We handle this in Fireproof with a deterministic default algorithm, in addition to having a hash-based tamperproof ledger of changes. Fireproof is not SQL based, it is more like CouchDB or MongoDB, but with cryptographic integrity. Apache 2.0 https://use-fireproof.com
In practice during CouchDB's heyday, with lots of heavy users, the conflict management API almost never mattered, as most people can make do with deterministic merges.
In practice during CouchDB's heyday, with lots of heavy users, the conflict management API almost never mattered, as most people can make do with deterministic merges.