.NET: Update M.A.AI.OpenAI implementations (#1018)

* Update M.A.AI.OpenAI implementations

- There was only a ChatClient-based agent. Add a Responses one, too.
- Fix the public extension methods to create OpenAI types even when not backed by the right OpenAI client.
- Add reusable AgentRunResponse{Update} to ChatResponse{Update} conversion routines that are then used by the OpenAI agents and elsewhere

* Address feedback

dotnet/src/Microsoft.Agents.AI.Abstractions/AgentRunResponseExtensions.cs

@@ -14,10 +14,91 @@ using Microsoft.Shared.Diagnostics;
 namespace Microsoft.Agents.AI;
 
 /// <summary>
-/// Provides extension methods for working with <see cref="AgentRunResponseUpdate"/> instances.
+/// Provides extension methods for working with <see cref="AgentRunResponse"/> and <see cref="AgentRunResponseUpdate"/> instances.
 /// </summary>
-public static class AgentRunResponseUpdateExtensions
+public static class AgentRunResponseExtensions
 {
+    /// <summary>
+    /// Creates a <see cref="ChatResponse"/> from an <see cref="AgentRunResponse"/>.
+    /// </summary>
+    /// <param name="response">The <see cref="AgentRunResponse"/>.</param>
+    /// <returns>A <see cref="ChatResponse"/> built from <paramref name="response"/>.</returns>
+    /// <remarks>
+    /// If the <paramref name="response"/>'s <see cref="AgentRunResponse.RawRepresentation"/> is a
+    /// <see cref="ChatResponse"/> instance, that instance is returned directly. Otherwise, a new
+    /// <see cref="ChatResponse"/> is created and populated with the data from the <paramref name="response"/>.
+    /// The instance is a shallow copy; any reference-type members (e.g. <see cref="AgentRunResponse.Messages"/>)
+    /// will be shared between the two instances.
+    /// </remarks>
+    public static ChatResponse AsChatResponse(this AgentRunResponse response)
+    {
+        Throw.IfNull(response);
+
+        return
+            response.RawRepresentation as ChatResponse ??
+            new()
+            {
+                AdditionalProperties = response.AdditionalProperties,
+                CreatedAt = response.CreatedAt,
+                Messages = response.Messages,
+                RawRepresentation = response,
+                ResponseId = response.ResponseId,
+                Usage = response.Usage,
+            };
+    }
+
+    /// <summary>
+    /// Creates a <see cref="ChatResponseUpdate"/> from an <see cref="AgentRunResponseUpdate"/>.
+    /// </summary>
+    /// <param name="responseUpdate">The <see cref="AgentRunResponseUpdate"/>.</param>
+    /// <returns>A <see cref="ChatResponseUpdate"/> built from <paramref name="responseUpdate"/>.</returns>
+    /// <remarks>
+    /// If the <paramref name="responseUpdate"/>'s <see cref="AgentRunResponseUpdate.RawRepresentation"/> is a
+    /// <see cref="ChatResponseUpdate"/> instance, that instance is returned directly. Otherwise, a new
+    /// <see cref="ChatResponseUpdate"/> is created and populated with the data from the <paramref name="responseUpdate"/>.
+    /// The instance is a shallow copy; any reference-type members (e.g. <see cref="AgentRunResponseUpdate.Contents"/>)
+    /// will be shared between the two instances.
+    /// </remarks>
+    public static ChatResponseUpdate AsChatResponseUpdate(this AgentRunResponseUpdate responseUpdate)
+    {
+        Throw.IfNull(responseUpdate);
+
+        return
+            responseUpdate.RawRepresentation as ChatResponseUpdate ??
+            new()
+            {
+                AdditionalProperties = responseUpdate.AdditionalProperties,
+                AuthorName = responseUpdate.AuthorName,
+                Contents = responseUpdate.Contents,
+                CreatedAt = responseUpdate.CreatedAt,
+                MessageId = responseUpdate.MessageId,
+                RawRepresentation = responseUpdate,
+                ResponseId = responseUpdate.ResponseId,
+                Role = responseUpdate.Role,
+            };
+    }
+
+    /// <summary>
+    /// Creates an asynchronous enumerable of <see cref="ChatResponseUpdate"/> instances from an asynchronous
+    /// enumerable of <see cref="AgentRunResponseUpdate"/> instances.
+    /// </summary>
+    /// <param name="responseUpdates">The sequence <see cref="AgentRunResponseUpdate"/>.</param>
+    /// <returns>A sequence of <see cref="ChatResponseUpdate"/> instances built from <paramref name="responseUpdates"/>.</returns>
+    /// <remarks>
+    /// Each <see cref="AgentRunResponseUpdate"/> is converted to a <see cref="ChatResponseUpdate"/> using
+    /// <see cref="AsChatResponseUpdate"/>.
+    /// </remarks>
+    public static async IAsyncEnumerable<ChatResponseUpdate> AsChatResponseUpdatesAsync(
+        this IAsyncEnumerable<AgentRunResponseUpdate> responseUpdates)
+    {
+        Throw.IfNull(responseUpdates);
+
+        await foreach (var responseUpdate in responseUpdates.ConfigureAwait(false))
+        {
+            yield return responseUpdate.AsChatResponseUpdate();
+        }
+    }
+
     /// <summary>Combines <see cref="AgentRunResponseUpdate"/> instances into a single <see cref="AgentRunResponse"/>.</summary>
     /// <param name="updates">The updates to be combined.</param>
     /// <returns>The combined <see cref="AgentRunResponse"/>.</returns>

