Merge branch 'main' into flaky-test-report

dotnet/agent-framework-dotnet.slnx

@@ -163,10 +163,10 @@
     <Project Path="samples/02-agents/AgentsWithFoundry/Agent_Step25_ToolboxServerSideTools/Agent_Step25_ToolboxServerSideTools.csproj" />
   </Folder>
   <Folder Name="/Samples/02-agents/Evaluation/">
-    <Project Path="samples/02-agents/Evaluation/Evaluation_SimpleEval/Evaluation_SimpleEval.csproj" />
     <Project Path="samples/02-agents/Evaluation/Evaluation_CustomEvals/Evaluation_CustomEvals.csproj" />
     <Project Path="samples/02-agents/Evaluation/Evaluation_ExpectedOutputs/Evaluation_ExpectedOutputs.csproj" />
     <Project Path="samples/02-agents/Evaluation/Evaluation_Multimodal/Evaluation_Multimodal.csproj" />
+    <Project Path="samples/02-agents/Evaluation/Evaluation_SimpleEval/Evaluation_SimpleEval.csproj" />
   </Folder>
   <Folder Name="/Samples/02-agents/AgentWithMemory/">
     <File Path="samples/02-agents/AgentWithMemory/README.md" />
@@ -226,6 +226,7 @@
     <Project Path="samples/03-workflows/Declarative/HostedWorkflow/HostedWorkflow.csproj" />
     <Project Path="samples/03-workflows/Declarative/InputArguments/InputArguments.csproj" />
     <Project Path="samples/03-workflows/Declarative/InvokeFunctionTool/InvokeFunctionTool.csproj" />
+    <Project Path="samples/03-workflows/Declarative/InvokeHttpRequest/InvokeHttpRequest.csproj" />
     <Project Path="samples/03-workflows/Declarative/InvokeMcpTool/InvokeMcpTool.csproj" />
     <Project Path="samples/03-workflows/Declarative/Marketing/Marketing.csproj" />
     <Project Path="samples/03-workflows/Declarative/StudentTeacher/StudentTeacher.csproj" />
@@ -347,17 +348,17 @@
     <File Path="samples/02-agents/A2A/README.md" />
     <Project Path="samples/02-agents/A2A/A2AAgent_AsFunctionTools/A2AAgent_AsFunctionTools.csproj" />
     <Project Path="samples/02-agents/A2A/A2AAgent_PollingForTaskCompletion/A2AAgent_PollingForTaskCompletion.csproj" />
-    <Project Path="samples/02-agents/A2A/A2AAgent_StreamReconnection/A2AAgent_StreamReconnection.csproj" />
     <Project Path="samples/02-agents/A2A/A2AAgent_ProtocolSelection/A2AAgent_ProtocolSelection.csproj" />
+    <Project Path="samples/02-agents/A2A/A2AAgent_StreamReconnection/A2AAgent_StreamReconnection.csproj" />
   </Folder>  
   <Folder Name="/Samples/05-end-to-end/">
     <Project Path="samples/05-end-to-end/AgentWithPurview/AgentWithPurview.csproj" />
     <Project Path="samples/05-end-to-end/M365Agent/M365Agent.csproj" />
   </Folder>
   <Folder Name="/Samples/05-end-to-end/Evaluation/">
+    <Project Path="samples/05-end-to-end/Evaluation/Evaluation_ConversationSplits/Evaluation_ConversationSplits.csproj" />
     <Project Path="samples/05-end-to-end/Evaluation/Evaluation_FoundryQuality/Evaluation_FoundryQuality.csproj" />
     <Project Path="samples/05-end-to-end/Evaluation/Evaluation_MixedProviders/Evaluation_MixedProviders.csproj" />
-    <Project Path="samples/05-end-to-end/Evaluation/Evaluation_ConversationSplits/Evaluation_ConversationSplits.csproj" />
   </Folder>
   <Folder Name="/Samples/05-end-to-end/A2AClientServer/">
     <File Path="samples/05-end-to-end/A2AClientServer/README.md" />
@@ -543,8 +544,8 @@
     <Project Path="src/Microsoft.Agents.AI.Declarative/Microsoft.Agents.AI.Declarative.csproj" />
     <Project Path="src/Microsoft.Agents.AI.DevUI/Microsoft.Agents.AI.DevUI.csproj" />
     <Project Path="src/Microsoft.Agents.AI.DurableTask/Microsoft.Agents.AI.DurableTask.csproj" />
-    <Project Path="src/Microsoft.Agents.AI.Foundry/Microsoft.Agents.AI.Foundry.csproj" />
     <Project Path="src/Microsoft.Agents.AI.Foundry.Hosting/Microsoft.Agents.AI.Foundry.Hosting.csproj" />
+    <Project Path="src/Microsoft.Agents.AI.Foundry/Microsoft.Agents.AI.Foundry.csproj" />
     <Project Path="src/Microsoft.Agents.AI.GitHub.Copilot/Microsoft.Agents.AI.GitHub.Copilot.csproj" />
     <Project Path="src/Microsoft.Agents.AI.Hosting.A2A.AspNetCore/Microsoft.Agents.AI.Hosting.A2A.AspNetCore.csproj" />
     <Project Path="src/Microsoft.Agents.AI.Hosting.A2A/Microsoft.Agents.AI.Hosting.A2A.csproj" />

dotnet/samples/03-workflows/Declarative/InvokeHttpRequest/InvokeHttpRequest.csproj

@@ -0,0 +1,38 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <InjectIsExternalInitOnLegacy>true</InjectIsExternalInitOnLegacy>
+    <InjectSharedFoundryAgents>true</InjectSharedFoundryAgents>
+    <InjectSharedWorkflowsExecution>true</InjectSharedWorkflowsExecution>
+    <InjectSharedWorkflowsSettings>true</InjectSharedWorkflowsSettings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Configuration" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Binder" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Json" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
+    <PackageReference Include="Microsoft.Extensions.Logging" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.Workflows.Declarative\Microsoft.Agents.AI.Workflows.Declarative.csproj" />
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.Workflows.Declarative.Foundry\Microsoft.Agents.AI.Workflows.Declarative.Foundry.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Include="InvokeHttpRequest.yaml">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

dotnet/samples/03-workflows/Declarative/InvokeHttpRequest/InvokeHttpRequest.yaml

@@ -0,0 +1,76 @@
+#
+# This workflow demonstrates using HttpRequestAction to call a REST API directly
+# from the workflow without going through an AI agent first.
+#
+# HttpRequestAction allows workflows to:
+# - Fetch data from external HTTP endpoints
+# - Store the parsed response in workflow variables for later use
+# - Add the response body to the conversation so a downstream agent can
+#   answer questions based on it
+#
+# This sample fetches public metadata for the dotnet/runtime repository from
+# the GitHub REST API (no authentication required) and uses an agent to
+# answer follow-up questions about it.
+#
+# Example input:
+# How many subscribers does the repository have?
+#
+kind: Workflow
+trigger:
+
+  kind: OnConversationStart
+  id: workflow_invoke_http_request_demo
+  actions:
+
+    # Capture the original user message for input to the follow-up agent.
+    - kind: SetVariable
+      id: set_user_message
+      variable: Local.InputMessage
+      value: =System.LastMessage
+
+    # Set the repository org/name used to form the request URL.
+    - kind: SetVariable
+      id: set_repo_name
+      variable: Local.RepoName
+      value: microsoft/agent-framework
+
+    # Invoke the GitHub repo API. The response body is parsed into Local.RepoInfo
+    # and also added to the conversation (via conversationId) so the agent below
+    # can answer questions based on it.
+    - kind: HttpRequestAction
+      id: fetch_repo_info
+      conversationId: =System.ConversationId
+      method: GET
+      url: =Concatenate("https://api.github.com/repos/", Local.RepoName)
+      headers:
+        Accept: application/vnd.github+json
+        User-Agent: agent-framework-sample
+      response: Local.RepoInfo
+
+    # Display a confirmation message showing key fields from the parsed response.
+    - kind: SendMessage
+      id: show_repo_summary
+      message: "Fetched repo: visibility={Local.RepoInfo.visibility}, description={Local.RepoInfo.description}"
+
+    # Use the agent to summarize the repo using the conversation context.
+    - kind: InvokeAzureAgent
+      id: summarize_repo
+      conversationId: =System.ConversationId
+      agent:
+        name: GitHubRepoInfoAgent
+      input:
+        messages: =UserMessage("Please provide a brief summary of this GitHub repository based on the data already in the conversation.")
+      output:
+        autoSend: true
+        messages: Local.AgentResponse
+
+    # Allow the user to ask follow-up questions about the repo in a loop.
+    - kind: InvokeAzureAgent
+      id: invoke_followup
+      conversationId: =System.ConversationId
+      agent:
+        name: GitHubRepoInfoAgent
+      input:
+        messages: =Local.InputMessage
+        externalLoop:
+          when: =Upper(System.LastMessage.Text) <> "EXIT"

dotnet/samples/03-workflows/Declarative/InvokeHttpRequest/Program.cs

@@ -0,0 +1,95 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Azure.AI.Projects;
+using Azure.AI.Projects.Agents;
+using Azure.Identity;
+using Microsoft.Agents.AI.Workflows.Declarative;
+using Microsoft.Extensions.Configuration;
+using Shared.Foundry;
+using Shared.Workflows;
+
+namespace Demo.Workflows.Declarative.InvokeHttpRequest;
+
+/// <summary>
+/// Demonstrates a workflow that uses HttpRequestAction to call a REST API
+/// directly from the workflow.
+/// </summary>
+/// <remarks>
+/// <para>
+/// The HttpRequestAction allows workflows to issue HTTP requests and:
+/// </para>
+/// <list type="bullet">
+/// <item>Fetch data from external REST endpoints</item>
+/// <item>Store the parsed response in workflow variables</item>
+/// <item>Add the response body to the conversation so an agent can answer
+///       questions based on it</item>
+/// </list>
+/// <para>
+/// This sample fetches public metadata for the dotnet/runtime repository from
+/// the GitHub REST API (no authentication required) and uses a Foundry agent
+/// to answer follow-up questions about it. Type "EXIT" to end the conversation.
+/// </para>
+/// <para>
+/// See the README.md file in the parent folder (../README.md) for detailed
+/// information about the configuration required to run this sample.
+/// </para>
+/// </remarks>
+internal sealed class Program
+{
+    public static async Task Main(string[] args)
+    {
+        // Initialize configuration
+        IConfiguration configuration = Application.InitializeConfig();
+        Uri foundryEndpoint = new(configuration.GetValue(Application.Settings.FoundryEndpoint));
+
+        // Ensure sample agent exists in Foundry. The agent has no tools - it answers
+        // questions about the GitHub repository using only the JSON data that the
+        // HttpRequestAction adds to the conversation.
+        await CreateAgentAsync(foundryEndpoint, configuration);
+
+        // Get input from command line or console
+        string workflowInput = Application.GetInput(args);
+
+        // The default HttpRequestHandler is sufficient for this sample because the
+        // GitHub REST endpoint used here does not require authentication. For
+        // authenticated endpoints, supply a custom Func<HttpRequestInfo, ..., HttpClient?>
+        // to DefaultHttpRequestHandler so each request can be routed through a
+        // pre-configured (cached) HttpClient with the appropriate credentials.
+        await using DefaultHttpRequestHandler httpRequestHandler = new();
+
+        // Create the workflow factory with the HTTP request handler
+        WorkflowFactory workflowFactory = new("InvokeHttpRequest.yaml", foundryEndpoint)
+        {
+            HttpRequestHandler = httpRequestHandler
+        };
+
+        // Execute the workflow
+        WorkflowRunner runner = new() { UseJsonCheckpoints = true };
+        await runner.ExecuteAsync(workflowFactory.CreateWorkflow, workflowInput);
+    }
+
+    private static async Task CreateAgentAsync(Uri foundryEndpoint, IConfiguration configuration)
+    {
+        // WARNING: DefaultAzureCredential is convenient for development but requires careful consideration in production.
+        AIProjectClient aiProjectClient = new(foundryEndpoint, new DefaultAzureCredential());
+
+        await aiProjectClient.CreateAgentAsync(
+            agentName: "GitHubRepoInfoAgent",
+            agentDefinition: DefineAgent(configuration),
+            agentDescription: "Answers questions about a GitHub repository using HTTP response data in the conversation");
+    }
+
+    private static DeclarativeAgentDefinition DefineAgent(IConfiguration configuration)
+    {
+        return new DeclarativeAgentDefinition(configuration.GetValue(Application.Settings.FoundryModel))
+        {
+            Instructions =
+                """
+                Answer the user's questions about the GitHub repository using only the
+                JSON data already present in the conversation history.
+                If the answer is not contained in the conversation, say so plainly
+                rather than guessing. Be concise and helpful.
+                """
+        };
+    }
+}

dotnet/src/Microsoft.Agents.AI.Foundry.Hosting/AgentFrameworkResponseHandler.cs

@@ -297,6 +297,7 @@ public class AgentFrameworkResponseHandler : ResponseHandler
             var agent = this._serviceProvider.GetKeyedService<AIAgent>(agentName);
             if (agent is not null)
             {
+                FoundryHostingExtensions.TryApplyUserAgent(agent);
                 return FoundryHostingExtensions.ApplyOpenTelemetry(agent);
             }
 
