How can we tell if a snapshot we examine is the latest, most current snapshot?
The LookBack API will return the analytics snapshots to your queries. Each snapshot has two fields: _ValidFrom and _ValidTo. These fields mark the time frame where this snapshot was 'active' or 'current'.
For example, If _ValidFrom = "2018-08-28T00:00:00.000Z" and _ValidTo = "2018-08-31T00:00:00.000Z" then this means this snapshot was valid between Aug-28.2018 and thru Aug-31-2018.
The current, active snapshot has the field _ValidTo set with value of: "9999-01-01T00:00:00.000Z".
So, to be certain if a snapshot you're examining is the latest or current, check the _ValidTo field and look for this value.
Upon every change that is made to an artifact for any of the fields which are included by the Analytics service, upon each such change a snapshot is created. The snapshot that was current is stamped with _ValidTo that has the value of the time stamp of the change, whereas a new snapshot is created with _ValidTo being "9999-01-01T00:00:00.000Z".