We introduce Delta State Conflict-Free Replicated Data Types (δ-CRDT) that can achieve the best of both operation-based and state-based CRDTs: small messages with an incremental nature, as in operation-based CRDTs, disseminated over unreliable communication channels, as in traditional state-based CRDTs.

Another very interesting paper describing a data structure very much like the one I've been working on for replicating Fediverse data between instances.

Typical that I spend ages working on something only to find out that somebody else already invented it!