.NET: Include workflow outputs in hosted agent responses

dotnet/samples/02-agents/DevUI/DevUI_Step01_BasicUsage/README.md

@@ -63,6 +63,12 @@ To add DevUI to your ASP.NET Core application:
        .AddAsAIAgent();
    ```
 
+   `AddAsAIAgent()` includes the workflow's final output in the hosted agent response. This is
+   required when the workflow is exposed through `MapOpenAIResponses()` or
+   `MapOpenAIConversations()`; otherwise the output can be visible in streaming workflow events
+   while the completed response has no output items. If you create an agent directly from a
+   `Workflow`, opt in with `workflow.AsAIAgent(includeWorkflowOutputsInResponse: true)`.
+
 3. Add OpenAI services and map the endpoints for OpenAI and DevUI:
    ```csharp
    // Register services for OpenAI responses and conversations (also required for DevUI)

dotnet/src/Microsoft.Agents.AI.Hosting/HostedWorkflowBuilderExtensions.cs

@@ -15,6 +15,7 @@ public static class HostedWorkflowBuilderExtensions
     /// </summary>
     /// <param name="builder">The <see cref="IHostedWorkflowBuilder"/> instance to extend.</param>
     /// <param name="lifetime">The DI service lifetime for the agent registration. Defaults to <see cref="ServiceLifetime.Singleton"/>.</param>
+    /// <remarks>Workflow outputs are included in the hosted agent response.</remarks>
     /// <returns>An <see cref="IHostedAgentBuilder"/> that can be used to further configure the agent.</returns>
     public static IHostedAgentBuilder AddAsAIAgent(this IHostedWorkflowBuilder builder, ServiceLifetime lifetime = ServiceLifetime.Singleton)
         => builder.AddAsAIAgent(name: null, lifetime: lifetime);
@@ -25,13 +26,16 @@ public static IHostedAgentBuilder AddAsAIAgent(this IHostedWorkflowBuilder build
     /// <param name="builder">The <see cref="IHostedWorkflowBuilder"/> instance to extend.</param>
     /// <param name="name">The optional name for the AI agent. If not specified, the workflow name is used.</param>
     /// <param name="lifetime">The DI service lifetime for the agent registration. Defaults to <see cref="ServiceLifetime.Singleton"/>.</param>
+    /// <remarks>Workflow outputs are included in the hosted agent response.</remarks>
     /// <returns>An <see cref="IHostedAgentBuilder"/> that can be used to further configure the agent.</returns>
     public static IHostedAgentBuilder AddAsAIAgent(this IHostedWorkflowBuilder builder, string? name, ServiceLifetime lifetime = ServiceLifetime.Singleton)
     {
         var workflowName = builder.Name;
         var agentName = name ?? workflowName;
 
         return builder.HostApplicationBuilder.AddAIAgent(agentName, (sp, key) =>
-            sp.GetRequiredKeyedService<Workflow>(workflowName).AsAIAgent(name: key), lifetime);
+            sp.GetRequiredKeyedService<Workflow>(workflowName).AsAIAgent(
+                name: key,
+                includeWorkflowOutputsInResponse: true), lifetime);
     }
 }

dotnet/tests/Microsoft.Agents.AI.Hosting.UnitTests/ChatMessageOutputWorkflow.cs

@@ -0,0 +1,33 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Agents.AI.Workflows;
+using Microsoft.Extensions.AI;
+
+namespace Microsoft.Agents.AI.Hosting.UnitTests;
+
+internal static class ChatMessageOutputWorkflow
+{
+    internal static Workflow Build(string name)
+    {
+        var output = new OutputExecutor("output");
+        return new WorkflowBuilder(output)
+            .WithName(name)
+            .WithOutputFrom(output)
+            .Build();
+    }
+
+    private sealed class OutputExecutor(string id) : ChatProtocolExecutor(id)
+    {
+        protected override ValueTask TakeTurnAsync(
+            List<ChatMessage> messages,
+            IWorkflowContext context,
+            bool? emitEvents,
+            CancellationToken cancellationToken = default)
+            => context.AddEventAsync(
+                new WorkflowOutputEvent(new ChatMessage(ChatRole.Assistant, "workflow output"), this.Id),
+                cancellationToken);
+    }
+}

dotnet/tests/Microsoft.Agents.AI.Hosting.UnitTests/HostApplicationBuilderWorkflowExtensionsTests.cs

@@ -2,7 +2,9 @@
 
 using System;
 using System.Linq;
+using System.Threading.Tasks;
 using Microsoft.Agents.AI.Workflows;
+using Microsoft.Extensions.AI;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Moq;
@@ -186,6 +188,27 @@ public void AddAsAIAgent_WithoutName_UsesWorkflowName()
         Assert.NotNull(agentDescriptor);
     }
 
+    /// <summary>
+    /// Verifies that a workflow registered as an AI agent includes its chat-message output in the response.
+    /// </summary>
+    [Fact]
+    public async Task AddAsAIAgent_IncludesWorkflowOutputInResponseAsync()
+    {
+        // Arrange
+        var builder = new HostApplicationBuilder();
+        const string WorkflowName = "outputWorkflow";
+        builder.AddWorkflow(WorkflowName, (sp, key) => ChatMessageOutputWorkflow.Build(key))
+            .AddAsAIAgent();
+        using var host = builder.Build();
+        AIAgent agent = host.Services.GetRequiredKeyedService<AIAgent>(WorkflowName);
+
+        // Act
+        AgentResponse response = await agent.RunAsync(new ChatMessage(ChatRole.User, "hello"));
+
+        // Assert
+        Assert.Equal("workflow output", response.Text);
+    }
+
     /// <summary>
     /// Verifies that AddAsAIAgent with a name parameter uses that name instead of the workflow name.
     /// </summary>