@@ -310,12 +311,13 @@ public class AgentFrameworkResponseHandler : ResponseHandler
         var defaultAgent = this._serviceProvider.GetService<AIAgent>();
         if (defaultAgent is not null)
         {
+            FoundryHostingExtensions.TryApplyUserAgent(defaultAgent);
             return FoundryHostingExtensions.ApplyOpenTelemetry(defaultAgent);
         }
 
         var errorMessage = string.IsNullOrEmpty(agentName)
             ? "No agent name specified in the request (via agent.name or metadata[\"entity_id\"]) and no default AIAgent is registered."
-            : $"Agent '{agentName}' not found. Ensure it is registered via AddAIAgent(\"{agentName}\", ...) or as a default AIAgent.";
+            : $"Agent '{agentName}' not found. Ensure it is registered via AddFoundryResponses(services, agent) or services.AddKeyedSingleton<AIAgent>(\"{agentName}\", ...).";
 
         throw new InvalidOperationException(errorMessage);
     }
@@ -352,7 +354,7 @@ public class AgentFrameworkResponseHandler : ResponseHandler
 
         var errorMessage = string.IsNullOrEmpty(agentName)
             ? "No agent name specified in the request (via agent.name or metadata[\"entity_id\"]) and no default AgentSessionStore is registered."
-            : $"Agent '{agentName}' not found. Ensure it is registered via AddAIAgent(\"{agentName}\", ...) or as a default AgentSessionStore.";
+            : $"AgentSessionStore for agent '{agentName}' not found. Ensure it is registered via AddFoundryResponses(services, agent, agentSessionStore) or services.AddKeyedSingleton<AgentSessionStore>(\"{agentName}\", ...).";
 
         throw new InvalidOperationException(errorMessage);
     }

dotnet/src/Microsoft.Agents.AI.Foundry.Hosting/DelegatingResponsesClient.cs

@@ -0,0 +1,113 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.ClientModel;
+using System.ClientModel.Primitives;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using OpenAI;
+using OpenAI.Responses;
+
+#pragma warning disable OPENAI001, SCME0001
+
+namespace Microsoft.Agents.AI.Foundry.Hosting;
+
+/// <summary>
+/// A <see cref="ResponsesClient"/> subclass that delegates every protocol-level request to a
+/// wrapped <see cref="ResponsesClient"/>. Before each call, a
+/// <see cref="HostedAgentUserAgentPolicy"/> is added to the per-call
+/// <see cref="RequestOptions"/> so the wrapped client's pipeline appends the hosted-agent
+/// <c>User-Agent</c> segment on the wire.
+/// </summary>
+/// <remarks>
+/// <para>
+/// The streaming overloads MEAI binds via reflection (<c>internal CreateResponseStreamingAsync(CreateResponseOptions, RequestOptions)</c>
+/// and <c>internal GetResponseStreamingAsync(GetResponseOptions, RequestOptions)</c>) bottom out
+/// in calls to the public-virtual non-streaming protocol overloads on <see langword="this"/>. Overriding those
+/// non-streaming overloads is therefore sufficient to intercept both streaming and non-streaming traffic.
+/// </para>
+/// <para>
+/// The base pipeline supplied to <see cref="ResponsesClient(ClientPipeline, OpenAIClientOptions)"/>
+/// is a dummy pipeline whose terminal transport throws if invoked. Every override on this class
+/// delegates to the inner client BEFORE any code path reaches <see cref="ResponsesClient.Pipeline"/>, so the dummy is
+/// never expected to run; the throwing transport surfaces any unexpected escape route loudly.
+/// </para>
+/// </remarks>
+internal sealed class DelegatingResponsesClient : ResponsesClient
+{
+    private readonly ResponsesClient _inner;
+
+    public DelegatingResponsesClient(ResponsesClient inner)
+        : base(BuildDummyPipeline(), new OpenAIClientOptions { Endpoint = inner?.Endpoint })
+    {
+        this._inner = inner ?? throw new ArgumentNullException(nameof(inner));
+    }
+
+    public override async Task<ClientResult> CreateResponseAsync(BinaryContent content, RequestOptions? options = null)
+        => await this._inner.CreateResponseAsync(content, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult CreateResponse(BinaryContent content, RequestOptions? options = null)
+        => this._inner.CreateResponse(content, AddUserAgentPolicy(options));
+
+    public override async Task<ClientResult> GetResponseAsync(string responseId, IEnumerable<IncludedResponseProperty>? include, bool? stream, int? startingAfter, bool? includeObfuscation, RequestOptions options)
+        => await this._inner.GetResponseAsync(responseId, include, stream, startingAfter, includeObfuscation, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult GetResponse(string responseId, IEnumerable<IncludedResponseProperty>? include, bool? stream, int? startingAfter, bool? includeObfuscation, RequestOptions options)
+        => this._inner.GetResponse(responseId, include, stream, startingAfter, includeObfuscation, AddUserAgentPolicy(options));
+
+    public override async Task<ClientResult> DeleteResponseAsync(string responseId, RequestOptions options)
+        => await this._inner.DeleteResponseAsync(responseId, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult DeleteResponse(string responseId, RequestOptions options)
+        => this._inner.DeleteResponse(responseId, AddUserAgentPolicy(options));
+
+    public override async Task<ClientResult> CancelResponseAsync(string responseId, RequestOptions options)
+        => await this._inner.CancelResponseAsync(responseId, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult CancelResponse(string responseId, RequestOptions options)
+        => this._inner.CancelResponse(responseId, AddUserAgentPolicy(options));
+
+    public override async Task<ClientResult> GetInputTokenCountAsync(string contentType, BinaryContent content, RequestOptions? options = null)
+        => await this._inner.GetInputTokenCountAsync(contentType, content, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult GetInputTokenCount(string contentType, BinaryContent content, RequestOptions? options = null)
+        => this._inner.GetInputTokenCount(contentType, content, AddUserAgentPolicy(options));
+
+    public override async Task<ClientResult> CompactResponseAsync(string contentType, BinaryContent content, RequestOptions? options = null)
+        => await this._inner.CompactResponseAsync(contentType, content, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult CompactResponse(string contentType, BinaryContent content, RequestOptions? options = null)
+        => this._inner.CompactResponse(contentType, content, AddUserAgentPolicy(options));
+
+    public override async Task<ClientResult> GetResponseInputItemCollectionPageAsync(string responseId, int? limit, string order, string after, string before, RequestOptions options)
+        => await this._inner.GetResponseInputItemCollectionPageAsync(responseId, limit, order, after, before, AddUserAgentPolicy(options)).ConfigureAwait(false);
+
+    public override ClientResult GetResponseInputItemCollectionPage(string responseId, int? limit, string order, string after, string before, RequestOptions options)
+        => this._inner.GetResponseInputItemCollectionPage(responseId, limit, order, after, before, AddUserAgentPolicy(options));
+
+    private static RequestOptions AddUserAgentPolicy(RequestOptions? options)
+    {
+        options ??= new RequestOptions();
+        options.AddPolicy(HostedAgentUserAgentPolicy.Instance, PipelinePosition.PerCall);
+        return options;
+    }
+
+    private static ClientPipeline BuildDummyPipeline()
+    {
+        var options = new ClientPipelineOptions
+        {
+            Transport = new ThrowingTransport(),
+        };
+        return ClientPipeline.Create(options, default, default, default);
+    }
+
+    private sealed class ThrowingTransport : PipelineTransport
+    {
+        private const string Message =
+            "DelegatingResponsesClient transport invoked bypassed the override-and-delegate design. This exception should be unreachable and should never be thrown following the correct usage of DelegatingResponsesClient.";
+
+        protected override PipelineMessage CreateMessageCore() => throw new InvalidOperationException(Message);
+        protected override void ProcessCore(PipelineMessage message) => throw new InvalidOperationException(Message);
+        protected override ValueTask ProcessCoreAsync(PipelineMessage message) => throw new InvalidOperationException(Message);
+    }
+}

dotnet/src/Microsoft.Agents.AI.Foundry.Hosting/HostedAgentUserAgentPolicy.cs

@@ -0,0 +1,84 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.ClientModel.Primitives;
+using System.Collections.Generic;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace Microsoft.Agents.AI.Foundry.Hosting;
+
+/// <summary>
+/// Pipeline policy that appends the hosted-agent <c>User-Agent</c> segment
+/// (e.g. <c>"foundry-hosting/agent-framework-dotnet/{version}"</c>) to outgoing requests.
+/// </summary>
+/// <remarks>
+/// <para>
+/// The supplement value is computed once from the Microsoft.Agents.AI.Foundry.Hosting
+/// assembly's informational version. The policy is idempotent on retries: if the segment
+/// is already present in the <c>User-Agent</c> header, the policy does not append it again.
+/// </para>
+/// <para>
+/// This policy is added at request time (per-call <see cref="PipelinePosition"/>)
+/// by <see cref="DelegatingResponsesClient"/> when invoking the wrapped
+/// <see cref="OpenAI.Responses.ResponsesClient"/>. It is only registered when an agent is
+/// resolved by the Foundry hosting layer.
+/// </para>
+/// </remarks>
+internal sealed class HostedAgentUserAgentPolicy : PipelinePolicy
+{
+    public static HostedAgentUserAgentPolicy Instance { get; } = new HostedAgentUserAgentPolicy();
+
+    private static readonly string s_supplementValue = CreateSupplementValue();
+
+    public override void Process(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
+    {
+        AppendHeader(message);
+        ProcessNext(message, pipeline, currentIndex);
+    }
+
+    public override async ValueTask ProcessAsync(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
+    {
+        AppendHeader(message);
+        await ProcessNextAsync(message, pipeline, currentIndex).ConfigureAwait(false);
+    }
+
+    private static void AppendHeader(PipelineMessage message)
+    {
+        if (message.Request.Headers.TryGetValue("User-Agent", out var existing) && !string.IsNullOrEmpty(existing))
+        {
+            // Guard against double-append on retries or when the policy
+            // is registered on multiple pipeline positions.
+            if (existing.Contains(s_supplementValue))
+            {
+                return;
+            }
+
+            message.Request.Headers.Set("User-Agent", $"{existing} {s_supplementValue}");
+        }
+        else
+        {
+            message.Request.Headers.Set("User-Agent", s_supplementValue);
+        }
+    }
+
+    private static string CreateSupplementValue()
+    {
+        const string Name = "foundry-hosting/agent-framework-dotnet";
+
+        if (typeof(HostedAgentUserAgentPolicy).Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion is string version)
+        {
+            int pos = version.IndexOf('+');
+            if (pos >= 0)
+            {
+                version = version.Substring(0, pos);
+            }
+
+            if (version.Length > 0)
+            {
+                return $"{Name}/{version}";
+            }
+        }
+
+        return Name;
+    }
+}

dotnet/src/Microsoft.Agents.AI.Foundry.Hosting/ServiceCollectionExtensions.cs

@@ -3,16 +3,15 @@
 using System;
 using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
-using System.Threading.Tasks;
 using Azure.AI.AgentServer.Responses;
 using Azure.Core;
 using Azure.Identity;
-using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.AI;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Shared.DiagnosticIds;
+using OpenAI.Responses;
 
 namespace Microsoft.Agents.AI.Foundry.Hosting;
 
