A timestamp would be sufficient in that case. If you think of most editors and word processors, they have undo and redo features that allow users to go back an

A timestamp would be sufficient in that case. If you think of most editors and word processors, they have undo and redo features that allow users to go back and forth in terms of the history of their edits. Those features normally don't support branches and if you make a change in the middle of a redo, you lose access the rest of the other redo steps. So you could tell the designer that you have the version they sent you on Friday August 13, 2021 at 3:12 PM EDT. Did they make any changes after that, or did they mean to send you a version they made prior to that?