ci: harden project status sync workflow

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

.github/workflows/project-status-sync.yml

@@ -0,0 +1,159 @@
+name: Sync Project Status to Labels
+
+on:
+  projects_v2_item:
+    types: [edited]
+
+# Prevent race conditions when status changes rapidly.
+# Key by project item (node_id) so updates for the same card serialize.
+concurrency:
+  group: status-sync-${{ github.event.projects_v2_item.node_id }}
+  cancel-in-progress: true
+
+jobs:
+  sync_status:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+
+    steps:
+      - uses: actions/github-script@v8
+        with:
+          # Use PAT/App token because Projects GraphQL often requires project scope.
+          # GITHUB_TOKEN is repo-scoped and may not access org Projects. 【4-75ee64】【5-e66679】
+          github-token: ${{ secrets.GH_ACTIONS_PR_WRITE }}
+          script: |
+            const item = context.payload.projects_v2_item;
+            const changes = context.payload.changes || {};
+
+            // 1) Logging project id so that we can filter out by project in next revision.
+            console.log(`Processing issue from project: ${item.project_node_id}`);
+
+            // 2) Only act on Issues
+            if (item.content_type !== "Issue") return;
+
+            // 3) Map project Status values to labels
+            const labelMap = {
+              "Planned": "status:planned",
+              "In Progress": "status:in-progress",
+              "In Review": "status:in-review",
+              "Done": "status:done"
+            };
+            const allStatusLabels = Object.values(labelMap);
+
+            // 4) Fast path: If this edit is a Status change and the payload includes "to.name", use it.
+            // Some payloads include field_value.to with { name, ... } for single-select fields. 【6-4092ed】【3-e3ddba】
+            let statusValue = null;
+            const fv = changes.field_value;
+            if (fv && fv.field_name === "Status" && fv.to && fv.to.name) {
+              statusValue = fv.to.name;
+              console.log(`Fast path: Status changed to "${statusValue}"`);
+            }
+
+            // 5) Otherwise, query GraphQL once to get both Issue number and Status field value.
+            if (!statusValue) {
+              try {
+                const result = await github.graphql(
+                  `query($id: ID!) {
+                    node(id: $id) {
+                      ... on ProjectV2Item {
+                        content { ... on Issue { number } }
+                        fieldValues(first: 50) {
+                          nodes {
+                            ... on ProjectV2ItemFieldSingleSelectValue {
+                              name
+                              field { ... on ProjectV2SingleSelectField { name } }
+                            }
+                          }
+                        }
+                      }
+                    }
+                  }`,
+                  { id: item.node_id }
+                );
+
+                const node = result?.node;
+                const values = node?.fieldValues?.nodes ?? [];
+                statusValue = values.find(v => v.field?.name === "Status")?.name;
+
+                // If no status found, nothing to do.
+                if (!statusValue) {
+                  console.log("No Status field value found in project item");
+                  return;
+                }
+
+                // Fetch issue number from GraphQL content if present
+                var issue_number = node?.content?.number;
+                if (!issue_number) {
+                  console.error("Could not extract issue number from GraphQL response");
+                  return;
+                }
+              } catch (graphqlError) {
+                console.error(`GraphQL query failed: ${graphqlError.message}`);
+                throw graphqlError;
+              }
+            } else {
+              // If we used fast-path for status, we still need issue_number:
+              try {
+                const result = await github.graphql(
+                  `query($id: ID!) { node(id: $id) { ... on Issue { number } } }`,
+                  { id: item.content_node_id }
+                );
+                var issue_number = result?.node?.number;
+              } catch (graphqlError) {
+                console.error(`Failed to fetch issue number: ${graphqlError.message}`);
+                throw graphqlError;
+              }
+              if (!issue_number) return;
+            }
+
+            const targetLabel = labelMap[statusValue];
+            if (!targetLabel) {
+              console.warn(`Status "${statusValue}" has no mapped label. Skipping.`);
+              return;
+            }
+            console.log(`Mapped status "${statusValue}" to label "${targetLabel}"`);
+
+            // 6) Get existing labels
+            let issue;
+            try {
+              const response = await github.rest.issues.get({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number
+              });
+              issue = response.data;
+            } catch (restError) {
+              console.error(`Failed to fetch issue #${issue_number}: ${restError.message}`);
+              throw restError;
+            }
+
+            const existingLabels = issue.labels.map(l => l.name);
+
+            // If already correct, exit (reduces churn)
+            if (existingLabels.includes(targetLabel) &&
+                existingLabels.filter(l => allStatusLabels.includes(l)).length === 1) {
+              console.log(`Issue #${issue_number} already has correct label "${targetLabel}". No changes needed.`);
+              return;
+            }
+
+            // 7) Avoid "remove then add" partial failure by using setLabels once.
+            // This preserves all non-status labels and ensures exactly one status label.
+            const nextLabels = existingLabels
+              .filter(l => !allStatusLabels.includes(l))
+              .concat([targetLabel]);
+
+            const removedLabels = existingLabels.filter(l => allStatusLabels.includes(l) && l !== targetLabel);
+            try {
+              await github.rest.issues.setLabels({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number,
+                labels: nextLabels
+              });
+              console.log(`Updated issue #${issue_number}: removed [${removedLabels.join(", ")}], added "${targetLabel}"`);
+            } catch (updateError) {
+              console.error(`Failed to update labels for issue #${issue_number}: ${updateError.message}`);
+              throw updateError;
+            }
+            