dotnet/src/Microsoft.Agents.AI.Abstractions/AgentRunResponseUpdate.cs

@@ -22,7 +22,7 @@ namespace Microsoft.Agents.AI;
 /// </para>
 /// <para>
 /// The relationship between <see cref="AgentRunResponse"/> and <see cref="AgentRunResponseUpdate"/> is
-/// codified in the <see cref="AgentRunResponseUpdateExtensions.ToAgentRunResponseAsync"/> and
+/// codified in the <see cref="AgentRunResponseExtensions.ToAgentRunResponseAsync"/> and
 /// <see cref="AgentRunResponse.ToAgentRunResponseUpdates"/>, which enable bidirectional conversions
 /// between the two. Note, however, that the provided conversions may be lossy, for example if multiple
 /// updates all have different <see cref="RawRepresentation"/> objects whereas there's only one slot for
@@ -135,7 +135,7 @@ public class AgentRunResponseUpdate
     /// Some providers may consider streaming responses to be a single message, and in that case
     /// the value of this property may be the same as the response ID.
     ///
-    /// This value is used when <see cref="AgentRunResponseUpdateExtensions.ToAgentRunResponseAsync(IAsyncEnumerable{AgentRunResponseUpdate}, System.Threading.CancellationToken)"/>
+    /// This value is used when <see cref="AgentRunResponseExtensions.ToAgentRunResponseAsync(IAsyncEnumerable{AgentRunResponseUpdate}, System.Threading.CancellationToken)"/>
     /// groups <see cref="AgentRunResponseUpdate"/> instances into <see cref="AgentRunResponse"/> instances.
     /// The value must be unique to each call to the underlying provider, and must be shared by
     /// all updates that are part of the same logical message within a streaming response.

dotnet/src/Microsoft.Agents.AI.OpenAI/ChatClient/AsyncStreamingUpdateCollectionResult.cs

@@ -3,7 +3,7 @@
 using System.ClientModel;
 using OpenAI.Chat;
 
-namespace Microsoft.Agents.AI.OpenAI.ChatClient;
+namespace Microsoft.Agents.AI.OpenAI;
 
 internal sealed class AsyncStreamingUpdateCollectionResult : AsyncCollectionResult<StreamingChatCompletionUpdate>
 {
@@ -19,13 +19,10 @@ internal sealed class AsyncStreamingUpdateCollectionResult : AsyncCollectionResu
     public override IAsyncEnumerable<ClientResult> GetRawPagesAsync() =>
         AsyncEnumerable.Repeat(ClientResult.FromValue(this._updates, new StreamingUpdatePipelineResponse(this._updates)), 1);
 
-    protected override async IAsyncEnumerable<StreamingChatCompletionUpdate> GetValuesFromPageAsync(ClientResult page)
+    protected override IAsyncEnumerable<StreamingChatCompletionUpdate> GetValuesFromPageAsync(ClientResult page)
     {
         var updates = ((ClientResult<IAsyncEnumerable<AgentRunResponseUpdate>>)page).Value;
 
