Great to know early in this customer<->business relationship that OneDrive will occasionally decide our Photographs directory needs to be deleted.
This illuminates for us that:
1) Microsoft can't restore anything for us
2) the only way to restore files is to use their infinite scroll online Recycle Bin
3) there's no way to restore an entire directory
4) we'll have to select each file one at a time if we don't want to restore everything in there (do we? how would we ever know?)