The atomic write point is the one that stood out to me. A crash in the middle of a save should never cost someone hours of progress — that is the kind of thing that loses trust fast, whether it is a game or any other tool people rely on.

I also liked the DTO boundary idea. Keeping the saved data separate from the gameplay code makes updates a lot less risky. The corrupt-file recovery test is a good call too. Planning for the save that does not load cleanly is what separates a system that works in testing from one that holds up in real use.