MeshGrpcBoundaryTests replaces the MeshClusterClientBoundaryTests deleted in step 1. Three
self-seeded single-member clusters sharing the ActorSystem name, joined ONLY by gRPC, driving
the REAL CentralCommunicationActor -> MeshGrpcCommandDialer -> Kestrel h2c ->
MeshCommandAuthInterceptor -> NodeCommandGrpcService -> NodeCommunicationActor -> EventStream:
1. No_cross_mesh_Akka_association_forms_between_central_and_either_site — the program's own
point, kept as a test rather than a live-gate note: each cluster stays single-member and
none ever holds another's address as a member.
2. One_dispatch_through_central_reaches_a_node_in_every_cluster_mesh — the fan, with each
site holding its OWN per-cluster PSK, so a dial that selected the wrong cluster's key
would be refused at the far side.
3. Falsifiability_control_a_dial_carrying_the_wrong_cluster_key_delivers_nothing — without
it, (2) cannot distinguish "the gRPC boundary carried it" from "something else in the
process did". The same node then accepts the right key, so the silence is the auth gate
and not a dead endpoint.
All three run fully offline — no Docker fixture — and pass.
Comment sweep across every remaining clusterclient|receptionist hit in src/ and tests/:
the program label becomes "mesh gRPC command plane", and every comment that described the
deleted transport as live now describes what actually runs (Dps = pair-local default,
Grpc = cross-mesh). mesh_transport.proto's header/service comments are reworded; no message,
field or enum is touched — the contract is locked. MeshCommActorPathTests is reshaped rather
than retired: the two paths still exist and still matter, but what a mismatch costs is now a
misleading Unavailable from the gRPC ingress rather than a silently dropped receptionist send.
The only surviving mentions of the old names are the ones that must survive: the fail-closed
rules that name "ClusterClient" as a retired value refused at boot, their tests, and this
test class's own account of what it replaces.
Phase 1A security register items 1 and 2, landed ahead of the command
fan-out because they are independently testable and the fan-out is the
first caller of TryGetPsk.
Item 1 — known-cluster gate. MeshPskProvider gains SetKnownClusters, an
atomic whole-set swap consulted by TryGetPsk BEFORE the config map and
before the secret store. A cluster id outside the set is refused in O(1)
with no store read and no audit write, which closes two things at once:
the pre-auth store/audit flood an unauthenticated caller could drive with
a forged x-otopcua-cluster header, and the timing oracle that defeated
CentralCommandAuthInterceptor's uniform denial text (unknown clusters are
never cached, so they paid a store read on every probe while known ones
answered from memory). Empty or never-published leaves the gate inactive
— central publishes the set from its DB contact refresh, and 'the DB told
me nothing' must not become a fleet-wide authentication outage during
admin boot.
Item 2 — bool Matches(clusterId, presented) on IMeshPskProvider, with
FixedTimeEquals inside the provider. CentralCommandAuthInterceptor now
calls it and never holds key material; its two provider-side denial logs
collapse into one (the provider answers both as false) and the operator
hint is restated there.
No production caller publishes a cluster set yet, so behaviour is
unchanged until the fan-out commit wires the contact refresh.
ControlPlane.Tests 190 -> 205, Host.Tests 91 -> 92.
Joseph Doherty