-        await foreach (var update in updates.ConfigureAwait(false))
-        {
-            yield return update.AsStreamingChatCompletionUpdate();
-        }
+        return updates.AsChatResponseUpdatesAsync().AsOpenAIStreamingChatCompletionUpdatesAsync();
     }
 }

dotnet/src/Microsoft.Agents.AI.OpenAI/ChatClient/StreamingUpdatePipelineResponse.cs

@@ -2,7 +2,7 @@
 
 using System.ClientModel.Primitives;
 
-namespace Microsoft.Agents.AI.OpenAI.ChatClient;
+namespace Microsoft.Agents.AI.OpenAI;
 
 internal sealed class StreamingUpdatePipelineResponse : PipelineResponse
 {

dotnet/src/Microsoft.Agents.AI.OpenAI/Extensions/AIAgentWithOpenAIExtensions.cs

@@ -2,7 +2,7 @@
 
 using System.ClientModel;
 using Microsoft.Agents.AI;
-using Microsoft.Agents.AI.OpenAI.ChatClient;
+using Microsoft.Agents.AI.OpenAI;
 using Microsoft.Shared.Diagnostics;
 using OpenAI.Chat;
 
@@ -34,7 +34,7 @@ public static class AIAgentWithOpenAIExtensions
     /// <exception cref="NotSupportedException">Thrown when any message in <paramref name="messages"/> has a type that is not supported by the message conversion method.</exception>
     /// <remarks>
     /// This method converts the OpenAI chat messages to the Microsoft Extensions AI format using the appropriate conversion method,
-    /// runs the agent with the converted message collection, and then extracts the native OpenAI <see cref="ChatCompletion"/> from the response using <see cref="AgentRunResponseExtensions.AsChatCompletion"/>.
+    /// runs the agent with the converted message collection, and then extracts the native OpenAI <see cref="ChatCompletion"/> from the response using <see cref="AgentRunResponseExtensions.AsOpenAIChatCompletion"/>.
     /// </remarks>
     public static async Task<ChatCompletion> RunAsync(this AIAgent agent, IEnumerable<ChatMessage> messages, AgentThread? thread = null, AgentRunOptions? options = null, CancellationToken cancellationToken = default)
     {
@@ -43,7 +43,7 @@ public static class AIAgentWithOpenAIExtensions
 
         var response = await agent.RunAsync([.. messages.AsChatMessages()], thread, options, cancellationToken).ConfigureAwait(false);
 
-        return response.AsChatCompletion();
+        return response.AsOpenAIChatCompletion();
     }
 
     /// <summary>
@@ -60,7 +60,7 @@ public static class AIAgentWithOpenAIExtensions
     /// <exception cref="NotSupportedException">Thrown when the <paramref name="messages"/> type is not supported by the message conversion method.</exception>
     /// <remarks>
     /// This method converts the OpenAI chat messages to the Microsoft Extensions AI format using the appropriate conversion method,
-    /// runs the agent, and then extracts the native OpenAI <see cref="ChatCompletion"/> from the response using <see cref="AgentRunResponseExtensions.AsChatCompletion"/>.
+    /// runs the agent, and then extracts the native OpenAI <see cref="ChatCompletion"/> from the response using <see cref="AgentRunResponseExtensions.AsOpenAIChatCompletion"/>.
     /// </remarks>
     public static AsyncCollectionResult<StreamingChatCompletionUpdate> RunStreamingAsync(this AIAgent agent, IEnumerable<ChatMessage> messages, AgentThread? thread = null, AgentRunOptions? options = null, CancellationToken cancellationToken = default)
     {

dotnet/src/Microsoft.Agents.AI.OpenAI/Extensions/AgentRunResponseExtensions.cs

@@ -1,52 +1,45 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using Microsoft.Agents.AI;
-using Microsoft.Extensions.AI;
 using Microsoft.Shared.Diagnostics;
 using OpenAI.Chat;
+using OpenAI.Responses;
 
 namespace OpenAI;
 
