microsoft · SergeyMenshykh · Jan 30, 2026 · Jan 30, 2026
diff --git a/dotnet/samples/AGUIClientServer/AGUIDojoServer/AgenticUI/AgenticUIAgent.cs b/dotnet/samples/AGUIClientServer/AGUIDojoServer/AgenticUI/AgenticUIAgent.cs
@@ -79,10 +79,7 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
                     Role = update.Role,
                     ContinuationToken = update.ContinuationToken,
                     AdditionalProperties = update.AdditionalProperties,
-                })
-            {
-                AgentId = update.AgentId
-            };
+                });
         }
     }
 }
diff --git a/...les/AGUIClientServer/AGUIDojoServer/PredictiveStateUpdates/PredictiveStateUpdatesAgent.cs b/...les/AGUIClientServer/AGUIDojoServer/PredictiveStateUpdates/PredictiveStateUpdatesAgent.cs
@@ -88,10 +88,7 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
                             AdditionalProperties = update.AdditionalProperties,
                             AuthorName = update.AuthorName,
                             ContinuationToken = update.ContinuationToken,
-                        })
-                    {
-                        AgentId = update.AgentId
-                    };
+                        });
 
                     // Small delay to simulate streaming
                     await Task.Delay(50, cancellationToken).ConfigureAwait(false);

diff --git a/...amples/GettingStarted/AGUI/Step04_HumanInLoop/Client/ServerFunctionApprovalClientAgent.cs b/...amples/GettingStarted/AGUI/Step04_HumanInLoop/Client/ServerFunctionApprovalClientAgent.cs
@@ -227,7 +227,6 @@ private static AgentResponseUpdate ProcessIncomingServerApprovalRequests(
                 AdditionalProperties = chatUpdate.AdditionalProperties
             })
             {
-                AgentId = update.AgentId,
                 ContinuationToken = update.ContinuationToken,
             };
         }

diff --git a/...amples/GettingStarted/AGUI/Step04_HumanInLoop/Server/ServerFunctionApprovalServerAgent.cs b/...amples/GettingStarted/AGUI/Step04_HumanInLoop/Server/ServerFunctionApprovalServerAgent.cs
@@ -219,7 +219,6 @@ private static AgentResponseUpdate ProcessOutgoingApprovalRequests(
                 AdditionalProperties = chatUpdate.AdditionalProperties
             })
             {
-                AgentId = update.AgentId,
                 ContinuationToken = update.ContinuationToken
             };
         }

diff --git a/dotnet/samples/GettingStarted/AgentProviders/Agent_With_CustomImplementation/Program.cs b/dotnet/samples/GettingStarted/AgentProviders/Agent_With_CustomImplementation/Program.cs
@@ -60,7 +60,6 @@ protected override async Task<AgentResponse> RunCoreAsync(IEnumerable<ChatMessag
 
             return new AgentResponse
             {
-                AgentId = this.Id,
                 ResponseId = Guid.NewGuid().ToString("N"),
                 Messages = responseMessages
             };
@@ -94,7 +93,6 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
             {
                 yield return new AgentResponseUpdate
                 {
-                    AgentId = this.Id,
                     AuthorName = message.AuthorName,
                     Role = ChatRole.Assistant,
                     Contents = message.Contents,

diff --git a/dotnet/samples/GettingStarted/Workflows/Declarative/HostedWorkflow/Program.cs b/dotnet/samples/GettingStarted/Workflows/Declarative/HostedWorkflow/Program.cs
@@ -72,7 +72,7 @@ await aiProjectClient
         {
             if (responseUpdate.MessageId != lastMessageId)
             {
-                Console.WriteLine($"\n\n{responseUpdate.AuthorName ?? responseUpdate.AgentId}");
+                Console.WriteLine($"\n\n{responseUpdate.AuthorName ?? agent.Id}");
             }
 
             lastMessageId = responseUpdate.MessageId;

diff --git a/dotnet/src/Microsoft.Agents.AI.A2A/A2AAgent.cs b/dotnet/src/Microsoft.Agents.AI.A2A/A2AAgent.cs
@@ -101,7 +101,6 @@ protected override async Task<AgentResponse> RunCoreAsync(IEnumerable<ChatMessag
 
             return new AgentResponse
             {
-                AgentId = this.Id,
                 ResponseId = message.MessageId,
                 RawRepresentation = message,
                 Messages = [message.ToChatMessage()],
@@ -115,7 +114,6 @@ protected override async Task<AgentResponse> RunCoreAsync(IEnumerable<ChatMessag
 
