Phase 3 Task 5. Under ConfigSource:Mode=FetchAndCache, a DispatchDeployment whose
revision differs from _currentRevision kicks off a gRPC artifact fetch that PipeTo's
its result back to Self as FetchedForApply (never a blocking await in a receive — that
would freeze the mailbox for the fetch deadline). HandleFetchedForApply then applies
synchronously on the actor thread, mirroring ApplyAndAck: null bytes = apply FAILURE
(keep last-known-good, do not advance the revision, ack Failed — #485); non-null bytes
reconcile drivers, rebuild the address space and push subscriptions FROM the bytes in
hand (OpcUaPublishActor never reads central SQL), then cache them. A faulted fetch task
maps to null bytes so it can't escape as an unhandled message.
Extracted ReconcileDriversFromBlob from ReconcileDrivers so Direct-read, FetchAndCache
and boot-from-cache share one reconcile body (the #485 empty guard moves into it);
ApplyCachedArtifact now reuses it instead of duplicating the spawn-plan logic.
DI: DriverHostActor.Props gains fetchAndCacheMode + artifactFetcher (LAST, per the
positional-forwarding warning); Runtime resolves them from IOptions<ConfigSourceOptions>
(fetcher only in FetchAndCache mode); Host registers GrpcDeploymentArtifactFetcher under
hasDriver.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty
648f173b18