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.NET: fix: HandoffAgentExecutor does not output any response when non-streaming #4745

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.NET: fix: HandoffAgentExecutor does not output any response when non-streaming #4745

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184fc14
fix: HandoffAgentExecutor does not output any reponse when non-streaming
lokitoth Mar 17, 2026
b4d1b49
fix: Ensure Workflow outputs persisted in chat history when hosted As…
lokitoth Mar 17, 2026
9665b2d
fix: Remove duplicate history entry creation and ad test
lokitoth Mar 17, 2026
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13 changes: 12 additions & 1 deletion dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/HandoffAgentExecutor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -250,7 +250,18 @@ await AddUpdateAsync(
}
}

allMessages.AddRange(updates.ToAgentResponse().Messages);
AgentResponse agentResponse = updates.ToAgentResponse();

// Since there is no good way to configure the agent output behaviour due to how we add it to Handoff orchestration
// configurations, treat the emitEvents flag as simply determining whether to stream updates or to emit the whole response
// It would make little sense to avoid emitting any agent responses since this is only used in Orchestration workflows,
// which are Agent-only, and thus would do nothing.
if (message.TurnToken.EmitEvents is not true)
{
await context.YieldOutputAsync(agentResponse, cancellationToken).ConfigureAwait(false);
}

allMessages.AddRange(agentResponse.Messages);

roleChanges.ResetUserToAssistantForChangedRoles();

Expand Down
8 changes: 7 additions & 1 deletion dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowChatHistoryProvider.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ internal void AddMessages(AgentSession session, params IEnumerable<ChatMessage>
=> this._sessionState.GetOrInitializeState(session).Messages.AddRange(messages);

protected override ValueTask<IEnumerable<ChatMessage>> ProvideChatHistoryAsync(InvokingContext context, CancellationToken cancellationToken = default)
=> new(this._sessionState.GetOrInitializeState(context.Session).Messages);
=> new(this._sessionState.GetOrInitializeState(context.Session).Messages.AsReadOnly());

protected override ValueTask StoreChatHistoryAsync(InvokedContext context, CancellationToken cancellationToken = default)
{
Expand All @@ -62,6 +62,12 @@ public IEnumerable<ChatMessage> GetFromBookmark(AgentSession session)
}
}

public IEnumerable<ChatMessage> GetAllMessages(AgentSession session)
{
var state = this._sessionState.GetOrInitializeState(session);
return state.Messages.AsReadOnly();
}

public void UpdateBookmark(AgentSession session)
{
var state = this._sessionState.GetOrInitializeState(session);
Expand Down
17 changes: 14 additions & 3 deletions dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowHostAgent.cs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -119,13 +119,17 @@ Task<AgentResponse> RunCoreAsync(
MessageMerger merger = new();

await foreach (AgentResponseUpdate update in workflowSession.InvokeStageAsync(cancellationToken)
.ConfigureAwait(false)
.WithCancellation(cancellationToken))
.ConfigureAwait(false)
.WithCancellation(cancellationToken))
{
merger.AddUpdate(update);
}

return merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
AgentResponse response = merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
workflowSession.ChatHistoryProvider.AddMessages(workflowSession, response.Messages);
workflowSession.ChatHistoryProvider.UpdateBookmark(workflowSession);

return response;
}

protected override async
Expand All @@ -138,11 +142,18 @@ IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingAsync(
await this.ValidateWorkflowAsync().ConfigureAwait(false);

WorkflowSession workflowSession = await this.UpdateSessionAsync(messages, session, cancellationToken).ConfigureAwait(false);
MessageMerger merger = new();

await foreach (AgentResponseUpdate update in workflowSession.InvokeStageAsync(cancellationToken)
.ConfigureAwait(false)
.WithCancellation(cancellationToken))
{
merger.AddUpdate(update);
yield return update;
}

AgentResponse response = merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
workflowSession.ChatHistoryProvider.AddMessages(workflowSession, response.Messages);
workflowSession.ChatHistoryProvider.UpdateBookmark(workflowSession);
}
}
164 changes: 74 additions & 90 deletions dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowSession.cs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -110,35 +110,27 @@ public AgentResponseUpdate CreateUpdate(string responseId, object raw, params AI
{
Throw.IfNullOrEmpty(parts);

AgentResponseUpdate update = new(ChatRole.Assistant, parts)
return new(ChatRole.Assistant, parts)
{
CreatedAt = DateTimeOffset.UtcNow,
MessageId = Guid.NewGuid().ToString("N"),
Role = ChatRole.Assistant,
ResponseId = responseId,
RawRepresentation = raw
};

this.ChatHistoryProvider.AddMessages(this, update.ToChatMessage());

return update;
}

public AgentResponseUpdate CreateUpdate(string responseId, object raw, ChatMessage message)
{
Throw.IfNull(message);

AgentResponseUpdate update = new(message.Role, message.Contents)
return new(message.Role, message.Contents)
{
CreatedAt = message.CreatedAt ?? DateTimeOffset.UtcNow,
MessageId = message.MessageId ?? Guid.NewGuid().ToString("N"),
ResponseId = responseId,
RawRepresentation = raw
};

this.ChatHistoryProvider.AddMessages(this, update.ToChatMessage());

return update;
}

private async ValueTask<StreamingRun> CreateOrResumeRunAsync(List<ChatMessage> messages, CancellationToken cancellationToken = default)
Expand Down Expand Up @@ -170,94 +162,86 @@ internal async
IAsyncEnumerable<AgentResponseUpdate> InvokeStageAsync(
[EnumeratorCancellation] CancellationToken cancellationToken = default)
{
try
{
this.LastResponseId = Guid.NewGuid().ToString("N");
List<ChatMessage> messages = this.ChatHistoryProvider.GetFromBookmark(this).ToList();
this.LastResponseId = Guid.NewGuid().ToString("N");
List<ChatMessage> messages = this.ChatHistoryProvider.GetFromBookmark(this).ToList();