             var response = new AgentResponse
             {
-                AgentId = this.Id,
                 ResponseId = agentTask.Id,
                 RawRepresentation = agentTask,
                 Messages = agentTask.ToChatMessages() ?? [],
@@ -295,7 +293,6 @@ private AgentResponseUpdate ConvertToAgentResponseUpdate(AgentMessage message)
     {
         return new AgentResponseUpdate
         {
-            AgentId = this.Id,
             ResponseId = message.MessageId,
             RawRepresentation = message,
             Role = ChatRole.Assistant,
@@ -309,7 +306,6 @@ private AgentResponseUpdate ConvertToAgentResponseUpdate(AgentTask task)
     {
         return new AgentResponseUpdate
         {
-            AgentId = this.Id,
             ResponseId = task.Id,
             RawRepresentation = task,
             Role = ChatRole.Assistant,
@@ -322,7 +318,6 @@ private AgentResponseUpdate ConvertToAgentResponseUpdate(TaskUpdateEvent taskUpd
     {
         AgentResponseUpdate responseUpdate = new()
         {
-            AgentId = this.Id,
             ResponseId = taskUpdateEvent.TaskId,
             RawRepresentation = taskUpdateEvent,
             Role = ChatRole.Assistant,

diff --git a/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentResponse.cs b/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentResponse.cs
@@ -140,18 +140,6 @@ public IList<ChatMessage> Messages
     [JsonIgnore]
     public IEnumerable<UserInputRequestContent> UserInputRequests => this._messages?.SelectMany(x => x.Contents).OfType<UserInputRequestContent>() ?? [];
 
-    /// <summary>
-    /// Gets or sets the identifier of the agent that generated this response.
-    /// </summary>
-    /// <value>
-    /// A unique string identifier for the agent, or <see langword="null"/> if not specified.
-    /// </value>
-    /// <remarks>
-    /// This identifier helps track which agent generated the response in multi-agent scenarios
-    /// or for debugging and telemetry purposes.
-    /// </remarks>
-    public string? AgentId { get; set; }
-
     /// <summary>
     /// Gets or sets the unique identifier for this specific response.
     /// </summary>
@@ -276,7 +264,6 @@ public AgentResponseUpdate[] ToAgentResponseUpdates()
                 RawRepresentation = message.RawRepresentation,
                 Role = message.Role,
 
-                AgentId = this.AgentId,
                 ResponseId = this.ResponseId,
                 MessageId = message.MessageId,
                 CreatedAt = this.CreatedAt,

diff --git a/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentResponseExtensions.cs b/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentResponseExtensions.cs
@@ -118,15 +118,11 @@ public static AgentResponse ToAgentResponse(
     {
         _ = Throw.IfNull(updates);
 
-        AgentResponseDetails additionalDetails = new();
         ChatResponse chatResponse =
-            AsChatResponseUpdatesWithAdditionalDetails(updates, additionalDetails)
+            AsChatResponseUpdates(updates)
             .ToChatResponse();
 
-        return new AgentResponse(chatResponse)
-        {
-            AgentId = additionalDetails.AgentId,
-        };
+        return new AgentResponse(chatResponse);
     }
 
     /// <summary>
@@ -160,52 +156,31 @@ static async Task<AgentResponse> ToAgentResponseAsync(
             IAsyncEnumerable<AgentResponseUpdate> updates,
             CancellationToken cancellationToken)
         {
-            AgentResponseDetails additionalDetails = new();
             ChatResponse chatResponse = await
-                AsChatResponseUpdatesWithAdditionalDetailsAsync(updates, additionalDetails, cancellationToken)
+                AsChatResponseUpdatesAsync(updates, cancellationToken)
                 .ToChatResponseAsync(cancellationToken)
                 .ConfigureAwait(false);
 
-            return new AgentResponse(chatResponse)
-            {
-                AgentId = additionalDetails.AgentId,
-            };
+            return new AgentResponse(chatResponse);
         }
     }
 
-    private static IEnumerable<ChatResponseUpdate> AsChatResponseUpdatesWithAdditionalDetails(
-        IEnumerable<AgentResponseUpdate> updates,
-        AgentResponseDetails additionalDetails)
+    private static IEnumerable<ChatResponseUpdate> AsChatResponseUpdates(
+        IEnumerable<AgentResponseUpdate> updates)
     {
         foreach (var update in updates)
         {
-            UpdateAdditionalDetails(update, additionalDetails);
             yield return update.AsChatResponseUpdate();
         }
     }
 
