Add AutoYieldOutputHandlerResultObject support to WorkflowHostExecutor

- Added YieldOutputAsync method to ISuperStepJoinContext interface
- Implemented YieldOutputAsync in InProcessRunnerContext
- Updated WorkflowHostExecutor to check AutoYieldOutputHandlerResultObject option
- Updated TestRunContext to implement YieldOutputAsync
- Added unit tests for the new functionality

Co-authored-by: lokitoth <6936551+lokitoth@users.noreply.github.com>

dotnet/src/Microsoft.Agents.AI.Workflows/Execution/ISuperStepJoinContext.cs

@@ -13,6 +13,7 @@ internal interface ISuperStepJoinContext
 
     ValueTask ForwardWorkflowEventAsync(WorkflowEvent workflowEvent, CancellationToken cancellationToken = default);
     ValueTask SendMessageAsync<TMessage>(string senderId, [DisallowNull] TMessage message, CancellationToken cancellationToken = default);
+    ValueTask YieldOutputAsync(string sourceId, object output, CancellationToken cancellationToken = default);
 
     ValueTask<string> AttachSuperstepAsync(ISuperStepRunner superStepRunner, CancellationToken cancellationToken = default);
     ValueTask<bool> DetachSuperstepAsync(string id);

dotnet/src/Microsoft.Agents.AI.Workflows/InProc/InProcessRunnerContext.cs

@@ -429,4 +429,21 @@ internal sealed class InProcessRunnerContext : IRunnerContext
 
     ValueTask ISuperStepJoinContext.SendMessageAsync<TMessage>(string senderId, [DisallowNull] TMessage message, CancellationToken cancellationToken)
         => this.SendMessageAsync(senderId, Throw.IfNull(message), cancellationToken: cancellationToken);
+
+    async ValueTask ISuperStepJoinContext.YieldOutputAsync(string sourceId, object output, CancellationToken cancellationToken)
+    {
+        this.CheckEnded();
+        Throw.IfNull(output);
+
+        Executor sourceExecutor = await this.EnsureExecutorAsync(sourceId, tracer: null, cancellationToken).ConfigureAwait(false);
+        if (!sourceExecutor.CanOutput(output.GetType()))
+        {
+            throw new InvalidOperationException($"Cannot output object of type {output.GetType().Name}. Expecting one of [{string.Join(", ", sourceExecutor.OutputTypes)}].");
+        }
+
+        if (this._outputFilter.CanOutput(sourceId, output))
+        {
+            await this.AddEventAsync(new WorkflowOutputEvent(output, sourceId), cancellationToken).ConfigureAwait(false);
+        }
+    }
 }

dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/WorkflowHostExecutor.cs

@@ -192,11 +192,16 @@ internal class WorkflowHostExecutor : Executor, IAsyncDisposable
                     resultTask = this._joinContext?.ForwardWorkflowEventAsync(new SubworkflowErrorEvent(this.Id, errorEvent.Data as Exception)).AsTask() ?? Task.CompletedTask;
                     break;
                 case WorkflowOutputEvent outputEvent:
-                    if (this._joinContext != null &&
-                        this._options.AutoSendMessageHandlerResultObject
-                        && outputEvent.Data != null)
+                    if (this._joinContext != null && outputEvent.Data != null)
                     {
-                        resultTask = this._joinContext.SendMessageAsync(this.Id, outputEvent.Data).AsTask();
+                        if (this._options.AutoSendMessageHandlerResultObject)
+                        {
+                            resultTask = this._joinContext.SendMessageAsync(this.Id, outputEvent.Data).AsTask();
+                        }
+                        else if (this._options.AutoYieldOutputHandlerResultObject)
+                        {
+                            resultTask = this._joinContext.YieldOutputAsync(this.Id, outputEvent.Data).AsTask();
+                        }
                     }
                     break;
                 case RequestHaltEvent requestHaltEvent:

dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/TestRunContext.cs

@@ -107,6 +107,9 @@ public class TestRunContext : IRunnerContext
     public ValueTask SendMessageAsync<TMessage>(string senderId, [System.Diagnostics.CodeAnalysis.DisallowNull] TMessage message, CancellationToken cancellationToken = default)
         => this.SendMessageAsync(senderId, message, cancellationToken);
 
