interfere with keeping the user logged in, as it is not used to store the actual credentials afaik (at least with the nextcloud app also logged in). Instead it could be a nudge to migrate away from this construct. Android has nowadays other means to regularly sync articles in the background.

An example commit introducing backup support might help: grote/Transportr@4dc38f4

[David-Development]

Thanks for the detailed bug report. We actually disabled the backup in Version 0.9.9.68 since we couldn't make sure that the Single Sign-On Tokens (which requires a token exchange between the News and the Files app) would be backed up properly (the files app would need to back up that token as well). If I remember correctly the fastest solution was just to ditch the backup all together - since through the Single Sign-On Feature you don't really loose anything. Except - yes I agree - the settings in case you are not using the default settings.

Yes, the system account is only used for sync purposes - the Single Sign-On Feature does not require the account. That would definitely an improvement to move to a more modern construct for synchronization. Unfortunately my time is extremely limited right now so that I won't be able to work on this in a while. It sounds like you have experience with Android development - in case you want to give it a try I'd be happy to review the pull request.

[Mynacol]

Thanks for the fast reply. I absolutely missed the changelog entry.

I added the Single-Sign-On token discussion at the Nextcloud files app issue (referenced above this comment). Maybe they save the tokens in the future.

Until then I'd argue we should save the app settings. During migration I had to check the settings on the old phone to align them on the new phone. This step could be eliminated.
I don't see how this would break with user expectations. Maybe they have to accept the login prompt again, but then their settings are set as before.

Unfortunately, I never got really into Android development and I also have limited time currently.