@@ -36,7 +35,7 @@ public static class FoundryHostingExtensions
     /// <para>
     /// Example:
     /// <code>
-    /// builder.AddAIAgent("my-agent", ...);
+    /// builder.Services.AddKeyedSingleton&lt;AIAgent&gt;("my-agent", myAgent);
     /// builder.Services.AddFoundryResponses();
     ///
     /// var app = builder.Build();
@@ -181,13 +180,6 @@ public static class FoundryHostingExtensions
     {
         ArgumentNullException.ThrowIfNull(endpoints);
         endpoints.MapResponsesServer(prefix);
-
-        if (endpoints is IApplicationBuilder app)
-        {
-            // Ensure the middleware is added to the pipeline
-            app.UseMiddleware<AgentFrameworkUserAgentMiddleware>();
-        }
-
         return endpoints;
     }
 
@@ -216,46 +208,85 @@ public static class FoundryHostingExtensions
                     .Build();
     }
 
-    private sealed class AgentFrameworkUserAgentMiddleware(RequestDelegate next)
+    /// <summary>
+    /// Attempts to wrap the agent's underlying <see cref="ResponsesClient"/>
+    /// with a <see cref="DelegatingResponsesClient"/> so every outgoing Responses-API request
+    /// carries the hosted-agent <c>User-Agent</c> segment.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Best-effort and idempotent. The method is a no-op when:
+    /// <list type="bullet">
+    /// <item><description><paramref name="agent"/> exposes no <see cref="IChatClient"/>;</description></item>
+    /// <item><description>the chat client is not backed by MEAI's internal <c>OpenAIResponsesChatClient</c> (e.g., a non-OpenAI provider or a custom impl);</description></item>
+    /// <item><description>the inner <see cref="ResponsesClient"/> is already a <see cref="DelegatingResponsesClient"/>.</description></item>
+    /// </list>
+    /// </para>
+    /// <para>
+    /// Works for any <see cref="ResponsesClient"/>-derived inner client — both the Foundry-specific
+    /// <see cref="Azure.AI.Extensions.OpenAI.ProjectResponsesClient"/> and the native OpenAI
+    /// <see cref="ResponsesClient"/> obtained from <see cref="OpenAI.OpenAIClient"/>. The wrapper preserves
+    /// the inner client's pipeline (Transport, RetryPolicy, NetworkTimeout, OrganizationId / ProjectId /
+    /// UserAgentApplicationId, custom policies) because every override delegates to the inner instance.
+    /// </para>
+    /// <para>
+    /// Returns the same <paramref name="agent"/> instance unchanged. Mutation happens via
+    /// reflection on MEAI's private <c>_responseClient</c> field; the agent itself is not wrapped.
+    /// </para>
+    /// </remarks>
+    internal static AIAgent TryApplyUserAgent(AIAgent agent)
     {
-        private static readonly string s_userAgentValue = CreateUserAgentValue();
-
-        public async Task InvokeAsync(HttpContext context)
+        var chatClient = agent.GetService<IChatClient>();
+        if (chatClient is null)
         {
-            var headers = context.Request.Headers;
-            var userAgent = headers.UserAgent.ToString();
-
-            if (string.IsNullOrEmpty(userAgent))
-            {
-                headers.UserAgent = s_userAgentValue;
-            }
-            else if (!userAgent.Contains(s_userAgentValue, StringComparison.OrdinalIgnoreCase))
-            {
-                headers.UserAgent = $"{userAgent} {s_userAgentValue}";
-            }
-
-            await next(context).ConfigureAwait(false);
+            return agent;
         }
 
-        private static string CreateUserAgentValue()
+        var meaiType = s_meaiResponsesChatClientType;
+        if (meaiType is null)
         {
-            const string Name = "agent-framework-dotnet";
-
-            if (typeof(AgentFrameworkUserAgentMiddleware).Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion is string version)
-            {
-                int pos = version.IndexOf('+');
-                if (pos >= 0)
-                {
-                    version = version.Substring(0, pos);
-                }
-
-                if (version.Length > 0)
-                {
-                    return $"{Name}/{version}";
-                }
-            }
-
-            return Name;
+            return agent;
         }
+
+        var meaiInstance = chatClient.GetService(meaiType);
+        if (meaiInstance is null)
+        {
+            return agent;
+        }
+
+        var field = s_meaiResponseClientField;
+        if (field is null)
+        {
+            return agent;
+        }
+
+        var current = field.GetValue(meaiInstance) as ResponsesClient;
+        if (current is null or DelegatingResponsesClient)
+        {
+            return agent;
+        }
+
+        field.SetValue(meaiInstance, new DelegatingResponsesClient(current));
+        return agent;
     }
+
+    /// <summary>
+    /// MEAI's internal <c>OpenAIResponsesChatClient</c> type, resolved once via reflection.
+    /// <see langword="null"/> if the type cannot be found (e.g., MEAI version drift).
+    /// </summary>
+    [UnconditionalSuppressMessage("Trimming", "IL2026:RequiresUnreferencedCode",
+        Justification = "MEAI's OpenAIResponsesChatClient is referenced through MicrosoftExtensionsAIResponsesExtensions and survives trimming.")]
+    [UnconditionalSuppressMessage("Trimming", "IL2073:RequiresUnreferencedCode",
+        Justification = "MEAI's OpenAIResponsesChatClient is referenced through MicrosoftExtensionsAIResponsesExtensions and survives trimming.")]
+    private static readonly Type? s_meaiResponsesChatClientType =
+        typeof(MicrosoftExtensionsAIResponsesExtensions).Assembly.GetType("Microsoft.Extensions.AI.OpenAIResponsesChatClient");
+
+    /// <summary>
+    /// MEAI's internal <c>_responseClient</c> field on <c>OpenAIResponsesChatClient</c>,
+    /// resolved once via reflection. <see langword="null"/> if the field cannot be found.
+    /// </summary>
+    [UnconditionalSuppressMessage("Trimming", "IL2080:RequiresDynamicallyAccessedMembers",
+        Justification = "OpenAIResponsesChatClient and its private fields are preserved by the polyfill design; MEAI does the same reflection internally.")]
+    private static readonly FieldInfo? s_meaiResponseClientField =
+        s_meaiResponsesChatClientType?.GetField("_responseClient", BindingFlags.NonPublic | BindingFlags.Instance);
 }

dotnet/src/Microsoft.Agents.AI.Foundry/RequestOptionsExtensions.cs

@@ -3,7 +3,6 @@
 using System.ClientModel.Primitives;
 using System.Collections.Generic;
 using System.Reflection;
-using System.Threading;
 using System.Threading.Tasks;
 
 namespace Microsoft.Agents.AI;
@@ -13,20 +12,6 @@ internal static class RequestOptionsExtensions
     /// <summary>Gets the singleton <see cref="PipelinePolicy"/> that adds a MEAI user-agent header.</summary>
     internal static PipelinePolicy UserAgentPolicy => MeaiUserAgentPolicy.Instance;
 
-    /// <summary>Creates a <see cref="RequestOptions"/> configured for use with Foundry Agents.</summary>
-    public static RequestOptions ToRequestOptions(this CancellationToken cancellationToken, bool streaming)
-    {
-        RequestOptions requestOptions = new()
-        {
-            CancellationToken = cancellationToken,
-            BufferResponse = !streaming
-        };
-
-        requestOptions.AddPolicy(MeaiUserAgentPolicy.Instance, PipelinePosition.PerCall);
-
-        return requestOptions;
-    }
-
     /// <summary>Provides a pipeline policy that adds a "MEAI/x.y.z" user-agent header.</summary>
     private sealed class MeaiUserAgentPolicy : PipelinePolicy
     {

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Extensions/ChatMessageExtensions.cs

@@ -16,6 +16,60 @@ internal static class ChatMessageExtensions
     public static RecordValue ToRecord(this ChatMessage message) =>
         FormulaValue.NewRecordFromFields(message.GetMessageFields());
 
+    /// <summary>
+    /// Merges the user-authored <paramref name="input"/> with the round-tripped
+    /// <paramref name="inputMessage"/> returned by <c>AgentProvider.CreateMessageAsync</c>
+    /// to produce the value stored in <c>System.LastMessage</c>.
+    /// </summary>
+    /// <remarks>
+    /// The agent service often strips or alters <see cref="TextContent"/> on round-trip,
+    /// while replacing inline media (<see cref="DataContent"/>, <see cref="UriContent"/>)
+    /// with server-side references (typically <see cref="HostedFileContent"/>).
+    /// We want both: the original text (so <c>=System.LastMessage.Text</c> works) and
+    /// the server's media references (so subsequent actions don't re-upload large blobs).
+    /// <para>
+    /// Strategy: keep <paramref name="inputMessage"/> as the base — it has the server-generated
+    /// <see cref="ChatMessage.MessageId"/> and any provider-augmented metadata, and is forward-
+    /// compatible with new properties added on <see cref="ChatMessage"/> in the abstractions
+    /// layer. Only the <see cref="ChatMessage.Contents"/> list is mutated to substitute
+    /// original <see cref="TextContent"/> items in place (and append any extras the round-trip
+    /// dropped). Non-text content items returned by the service are left untouched so
+    /// server-side references survive.
+    /// </para>
+    /// </remarks>
+    public static ChatMessage MergeForLastMessage(this ChatMessage input, ChatMessage? inputMessage)
+    {
+        if (inputMessage is null)
+        {
+            return input;
+        }
+
+        // Build a queue of the original text items, in order. Fall back to ChatMessage.Text
+        // if the input has no explicit TextContent entries.
+        Queue<TextContent> originalTexts = new(input.Contents.OfType<TextContent>());
+        if (originalTexts.Count == 0 && !string.IsNullOrEmpty(input.Text))
+        {
+            originalTexts.Enqueue(new TextContent(input.Text));
+        }
+
+        // Replace TextContent items in inputMessage.Contents with the originals, in order.
+        for (int i = 0; i < inputMessage.Contents.Count && originalTexts.Count > 0; i++)
+        {
+            if (inputMessage.Contents[i] is TextContent)
+            {
+                inputMessage.Contents[i] = originalTexts.Dequeue();
+            }
+        }
+
+        // Append any remaining original text items that the round-trip dropped entirely.
+        while (originalTexts.Count > 0)
+        {
+            inputMessage.Contents.Add(originalTexts.Dequeue());
+        }
+
+        return inputMessage;
+    }
+
     public static TableValue ToTable(this IEnumerable<ChatMessage> messages) =>
         FormulaValue.NewTable(TypeSchema.Message.RecordType, messages.Select(message => message.ToRecord()));
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Interpreter/DeclarativeWorkflowExecutor.cs

@@ -43,7 +43,11 @@ internal sealed class DeclarativeWorkflowExecutor<TInput>(
         await declarativeContext.QueueConversationUpdateAsync(conversationId, isExternal: true, cancellationToken).ConfigureAwait(false);
 
         ChatMessage inputMessage = await options.AgentProvider.CreateMessageAsync(conversationId, input, cancellationToken).ConfigureAwait(false);
-        await declarativeContext.SetLastMessageAsync(inputMessage).ConfigureAwait(false);
+
+        // Use the original input for System.LastMessage to ensure Text is preserved (the
+        // service may strip text on round-trip), but substitute server-side media references
+        // (e.g., HostedFileContent) so subsequent actions don't re-upload large blobs.
+        await declarativeContext.SetLastMessageAsync(input.MergeForLastMessage(inputMessage)).ConfigureAwait(false);
 
         await context.SendResultMessageAsync(this.Id, cancellationToken).ConfigureAwait(false);
     }

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Kit/RootExecutor.cs

@@ -58,7 +58,6 @@ public abstract class RootExecutor<TInput> : Executor<TInput>, IResettableExecut
     public override async ValueTask HandleAsync(TInput message, IWorkflowContext context, CancellationToken cancellationToken)
     {
         DeclarativeWorkflowContext declarativeContext = new(context, this._state);
-        await this.ExecuteAsync(message, declarativeContext, cancellationToken).ConfigureAwait(false);
 
