Here another short update.
Stanza acknowledgement from client to server is working now and chat dialogs get notified when a message sent by them has been acked by the server. The only thing left here is the visual representation in chat dialogs of unacked and acked messages.
After that is done I'll try to add support for session resumption and hopefully get it done till mid-term evaluation next week. Most of this stuff doesn't sound hard to implement however there is currently only one server implementation of XEP-0198 and that one only supports stanza acknowledgement, so it's a bit hard to test my client side implementation of it. XEP-0198 resulted out of long discussions in the XSF on how to improve reliability and the overall experience of chatting over XMPP. It's important that this extension is implemented so we can test in real life whether these changes help or not.
50% of my end semester exams are taken and the rest is following in the next week. After those I'll have plenty of time to start the second big part of this project, UI improvements in Psi.