the generation the primary advertises as complete
the replica's applied authoritative generation
the replica's fingerprint at appliedGeneration, or null when it has not computed one
collections the replica holds at least one row of
(collection, name) pairs the replica actually holds
the primary's fingerprint at advertisedGeneration, or null when unpublished
the schema version the pack was built at, on each side
what an admission decision is made from; every field is something a replica can lack