dotnet/Directory.Packages.props

@@ -25,7 +25,7 @@
     <PackageVersion Include="Azure.AI.AgentServer.Core" Version="1.0.0-beta.23" />
     <PackageVersion Include="Azure.AI.AgentServer.Invocations" Version="1.0.0-beta.3" />
     <PackageVersion Include="Azure.AI.AgentServer.Responses" Version="1.0.0-beta.4" />
-    <PackageVersion Include="Azure.AI.Projects" Version="2.0.0" />
+    <PackageVersion Include="Azure.AI.Projects" Version="2.1.0-beta.1" />
     <PackageVersion Include="Azure.AI.Agents.Persistent" Version="1.2.0-beta.10" />
     <PackageVersion Include="Azure.AI.OpenAI" Version="2.9.0-beta.1" />
     <PackageVersion Include="Azure.Core" Version="1.53.0" />

dotnet/agent-framework-release.slnf

@@ -30,7 +30,8 @@
       "src\\Microsoft.Agents.AI.Workflows.Generators\\Microsoft.Agents.AI.Workflows.Generators.csproj",
       "src\\Microsoft.Agents.AI.Workflows\\Microsoft.Agents.AI.Workflows.csproj",
       "src\\Microsoft.Agents.AI\\Microsoft.Agents.AI.csproj",
-      "src\\Aspire.Hosting.AgentFramework.DevUI\\Aspire.Hosting.AgentFramework.DevUI.csproj"
+      "src\\Aspire.Hosting.AgentFramework.DevUI\\Aspire.Hosting.AgentFramework.DevUI.csproj",
+      "src\\Microsoft.Agents.AI.Hyperlight\\Microsoft.Agents.AI.Hyperlight.csproj"
     ]
   }
 }

dotnet/nuget/nuget-package.props

@@ -1,14 +1,14 @@
 <Project>
   <PropertyGroup>
     <!-- Central version prefix - applies to all nuget packages. -->
-    <VersionPrefix>1.4.0</VersionPrefix>
+    <VersionPrefix>1.5.0</VersionPrefix>
     <RCNumber>1</RCNumber>
-    <DateSuffix>260505</DateSuffix>
+    <DateSuffix>260507</DateSuffix>
     <PackageVersion Condition="'$(IsReleaseCandidate)' == 'true'">$(VersionPrefix)-rc$(RCNumber)</PackageVersion>
     <PackageVersion Condition="'$(IsReleaseCandidate)' != 'true' AND '$(VersionSuffix)' != ''">$(VersionPrefix)-$(VersionSuffix).$(DateSuffix).1</PackageVersion>
     <PackageVersion Condition="'$(IsReleaseCandidate)' != 'true' AND '$(VersionSuffix)' == ''">$(VersionPrefix)-preview.$(DateSuffix).1</PackageVersion>
     <PackageVersion Condition="'$(IsReleased)' == 'true'">$(VersionPrefix)</PackageVersion>
-    <GitTag>1.4.0</GitTag>
+    <GitTag>1.5.0</GitTag>
 
     <Configurations>Debug;Release;Publish</Configurations>
     <IsPackable>true</IsPackable>

dotnet/samples/02-agents/Agents/Agent_Step19_InFunctionLoopCheckpointing/Program.cs

