First of, thanks a lot for this, having a native app that can do both standalone and secondary client on Linux is amazing!
I've been trying the app on the PinePhone with ManjaroARM (Plasma Mobile) and I thought I would give some feedback about it.
The first issue I noticed (because there are no push notifications for Signal at the moment) is that the notifications just pile up (on the lockscreen or as popups if unlock) when the client catches up with multiple new messages. I imagine that there is no simple cross-DE way to update existing notifications so the client probably would need to first make sure that all incoming messages have been processed before issuing notifications to avoid this?
The others issues I encountered were with groups: it seems that some groups names are not properly detected (I get an awfully long string of numbers and letters). This may be related to groups that where updated from V1 to V2, I'm not sure anymore which groups were pre-V2 and which were not. On a related note, trying to rename a group led to a duplication: the renamed group now appears twice. Finally, one of the groups (only one, and one where the name was properly handled) seems to have a wrong bounding box in the conversation lists because the conversation above overflows over it.
Overall, though the notification issue is somewhat annoying, I must say the client works amazingly well at such an early state, so congrats!
The group thing is interesting - It would be caused by the group state message not being properly decrypted/updated. If I had to guess, it might be visual - i.e. the chat name not getting updated visually when the group name gets decrypted. I'll look into that and generally doing a minor overhaul on the chat name state, which should handle both that and the renaming bug you noticed. The notification thing is definitely an issue I've noticed - I need to look into DE-specific notification APIs, I think. At the very least, I want to support plasma mobile notifications more robustly. Thanks for the feedback! There's still a fair amount of polishing to be done, but this is very helpful.