Hooks the Bootstrap catch that previously went straight to Stale. On a cache hit the
node serves its last-known-good configuration through the outage instead of coming
up with an empty address space; on a miss, behaviour is byte-for-byte what it was.
The read is unkeyed because ClusterId is only derivable from an artifact you already
hold or from the unreachable central DB (recon D-1). Newest pointer wins, which is
correct in every real topology - a node belongs to one cluster and its peer
replicates that same row.
Splits PushDesiredSubscriptionsFromArtifact out of PushDesiredSubscriptions: the
cache path runs precisely when the ConfigDb read cannot succeed, so re-reading the
artifact there would fail by definition.
RunningFromCache is surfaced on NodeDiagnosticsSnapshot (optional param, existing
call sites unaffected). A node running from cache looks entirely healthy from
outside - full address space, live values - but its config is frozen and no deploy
can reach it. It clears only on a real apply from central.
Joseph Doherty