         ChatMessage input = (this._inputTransform ?? DefaultInputTransform).Invoke(message);
 
@@ -69,7 +68,13 @@ public abstract class RootExecutor<TInput> : Executor<TInput>, IResettableExecut
         await declarativeContext.QueueConversationUpdateAsync(this._conversationId, isExternal: true, cancellationToken).ConfigureAwait(false);
 
         ChatMessage inputMessage = await this._agentProvider.CreateMessageAsync(this._conversationId, input, cancellationToken).ConfigureAwait(false);
-        await declarativeContext.SetLastMessageAsync(inputMessage).ConfigureAwait(false);
+
+        // Use the original input for System.LastMessage to ensure Text is preserved (the
+        // service may strip text on round-trip), but substitute server-side media references
+        // (e.g., HostedFileContent) so subsequent actions don't re-upload large blobs.
+        await declarativeContext.SetLastMessageAsync(input.MergeForLastMessage(inputMessage)).ConfigureAwait(false);
+
+        await this.ExecuteAsync(message, declarativeContext, cancellationToken).ConfigureAwait(false);
 
         await declarativeContext.SendResultMessageAsync(this.Id, cancellationToken).ConfigureAwait(false);
     }

dotnet/src/Shared/Workflows/Execution/WorkflowFactory.cs

@@ -25,6 +25,9 @@ internal sealed class WorkflowFactory(string workflowFile, Uri foundryEndpoint)
     // Assign to provide MCP tool capabilities
     public IMcpToolHandler? McpToolHandler { get; init; }
 
+    // Assign to enable HttpRequestAction support
+    public IHttpRequestHandler? HttpRequestHandler { get; init; }
+
     /// <summary>
     /// Create the workflow from the declarative YAML.  Includes definition of the
     /// <see cref="DeclarativeWorkflowOptions" /> and the associated <see cref="ResponseAgentProvider"/>.
@@ -46,6 +49,7 @@ internal sealed class WorkflowFactory(string workflowFile, Uri foundryEndpoint)
                 ConversationId = this.ConversationId,
                 LoggerFactory = this.LoggerFactory,
                 McpToolHandler = this.McpToolHandler,
+                HttpRequestHandler = this.HttpRequestHandler,
             };
 
         string workflowPath = Path.Combine(AppContext.BaseDirectory, workflowFile);

dotnet/src/Shared/Workflows/Execution/WorkflowRunner.cs

@@ -162,7 +162,10 @@ internal sealed class WorkflowRunner
 
                 case RequestInfoEvent requestInfo:
                     Debug.WriteLine($"REQUEST #{requestInfo.Request.RequestId}");
-                    externalResponse = requestInfo.Request;
+                    if (response is null || !string.Equals(requestInfo.Request.RequestId, response.RequestId, StringComparison.Ordinal))
+                    {
+                        externalResponse = requestInfo.Request;
+                    }
                     break;
 
                 case ConversationUpdateEvent invokeEvent:

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/Hosting/DelegatingResponsesClientTests.cs

@@ -0,0 +1,453 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.ClientModel;
+using System.ClientModel.Primitives;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
+using System.Reflection;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Azure.AI.Extensions.OpenAI;
+using Microsoft.Agents.AI.Foundry.Hosting;
+using Microsoft.Extensions.AI;
+using OpenAI;
+using OpenAI.Responses;
+
+#pragma warning disable OPENAI001, SCME0001, SCME0002, MEAI001
+
+namespace Microsoft.Agents.AI.Foundry.UnitTests.Hosting;
+
+/// <summary>
+/// Verifies that <see cref="DelegatingResponsesClient"/> preserves user-supplied client options
+/// (Transport, RetryPolicy, UserAgentApplicationId, OrganizationId, ProjectId) and adds the
+/// hosted-agent User-Agent supplement on every outgoing request, including streaming.
+/// Covers both the Azure-flavored <see cref="ProjectResponsesClient"/> and the native OpenAI
+/// <see cref="ResponsesClient"/>.
+/// </summary>
+public sealed partial class DelegatingResponsesClientTests
+{
+    private const string TestEndpoint = "https://fake-foundry.example.com/api/projects/fake-prj";
+    private const string OpenAIEndpoint = "https://fake-openai.example.com/v1";
+    private const string Deployment = "fake-deployment";
+
+    [System.Text.RegularExpressions.GeneratedRegex("foundry-hosting/agent-framework-dotnet")]
+    private static partial System.Text.RegularExpressions.Regex SupplementRegex();
+
+    [Fact]
+    public async Task Polyfill_NonStreaming_PreservesAppId_ThroughCustomTransport_AddsSupplementAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        _ = await chat.GetResponseAsync("hello");
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("MEAI/", req.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+        Assert.StartsWith(TestEndpoint, req.Uri);
+    }
+
+    [Fact]
+    public async Task Polyfill_Streaming_PreservesAppId_ThroughCustomTransport_AddsSupplementAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler(MinimalSseResponse());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        await foreach (var _ in chat.GetStreamingResponseAsync("hello"))
+        {
+        }
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("MEAI/", req.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+        Assert.StartsWith(TestEndpoint, req.Uri);
+    }
+
+    [Fact]
+    public async Task Polyfill_PreservesOrganizationAndProjectHeadersAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient,
+            userAgentApplicationId: "MY_APP_ID",
+            organizationId: "org_xyz",
+            projectId: "proj_abc");
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        _ = await chat.GetResponseAsync("hello");
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+    }
+
+    [Fact]
+    public async Task Polyfill_HonorsUserSuppliedRetryPolicy_ByCountingRetriesAsync()
+    {
+        // Arrange
+        var retryPolicy = new CountingRetryPolicy(extraAttempts: 2);
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient, userAgentApplicationId: "MY_APP_ID", retryPolicy: retryPolicy);
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        _ = await chat.GetResponseAsync("hello");
+
+        // Assert: retry policy ran (1 + 2 extras = 3 attempts).
+        Assert.Equal(3, handler.Requests.Count);
+        Assert.Equal(3, retryPolicy.InvocationCount);
+        foreach (var req in handler.Requests)
+        {
+            Assert.Contains("MY_APP_ID", req.UserAgent);
+            Assert.Contains("MEAI/", req.UserAgent);
+            Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+        }
+    }
+
+    [Fact]
+    public async Task Baseline_NonStreaming_DoesNotInjectSupplementAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        var chat = inner.AsIChatClient(Deployment);
+
+        // Act
+        _ = await chat.GetResponseAsync("hello");
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("MEAI/", req.UserAgent);
+        Assert.DoesNotContain("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+    }
+
+    [Fact]
+    public async Task Polyfill_NativeOpenAIResponsesClient_NonStreaming_AddsSupplementAsync()
+    {
+        // Arrange: use the NATIVE OpenAI SDK ResponsesClient (no Foundry / Azure project involved).
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildOpenAIInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        _ = await chat.GetResponseAsync("hello");
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("MEAI/", req.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+        Assert.StartsWith(OpenAIEndpoint, req.Uri);
+    }
+
+    [Fact]
+    public async Task Polyfill_NativeOpenAIResponsesClient_Streaming_AddsSupplementAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler(MinimalSseResponse());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildOpenAIInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        await foreach (var _ in chat.GetStreamingResponseAsync("hello"))
+        {
+        }
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("MEAI/", req.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+        Assert.StartsWith(OpenAIEndpoint, req.Uri);
+    }
+
+    [Theory]
+    [InlineData("DeleteResponseAsync")]
+    [InlineData("CancelResponseAsync")]
+    [InlineData("GetInputTokenCountAsync")]
+    [InlineData("CompactResponseAsync")]
+    [InlineData("GetResponseInputItemCollectionPageAsync")]
+    public async Task Polyfill_AncillaryProtocolMethod_AddsSupplementAsync(string method)
+    {
+        // Arrange: hit the wrapper DIRECTLY (no MEAI in the chain) to simulate user code that
+        // grabs the underlying ResponsesClient via chat.GetService<ResponsesClient>() and invokes
+        // a non-Create/Get protocol method. This is the regression path: without overriding these,
+        // the wrapper's dummy throwing pipeline would fire.
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildOpenAIInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        var wrapper = new DelegatingResponsesClient(inner);
+
+        // Act
+        switch (method)
+        {
+            case "DeleteResponseAsync":
+                _ = await wrapper.DeleteResponseAsync("resp_1", options: null!);
+                break;
+            case "CancelResponseAsync":
+                _ = await wrapper.CancelResponseAsync("resp_1", options: null!);
+                break;
+            case "GetInputTokenCountAsync":
+                _ = await wrapper.GetInputTokenCountAsync("application/json", BinaryContent.Create(BinaryData.FromString("{}")));
+                break;
+            case "CompactResponseAsync":
+                _ = await wrapper.CompactResponseAsync("application/json", BinaryContent.Create(BinaryData.FromString("{}")));
+                break;
+            case "GetResponseInputItemCollectionPageAsync":
+                _ = await wrapper.GetResponseInputItemCollectionPageAsync("resp_1", limit: null, order: "asc", after: "a", before: "b", options: null!);
+                break;
+            default:
+                Assert.Fail($"Unhandled method: {method}");
+                break;
+        }
+
+        // Assert
+        var req = Assert.Single(handler.Requests);
+        Assert.Contains("MY_APP_ID", req.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", req.UserAgent);
+    }
+
+    [Fact]
+    public async Task Polyfill_RetryWithinCall_DoesNotDuplicateSupplementInUserAgentAsync()
+    {
+        // Arrange: a custom retry policy that re-runs the inner pipeline on the SAME message,
+        // so the per-call HostedAgentUserAgentPolicy fires multiple times against the same headers.
+        // The policy's Contains-guard must prevent the supplement from appearing twice.
+        var retryPolicy = new CountingRetryPolicy(extraAttempts: 2);
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient, userAgentApplicationId: "MY_APP_ID", retryPolicy: retryPolicy);
+        var chat = MakeWithDelegating(inner);
+
+        // Act
+        _ = await chat.GetResponseAsync("hello");
+
+        // Assert: each retry attempt must have exactly ONE foundry-hosting segment, never two.
+        Assert.Equal(3, handler.Requests.Count);
+        foreach (var req in handler.Requests)
+        {
+            int matches = SupplementRegex().Matches(req.UserAgent).Count;
+            Assert.True(matches == 1, $"Expected exactly one foundry-hosting segment per retry attempt, got {matches}. UA: {req.UserAgent}");
+        }
+    }
+
+    [Fact]
+    public async Task TryApplyUserAgent_CalledTwiceOnSameAgent_DoesNotDoubleWrapAsync()
+    {
+        // Arrange: build a real ChatClientAgent whose IChatClient resolves to MEAI's
+        // OpenAIResponsesChatClient → ProjectResponsesClient (with a fake transport).
+        using var handler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var inner = BuildInner(httpClient, userAgentApplicationId: "MY_APP_ID");
+        IChatClient chatClient = inner.AsIChatClient(Deployment);
+        AIAgent agent = new ChatClientAgent(chatClient);
+
+        // Act: apply twice.
+        FoundryHostingExtensions.TryApplyUserAgent(agent);
+        FoundryHostingExtensions.TryApplyUserAgent(agent);
+
+        // Assert: invoking the agent produces exactly ONE outbound request whose UA contains
+        // the supplement EXACTLY ONCE (would be twice if the wrapper were nested).
+        _ = await chatClient.GetResponseAsync("hello");
+        var req = Assert.Single(handler.Requests);
+        int matches = SupplementRegex().Matches(req.UserAgent).Count;
+        Assert.True(matches == 1, $"Expected exactly one foundry-hosting segment, got {matches}. UA: {req.UserAgent}");
+    }
+
+    [Fact]
+    public void OpenAIResponsesChatClient_ResponseClientField_ReflectionGuard()
+    {
+        // Guards the polyfill's reflection target. Failure here means MEAI internals
+        // changed and the polyfill needs updating.
+        var meaiType = typeof(MicrosoftExtensionsAIResponsesExtensions).Assembly
+            .GetType("Microsoft.Extensions.AI.OpenAIResponsesChatClient");
+        Assert.NotNull(meaiType);
+
+        var field = meaiType!.GetField("_responseClient", BindingFlags.NonPublic | BindingFlags.Instance);
+        Assert.NotNull(field);
+        Assert.True(typeof(ResponsesClient).IsAssignableFrom(field!.FieldType),
+            $"Expected _responseClient to be assignable to ResponsesClient but was {field.FieldType}.");
+    }
+
+    [Fact]
+    public void ResponsesClient_PipelineProperty_ReflectionGuard()
+    {
+        // The polyfill design assumes ResponsesClient.Pipeline remains accessible.
+        var pipelineProp = typeof(ResponsesClient).GetProperty("Pipeline", BindingFlags.Public | BindingFlags.Instance);
+        Assert.NotNull(pipelineProp);
+        Assert.Equal(typeof(ClientPipeline), pipelineProp!.PropertyType);
+    }
+
+    private static IChatClient MakeWithDelegating(ResponsesClient inner)
+    {
+        IChatClient meai = inner.AsIChatClient(Deployment);
+        var meaiType = meai.GetType();
+        var field = meaiType.GetField("_responseClient", BindingFlags.NonPublic | BindingFlags.Instance)!;
+        field.SetValue(meai, new DelegatingResponsesClient(inner));
+        return meai;
+    }
+
+    private static ProjectResponsesClient BuildInner(
+        HttpClient httpClient,
+        string? userAgentApplicationId = null,
+        string? organizationId = null,
+        string? projectId = null,
+        PipelinePolicy? retryPolicy = null)
+    {
+        var options = new ProjectResponsesClientOptions
+        {
+            Transport = new HttpClientPipelineTransport(httpClient),
+        };
+        if (userAgentApplicationId is not null)
+        {
+            options.UserAgentApplicationId = userAgentApplicationId;
+        }
+        if (organizationId is not null)
+        {
+            options.OrganizationId = organizationId;
+        }
+        if (projectId is not null)
+        {
+            options.ProjectId = projectId;
+        }
+        if (retryPolicy is not null)
+        {
+            options.RetryPolicy = retryPolicy;
+        }
+
+        return new ProjectResponsesClient(new Uri(TestEndpoint), new FakeAuthenticationTokenProvider(), options);
+    }
+
+    private static ResponsesClient BuildOpenAIInner(
+        HttpClient httpClient,
+        string? userAgentApplicationId = null)
+    {
+        var options = new OpenAIClientOptions
+        {
+            Transport = new HttpClientPipelineTransport(httpClient),
+            Endpoint = new Uri(OpenAIEndpoint),
+        };
+        if (userAgentApplicationId is not null)
+        {
+            options.UserAgentApplicationId = userAgentApplicationId;
+        }
+
+        return new ResponsesClient(new ApiKeyCredential("test-key"), options);
+    }
+
+    private static string MinimalResponseJson() => """
+        {
+          "id":"resp_1","object":"response","created_at":1700000000,"status":"completed",
+          "model":"fake","output":[],"usage":{"input_tokens":1,"output_tokens":1,"total_tokens":2}
+        }
+        """;
+
+    private static string MinimalSseResponse()
+    {
+        var sb = new StringBuilder();
+        sb.Append("event: response.completed\n");
+        sb.Append("data: ").Append("""{"type":"response.completed","response":{"id":"resp_1","object":"response","created_at":1700000000,"status":"completed","model":"fake","output":[],"usage":{"input_tokens":1,"output_tokens":1,"total_tokens":2}}}""").Append("\n\n");
+        sb.Append("data: [DONE]\n\n");
+        return sb.ToString();
+    }
+
+    private sealed class RecordingHandler : HttpClientHandler
+    {
+        private readonly string _body;
+        public List<RecordedRequest> Requests { get; } = [];
+
+        public RecordingHandler(string body)
+        {
+            this._body = body;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            string ua = request.Headers.TryGetValues("User-Agent", out var values)
+                ? string.Join(",", values)
+                : "(none)";
+            this.Requests.Add(new RecordedRequest(request.Method.Method, request.RequestUri?.ToString() ?? "?", ua));
+
+            var resp = new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(this._body, Encoding.UTF8, "application/json"),
+                RequestMessage = request,
+            };
+            return Task.FromResult(resp);
+        }
+    }
+
+    private readonly record struct RecordedRequest(string Method, string Uri, string UserAgent);
+
+    private sealed class CountingRetryPolicy : PipelinePolicy
+    {
+        private readonly int _extraAttempts;
+        public int InvocationCount { get; private set; }
+
+        public CountingRetryPolicy(int extraAttempts)
+        {
+            this._extraAttempts = extraAttempts;
+        }
+
+        public override void Process(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
+        {
+            for (int i = 0; i <= this._extraAttempts; i++)
+            {
+                this.InvocationCount++;
+                ProcessNext(message, pipeline, currentIndex);
+            }
+        }
+
+        public override async ValueTask ProcessAsync(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
+        {
+            for (int i = 0; i <= this._extraAttempts; i++)
+            {
+                this.InvocationCount++;
+                await ProcessNextAsync(message, pipeline, currentIndex).ConfigureAwait(false);
+            }
+        }
+    }
+}