+    public ValueTask YieldOutputAsync(string sourceId, object output, CancellationToken cancellationToken = default)
+        => this.AddEventAsync(new WorkflowOutputEvent(output, sourceId), cancellationToken);
+
     ValueTask<string> ISuperStepJoinContext.AttachSuperstepAsync(ISuperStepRunner superStepRunner, CancellationToken cancellationToken) => new(string.Empty);
     ValueTask<bool> ISuperStepJoinContext.DetachSuperstepAsync(string joinId) => new(false);
 }

dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/WorkflowHostExecutorTests.cs

@@ -0,0 +1,171 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.Agents.AI.Workflows.Specialized;
+
+namespace Microsoft.Agents.AI.Workflows.UnitTests;
+
+public sealed class WorkflowHostExecutorTests
+{
+    [Fact]
+    public async Task ForwardWorkflowEventAsync_WithAutoYieldOutputHandlerResultObjectTrue_YieldsOutput()
+    {
+        // Arrange
+        const string testData = "test output data";
+        WorkflowOutputEvent outputEvent = new(testData, "SubworkflowExecutor");
+
+        TestRunContext testContext = new();
+
+        ExecutorOptions options = new()
+        {
+            AutoSendMessageHandlerResultObject = false,
+            AutoYieldOutputHandlerResultObject = true
+        };
+
+        Workflow emptyWorkflow = new WorkflowBuilder(new SimpleTestExecutor("start")).Build();
+        TestableWorkflowHostExecutor hostExecutor = new("TestHost", emptyWorkflow, "run1", new object(), options);
+
+        await hostExecutor.AttachSuperStepContextAsync(testContext);
+
+        // Act
+        await hostExecutor.SimulateForwardWorkflowEventAsync(outputEvent);
+
+        // Assert
+        testContext.Events.OfType<WorkflowOutputEvent>().Should().HaveCount(1, "YieldOutputAsync should create one WorkflowOutputEvent");
+        WorkflowOutputEvent? yieldedEvent = testContext.Events.OfType<WorkflowOutputEvent>().FirstOrDefault();
+        yieldedEvent.Should().NotBeNull();
+        yieldedEvent!.SourceId.Should().Be("TestHost");
+        yieldedEvent.As<string>().Should().Be(testData);
+
+        testContext.QueuedMessages.Should().BeEmpty("SendMessageAsync should not be called");
+    }
+
+    [Fact]
+    public async Task ForwardWorkflowEventAsync_WithAutoSendMessageHandlerResultObjectTrue_SendsMessage()
+    {
+        // Arrange
+        const string testData = "test output data";
+        WorkflowOutputEvent outputEvent = new(testData, "SubworkflowExecutor");
+
+        TestRunContext testContext = new();
+
+        ExecutorOptions options = new()
+        {
+            AutoSendMessageHandlerResultObject = true,
+            AutoYieldOutputHandlerResultObject = false
+        };
+
+        Workflow emptyWorkflow = new WorkflowBuilder(new SimpleTestExecutor("start")).Build();
+        TestableWorkflowHostExecutor hostExecutor = new("TestHost", emptyWorkflow, "run1", new object(), options);
+
+        await hostExecutor.AttachSuperStepContextAsync(testContext);
+
+        // Act
+        await hostExecutor.SimulateForwardWorkflowEventAsync(outputEvent);
+
+        // Assert
+        testContext.QueuedMessages.Should().ContainKey("TestHost");
+        testContext.QueuedMessages["TestHost"].Should().HaveCount(1);
+        testContext.QueuedMessages["TestHost"][0].Message.Should().Be(testData);
+
+        testContext.Events.OfType<WorkflowOutputEvent>().Should().BeEmpty("YieldOutputAsync should not be called");
+    }
+
+    [Fact]
+    public async Task ForwardWorkflowEventAsync_WithBothOptionsFalse_DoesNothing()
+    {
