fix: populate MessageId from TaskStatusUpdateEvent.Status.Message (#6043)

When A2AAgent receives a TaskStatusUpdateEvent during streaming,
ConvertToAgentResponseUpdate now sets AgentResponseUpdate.MessageId
from Status.Message.MessageId when the message is present.

This fixes the missing message correlation metadata reported in
microsoft/agent-framework#4987.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

dotnet/src/Microsoft.Agents.AI.A2A/A2AAgent.cs

@@ -474,6 +474,7 @@ public sealed class A2AAgent : AIAgent
             ResponseId = statusUpdateEvent.TaskId,
             RawRepresentation = statusUpdateEvent,
             Role = ChatRole.Assistant,
+            MessageId = statusUpdateEvent.Status.Message?.MessageId,
             FinishReason = MapTaskStateToFinishReason(statusUpdateEvent.Status.State),
             AdditionalProperties = statusUpdateEvent.Metadata?.ToAdditionalProperties() ?? [],
             Contents = statusUpdateEvent.Status.GetUserInputRequests(),

dotnet/tests/Microsoft.Agents.AI.A2A.UnitTests/A2AAgentTests.cs

@@ -1124,6 +1124,7 @@ public sealed class A2AAgentTests : IDisposable
         Assert.Equal(TaskId, update0.ResponseId);
         Assert.Equal(this._agent.Id, update0.AgentId);
         Assert.Null(update0.FinishReason);
+        Assert.Null(update0.MessageId);
         Assert.IsType<TaskStatusUpdateEvent>(update0.RawRepresentation);
 
         // Assert - session should be updated with context and task IDs
@@ -1132,6 +1133,50 @@ public sealed class A2AAgentTests : IDisposable
         Assert.Equal(TaskId, a2aSession.TaskId);
     }
 
+    [Fact]
+    public async Task RunStreamingAsync_WithTaskStatusUpdateEventAndMessageId_YieldsMessageIdAsync()
+    {
+        // Arrange
+        const string TaskId = "task-status-msg-123";
+        const string ContextId = "ctx-status-msg-456";
+        const string ExpectedMessageId = "msg-status-789";
+
+        this._handler.StreamingResponseToReturn = new StreamResponse
+        {
+            StatusUpdate = new TaskStatusUpdateEvent
+            {
+                TaskId = TaskId,
+                ContextId = ContextId,
+                Status = new()
+                {
+                    State = TaskState.Working,
+                    Message = new Message
+                    {
+                        MessageId = ExpectedMessageId,
+                        Parts = [Part.FromText("Processing your request...")]
+                    }
+                }
+            }
+        };
+
+        var session = await this._agent.CreateSessionAsync();
+
+        // Act
+        var updates = new List<AgentResponseUpdate>();
+        await foreach (var update in this._agent.RunStreamingAsync("Check task status", session))
+        {
+            updates.Add(update);
+        }
+
+        // Assert
+        Assert.Single(updates);
+
+        var update0 = updates[0];
+        Assert.Equal(ExpectedMessageId, update0.MessageId);
+        Assert.Equal(TaskId, update0.ResponseId);
+        Assert.IsType<TaskStatusUpdateEvent>(update0.RawRepresentation);
+    }
+
     [Fact]
     public async Task RunStreamingAsync_WithInputRequiredStatusUpdate_YieldsStatusContentsAsync()
     {
@@ -1150,6 +1195,7 @@ public sealed class A2AAgentTests : IDisposable
                     State = TaskState.InputRequired,
                     Message = new Message
                     {
+                        MessageId = "input-msg-789",
                         Parts = [Part.FromText("Where would you like to fly?")]
                     }
                 }
@@ -1170,6 +1216,7 @@ public sealed class A2AAgentTests : IDisposable
 
         var update0 = updates[0];
         Assert.Equal(TaskId, update0.ResponseId);
+        Assert.Equal("input-msg-789", update0.MessageId);
         Assert.Null(update0.FinishReason);
 
         var textContent = Assert.Single(update0.Contents.OfType<TextContent>());