 /// <summary>
-/// Provides extension methods for <see cref="AgentRunResponse"/> to extract native OpenAI response objects
-/// from the Microsoft Agent Framework responses.
+/// Provides extension methods for <see cref="AgentRunResponse"/> and <see cref="AgentRunResponseUpdate"/> instances to
+/// create or extract native OpenAI response objects from the Microsoft Agent Framework responses.
 /// </summary>
-/// <remarks>
-/// These extensions enable developers to access the underlying OpenAI SDK objects when working with
-/// AI agents that are backed by OpenAI services. The methods extract strongly-typed OpenAI responses
-/// from the <see cref="AgentRunResponse.RawRepresentation"/> property, providing a bridge between
-/// the Microsoft Extensions AI framework and the native OpenAI SDK types.
-/// </remarks>
 public static class AgentRunResponseExtensions
 {
     /// <summary>
-    /// Extracts a native OpenAI <see cref="ChatCompletion"/> object from an <see cref="AgentRunResponse"/>.
+    /// Creates or extracts a native OpenAI <see cref="ChatCompletion"/> object from an <see cref="AgentRunResponse"/>.
     /// </summary>
-    /// <param name="agentResponse">The agent response containing the raw OpenAI representation.</param>
-    /// <returns>The native OpenAI <see cref="ChatCompletion"/> object.</returns>
-    /// <exception cref="ArgumentNullException">Thrown when <paramref name="agentResponse"/> is <see langword="null"/>.</exception>
-    /// <exception cref="ArgumentException">
-    /// Thrown when the <see cref="AgentRunResponse.RawRepresentation"/> is not a <see cref="ChatCompletion"/> object.
-    /// This typically occurs when the agent response was not generated by an OpenAI chat completion service
-    /// or when the underlying representation has been modified or corrupted.
-    /// </exception>
-    /// <remarks>
-    /// <para>
-    /// This method provides access to the native OpenAI <see cref="ChatCompletion"/> object that was used
-    /// to generate the agent response. This is useful when you need to access OpenAI-specific properties
-    /// or metadata that are not exposed through the Microsoft Extensions AI abstractions.
-    /// </para>
-    /// </remarks>
-    public static ChatCompletion AsChatCompletion(this AgentRunResponse agentResponse)
+    /// <param name="response">The agent response.</param>
+    /// <returns>The OpenAI <see cref="ChatCompletion"/> object.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="response"/> is <see langword="null"/>.</exception>
+    public static ChatCompletion AsOpenAIChatCompletion(this AgentRunResponse response)
     {
-        Throw.IfNull(agentResponse);
+        Throw.IfNull(response);
 
-        if (agentResponse.RawRepresentation is ChatResponse chatResponse)
-        {
-            return chatResponse.RawRepresentation is ChatCompletion chatCompletion
-                ? chatCompletion
-                : throw new ArgumentException("ChatResponse.RawRepresentation must be a ChatCompletion");
-        }
-        throw new ArgumentException("AgentRunResponse.RawRepresentation must be a ChatResponse");
+        return
+            response.RawRepresentation as ChatCompletion ??
+            response.AsChatResponse().AsOpenAIChatCompletion();
+    }
+
+    /// <summary>
+    /// Creates or extracts a native OpenAI <see cref="OpenAIResponse"/> object from an <see cref="AgentRunResponse"/>.
+    /// </summary>
+    /// <param name="response">The agent response.</param>
+    /// <returns>The OpenAI <see cref="OpenAIResponse"/> object.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="response"/> is <see langword="null"/>.</exception>
+    public static OpenAIResponse AsOpenAIResponse(this AgentRunResponse response)
+    {
+        Throw.IfNull(response);
+
+        return
+            response.RawRepresentation as OpenAIResponse ??
+            response.AsChatResponse().AsOpenAIResponse();
     }
 }

dotnet/src/Microsoft.Agents.AI.OpenAI/Extensions/AgentRunResponseUpdateExtensions.cs