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/Hosting/HostedOutboundUserAgentTests.cs

@@ -0,0 +1,165 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.ClientModel.Primitives;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Azure.AI.Extensions.OpenAI;
+using Microsoft.Agents.AI.Foundry.Hosting;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting.Server;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.DependencyInjection;
+
+#pragma warning disable OPENAI001, SCME0001, SCME0002, MEAI001
+
+namespace Microsoft.Agents.AI.Foundry.UnitTests.Hosting;
+
+/// <summary>
+/// End-to-end tests that exercise the FULL hosted ASP.NET Core pipeline:
+/// inbound HTTP → MapFoundryResponses → AgentFrameworkResponseHandler → TryApplyUserAgent →
+/// agent invocation → outbound HTTP from inside the hosted environment.
+/// Verifies that the hosted-agent <c>User-Agent</c> supplement reaches the outbound wire,
+/// not just the inbound request.
+/// </summary>
+public sealed class HostedOutboundUserAgentTests : IAsyncDisposable
+{
+    private const string TestEndpoint = "https://fake-foundry.example.com/api/projects/fake-prj";
+    private const string Deployment = "fake-deployment";
+
+    private WebApplication? _app;
+    private HttpClient? _inboundClient;
+    private RecordingHandler? _outboundHandler;
+
+    public async ValueTask DisposeAsync()
+    {
+        this._inboundClient?.Dispose();
+        this._outboundHandler?.Dispose();
+        if (this._app is not null)
+        {
+            await this._app.DisposeAsync();
+        }
+    }
+
+    [Fact]
+    public async Task Hosted_InboundResponsesRequest_TriggersOutboundCall_WithFoundryHostingSupplementAsync()
+    {
+        // Arrange: spin up a real ASP.NET Core TestServer that hosts an AIAgent backed by MEAI's
+        // OpenAIResponsesChatClient → ProjectResponsesClient → fake HTTP transport. This is the
+        // exact production stack minus the network: the only thing not real is the wire transport.
+        await this.StartHostedServerAsync();
+
+        // Act: send an inbound /openai/v1/responses request as the Foundry runtime would.
+        using var inboundRequest = new HttpRequestMessage(HttpMethod.Post, "/responses")
+        {
+            Content = new StringContent(InboundResponsesRequestJson(), Encoding.UTF8, "application/json"),
+        };
+        using var inboundResponse = await this._inboundClient!.SendAsync(inboundRequest);
+        var inboundBody = await inboundResponse.Content.ReadAsStringAsync();
+
+        // Assert: at least one OUTBOUND request reached the fake transport, AND it carries the
+        // foundry-hosting/agent-framework-dotnet/{version} supplement on its User-Agent.
+        // (We don't care about the inbound response shape — only that the agent's call to MEAI
+        // triggered an outbound request whose UA reaches the sandbox boundary correctly.)
+        Assert.True(this._outboundHandler!.Requests.Count > 0,
+            $"Expected at least one outbound request. Inbound status: {(int)inboundResponse.StatusCode}, body: {inboundBody}");
+        var outbound = this._outboundHandler.Requests[0];
+        Assert.StartsWith(TestEndpoint, outbound.Uri);
+        Assert.Contains("MEAI/", outbound.UserAgent);
+        Assert.Contains("foundry-hosting/agent-framework-dotnet", outbound.UserAgent);
+    }
+
+    private async Task StartHostedServerAsync()
+    {
+        var builder = WebApplication.CreateBuilder();
+        builder.WebHost.UseTestServer();
+
+        // Build a real ChatClientAgent whose IChatClient is MEAI's OpenAIResponsesChatClient
+        // wrapping a ProjectResponsesClient backed by a fake HTTP handler. After AgentFrameworkResponseHandler
+        // resolves this agent, TryApplyUserAgent will swap the inner _responseClient with our wrapper.
+        this._outboundHandler = new RecordingHandler(MinimalResponseJson());
+#pragma warning disable CA5399
+        var outboundHttpClient = new HttpClient(this._outboundHandler);
+#pragma warning restore CA5399
+
+        var projectOptions = new ProjectResponsesClientOptions
+        {
+            Transport = new HttpClientPipelineTransport(outboundHttpClient),
+        };
+        var projectResponsesClient = new ProjectResponsesClient(
+            new Uri(TestEndpoint),
+            new FakeAuthenticationTokenProvider(),
+            projectOptions);
+
+        IChatClient chatClient = projectResponsesClient.AsIChatClient(Deployment);
+        AIAgent agent = new ChatClientAgent(chatClient);
+
+        builder.Services.AddFoundryResponses(agent);
+        builder.Services.AddLogging();
+
+        this._app = builder.Build();
+        this._app.MapFoundryResponses();
+
+        await this._app.StartAsync();
+
+        var testServer = this._app.Services.GetRequiredService<IServer>() as TestServer
+            ?? throw new InvalidOperationException("TestServer not found");
+
+        this._inboundClient = testServer.CreateClient();
+    }
+
+    private static string InboundResponsesRequestJson() => """
+        {
+          "model": "fake-deployment",
+          "input": [
+            {
+              "type": "message",
+              "id": "msg_1",
+              "status": "completed",
+              "role": "user",
+              "content": [{ "type": "input_text", "text": "Hello" }]
+            }
+          ]
+        }
+        """;
+
+    private static string MinimalResponseJson() => """
+        {
+          "id":"resp_1","object":"response","created_at":1700000000,"status":"completed",
+          "model":"fake","output":[],"usage":{"input_tokens":1,"output_tokens":1,"total_tokens":2}
+        }
+        """;
+
+    private sealed class RecordingHandler : HttpClientHandler
+    {
+        private readonly string _body;
+        public List<RecordedRequest> Requests { get; } = [];
+
+        public RecordingHandler(string body)
+        {
+            this._body = body;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            string ua = request.Headers.TryGetValues("User-Agent", out var values)
+                ? string.Join(",", values)
+                : "(none)";
+            this.Requests.Add(new RecordedRequest(request.RequestUri?.ToString() ?? "?", ua));
+
+            var resp = new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(this._body, Encoding.UTF8, "application/json"),
+                RequestMessage = request,
+            };
+            return Task.FromResult(resp);
+        }
+    }
+
+    private readonly record struct RecordedRequest(string Uri, string UserAgent);
+}

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/Hosting/ServiceCollectionExtensionsTests.cs

@@ -4,8 +4,10 @@ using System;
 using System.Linq;
 using Azure.AI.AgentServer.Responses;
 using Microsoft.Agents.AI.Foundry.Hosting;
+using Microsoft.Extensions.AI;
 using Microsoft.Extensions.DependencyInjection;
 using Moq;
+using OpenAI.Responses;
 
 namespace Microsoft.Agents.AI.Foundry.UnitTests.Hosting;
 
