For similar functionality in nano, if anyone's interested, every time you save (regardless of exiting), nano keeps a backup.

Not on by default, you have to enable it in your .nanorc (not least because you need to provide a backup folder where you want to store these backups).

Very handy. Occasionally I've deleted files accidentally or made destructive changes, and could restore a working version from the past as if I had a timemachine.