@@ -8,6 +8,11 @@
 // even if the process is interrupted mid-loop, but may also result in chat history that is not
 // yet finalized (e.g., tool calls without results) being persisted, which may be undesirable in some cases.
 //
+// Additionally, this sample demonstrates the MessageInjectingChatClient feature, which allows tool
+// code to inject new user messages during the function execution loop. When a tool or anything else enqueues
+// a message via MessageInjectingChatClient.EnqueueMessages during the tool execution loop, the PerServiceCallChatHistoryPersistingChatClient
+// detects the pending message before the next service call and includes the injected message in the request.
+//
 // To use end-of-run persistence instead (atomic run semantics), remove the
 // RequirePerServiceCallChatHistoryPersistence = true setting (or set it to false). End-of-run
 // persistence is the default behavior.
@@ -54,6 +59,37 @@ static string GetTime([Description("The city name.")] string city) =>
         _ => $"{city}: time data not available."
     };
 
+// This tool demonstrates message injection during the function execution loop.
+// When called, it checks travel advisories for a city. If an advisory is active, it uses
+// the ambient run context to resolve MessageInjectingChatClient and injects a follow-up user message
+// asking for alternative destinations. The model will process this injected message on the next
+// service call — even though the parent FunctionInvokingChatClient loop would otherwise stop.
+[Description("Check current travel advisories for a city.")]
+static string CheckTravelAdvisory([Description("The city name.")] string city)
+{
+    // Simulated travel advisory data.
+    var advisory = city.ToUpperInvariant() switch
+    {
+        "LONDON" => "Travel advisory: Severe fog warnings in London. Flights may be delayed or cancelled.",
+        "SEATTLE" => "Travel advisory: Heavy rainfall expected. Flooding possible in low-lying areas.",
+        _ => null
+    };
+
+    if (advisory is null)
+    {
+        return $"{city}: No active travel advisories.";
+    }
+
+    // When an advisory is found, inject a follow-up question so the model automatically
+    // suggests alternatives without the user needing to ask.
+    var runContext = AIAgent.CurrentRunContext!;
+    runContext.Agent.GetService<MessageInjectingChatClient>()?.EnqueueMessages(
+        runContext.Session!,
+        [new ChatMessage(ChatRole.User, $"Given the travel advisory for {city}, what alternative cities would you recommend instead?")]);
+
+    return advisory;
+}
+
 // Create the agent — per-service-call persistence is enabled via RequirePerServiceCallChatHistoryPersistence.
 // The in-memory ChatHistoryProvider is used by default when the service does not require service stored chat
 // history, so for those cases, we can inspect the chat history via session.TryGetInMemoryChatHistory().
@@ -65,10 +101,11 @@ AIAgent agent = chatClient.AsAIAgent(
     {
         Name = "WeatherAssistant",
         RequirePerServiceCallChatHistoryPersistence = true,
+        EnableMessageInjection = true,
         ChatOptions = new()
         {
-            Instructions = "You are a helpful assistant. When asked about multiple cities, call the appropriate tool for each city.",
-            Tools = [AIFunctionFactory.Create(GetWeather), AIFunctionFactory.Create(GetTime)]
+            Instructions = "You are a helpful travel assistant. When asked about cities, call the appropriate tools for each city.",
+            Tools = [AIFunctionFactory.Create(GetWeather), AIFunctionFactory.Create(GetTime), AIFunctionFactory.Create(CheckTravelAdvisory)]
         },
     });
 
@@ -109,6 +146,18 @@ async Task RunNonStreamingAsync()
     response = await agent.RunAsync(FollowUp2, session);
     PrintAgentResponse(response.Text);
     PrintChatHistory(session, "After third run", ref lastChatHistorySize, ref lastConversationId);
+
+    // Fourth turn — demonstrates message injection during the function loop.
+    // The CheckTravelAdvisory tool detects an advisory for London and injects a follow-up
+    // user message asking for alternative cities. After the tool completes, the internal loop
+    // in PerServiceCallChatHistoryPersistingChatClient detects the pending injected message
+    // and calls the service again, so the model answers the follow-up automatically.
+    const string TravelPrompt = "I'm planning to travel to London next week. Check if there are any travel advisories.";
+    PrintUserMessage(TravelPrompt);
+
+    response = await agent.RunAsync(TravelPrompt, session);
+    PrintAgentResponse(response.Text);
+    PrintChatHistory(session, "After travel advisory run", ref lastChatHistorySize, ref lastConversationId);
 }
 
 async Task RunStreamingAsync()
@@ -181,6 +230,30 @@ async Task RunStreamingAsync()
 