#pragma warning disable CA2007 // Analyzer misfiring and not seeing .ConfigureAwait(false) below.
await using StreamingRun run =
await this.CreateOrResumeRunAsync(messages, cancellationToken).ConfigureAwait(false);
await using StreamingRun run =
await this.CreateOrResumeRunAsync(messages, cancellationToken).ConfigureAwait(false);
#pragma warning restore CA2007

await run.TrySendMessageAsync(new TurnToken(emitEvents: true)).ConfigureAwait(false);
await foreach (WorkflowEvent evt in run.WatchStreamAsync(blockOnPendingRequest: false, cancellationToken)
.ConfigureAwait(false)
.WithCancellation(cancellationToken))
await run.TrySendMessageAsync(new TurnToken(emitEvents: true)).ConfigureAwait(false);
await foreach (WorkflowEvent evt in run.WatchStreamAsync(blockOnPendingRequest: false, cancellationToken)
.ConfigureAwait(false)
.WithCancellation(cancellationToken))
{
switch (evt)
{
switch (evt)
{
case AgentResponseUpdateEvent agentUpdate:
yield return agentUpdate.Update;
break;

case RequestInfoEvent requestInfo:
FunctionCallContent fcContent = requestInfo.Request.ToFunctionCall();
AgentResponseUpdate update = this.CreateUpdate(this.LastResponseId, evt, fcContent);
yield return update;
break;

case WorkflowErrorEvent workflowError:
Exception? exception = workflowError.Exception;
if (exception is TargetInvocationException tie && tie.InnerException != null)
{
exception = tie.InnerException;
}

if (exception != null)
{
string message = this._includeExceptionDetails
? exception.Message
: "An error occurred while executing the workflow.";

ErrorContent errorContent = new(message);
yield return this.CreateUpdate(this.LastResponseId, evt, errorContent);
}

break;

case SuperStepCompletedEvent stepCompleted:
this.LastCheckpoint = stepCompleted.CompletionInfo?.Checkpoint;
case AgentResponseUpdateEvent agentUpdate:
yield return agentUpdate.Update;
break;

case RequestInfoEvent requestInfo:
FunctionCallContent fcContent = requestInfo.Request.ToFunctionCall();
AgentResponseUpdate update = this.CreateUpdate(this.LastResponseId, evt, fcContent);
yield return update;
break;

case WorkflowErrorEvent workflowError:
Exception? exception = workflowError.Exception;
if (exception is TargetInvocationException tie && tie.InnerException != null)
{
exception = tie.InnerException;
}

if (exception != null)
{
string message = this._includeExceptionDetails
? exception.Message
: "An error occurred while executing the workflow.";

ErrorContent errorContent = new(message);
yield return this.CreateUpdate(this.LastResponseId, evt, errorContent);
}

break;

case SuperStepCompletedEvent stepCompleted:
this.LastCheckpoint = stepCompleted.CompletionInfo?.Checkpoint;
goto default;

case WorkflowOutputEvent output:
IEnumerable<ChatMessage>? updateMessages = output.Data switch
{
IEnumerable<ChatMessage> chatMessages => chatMessages,
ChatMessage chatMessage => [chatMessage],
_ => null
};

if (!this._includeWorkflowOutputsInResponse || updateMessages == null)
{
goto default;

case WorkflowOutputEvent output:
IEnumerable<ChatMessage>? updateMessages = output.Data switch
{
IEnumerable<ChatMessage> chatMessages => chatMessages,
ChatMessage chatMessage => [chatMessage],
_ => null
};

if (!this._includeWorkflowOutputsInResponse || updateMessages == null)
{
goto default;
}

foreach (ChatMessage message in updateMessages)
{
yield return this.CreateUpdate(this.LastResponseId, evt, message);
}
break;

default:
// Emit all other workflow events for observability (DevUI, logging, etc.)
yield return new AgentResponseUpdate(ChatRole.Assistant, [])
{
CreatedAt = DateTimeOffset.UtcNow,
MessageId = Guid.NewGuid().ToString("N"),
Role = ChatRole.Assistant,
ResponseId = this.LastResponseId,
RawRepresentation = evt
};
break;
}
}

foreach (ChatMessage message in updateMessages)
{
yield return this.CreateUpdate(this.LastResponseId, evt, message);
}
break;

default:
// Emit all other workflow events for observability (DevUI, logging, etc.)
yield return new AgentResponseUpdate(ChatRole.Assistant, [])
{
CreatedAt = DateTimeOffset.UtcNow,
MessageId = Guid.NewGuid().ToString("N"),
Role = ChatRole.Assistant,
ResponseId = this.LastResponseId,
RawRepresentation = evt
};
break;
}
}
finally
{
// Do we want to try to undo the step, and not update the bookmark?
this.ChatHistoryProvider.UpdateBookmark(this);
}
}

public string? LastResponseId { get; set; }
Expand Down
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