I have implemented a JSON-like CRDT using this nice tutorial [1], which is a tree, but never an append-only DAG.

I'm curious how two edges meeting the same vertex will make it difficult to resolve the conflict automatically? Is it that two users will create the same vertex (concurrently) with slightly different attributes, and attribute-merging requires human-in-the-loop?

Of course if the DAG is not append-only, but supports, say, "moving" of edges/branches, it is a totally different problem. Martin has something to say about this [2].

[1] https://www.bartoszsypytkowski.com/operation-based-crdts-jso... [2] https://martin.kleppmann.com/papers/move-op.pdf