@@ -93,4 +95,45 @@ public class ServiceCollectionExtensionsTests
 
         Assert.Same(instrumented, result);
     }
+
+    [Fact]
+    public void TryApplyUserAgent_AgentWithoutChatClient_NoOp()
+    {
+        // Arrange: agent.GetService<IChatClient>() returns null.
+        var mockAgent = new Mock<AIAgent>();
+
+        // Act
+        var result = FoundryHostingExtensions.TryApplyUserAgent(mockAgent.Object);
+
+        // Assert
+        Assert.Same(mockAgent.Object, result);
+    }
+
+    [Fact]
+    public void TryApplyUserAgent_AgentWithNonMeaiChatClient_NoOp()
+    {
+        // Arrange: chat client that does not return MEAI's OpenAIResponsesChatClient via GetService.
+        var mockChatClient = new Mock<IChatClient>();
+        mockChatClient.Setup(c => c.GetService(It.IsAny<Type>(), It.IsAny<object?>())).Returns(null!);
+
+        var mockAgent = new Mock<AIAgent>();
+        mockAgent.Setup(a => a.GetService(typeof(IChatClient), It.IsAny<object?>())).Returns(mockChatClient.Object);
+
+        // Act
+        var result = FoundryHostingExtensions.TryApplyUserAgent(mockAgent.Object);
+
+        // Assert
+        Assert.Same(mockAgent.Object, result);
+    }
+
+    [Fact]
+    public void MeaiOpenAIResponsesChatClient_TypeFullName_ReflectionGuard()
+    {
+        // Guards the polyfill's reflection target type-name.
+        var meaiType = typeof(MicrosoftExtensionsAIResponsesExtensions).Assembly
+            .GetType("Microsoft.Extensions.AI.OpenAIResponsesChatClient");
+        Assert.NotNull(meaiType);
+        Assert.True(typeof(IChatClient).IsAssignableFrom(meaiType!),
+            $"Expected MEAI {meaiType!.FullName} to implement IChatClient.");
+    }
 }

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/Hosting/UserAgentMiddlewareTests.cs

@@ -1,134 +0,0 @@
-// Copyright (c) Microsoft. All rights reserved.
-
-using System;
-using System.Net.Http;
-using System.Text.RegularExpressions;
-using System.Threading.Tasks;
-using Microsoft.Agents.AI.Foundry.Hosting;
-using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Hosting.Server;
-using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.TestHost;
-using Microsoft.Extensions.DependencyInjection;
-using Moq;
-
-namespace Microsoft.Agents.AI.Foundry.UnitTests.Hosting;
-
-/// <summary>
-/// Tests for the <c>AgentFrameworkUserAgentMiddleware</c> registered by
-/// <see cref="FoundryHostingExtensions.MapFoundryResponses"/>.
-/// </summary>
-public sealed partial class UserAgentMiddlewareTests : IAsyncDisposable
-{
-    private const string VersionedUserAgentPattern = @"agent-framework-dotnet/\d+\.\d+\.\d+(-[\w.]+)?";
-
-    private WebApplication? _app;
-    private HttpClient? _httpClient;
-
-    public async ValueTask DisposeAsync()
-    {
-        this._httpClient?.Dispose();
-        if (this._app != null)
-        {
-            await this._app.DisposeAsync();
-        }
-    }
-
-    [Fact]
-    public async Task MapFoundryResponses_NoUserAgentHeader_SetsAgentFrameworkUserAgentAsync()
-    {
-        // Arrange
-        await this.CreateTestServerAsync();
-
-        using var request = new HttpRequestMessage(HttpMethod.Get, "/test-ua");
-
-        // Act
-        var response = await this._httpClient!.SendAsync(request);
-        var userAgent = await response.Content.ReadAsStringAsync();
-
-        // Assert
-        Assert.Matches(VersionedUserAgentPattern, userAgent);
-    }
-
-    [Fact]
-    public async Task MapFoundryResponses_WithExistingUserAgent_AppendsAgentFrameworkUserAgentAsync()
-    {
-        // Arrange
-        await this.CreateTestServerAsync();
-
-        using var request = new HttpRequestMessage(HttpMethod.Get, "/test-ua");
-        request.Headers.TryAddWithoutValidation("User-Agent", "MyApp/1.0");
-
-        // Act
-        var response = await this._httpClient!.SendAsync(request);
-        var userAgent = await response.Content.ReadAsStringAsync();
-
-        // Assert
-        Assert.StartsWith("MyApp/1.0", userAgent);
-        Assert.Matches(VersionedUserAgentPattern, userAgent);
-    }
-
-    [Fact]
-    public async Task MapFoundryResponses_AlreadyContainsUserAgent_DoesNotDuplicateAsync()
-    {
-        // Arrange
-        await this.CreateTestServerAsync();
-
-        // First request to capture the actual middleware-generated value
-        using var firstRequest = new HttpRequestMessage(HttpMethod.Get, "/test-ua");
-        var firstResponse = await this._httpClient!.SendAsync(firstRequest);
-        var middlewareValue = await firstResponse.Content.ReadAsStringAsync();
-
-        // Act: send a second request that already contains the middleware value
-        using var secondRequest = new HttpRequestMessage(HttpMethod.Get, "/test-ua");
-        secondRequest.Headers.TryAddWithoutValidation("User-Agent", $"MyApp/2.0 {middlewareValue}");
-        var secondResponse = await this._httpClient!.SendAsync(secondRequest);
-        var userAgent = await secondResponse.Content.ReadAsStringAsync();
-
-        // Assert: should remain unchanged (no duplication)
-        Assert.Equal($"MyApp/2.0 {middlewareValue}", userAgent);
-        Assert.Single(VersionedUserAgentRegex().Matches(userAgent));
-    }
-
-    [Fact]
-    public async Task MapFoundryResponses_UserAgentValue_ContainsVersionAsync()
-    {
-        // Arrange
-        await this.CreateTestServerAsync();
-
-        using var request = new HttpRequestMessage(HttpMethod.Get, "/test-ua");
-
-        // Act
-        var response = await this._httpClient!.SendAsync(request);
-        var userAgent = await response.Content.ReadAsStringAsync();
-
-        // Assert: should match "agent-framework-dotnet/x.y.z" pattern
-        Assert.Matches(VersionedUserAgentPattern, userAgent);
-    }
-
-    private async Task CreateTestServerAsync()
-    {
-        var builder = WebApplication.CreateBuilder();
-        builder.WebHost.UseTestServer();
-
-        var mockAgent = new Mock<AIAgent>();
-        builder.Services.AddFoundryResponses(mockAgent.Object);
-
-        this._app = builder.Build();
-        this._app.MapFoundryResponses();
-
-        // Test endpoint that echoes the User-Agent header after middleware processing
-        this._app.MapGet("/test-ua", (HttpContext ctx) =>
-            Results.Text(ctx.Request.Headers.UserAgent.ToString()));
-
-        await this._app.StartAsync();
-
-        var testServer = this._app.Services.GetRequiredService<IServer>() as TestServer
-            ?? throw new InvalidOperationException("TestServer not found");
-
-        this._httpClient = testServer.CreateClient();
-    }
-
-    [GeneratedRegex(VersionedUserAgentPattern)]
-    private static partial Regex VersionedUserAgentRegex();
-}

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/RequestOptionsExtensionsTests.cs

@@ -0,0 +1,115 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.ClientModel.Primitives;
+using System.Net;
+using System.Net.Http;
+using System.Reflection;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.Agents.AI.Foundry.UnitTests;
+
+/// <summary>
+/// Verifies the per-call <c>MeaiUserAgentPolicy</c> exposed via
+/// <see cref="RequestOptionsExtensions.UserAgentPolicy"/>. The policy is reachable through the
+/// public <see cref="FoundryAgent"/> constructors (which add it to the internally-built
+/// <see cref="Azure.AI.Projects.AIProjectClient"/>'s pipeline), so its behavior is part of the
+/// public API surface.
+/// </summary>
+public sealed class RequestOptionsExtensionsTests
+{
+    [Fact]
+    public async Task MeaiUserAgentPolicy_AddsMeaiSegment_ToOutgoingRequestAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler();
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var pipeline = ClientPipeline.Create(
+            new ClientPipelineOptions { Transport = new HttpClientPipelineTransport(httpClient) },
+            perCallPolicies: [RequestOptionsExtensions.UserAgentPolicy],
+            perTryPolicies: default,
+            beforeTransportPolicies: default);
+
+        // Act
+        var message = pipeline.CreateMessage();
+        message.Request.Method = "POST";
+        message.Request.Uri = new System.Uri("https://example.test/anything");
+        await pipeline.SendAsync(message);
+
+        // Assert
+        Assert.Equal(1, handler.Count);
+        Assert.NotNull(handler.LastUserAgent);
+        Assert.Contains("MEAI/", handler.LastUserAgent);
+    }
+
+    [Fact]
+    public async Task MeaiUserAgentPolicy_DoesNotAddFoundryHostingSegmentAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler();
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        var pipeline = ClientPipeline.Create(
+            new ClientPipelineOptions { Transport = new HttpClientPipelineTransport(httpClient) },
+            perCallPolicies: [RequestOptionsExtensions.UserAgentPolicy],
+            perTryPolicies: default,
+            beforeTransportPolicies: default);
+
+        // Act
+        var message = pipeline.CreateMessage();
+        message.Request.Method = "POST";
+        message.Request.Uri = new System.Uri("https://example.test/anything");
+        await pipeline.SendAsync(message);
+
+        // Assert: the policy is MEAI-only; the foundry-hosting supplement is added elsewhere
+        // (by the polyfill DelegatingResponsesClient → HostedAgentUserAgentPolicy).
+        Assert.NotNull(handler.LastUserAgent);
+        Assert.DoesNotContain("foundry-hosting/agent-framework-dotnet", handler.LastUserAgent);
+    }
+
+    [Fact]
+    public void UserAgentPolicy_ExposesSingletonInstance()
+    {
+        // Two reads of the static property must return the same instance — the policy is stateless and shared.
+        var first = RequestOptionsExtensions.UserAgentPolicy;
+        var second = RequestOptionsExtensions.UserAgentPolicy;
+        Assert.Same(first, second);
+    }
+
+    [Fact]
+    public void MeaiUserAgentPolicy_ValueIncludesAFFoundryAssemblyVersion_ReflectionGuard()
+    {
+        // The policy emits "MEAI/{Microsoft.Agents.AI.Foundry assembly InformationalVersion}".
+        // If the assembly metadata stops being readable, the policy falls back to "MEAI" without a version,
+        // which is a measurable telemetry regression.
+        var attr = typeof(RequestOptionsExtensions).Assembly
+            .GetCustomAttribute<AssemblyInformationalVersionAttribute>();
+        Assert.NotNull(attr);
+        Assert.False(string.IsNullOrEmpty(attr!.InformationalVersion));
+    }
+
+    private sealed class RecordingHandler : HttpClientHandler
+    {
+        public int Count { get; private set; }
+        public string? LastUserAgent { get; private set; }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            this.Count++;
+            this.LastUserAgent = request.Headers.TryGetValues("User-Agent", out var values)
+                ? string.Join(",", values)
+                : null;
+
+            var resp = new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("{}", Encoding.UTF8, "application/json"),
+                RequestMessage = request,
+            };
+            return Task.FromResult(resp);
+        }
+    }
+}

dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/Extensions/ChatMessageExtensionsTests.cs