@@ -1,52 +0,0 @@
-// Copyright (c) Microsoft. All rights reserved.
-
-using Microsoft.Extensions.AI;
-using Microsoft.Shared.Diagnostics;
-using OpenAI.Chat;
-
-namespace Microsoft.Agents.AI;
-
-/// <summary>
-/// Provides extension methods for <see cref="AgentRunResponseUpdate"/> to extract native OpenAI response objects
-/// from the Microsoft Agent Framework responses.
-/// </summary>
-/// <remarks>
-/// These extensions enable developers to access the underlying OpenAI SDK objects when working with
-/// AI agents that are backed by OpenAI services. The methods extract strongly-typed OpenAI responses
-/// from the <see cref="AgentRunResponseUpdate.RawRepresentation"/> property, providing a bridge between
-/// the Microsoft Extensions AI framework and the native OpenAI SDK types.
-/// </remarks>
-public static class AgentRunResponseUpdateExtensions
-{
-    /// <summary>
-    /// Extracts a native OpenAI <see cref="StreamingChatCompletionUpdate"/> object from an <see cref="AgentRunResponseUpdate"/>.
-    /// </summary>
-    /// <param name="agentResponseUpdate">The agent response containing the raw OpenAI representation.</param>
-    /// <returns>The native OpenAI <see cref="StreamingChatCompletionUpdate"/> object.</returns>
-    /// <exception cref="ArgumentNullException">Thrown when <paramref name="agentResponseUpdate"/> is <see langword="null"/>.</exception>
-    /// <exception cref="ArgumentException">
-    /// Thrown when the <see cref="AgentRunResponseUpdate.RawRepresentation"/> is not a <see cref="ChatResponseUpdate"/> object,
-    /// or when the nested <see cref="ChatResponseUpdate.RawRepresentation"/> is not a <see cref="StreamingChatCompletionUpdate"/> object.
-    /// This typically occurs when the agent response was not generated by an OpenAI streaming chat completion service
-    /// or when the underlying representation has been modified or corrupted.
-    /// </exception>
-    /// <remarks>
-    /// <para>
-    /// This method provides access to the native OpenAI <see cref="StreamingChatCompletionUpdate"/> object that was used
-    /// to generate the agent response. This is useful when you need to access OpenAI-specific properties
-    /// or metadata that are not exposed through the Microsoft Extensions AI abstractions.
-    /// </para>
-    /// </remarks>
-    public static StreamingChatCompletionUpdate AsStreamingChatCompletionUpdate(this AgentRunResponseUpdate agentResponseUpdate)
-    {
-        Throw.IfNull(agentResponseUpdate);
-
-        if (agentResponseUpdate.RawRepresentation is ChatResponseUpdate chatResponseUpdate)
-        {
-            return chatResponseUpdate.RawRepresentation is StreamingChatCompletionUpdate streamingChatCompletionUpdate
-                ? streamingChatCompletionUpdate
-                : throw new ArgumentException("ChatResponseUpdate.RawRepresentation must be a StreamingChatCompletionUpdate");
-        }
-        throw new ArgumentException("AgentRunResponseUpdate.RawRepresentation must be a ChatResponseUpdate");
-    }
-}

dotnet/src/Microsoft.Agents.AI.OpenAI/OpenAIChatClientAgent.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Microsoft. All rights reserved.
 
-using System.Text.Json;
 using Microsoft.Agents.AI;
 using Microsoft.Extensions.AI;
 using Microsoft.Extensions.Logging;
@@ -11,12 +10,10 @@ using ChatMessage = OpenAI.Chat.ChatMessage;
 namespace OpenAI;
 
 /// <summary>
-/// OpenAI chat completion based implementation of <see cref="AIAgent"/>.
+/// Provides an <see cref="AIAgent"/> backed by an OpenAI chat completion implementation.
 /// </summary>
-public class OpenAIChatClientAgent : AIAgent
+public class OpenAIChatClientAgent : DelegatingAIAgent
 {
-    private readonly ChatClientAgent _chatClientAgent;
-
     /// <summary>
     /// Initialize an instance of <see cref="OpenAIChatClientAgent"/>
     /// </summary>
@@ -30,20 +27,14 @@ public class OpenAIChatClientAgent : AIAgent
         string? instructions = null,
         string? name = null,
         string? description = null,
-        ILoggerFactory? loggerFactory = null)
+        ILoggerFactory? loggerFactory = null) :
+        this(client, new()
+        {
+            Name = name,
+            Description = description,
+            Instructions = instructions,
+        }, loggerFactory)
     {
-        Throw.IfNull(client);
-
-        var chatClient = client.AsIChatClient();
-        this._chatClientAgent = new(
-            chatClient,
-            new ChatClientAgentOptions()
-            {
-                Name = name,
-                Description = description,
-                Instructions = instructions,
-            },
-            loggerFactory);
     }
 
