It currently demonstrates how X3DH + Double Ratchet works. How out of order message delivery and message loss is handled and what happens when the receiver is offline. The goal is to eventually include PQXDH and the Sparse PQ Ratchet as well.
The Signal protocol is well documented but hard to grasp the first time. Especially what's happening under the hood while using a messaging app. I built an educational tool that lets you chat on a simulated phone and see protocol details in real time, completely offline. Enjoy!