@@ -769,4 +769,165 @@ public sealed class ChatMessageExtensionsTests
                 break;
         }
     }
+
+    [Fact]
+    public void MergeForLastMessageReturnsInputWhenInputMessageIsNull()
+    {
+        // Arrange
+        ChatMessage input = new(ChatRole.User, "hello") { MessageId = "local" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(null);
+
+        // Assert
+        Assert.Same(input, result);
+    }
+
+    [Fact]
+    public void MergeForLastMessageReturnsSameInstanceAsRoundTripped()
+    {
+        // Arrange: returning the round-tripped instance keeps the merge forward-compatible
+        // with future ChatMessage properties (e.g., new metadata fields) without explicit copies.
+        ChatMessage input = new(ChatRole.User, "original");
+        ChatMessage roundTripped = new(ChatRole.User, "stripped") { MessageId = "server" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert
+        Assert.Same(roundTripped, result);
+    }
+
+    [Fact]
+    public void MergeForLastMessagePrefersOriginalTextOverRoundTrippedText()
+    {
+        // Arrange
+        ChatMessage input = new(ChatRole.User, "original text");
+        ChatMessage roundTripped = new(ChatRole.User, "stripped") { MessageId = "server-id" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert
+        Assert.Equal("server-id", result.MessageId);
+        Assert.Equal("original text", result.Text);
+        TextContent text = Assert.IsType<TextContent>(Assert.Single(result.Contents));
+        Assert.Equal("original text", text.Text);
+    }
+
+    [Fact]
+    public void MergeForLastMessageReplacesTextInPlaceAndKeepsServerMedia()
+    {
+        // Arrange
+        HostedFileContent serverRef = new("file-abc");
+        ChatMessage input = new(ChatRole.User, [new TextContent("look at this:"), new DataContent("data:image/jpeg;base64,QUJD", "image/jpeg")]);
+        ChatMessage roundTripped = new(ChatRole.User, [new TextContent("stripped"), serverRef]) { MessageId = "server-id" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert: server's text slot is replaced with original text; server's media reference is preserved.
+        Assert.Equal("server-id", result.MessageId);
+        Assert.Collection(result.Contents,
+            c => Assert.Equal("look at this:", Assert.IsType<TextContent>(c).Text),
+            c => Assert.Same(serverRef, c));
+    }
+
+    [Fact]
+    public void MergeForLastMessageAppendsOriginalTextWhenRoundTripHasNoTextSlot()
+    {
+        // Arrange: round-tripped message has only media (no text slot to replace).
+        HostedFileContent serverRef = new("file-1");
+        ChatMessage input = new(ChatRole.User, [new TextContent("middle"), new DataContent("data:image/jpeg;base64,QUE=", "image/jpeg")]);
+        ChatMessage roundTripped = new(ChatRole.User, [serverRef]) { MessageId = "id" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert: media kept; original text appended at end.
+        Assert.Collection(result.Contents,
+            c => Assert.Same(serverRef, c),
+            c => Assert.Equal("middle", Assert.IsType<TextContent>(c).Text));
+    }
+
+    [Fact]
+    public void MergeForLastMessageReplacesMultipleTextSlotsInOrder()
+    {
+        // Arrange: input has two text items; round-tripped has two text slots interleaved with media.
+        HostedFileContent firstRef = new("file-1");
+        HostedFileContent secondRef = new("file-2");
+        ChatMessage input = new(ChatRole.User, [new TextContent("first"), new TextContent("second")]);
+        ChatMessage roundTripped = new(ChatRole.User, [firstRef, new TextContent("a"), secondRef, new TextContent("b")]) { MessageId = "id" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert
+        Assert.Collection(result.Contents,
+            c => Assert.Same(firstRef, c),
+            c => Assert.Equal("first", Assert.IsType<TextContent>(c).Text),
+            c => Assert.Same(secondRef, c),
+            c => Assert.Equal("second", Assert.IsType<TextContent>(c).Text));
+    }
+
+    [Fact]
+    public void MergeForLastMessageFallsBackToInputTextWhenInputHasNoTextContent()
+    {
+        // Arrange: ChatMessage(role, "string") populates Text but no explicit TextContent
+        // when Contents is initially empty in some construction paths. Verify we still
+        // recover the original Text via input.Text.
+        ChatMessage input = new(ChatRole.User, "fallback text");
+        ChatMessage roundTripped = new(ChatRole.User, [new TextContent("stripped")]) { MessageId = "id" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert
+        Assert.Equal("fallback text", Assert.IsType<TextContent>(Assert.Single(result.Contents)).Text);
+    }
+
+    [Fact]
+    public void MergeForLastMessagePreservesServerAuthoredProperties()
+    {
+        // Arrange: server (round-trip) is authoritative for metadata. Returning the
+        // round-tripped instance means any future ChatMessage property is automatically
+        // preserved without code changes here.
+        ChatMessage input = new(ChatRole.User, "hi")
+        {
+            AuthorName = "client-side",
+            AdditionalProperties = new AdditionalPropertiesDictionary { ["client"] = "value" },
+        };
+        ChatMessage roundTripped = new(ChatRole.User, [new TextContent("stripped")])
+        {
+            MessageId = "server",
+            AuthorName = "server-side",
+            AdditionalProperties = new AdditionalPropertiesDictionary { ["server"] = "value" },
+        };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert
+        Assert.Equal("server", result.MessageId);
+        Assert.Equal("server-side", result.AuthorName);
+        Assert.NotNull(result.AdditionalProperties);
+        Assert.True(result.AdditionalProperties.ContainsKey("server"));
+        Assert.False(result.AdditionalProperties.ContainsKey("client"));
+    }
+
+    [Fact]
+    public void MergeForLastMessageHandlesEmptyInputContents()
+    {
+        // Arrange
+        ChatMessage input = new(ChatRole.User, new List<AIContent>());
+        HostedFileContent serverRef = new("file-only");
+        ChatMessage roundTripped = new(ChatRole.User, [serverRef]) { MessageId = "id" };
+
+        // Act
+        ChatMessage result = input.MergeForLastMessage(roundTripped);
+
+        // Assert: nothing to splice; round-tripped returned unchanged.
+        Assert.Same(roundTripped, result);
+        Assert.Equal("file-only", Assert.IsType<HostedFileContent>(Assert.Single(result.Contents)).FileId);
+    }
 }

python/packages/anthropic/agent_framework_anthropic/_chat_client.py

@@ -872,6 +872,8 @@ class RawAnthropicClient(
         tool_mode = validate_tool_mode(options.get("tool_choice"))
         if tool_mode is None:
             return result or None
+        if "allowed_tools" in tool_mode:
+            logger.warning("allowed_tools is not supported by Anthropic; the setting will be ignored")
         allow_multiple = options.get("allow_multiple_tool_calls")
         match tool_mode.get("mode"):
             case "auto":

python/packages/bedrock/agent_framework_bedrock/_chat_client.py

@@ -405,6 +405,8 @@ class BedrockChatClient(
 
         tool_config = self._prepare_tools(options.get("tools"))
         if tool_mode := validate_tool_mode(options.get("tool_choice")):
+            if "allowed_tools" in tool_mode:
+                logger.warning("allowed_tools is not supported by Bedrock; the setting will be ignored")
             match tool_mode.get("mode"):
                 case "none":
                     # Bedrock doesn't support toolChoice "none".

python/packages/core/agent_framework/_types.py

@@ -3246,10 +3246,12 @@ class ToolMode(TypedDict, total=False):
     Fields:
         mode: One of "auto", "required", or "none".
         required_function_name: Optional function name when `mode == "required"`.
+        allowed_tools: Optional list of tool names when `mode` is `"auto"` or `"required"`.
     """
 
     mode: Literal["auto", "required", "none"]
     required_function_name: str
+    allowed_tools: list[str]
 
 
 # region TypedDict-based Chat Options
@@ -3482,7 +3484,7 @@ def validate_tool_mode(
 
     Returns:
         A ToolMode dict (contains keys: "mode", and optionally
-        "required_function_name"), or ``None`` when not provided.
+        "required_function_name" or "allowed_tools"), or ``None`` when not provided.
 
     Raises:
         ContentError: If the tool_choice string is invalid.
@@ -3499,6 +3501,17 @@ def validate_tool_mode(
         raise ContentError(f"Invalid tool choice: {tool_choice['mode']}")
     if tool_choice["mode"] != "required" and "required_function_name" in tool_choice:
         raise ContentError("tool_choice with mode other than 'required' cannot have 'required_function_name'")
+    if tool_choice["mode"] not in ("auto", "required") and "allowed_tools" in tool_choice:
+        raise ContentError("tool_choice 'allowed_tools' is only valid when mode is 'auto' or 'required'")
+    if "allowed_tools" in tool_choice:
+        allowed_tools = tool_choice["allowed_tools"]
+        if isinstance(allowed_tools, str) or not isinstance(allowed_tools, Sequence):
+            raise ContentError("tool_choice 'allowed_tools' must be a non-string sequence of strings")
+        if not all(isinstance(tool_name, str) for tool_name in allowed_tools):
+            raise ContentError("tool_choice 'allowed_tools' must contain only strings")
+        normalized_tool_choice = dict(tool_choice)
+        normalized_tool_choice["allowed_tools"] = list(allowed_tools)
+        return cast(ToolMode, normalized_tool_choice)
     return tool_choice
 
 

python/packages/core/tests/core/test_types.py

@@ -1087,16 +1087,20 @@ def test_chat_tool_mode():
     required_any: ToolMode = {"mode": "required"}
     required_mode: ToolMode = {"mode": "required", "required_function_name": "example_function"}
     none_mode: ToolMode = {"mode": "none"}
+    allowed_mode: ToolMode = {"mode": "auto", "allowed_tools": ["get_weather", "search_docs"]}
 
     # Check the type and content
     assert auto_mode["mode"] == "auto"
     assert "required_function_name" not in auto_mode
+    assert "allowed_tools" not in auto_mode
     assert required_any["mode"] == "required"
     assert "required_function_name" not in required_any
     assert required_mode["mode"] == "required"
     assert required_mode["required_function_name"] == "example_function"
     assert none_mode["mode"] == "none"
     assert "required_function_name" not in none_mode
+    assert allowed_mode["mode"] == "auto"
+    assert allowed_mode["allowed_tools"] == ["get_weather", "search_docs"]
 
     # equality of dicts
     assert {"mode": "required", "required_function_name": "example_function"} == {
@@ -1154,6 +1158,45 @@ def test_chat_options_tool_choice_validation():
     with raises(ContentError):
         validate_tool_mode({"mode": "auto", "required_function_name": "should_not_be_here"})
 
+    # Valid allowed_tools
+    assert validate_tool_mode({"mode": "auto", "allowed_tools": ["get_weather"]}) == {
+        "mode": "auto",
+        "allowed_tools": ["get_weather"],
+    }
+    assert validate_tool_mode({"mode": "auto", "allowed_tools": ["get_weather", "search_docs"]}) == {
+        "mode": "auto",
+        "allowed_tools": ["get_weather", "search_docs"],
+    }
+
+    # allowed_tools valid with required mode
+    assert validate_tool_mode({"mode": "required", "allowed_tools": ["get_weather"]}) == {
+        "mode": "required",
+        "allowed_tools": ["get_weather"],
+    }
+
+    # allowed_tools invalid with none mode
+    with raises(ContentError):
+        validate_tool_mode({"mode": "none", "allowed_tools": ["get_weather"]})
+
+    # allowed_tools must be a non-string sequence of strings
+    with raises(ContentError):
+        validate_tool_mode({"mode": "auto", "allowed_tools": "get_weather"})
+    with raises(ContentError):
+        validate_tool_mode({"mode": "auto", "allowed_tools": 123})
+    with raises(ContentError):
+        validate_tool_mode({"mode": "auto", "allowed_tools": ["get_weather", 123]})
+
+    # Empty list is valid (caller explicitly allows no tools)
+    assert validate_tool_mode({"mode": "auto", "allowed_tools": []}) == {
+        "mode": "auto",
+        "allowed_tools": [],
+    }
+
+    # Tuple is normalized to list
+    result = validate_tool_mode({"mode": "auto", "allowed_tools": ("get_weather",)})
+    assert result is not None
+    assert result["allowed_tools"] == ["get_weather"]
+
 
 def test_chat_options_merge(tool_tool, ai_tool) -> None:
     """Test merge_chat_options utility function."""