     /// <summary>
@@ -52,12 +43,10 @@ public class OpenAIChatClientAgent : AIAgent
     /// <param name="client">Instance of <see cref="ChatClient"/></param>
     /// <param name="options">Options to create the agent.</param>
     /// <param name="loggerFactory">Optional instance of <see cref="ILoggerFactory"/></param>
-    public OpenAIChatClientAgent(ChatClient client, ChatClientAgentOptions options, ILoggerFactory? loggerFactory = null)
+    public OpenAIChatClientAgent(
+        ChatClient client, ChatClientAgentOptions options, ILoggerFactory? loggerFactory = null) :
+        base(new ChatClientAgent(Throw.IfNull(client).AsIChatClient(), options, loggerFactory))
     {
-        Throw.IfNull(client);
-
-        var chatClient = client.AsIChatClient();
-        this._chatClientAgent = new(chatClient, options, loggerFactory);
     }
 
     /// <summary>
@@ -74,37 +63,35 @@ public class OpenAIChatClientAgent : AIAgent
         AgentRunOptions? options = null,
         CancellationToken cancellationToken = default)
     {
-        var response = await this.RunAsync([.. messages.AsChatMessages()], thread, options, cancellationToken).ConfigureAwait(false);
+        var response = await this.RunAsync(messages.AsChatMessages(), thread, options, cancellationToken).ConfigureAwait(false);
 
-        return response.AsChatCompletion();
+        return response.AsOpenAIChatCompletion();
+    }
+
+    /// <summary>
+    /// Run the agent streaming with the provided message and arguments.
+    /// </summary>
+    /// <param name="messages">The messages to pass to the agent.</param>
+    /// <param name="thread">The conversation thread to continue with this invocation. If not provided, creates a new thread. The thread will be mutated with the provided messages and agent response.</param>
+    /// <param name="options">Optional parameters for agent invocation.</param>
+    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
+    /// <returns>A <see cref="ChatCompletion"/> containing the list of <see cref="ChatMessage"/> items.</returns>
+    public virtual IAsyncEnumerable<StreamingChatCompletionUpdate> RunStreamingAsync(
+        IEnumerable<ChatMessage> messages,
+        AgentThread? thread = null,
+        AgentRunOptions? options = null,
+        CancellationToken cancellationToken = default)
+    {
+        var response = this.RunStreamingAsync(messages.AsChatMessages(), thread, options, cancellationToken);
+
+        return response.AsChatResponseUpdatesAsync().AsOpenAIStreamingChatCompletionUpdatesAsync(cancellationToken);
     }
 
     /// <inheritdoc/>
-    public sealed override AgentThread GetNewThread()
-        => this._chatClientAgent.GetNewThread();
+    public sealed override Task<AgentRunResponse> RunAsync(IEnumerable<Microsoft.Extensions.AI.ChatMessage> messages, AgentThread? thread = null, AgentRunOptions? options = null, CancellationToken cancellationToken = default) =>
+        base.RunAsync(messages, thread, options, cancellationToken);
 
     /// <inheritdoc/>
-    public sealed override AgentThread DeserializeThread(JsonElement serializedThread, JsonSerializerOptions? jsonSerializerOptions = null)
-        => this._chatClientAgent.DeserializeThread(serializedThread, jsonSerializerOptions);
-
-    /// <inheritdoc/>
-    public sealed override Task<AgentRunResponse> RunAsync(
-        IEnumerable<Microsoft.Extensions.AI.ChatMessage> messages,
-        AgentThread? thread = null,
-        AgentRunOptions? options = null,
-        CancellationToken cancellationToken = default)
-            => this._chatClientAgent.RunAsync(messages, thread, options, cancellationToken);
-
-    /// <inheritdoc/>
-    public sealed override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync(
-        IEnumerable<Microsoft.Extensions.AI.ChatMessage> messages,
-        AgentThread? thread = null,
-        AgentRunOptions? options = null,
-        CancellationToken cancellationToken = default)
-            => this._chatClientAgent.RunStreamingAsync(messages, thread, options, cancellationToken);
-
-    /// <inheritdoc/>
-    public override object? GetService(Type serviceType, object? serviceKey = null)
-        => base.GetService(serviceType, serviceKey)
-        ?? this._chatClientAgent.GetService(serviceType, serviceKey);
+    public override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync(IEnumerable<Microsoft.Extensions.AI.ChatMessage> messages, AgentThread? thread = null, AgentRunOptions? options = null, CancellationToken cancellationToken = default) =>
+        base.RunStreamingAsync(messages, thread, options, cancellationToken);
 }

