Phase 4 of the ClusterClient -> gRPC migration deleted the Akka transports
but left the naming behind: `ClusterClientSiteAuditClient` was transport-
agnostic and worked unchanged, so it survived the deletion under a name
that now describes a transport the repo no longer has. Same for a scatter
of doc-comments still framing gRPC as "the new transport" beside an Akka
one that is gone.
Renames it to `SiteCommunicationAuditClient` (and its test file) and
rewrites the stale comments to describe the single transport that exists.
Also tightens CLAUDE.md: drops the self-describing directory listing and
the 27-component enumeration in favour of the non-obvious parts only.
Behaviour-neutral: names and prose only. Recorded as the Phase 4
follow-up in docs/plans/2026-07-22-clusterclient-to-grpc-plan.md.
Introduce ICentralTransport as the site->central choke point inside
SiteCommunicationActor. The seven site->central sends (notification submit/
status, audit + cached-telemetry ingest, reconcile, health, heartbeat) now
delegate to an injected transport instead of owning ClusterClient.Send inline.
- AkkaCentralTransport: verbatim extraction of today's ClusterClient.Send path,
including the exact sender-forwarding that routes central's reply straight
back to the waiting Ask. Default when no transport is injected -> behaviour
unchanged, existing SiteCommunicationActorTests pass as-is.
- GrpcCentralTransport + CentralChannelProvider: dial CentralControlService with
sticky failover + background failback (1s-doubling-cap-60s), PSK +
x-scadabridge-site via ControlPlaneCredentials, per-call deadlines mirroring
today's Ask timeouts. Cross-node retry ONLY on provably-unsent
connect failures; never on DeadlineExceeded. Heartbeat stays fire-and-forget.
- StaticSitePskProvider: site's single own-key provider (fail-closed).
- CommunicationOptions: CentralTransport flag (default Akka) + CentralGrpcEndpoints
(validator: required when transport=Grpc). Host selects the impl; the
ClusterClient is created only on the Akka path.
Tests: actor-with-fake-transport (7 delegations + fault routing + heartbeat
no-fault), AkkaCentralTransport sender-forwarding, GrpcCentralTransport over
in-process TestServer (failover flip, sticky, failback, PSK+header, deadline,
no-retry-on-deadline), validator. Communication.Tests 371 green, Host.Tests 391
green; the three above-seam suites pass unmodified.
Joseph Doherty