fix(management-service): resolve ManagementService-004,006,007,013 — PipeTo dispatch, JsonDocument disposal, unified serialization, endpoint tests; re-triage MS-009

tests/ScadaLink.ManagementService.Tests/ManagementActorTests.cs

@@ -668,4 +668,66 @@ public class ManagementActorTests : TestKit, IDisposable
         var response = ExpectMsg<ManagementUnauthorized>(TimeSpan.FromSeconds(5));
         Assert.Equal(envelope.CorrelationId, response.CorrelationId);
     }
+
+    // ========================================================================
+    // Serialization (finding ManagementService-007)
+    //
+    // Command results are serialized with System.Text.Json configured with
+    // ReferenceHandler.IgnoreCycles, so an entity graph with a bidirectional
+    // navigation property does not throw. Property names are camelCase, which
+    // the CLI's case-insensitive deserializer accepts.
+    // ========================================================================
+
+    private sealed class CyclicNode
+    {
+        public string Name { get; set; } = "";
+        public CyclicNode? Parent { get; set; }
+        public List<CyclicNode> Children { get; set; } = new();
+    }
+
+    [Fact]
+    public void SerializeResult_WithCyclicGraph_DoesNotThrow()
+    {
+        var parent = new CyclicNode { Name = "Parent" };
+        var child = new CyclicNode { Name = "Child", Parent = parent };
+        parent.Children.Add(child); // parent <-> child cycle
+
+        var json = ManagementActor.SerializeResult(parent);
+
+        Assert.Contains("Parent", json);
+        Assert.Contains("Child", json);
+    }
+
+    [Fact]
+    public void SerializeResult_UsesCamelCasePropertyNames()
+    {
+        var json = ManagementActor.SerializeResult(new CyclicNode { Name = "X" });
+
+        Assert.Contains("\"name\"", json);
+        Assert.DoesNotContain("\"Name\"", json);
+    }
+
+    // ========================================================================
+    // PipeTo fault mapping (finding ManagementService-004)
+    //
+    // Command processing is piped back via PipeTo; a fault raised inside
+    // DispatchCommand must be mapped to ManagementError by the failure
+    // continuation rather than escaping or being silently dropped.
+    // ========================================================================
+
+    [Fact]
+    public void UnknownCommandType_FaultMappedToManagementError()
+    {
+        // ManagementEnvelope.Command is typed object; an unrecognised payload
+        // makes DispatchCommand throw NotSupportedException. The PipeTo failure
+        // continuation must map it to ManagementError.
+        var actor = CreateActor();
+        var envelope = Envelope("not-a-command");
+
+        actor.Tell(envelope);
+
+        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
+        Assert.Equal(envelope.CorrelationId, response.CorrelationId);
+        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
+    }
 }