python/packages/gemini/agent_framework_gemini/_chat_client.py

@@ -823,19 +823,28 @@ class RawGeminiChatClient(
 
         match tool_mode.get("mode"):
             case "auto":
-                function_calling_mode, allowed_names = types.FunctionCallingConfigMode.AUTO, None
+                if "allowed_tools" in tool_mode:
+                    function_calling_mode = types.FunctionCallingConfigMode.VALIDATED
+                    allowed_names = list(tool_mode["allowed_tools"])
+                else:
+                    function_calling_mode, allowed_names = types.FunctionCallingConfigMode.AUTO, None
             case "none":
                 function_calling_mode, allowed_names = types.FunctionCallingConfigMode.NONE, None
             case "required":
                 function_calling_mode = types.FunctionCallingConfigMode.ANY
                 name = tool_mode.get("required_function_name")
-                allowed_names = [name] if name else None
+                if name:
+                    allowed_names = [name]
+                elif "allowed_tools" in tool_mode:
+                    allowed_names = list(tool_mode["allowed_tools"])
+                else:
+                    allowed_names = None
             case unknown_mode:
                 logger.warning("Unsupported tool_choice mode for Gemini: %s", unknown_mode)
                 return None
 
         function_calling_kwargs: dict[str, Any] = {"mode": function_calling_mode}
-        if allowed_names:
+        if allowed_names is not None:
             function_calling_kwargs["allowed_function_names"] = allowed_names
 
         return types.ToolConfig(function_calling_config=types.FunctionCallingConfig(**function_calling_kwargs))

python/packages/gemini/tests/test_gemini_client.py

@@ -1157,6 +1157,86 @@ async def test_unknown_tool_choice_mode_is_ignored() -> None:
     assert not hasattr(config, "tool_config") or config.tool_config is None
 
 
+async def test_tool_choice_auto_with_allowed_tools_uses_VALIDATED() -> None:
+    """Maps auto + allowed_tools to FunctionCallingConfigMode.VALIDATED with allowed_function_names."""
+    tool = _make_dummy_tool()
+    client, mock = _make_gemini_client()
+    mock.aio.models.generate_content = AsyncMock(return_value=_make_response([_make_part(text="Hi")]))
+
+    await client.get_response(
+        messages=[Message(role="user", contents=[Content.from_text("Hi")])],
+        options={
+            "tools": [tool],
+            "tool_choice": {"mode": "auto", "allowed_tools": ["dummy", "other"]},
+        },
+    )
+
+    config: types.GenerateContentConfig = mock.aio.models.generate_content.call_args.kwargs["config"]
+    function_calling_config = config.tool_config.function_calling_config
+    assert function_calling_config.mode == "VALIDATED"
+    assert function_calling_config.allowed_function_names == ["dummy", "other"]
+
+
+async def test_tool_choice_auto_with_empty_allowed_tools_uses_VALIDATED() -> None:
+    """Maps auto + empty allowed_tools to VALIDATED with empty allowed_function_names."""
+    tool = _make_dummy_tool()
+    client, mock = _make_gemini_client()
+    mock.aio.models.generate_content = AsyncMock(return_value=_make_response([_make_part(text="Hi")]))
+
+    await client.get_response(
+        messages=[Message(role="user", contents=[Content.from_text("Hi")])],
+        options={
+            "tools": [tool],
+            "tool_choice": {"mode": "auto", "allowed_tools": []},
+        },
+    )
+
+    config: types.GenerateContentConfig = mock.aio.models.generate_content.call_args.kwargs["config"]
+    function_calling_config = config.tool_config.function_calling_config
+    assert function_calling_config.mode == "VALIDATED"
+    assert function_calling_config.allowed_function_names == []
+
+
+async def test_tool_choice_required_with_allowed_tools_uses_ANY() -> None:
+    """Maps required + allowed_tools to ANY with allowed_function_names."""
+    tool = _make_dummy_tool()
+    client, mock = _make_gemini_client()
+    mock.aio.models.generate_content = AsyncMock(return_value=_make_response([_make_part(text="Hi")]))
+
+    await client.get_response(
+        messages=[Message(role="user", contents=[Content.from_text("Hi")])],
+        options={
+            "tools": [tool],
+            "tool_choice": {"mode": "required", "allowed_tools": ["dummy"]},
+        },
+    )
+
+    config: types.GenerateContentConfig = mock.aio.models.generate_content.call_args.kwargs["config"]
+    function_calling_config = config.tool_config.function_calling_config
+    assert function_calling_config.mode == "ANY"
+    assert function_calling_config.allowed_function_names == ["dummy"]
+
+
+async def test_tool_choice_required_function_name_takes_precedence_over_allowed_tools() -> None:
+    """When both required_function_name and allowed_tools are present, required_function_name wins."""
+    tool = _make_dummy_tool()
+    client, mock = _make_gemini_client()
+    mock.aio.models.generate_content = AsyncMock(return_value=_make_response([_make_part(text="Hi")]))
+
+    await client.get_response(
+        messages=[Message(role="user", contents=[Content.from_text("Hi")])],
+        options={
+            "tools": [tool],
+            "tool_choice": {"mode": "required", "required_function_name": "dummy", "allowed_tools": ["other"]},
+        },
+    )
+
+    config: types.GenerateContentConfig = mock.aio.models.generate_content.call_args.kwargs["config"]
+    function_calling_config = config.tool_config.function_calling_config
+    assert function_calling_config.mode == "ANY"
+    assert function_calling_config.allowed_function_names == ["dummy"]
+
+
 # built-in tool factories
 
 

python/packages/openai/agent_framework_openai/_chat_client.py

@@ -1296,6 +1296,12 @@ class RawOpenAIChatClient(  # type: ignore[misc]
                             "type": "function",
                             "name": func_name,
                         }
+                    elif mode == "auto" and (allowed := tool_mode.get("allowed_tools")) is not None:
+                        run_options["tool_choice"] = {
+                            "type": "allowed_tools",
+                            "mode": "auto",
+                            "tools": [{"type": "function", "name": name} for name in allowed],
+                        }
                     else:
                         run_options["tool_choice"] = mode
         else:

python/packages/openai/agent_framework_openai/_chat_completion_client.py

@@ -662,6 +662,12 @@ class RawOpenAIChatCompletionClient(  # type: ignore[misc]
                         "type": "function",
                         "function": {"name": func_name},
                     }
+                elif mode in ("auto", "required") and tool_mode.get("allowed_tools") is not None:
+                    logger.warning(
+                        "allowed_tools is not supported by the Chat Completions API; "
+                        "the setting will be ignored. Use OpenAIChatClient (Responses API) instead."
+                    )
+                    run_options["tool_choice"] = mode
                 else:
                     run_options["tool_choice"] = mode
 

python/packages/openai/tests/openai/test_openai_chat_client.py

@@ -4272,6 +4272,12 @@ def test_with_callable_api_key() -> None:
             True,
             id="tool_choice_required",
         ),
+        param(
+            "tool_choice",
+            {"mode": "auto", "allowed_tools": ["get_weather"]},
+            True,
+            id="tool_choice_allowed_tools",
+        ),
         param("response_format", OutputStruct, True, id="response_format_pydantic"),
         param(
             "response_format",
@@ -4822,6 +4828,90 @@ async def test_prepare_options_excludes_continuation_token() -> None:
     assert run_options["background"] is True
 
 
+async def test_prepare_options_allowed_tools() -> None:
+    """Test that _prepare_options converts allowed_tools to OpenAI API format."""
+    client = OpenAIChatClient(model="test-model", api_key="test-key")
+
+    @tool
+    def get_weather(city: str) -> str:
+        """Get the weather for a city."""
+        return f"Sunny in {city}"
+
+    @tool
+    def search_docs(query: str) -> str:
+        """Search documentation."""
+        return f"Results for {query}"
+
+    messages = [Message(role="user", contents=[Content.from_text(text="Hello")])]
+    options: dict[str, Any] = {
+        "model": "test-model",
+        "tools": [get_weather, search_docs],
+        "tool_choice": {"mode": "auto", "allowed_tools": ["get_weather"]},
+    }
+
+    run_options = await client._prepare_options(messages, options)
+
+    assert run_options["tool_choice"] == {
+        "type": "allowed_tools",
+        "mode": "auto",
+        "tools": [{"type": "function", "name": "get_weather"}],
+    }
+
+
+async def test_prepare_options_allowed_tools_multiple() -> None:
+    """Test that _prepare_options converts multiple allowed_tools correctly."""
+    client = OpenAIChatClient(model="test-model", api_key="test-key")
+
+    @tool
+    def get_weather(city: str) -> str:
+        """Get the weather for a city."""
+        return f"Sunny in {city}"
+
+    @tool
+    def search_docs(query: str) -> str:
+        """Search documentation."""
+        return f"Results for {query}"
+
+    messages = [Message(role="user", contents=[Content.from_text(text="Hello")])]
+    options: dict[str, Any] = {
+        "model": "test-model",
+        "tools": [get_weather, search_docs],
+        "tool_choice": {"mode": "auto", "allowed_tools": ["get_weather", "search_docs"]},
+    }
+
+    run_options = await client._prepare_options(messages, options)
+
+    assert run_options["tool_choice"] == {
+        "type": "allowed_tools",
+        "mode": "auto",
+        "tools": [
+            {"type": "function", "name": "get_weather"},
+            {"type": "function", "name": "search_docs"},
+        ],
+    }
+
+
+async def test_prepare_options_auto_without_allowed_tools() -> None:
+    """Test that auto mode without allowed_tools still returns plain 'auto' string."""
+    client = OpenAIChatClient(model="test-model", api_key="test-key")
+
+    @tool
+    def get_weather(city: str) -> str:
+        """Get the weather for a city."""
+        return f"Sunny in {city}"
+
+    messages = [Message(role="user", contents=[Content.from_text(text="Hello")])]
+    options: dict[str, Any] = {
+        "model": "test-model",
+        "tools": [get_weather],
+        "tool_choice": {"mode": "auto"},
+    }
+
+    run_options = await client._prepare_options(messages, options)
+
+    assert run_options["tool_choice"] == "auto"
+
+
 # endregion
 
 

python/packages/openai/tests/openai/test_openai_chat_completion_client.py

@@ -1430,6 +1430,57 @@ def test_tool_choice_required_with_function_name(
     assert prepared_options["tool_choice"]["function"]["name"] == "get_weather"
 
 
+def test_tool_choice_allowed_tools_falls_back_to_mode(
+    openai_unit_test_env: dict[str, str],
+) -> None:
+    """Test that tool_choice with allowed_tools falls back to plain mode (Chat Completions API unsupported)."""
+    client = OpenAIChatCompletionClient()
+
+    messages = [Message(role="user", contents=["test"])]
+    options = {
+        "tools": [get_weather],
+        "tool_choice": {"mode": "auto", "allowed_tools": ["get_weather"]},
+    }
+
+    prepared_options = client._prepare_options(messages, options)
+
+    assert prepared_options["tool_choice"] == "auto"
+
+
+def test_tool_choice_allowed_tools_required_mode_falls_back(
+    openai_unit_test_env: dict[str, str],
+) -> None:
+    """Test that tool_choice with allowed_tools and required mode falls back to 'required'."""
+    client = OpenAIChatCompletionClient()
+
+    messages = [Message(role="user", contents=["test"])]
+    options = {
+        "tools": [get_weather],
+        "tool_choice": {"mode": "required", "allowed_tools": ["get_weather"]},
+    }
+
+    prepared_options = client._prepare_options(messages, options)
+
+    assert prepared_options["tool_choice"] == "required"
+
+
+def test_tool_choice_auto_dict_without_allowed_tools(
+    openai_unit_test_env: dict[str, str],
+) -> None:
+    """Test that tool_choice dict with mode auto and no allowed_tools falls through to plain 'auto'."""
+    client = OpenAIChatCompletionClient()
+
+    messages = [Message(role="user", contents=["test"])]
+    options = {
+        "tools": [get_weather],
+        "tool_choice": {"mode": "auto"},
+    }
+
+    prepared_options = client._prepare_options(messages, options)
+
+    assert prepared_options["tool_choice"] == "auto"
+
+
 def test_response_format_dict_passthrough(openai_unit_test_env: dict[str, str]) -> None:
     """Test that response_format as dict is passed through directly."""
     client = OpenAIChatCompletionClient()
@@ -1590,6 +1641,12 @@ class OutputStruct(BaseModel):
             False,
             id="tool_choice_required",
         ),
+        param(
+            "tool_choice",
+            {"mode": "auto", "allowed_tools": ["get_weather"]},
+            False,
+            id="tool_choice_allowed_tools",
+        ),
         param("response_format", OutputStruct, True, id="response_format_pydantic"),
         param(
             "response_format",