How do you handle backup and restore on a system like this? If the snapshots are at the OS level, and there is cross-app commingling of data objects, how can y

How do you handle backup and restore on a system like this? If the snapshots are at the OS level, and there is cross-app commingling of data objects, how can you restore the state of a particular application or object (formerly "file") without breaking everything? How do I restore a single document or a single contact in my address book?