Phase 3 Task 4. GrpcDeploymentArtifactFetcher streams the artifact from the first
configured central endpoint that answers, reassembles the chunks, and verifies
SHA-256(bytes) lowercase-hex == the dispatched RevisionHash (byte-identical to
ConfigComposer's Convert.ToHexStringLower(SHA256.HashData(blob))). Every per-endpoint
problem — RpcException, zero-length stream, or hash mismatch — is logged and the next
endpoint tried; if none yield verified bytes it returns null (apply failure, keep
last-known-good — the #485 contract), never throwing into the actor loop. A
Func<endpoint, client> seam keeps the gRPC boundary out of the unit tests (that is
Task 8's job); the real path caches one h2c GrpcChannel per endpoint.
Files live under the .DeploymentCache namespace (folder Deployment/) to avoid shadowing
the Configuration.Entities.Deployment type in the test assembly — same convention as
LocalDbDeploymentArtifactCache.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty
7a8fb5f129