-    private static async IAsyncEnumerable<ChatResponseUpdate> AsChatResponseUpdatesWithAdditionalDetailsAsync(
+    private static async IAsyncEnumerable<ChatResponseUpdate> AsChatResponseUpdatesAsync(
         IAsyncEnumerable<AgentResponseUpdate> updates,
-        AgentResponseDetails additionalDetails,
         [EnumeratorCancellation] CancellationToken cancellationToken)
     {
         await foreach (var update in updates.WithCancellation(cancellationToken).ConfigureAwait(false))
         {
-            UpdateAdditionalDetails(update, additionalDetails);
             yield return update.AsChatResponseUpdate();
         }
     }
-
-    private static void UpdateAdditionalDetails(AgentResponseUpdate update, AgentResponseDetails details)
-    {
-        if (update.AgentId is { Length: > 0 })
-        {
-            details.AgentId = update.AgentId;
-        }
-    }
-
-    private sealed class AgentResponseDetails
-    {
-        public string? AgentId { get; set; }
-    }
 }
diff --git a/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentResponseUpdate.cs b/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentResponseUpdate.cs
@@ -122,9 +122,6 @@ public IList<AIContent> Contents
     /// <summary>Gets or sets additional properties for the update.</summary>
     public AdditionalPropertiesDictionary? AdditionalProperties { get; set; }
 
-    /// <summary>Gets or sets the ID of the agent that produced the response.</summary>
-    public string? AgentId { get; set; }
-
     /// <summary>Gets or sets the ID of the response of which this update is a part.</summary>
     public string? ResponseId { get; set; }
 

diff --git a/dotnet/src/Microsoft.Agents.AI.CopilotStudio/CopilotStudioAgent.cs b/dotnet/src/Microsoft.Agents.AI.CopilotStudio/CopilotStudioAgent.cs
@@ -90,7 +90,6 @@ protected override async Task<AgentResponse> RunCoreAsync(
         // so that they can tell things like response boundaries.
         return new AgentResponse(responseMessagesList)
         {
-            AgentId = this.Id,
             ResponseId = responseMessagesList.LastOrDefault()?.MessageId,
         };
     }
@@ -127,7 +126,6 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
             // so that they can tell things like response boundaries.
             yield return new AgentResponseUpdate(message.Role, message.Contents)
             {
-                AgentId = this.Id,
                 AdditionalProperties = message.AdditionalProperties,
                 AuthorName = message.AuthorName,
                 RawRepresentation = message.RawRepresentation,

diff --git a/dotnet/src/Microsoft.Agents.AI.DurableTask/EntityAgentWrapper.cs b/dotnet/src/Microsoft.Agents.AI.DurableTask/EntityAgentWrapper.cs
@@ -21,20 +21,17 @@ internal sealed class EntityAgentWrapper(
     // The ID of the agent is always the entity ID.
     protected override string? IdCore => this._entityContext.Id.ToString();
 
-    protected override async Task<AgentResponse> RunCoreAsync(
+    protected override Task<AgentResponse> RunCoreAsync(
         IEnumerable<ChatMessage> messages,
         AgentSession? session = null,
         AgentRunOptions? options = null,
         CancellationToken cancellationToken = default)
     {
-        AgentResponse response = await base.RunCoreAsync(
+        return base.RunCoreAsync(
             messages,
             session,
             this.GetAgentEntityRunOptions(options),
             cancellationToken);
-
-        response.AgentId = this.Id;
-        return response;
     }
 
     protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingAsync(
@@ -49,7 +46,6 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
             this.GetAgentEntityRunOptions(options),
             cancellationToken))
         {
-            update.AgentId = this.Id;
             yield return update;
         }
     }

diff --git a/dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/InvokeAzureAgentExecutor.cs b/dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/InvokeAzureAgentExecutor.cs
@@ -70,7 +70,6 @@ private async ValueTask InvokeAgentAsync(IWorkflowContext context, IEnumerable<C
                 new(actionableMessages)
                 {
                     AdditionalProperties = agentResponse.AdditionalProperties,
-                    AgentId = agentResponse.AgentId,
                     CreatedAt = agentResponse.CreatedAt,
                     ResponseId = agentResponse.ResponseId,
                     Usage = agentResponse.Usage,

diff --git a/dotnet/src/Microsoft.Agents.AI.Workflows/MessageMerger.cs b/dotnet/src/Microsoft.Agents.AI.Workflows/MessageMerger.cs
@@ -119,11 +119,10 @@ private int CompareByDateTimeOffset(AgentResponse left, AgentResponse right)
         return left.CreatedAt.Value.CompareTo(right.CreatedAt.Value);
     }
 
