Last writer wins may be sufficient for some folks but for me, any potential data loss in an app like this is a deal breaker. I hope you'll consider some kind of

Last writer wins may be sufficient for some folks but for me, any potential data loss in an app like this is a deal breaker. I hope you'll consider some kind of merge conflict detection and surfacing that to the user. Even keeping a list of deleted items and showing that can be a good start.