dotnet/src/Microsoft.Agents.AI.OpenAI/OpenAIResponseClientAgent.cs

@@ -0,0 +1,115 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Runtime.CompilerServices;
+using Microsoft.Agents.AI;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.Logging;
+using Microsoft.Shared.Diagnostics;
+using OpenAI.Responses;
+
+namespace OpenAI;
+
+/// <summary>
+/// Provides an <see cref="AIAgent"/> backed by an OpenAI Responses implementation.
+/// </summary>
+public class OpenAIResponseClientAgent : DelegatingAIAgent
+{
+    /// <summary>
+    /// Initialize an instance of <see cref="OpenAIResponseClientAgent"/>.
+    /// </summary>
+    /// <param name="client">Instance of <see cref="OpenAIResponseClient"/></param>
+    /// <param name="instructions">Optional instructions for the agent.</param>
+    /// <param name="name">Optional name for the agent.</param>
+    /// <param name="description">Optional description for the agent.</param>
+    /// <param name="loggerFactory">Optional instance of <see cref="ILoggerFactory"/></param>
+    public OpenAIResponseClientAgent(
+        OpenAIResponseClient client,
+        string? instructions = null,
+        string? name = null,
+        string? description = null,
+        ILoggerFactory? loggerFactory = null) :
+        this(client, new()
+        {
+            Name = name,
+            Description = description,
+            Instructions = instructions,
+        }, loggerFactory)
+    {
+    }
+
+    /// <summary>
+    /// Initialize an instance of <see cref="OpenAIResponseClientAgent"/>.
+    /// </summary>
+    /// <param name="client">Instance of <see cref="OpenAIResponseClient"/></param>
+    /// <param name="options">Options to create the agent.</param>
+    /// <param name="loggerFactory">Optional instance of <see cref="ILoggerFactory"/></param>
+    public OpenAIResponseClientAgent(
+        OpenAIResponseClient client, ChatClientAgentOptions options, ILoggerFactory? loggerFactory = null) :
+        base(new ChatClientAgent(Throw.IfNull(client).AsIChatClient(), options, loggerFactory))
+    {
+    }
+
+    /// <summary>
+    /// Run the agent with the provided message and arguments.
+    /// </summary>
+    /// <param name="messages">The messages to pass to the agent.</param>
+    /// <param name="thread">The conversation thread to continue with this invocation. If not provided, creates a new thread. The thread will be mutated with the provided messages and agent response.</param>
+    /// <param name="options">Optional parameters for agent invocation.</param>
+    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
+    /// <returns>A <see cref="OpenAIResponse"/> containing the list of <see cref="ChatMessage"/> items.</returns>
+    public virtual async Task<OpenAIResponse> RunAsync(
+        IEnumerable<ResponseItem> messages,
+        AgentThread? thread = null,
+        AgentRunOptions? options = null,
+        CancellationToken cancellationToken = default)
+    {
+        var response = await this.RunAsync(messages.AsChatMessages(), thread, options, cancellationToken).ConfigureAwait(false);
+
+        return response.AsOpenAIResponse();
+    }
+
+    /// <summary>
+    /// Run the agent streaming with the provided message and arguments.
+    /// </summary>
+    /// <param name="messages">The messages to pass to the agent.</param>
+    /// <param name="thread">The conversation thread to continue with this invocation. If not provided, creates a new thread. The thread will be mutated with the provided messages and agent response.</param>
+    /// <param name="options">Optional parameters for agent invocation.</param>
+    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
+    /// <returns>A <see cref="OpenAIResponse"/> containing the list of <see cref="ChatMessage"/> items.</returns>
+    public virtual async IAsyncEnumerable<StreamingResponseUpdate> RunStreamingAsync(
+        IEnumerable<ResponseItem> messages,
+        AgentThread? thread = null,
+        AgentRunOptions? options = null,
+        [EnumeratorCancellation] CancellationToken cancellationToken = default)
+    {
+        var response = this.RunStreamingAsync(messages.AsChatMessages(), thread, options, cancellationToken);
+
+        await foreach (var update in response.ConfigureAwait(false))
+        {
+            switch (update.RawRepresentation)
+            {
+                case StreamingResponseUpdate rawUpdate:
+                    yield return rawUpdate;
+                    break;
+
+                case ChatResponseUpdate { RawRepresentation: StreamingResponseUpdate rawUpdate }:
+                    yield return rawUpdate;
+                    break;
+
+                default:
+                    // TODO: The OpenAI library does not currently expose model factory methods for creating
+                    // StreamingResponseUpdates. We are thus unable to manufacture such instances when there isn't
+                    // already one in the update and instead skip them.
+                    break;
+            }
+        }
+    }
+
+    /// <inheritdoc/>
+    public sealed override Task<AgentRunResponse> RunAsync(IEnumerable<ChatMessage> messages, AgentThread? thread = null, AgentRunOptions? options = null, CancellationToken cancellationToken = default) =>
+        base.RunAsync(messages, thread, options, cancellationToken);
+
+    /// <inheritdoc/>
+    public sealed override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync(IEnumerable<ChatMessage> messages, AgentThread? thread = null, AgentRunOptions? options = null, CancellationToken cancellationToken = default) =>
+        base.RunStreamingAsync(messages, thread, options, cancellationToken);
+}

