CacheAppliedArtifact ran only on a fresh apply (ApplyAndAck), never on the
bootstrap RestoreApplied path. So a node whose cache was lost — fresh/wiped
volume, disk failure — recovered its served state from central yet stayed
cache-less, unable to boot-from-cache on the NEXT central outage until some
future new deploy happened to land. Replication does not heal this: a peer's
already-acked cache rows are pruned from its oplog, so a fully-wiped, converged
node is never back-filled. RestoreApplied now writes the served artifact back to
the cache (invariant: the cache holds what the node serves). Found on the
docker-dev live gate wiping a node's LocalDb volume.
Joseph Doherty
c6a9f93a0c