test: add proto contract, cleanup verification, and regression guardrail tests

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

@@ -0,0 +1,51 @@
+using System.Reflection;
+using ScadaLink.Communication.Actors;
+
+namespace ScadaLink.Communication.Tests.Grpc;
+
+/// <summary>
+/// Regression tests ensuring that the old ClusterClient-based debug streaming
+/// path is not reintroduced. Debug streaming now flows through gRPC.
+///
+/// Note: The DebugStreamEvent type-does-not-exist check lives in
+/// ScadaLink.Commons.Tests/ArchitecturalConstraintTests.cs and is not
+/// duplicated here.
+/// </summary>
+public class NoClusterClientStreamingRegressionTests
+{
+    [Fact]
+    public void CentralCommunicationActor_DoesNotHave_HandleDebugStreamEvent()
+    {
+        var type = typeof(CentralCommunicationActor);
+        var method = type.GetMethod("HandleDebugStreamEvent",
+            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+        Assert.Null(method);
+    }
+
+    [Fact]
+    public void SiteCommunicationActor_DoesNotHave_HandleDebugStreamEvent()
+    {
+        var type = typeof(SiteCommunicationActor);
+        var method = type.GetMethod("HandleDebugStreamEvent",
+            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+        Assert.Null(method);
+    }
+
+    [Fact]
+    public void CentralCommunicationActor_DoesNotHave_ForwardDebugStreamEvent()
+    {
+        var type = typeof(CentralCommunicationActor);
+        var method = type.GetMethod("ForwardDebugStreamEvent",
+            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+        Assert.Null(method);
+    }
+
+    [Fact]
+    public void Communication_Assembly_DoesNotContain_DebugStreamEvent_Type()
+    {
+        // DebugStreamEvent should not exist in the Communication assembly either
+        var assembly = typeof(CentralCommunicationActor).Assembly;
+        var type = assembly.GetTypes().FirstOrDefault(t => t.Name == "DebugStreamEvent");
+        Assert.Null(type);
+    }
+}