-    public AgentResponse ComputeMerged(string primaryResponseId, string? primaryAgentId = null, string? primaryAgentName = null)
+    public AgentResponse ComputeMerged(string primaryResponseId)
     {
         List<ChatMessage> messages = [];
         Dictionary<string, AgentResponse> responses = [];
-        HashSet<string> agentIds = [];
 
         foreach (string responseId in this._mergeStates.Keys)
         {
@@ -146,11 +145,6 @@ public AgentResponse ComputeMerged(string primaryResponseId, string? primaryAgen
 
         foreach (AgentResponse response in responses.Values)
         {
-            if (response.AgentId is not null)
-            {
-                agentIds.Add(response.AgentId);
-            }
-
             if (response.CreatedAt.HasValue)
             {
                 createdTimes.Add(response.CreatedAt.Value);
@@ -179,9 +173,6 @@ public AgentResponse ComputeMerged(string primaryResponseId, string? primaryAgen
         return new AgentResponse(messages)
         {
             ResponseId = primaryResponseId,
-            AgentId = primaryAgentId
-                   ?? primaryAgentName
-                   ?? (agentIds.Count == 1 ? agentIds.First() : null),
             CreatedAt = DateTimeOffset.UtcNow,
             Usage = usage,
             AdditionalProperties = additionalProperties
@@ -204,7 +195,6 @@ static AgentResponse MergeResponses(AgentResponse? current, AgentResponse incomi
 
             return new()
             {
-                AgentId = incoming.AgentId ?? current.AgentId,
                 AdditionalProperties = MergeProperties(current.AdditionalProperties, incoming.AdditionalProperties),
                 CreatedAt = incoming.CreatedAt ?? current.CreatedAt,
                 Messages = current.Messages.Concat(incoming.Messages).ToList(),

diff --git a/dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/HandoffAgentExecutor.cs b/dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/HandoffAgentExecutor.cs
@@ -84,7 +84,6 @@ protected override RouteBuilder ConfigureRoutes(RouteBuilder routeBuilder) =>
                         await AddUpdateAsync(
                                 new AgentResponseUpdate
                                 {
-                                    AgentId = this._agent.Id,
                                     AuthorName = this._agent.Name ?? this._agent.Id,
                                     Contents = [new FunctionResultContent(fcc.CallId, "Transferred.")],
                                     CreatedAt = DateTimeOffset.UtcNow,

diff --git a/dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowHostAgent.cs b/dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowHostAgent.cs
@@ -105,7 +105,7 @@ Task<AgentResponse> RunCoreAsync(
             merger.AddUpdate(update);
         }
 
-        return merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
+        return merger.ComputeMerged(workflowSession.LastResponseId!);
     }
 
     protected override async

diff --git a/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs b/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs
@@ -262,7 +262,6 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
 
                 yield return new(update)
                 {
-                    AgentId = this.Id,
                     ContinuationToken = WrapContinuationToken(update.ContinuationToken, GetInputMessages(inputMessages, continuationToken), responseUpdates)
                 };
             }
@@ -465,11 +464,7 @@ private async Task<TAgentResponse> RunCoreAsync<TAgentResponse, TChatClientRespo
         // Notify the AIContextProvider of all new messages.
         await NotifyAIContextProviderOfSuccessAsync(safeSession, inputMessages, aiContextProviderMessages, chatResponse.Messages, cancellationToken).ConfigureAwait(false);
 
-        var agentResponse = agentResponseFactoryFunc(chatResponse);
-
-        agentResponse.AgentId = this.Id;
-
-        return agentResponse;
+        return agentResponseFactoryFunc(chatResponse);
     }
 
     /// <summary>

diff --git a/dotnet/src/Shared/Workflows/Execution/WorkflowRunner.cs b/dotnet/src/Shared/Workflows/Execution/WorkflowRunner.cs
@@ -185,7 +185,7 @@ public async Task ExecuteAsync(Func<Workflow> workflowProvider, string input)
 
                         if (messageId is not null)
                         {
-                            string? agentName = streamEvent.Update.AuthorName ?? streamEvent.Update.AgentId ?? nameof(ChatRole.Assistant);
+                            string? agentName = streamEvent.Update.AuthorName ?? streamEvent.ExecutorId ?? nameof(ChatRole.Assistant);
                             Console.ForegroundColor = ConsoleColor.Cyan;
                             Console.Write($"\n{agentName.ToUpperInvariant()}:");
                             Console.ForegroundColor = ConsoleColor.DarkGray;

diff --git a/dotnet/tests/AgentConformance.IntegrationTests/RunTests.cs b/dotnet/tests/AgentConformance.IntegrationTests/RunTests.cs
@@ -49,7 +49,6 @@ public virtual async Task RunWithStringReturnsExpectedResultAsync()
         Assert.NotNull(response);
         Assert.Single(response.Messages);
         Assert.Contains("Paris", response.Text);
-        Assert.Equal(agent.Id, response.AgentId);
     }
 
     [RetryFact(Constants.RetryCount, Constants.RetryDelay)]
-Original file line number
+Diff line change
@@ Expand Up @@
                     AdditionalProperties = chatUpdate.AdditionalProperties
                 })
                 {
-                    AgentId = update.AgentId,
                     ContinuationToken = update.ContinuationToken,
                 };
             }
@@ Expand Down @@