Comment by toomim

You can do this by (1) extending your CRDT into a CTM (see https://braid.org/time-machines) and then (2) use the antimatter algorithm (braid.org/antimatter), or something similar, for acknowledgements.

The antimatter algorithm allows peers to learn where the rest of the network has caught up to, without a central actor, or relying on consensus, across arbitrary P2P connection & disconnection events in the network. It even allows subnetworks, after a partition, to prune the history that they generate while partitioned, while still holding onto the necessary older history to reconnect with the other half of the partition.