+        // Arrange
+        const string testData = "test output data";
+        WorkflowOutputEvent outputEvent = new(testData, "SubworkflowExecutor");
+
+        TestRunContext testContext = new();
+
+        ExecutorOptions options = new()
+        {
+            AutoSendMessageHandlerResultObject = false,
+            AutoYieldOutputHandlerResultObject = false
+        };
+
+        Workflow emptyWorkflow = new WorkflowBuilder(new SimpleTestExecutor("start")).Build();
+        TestableWorkflowHostExecutor hostExecutor = new("TestHost", emptyWorkflow, "run1", new object(), options);
+
+        await hostExecutor.AttachSuperStepContextAsync(testContext);
+
+        // Act
+        await hostExecutor.SimulateForwardWorkflowEventAsync(outputEvent);
+
+        // Assert
+        testContext.QueuedMessages.Should().BeEmpty("SendMessageAsync should not be called");
+        testContext.Events.OfType<WorkflowOutputEvent>().Should().BeEmpty("YieldOutputAsync should not be called");
+    }
+
+    [Fact]
+    public async Task ForwardWorkflowEventAsync_WithNullOutputData_DoesNothing()
+    {
+        // Arrange
+        WorkflowOutputEvent outputEvent = new(null!, "SubworkflowExecutor");
+
+        TestRunContext testContext = new();
+
+        ExecutorOptions options = new()
+        {
+            AutoSendMessageHandlerResultObject = false,
+            AutoYieldOutputHandlerResultObject = true
+        };
+
+        Workflow emptyWorkflow = new WorkflowBuilder(new SimpleTestExecutor("start")).Build();
+        TestableWorkflowHostExecutor hostExecutor = new("TestHost", emptyWorkflow, "run1", new object(), options);
+
+        await hostExecutor.AttachSuperStepContextAsync(testContext);
+
+        // Act
+        await hostExecutor.SimulateForwardWorkflowEventAsync(outputEvent);
+
+        // Assert
+        testContext.Events.OfType<WorkflowOutputEvent>().Should().BeEmpty("YieldOutputAsync should not be called when data is null");
+        testContext.QueuedMessages.Should().BeEmpty("SendMessageAsync should not be called when data is null");
+    }
+
+    /// <summary>
+    /// Simple executor for testing that doesn't require type parameters.
+    /// </summary>
+    private sealed class SimpleTestExecutor : Executor
+    {
+        public SimpleTestExecutor(string id) : base(id)
+        {
+        }
+
+        protected override RouteBuilder ConfigureRoutes(RouteBuilder routeBuilder) => routeBuilder;
+    }
+
+    /// <summary>
+    /// Testable wrapper for WorkflowHostExecutor that exposes internal methods for testing.
+    /// </summary>
+    private sealed class TestableWorkflowHostExecutor : WorkflowHostExecutor
+    {
+        public TestableWorkflowHostExecutor(string id, Workflow workflow, string runId, object ownershipToken, ExecutorOptions? options = null)
+            : base(id, workflow, runId, ownershipToken, options)
+        {
+        }
+
+        public async ValueTask SimulateForwardWorkflowEventAsync(WorkflowEvent evt)
+        {
+            // Use reflection to invoke the private ForwardWorkflowEventAsync method
+            System.Reflection.MethodInfo? method = typeof(WorkflowHostExecutor)
+                .GetMethod("ForwardWorkflowEventAsync", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+
+            if (method != null)
+            {
+                object? result = method.Invoke(this, [null, evt]);
+                if (result is ValueTask valueTask)
+                {
+                    await valueTask;
+                }
+            }
+        }
+    }
+}