[Sammi]

My unfortunate point is that the dev cannot know what the user is doing, and so cannot in principle know what choice to make on behalf of the user in case of a conflict. This is not a code problem. It cannot be solved with code.

[sgt]

I've found that in almost all cases - the latest update "wins" strategy is fine. You could have two sessions working with conventional API calls and still have a conflict. As a dev you need to restrict what the user can do.