dotnet/src/Microsoft.Agents.AI.Workflows/MessageMerger.cs

@@ -72,19 +72,7 @@ internal sealed class MessageMerger
                     throw new InvalidOperationException($"No updates found for message ID '{messageId}' in response '{this.ResponseId}'.");
                 }
 
-                return updates.Select(oldUpdate =>
-                    oldUpdate.RawRepresentation as ChatResponseUpdate ??
-                    new()
-                    {
-                        AdditionalProperties = oldUpdate.AdditionalProperties,
-                        AuthorName = oldUpdate.AuthorName,
-                        Contents = oldUpdate.Contents,
-                        CreatedAt = oldUpdate.CreatedAt,
-                        MessageId = oldUpdate.MessageId,
-                        RawRepresentation = oldUpdate.RawRepresentation,
-                        Role = oldUpdate.Role,
-                        ResponseId = oldUpdate.ResponseId,
-                    }).ToChatResponse().Messages;
+                return updates.Select(oldUpdate => oldUpdate.AsChatResponseUpdate()).ToChatResponse().Messages;
             }
         }
     }

dotnet/src/Microsoft.Agents.AI/OpenTelemetryAgent.cs

@@ -182,15 +182,7 @@ public sealed class OpenTelemetryAgent : DelegatingAIAgent, IDisposable
             var response = await parentAgent.InnerAgent.RunAsync(messages, fo?.Thread, fo?.Options, cancellationToken).ConfigureAwait(false);
 
             // Wrap the response in a ChatResponse so we can pass it back through OpenTelemetryChatClient.
-            return new ChatResponse
-            {
-                AdditionalProperties = response.AdditionalProperties,
-                CreatedAt = response.CreatedAt,
-                Messages = response.Messages,
-                RawRepresentation = response,
-                ResponseId = response.ResponseId,
-                Usage = response.Usage,
-            };
+            return response.AsChatResponse();
         }
 
         public async IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseAsync(
@@ -205,17 +197,7 @@ public sealed class OpenTelemetryAgent : DelegatingAIAgent, IDisposable
             await foreach (var update in parentAgent.InnerAgent.RunStreamingAsync(messages, fo?.Thread, fo?.Options, cancellationToken).ConfigureAwait(false))
             {
                 // Wrap the response updates in ChatResponseUpdates so we can pass them back through OpenTelemetryChatClient.
-                yield return new ChatResponseUpdate
-                {
-                    AdditionalProperties = update.AdditionalProperties,
-                    AuthorName = update.AuthorName,
-                    Contents = update.Contents,
-                    CreatedAt = update.CreatedAt,
-                    MessageId = update.MessageId,
-                    RawRepresentation = update,
-                    ResponseId = update.ResponseId,
-                    Role = update.Role,
-                };
+                yield return update.AsChatResponseUpdate();
             }
         }