Decentralizers, attention! 😊
Last #deltachat releases introduced stable #p2p group membership not found in any other messenger. Members can add/remove peers also while being offline, and when everything comes online again, everyone has the same consistent membership view. We formalized and ran a simulation model using #TLA+ (invented by Leslie Lamport of vector clock fame):
https://github.com/chatmail/models/tree/main/group-membership
and a complementary #pytest model with more corner cases tested here:
https://github.com/chatmail/models/blob/main/gmc/test_gmc.py