fix(communication): resolve Communication-012..015 — endpoint-aware gRPC client cache, address-change recreation, correlation-id validation, node-flip tests

tests/ScadaLink.Communication.Tests/Grpc/SiteStreamGrpcServerTests.cs

@@ -207,6 +207,50 @@ public class SiteStreamGrpcServerTests : TestKit
         await streamTask;
     }
 
+    [Theory]
+    [InlineData("corr/with/slash")]
+    [InlineData("corr with space")]
+    [InlineData("")]
+    [InlineData("$weird")]
+    public async Task RejectsCorrelationIdThatIsNotActorNameSafe(string badCorrelationId)
+    {
+        // Communication-014 regression: a public gRPC SubscribeInstance must not feed
+        // an untrusted correlation_id straight into an Akka actor name. An unsafe id
+        // must be rejected cleanly with InvalidArgument rather than escaping as an
+        // unhandled InvalidActorNameException.
+        var server = CreateServer();
+        server.SetReady(Sys);
+
+        var writer = Substitute.For<IServerStreamWriter<SiteStreamEvent>>();
+        var context = CreateMockContext();
+
+        var ex = await Assert.ThrowsAsync<RpcException>(
+            () => server.SubscribeInstance(MakeRequest(badCorrelationId), writer, context));
+
+        Assert.Equal(StatusCode.InvalidArgument, ex.StatusCode);
+        Assert.Equal(0, server.ActiveStreamCount);
+    }
+
+    [Fact]
+    public async Task AcceptsActorNameSafeCorrelationId()
+    {
+        // A normal GUID-style correlation id (what central always supplies) is accepted.
+        var server = CreateServer();
+        server.SetReady(Sys);
+
+        var cts = new CancellationTokenSource();
+        var context = CreateMockContext(cts.Token);
+        var writer = Substitute.For<IServerStreamWriter<SiteStreamEvent>>();
+
+        var streamTask = Task.Run(() => server.SubscribeInstance(
+            MakeRequest(Guid.NewGuid().ToString()), writer, context));
+
+        await WaitForConditionAsync(() => server.ActiveStreamCount == 1);
+
+        cts.Cancel();
+        await streamTask;
+    }
+
     [Fact]
     public void SetReady_AllowsStreamCreation()
     {