     Console.WriteLine();
     PrintChatHistory(session, "After third run", ref lastChatHistorySize, ref lastConversationId);
+
+    // Fourth turn — demonstrates message injection during the function loop (streaming).
+    // The CheckTravelAdvisory tool detects an advisory for London and injects a follow-up
+    // user message asking for alternative cities. After the tool completes, the internal loop
+    // in PerServiceCallChatHistoryPersistingChatClient detects the pending injected message
+    // and calls the service again, so the model answers the follow-up automatically.
+    const string TravelPrompt = "I'm planning to travel to London next week. Check if there are any travel advisories.";
+    PrintUserMessage(TravelPrompt);
+
+    Console.ForegroundColor = ConsoleColor.Cyan;
+    Console.Write("\n[Agent] ");
+    Console.ResetColor();
+
+    await foreach (var update in agent.RunStreamingAsync(TravelPrompt, session))
+    {
+        Console.Write(update);
+
+        // During streaming we should be able to see updates to the chat history
+        // before the full run completes, as each service call is made and persisted.
+        PrintChatHistory(session, "During travel advisory run", ref lastChatHistorySize, ref lastConversationId);
+    }
+
+    Console.WriteLine();
+    PrintChatHistory(session, "After travel advisory run", ref lastChatHistorySize, ref lastConversationId);
 }
 
 void PrintUserMessage(string message)

dotnet/samples/02-agents/AgentsWithFoundry/Agent_Step25_ToolboxServerSideTools/Agent_Step25_ToolboxServerSideTools.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -11,7 +11,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.Foundry.Hosting\Microsoft.Agents.AI.Foundry.Hosting.csproj" />
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
   </ItemGroup>
 
 </Project>

dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-LocalTools/HostedLocalTools.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFrameworks>net10.0</TargetFrameworks>
@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="DotNetEnv" />
   </ItemGroup>

dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-McpTools/HostedMcpTools.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFrameworks>net10.0</TargetFrameworks>
@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="ModelContextProtocol" VersionOverride="1.2.0" />
     <PackageReference Include="DotNetEnv" />

dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Observability/HostedObservability.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFrameworks>net10.0</TargetFrameworks>
@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="DotNetEnv" />
   </ItemGroup>

dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-TextRag/HostedTextRag.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFrameworks>net10.0</TargetFrameworks>
@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="DotNetEnv" />
   </ItemGroup>

dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Toolbox/HostedToolbox.csproj

@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="DotNetEnv" />
   </ItemGroup>

dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Workflow-Simple/HostedWorkflowSimple.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFrameworks>net10.0</TargetFrameworks>
@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="DotNetEnv" />
   </ItemGroup>

dotnet/src/Microsoft.Agents.AI.Foundry.Hosting/Microsoft.Agents.AI.Foundry.Hosting.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFrameworks>$(TargetFrameworksCore)</TargetFrameworks>
@@ -31,7 +31,7 @@
 
   <ItemGroup>
     <PackageReference Include="Azure.AI.AgentServer.Responses" />
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="ModelContextProtocol" />
     <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" />

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

@@ -2,6 +2,7 @@
 
 using System;
 using System.ClientModel;
+using System.ClientModel.Primitives;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Threading;
@@ -38,7 +39,28 @@ namespace Microsoft.Agents.AI.Foundry;
 [Experimental(DiagnosticIds.Experiments.AIOpenAIResponses)]
 public sealed class FoundryAgent : DelegatingAIAgent
 {
-    private readonly AIProjectClient _aiProjectClient;
+    /// <summary>
+    /// Default OAuth scope for the Azure AI resource. Matches the scope used by
+    /// <c>Azure.AI.Extensions.OpenAI</c>'s internal authentication helper so the bearer token is
+    /// accepted by the Foundry control plane.
+    /// </summary>
+    private const string AzureAiResourceScope = "https://ai.azure.com/.default";
+
+    /// <summary>
+    /// The cached <see cref="AIProjectClient"/> when one was supplied or constructed by the active
+    /// constructor. Null when the agent was constructed via the agent-endpoint constructor, which
+    /// does not build a full <see cref="AIProjectClient"/>.
+    /// </summary>
+    private readonly AIProjectClient? _aiProjectClient;
+
+    /// <summary>
+    /// Project-scoped <see cref="ProjectOpenAIClient"/>. Always non-null. Used for project-level
+    /// operations such as <see cref="CreateConversationSessionAsync(CancellationToken)"/>.
+    /// In agent-endpoint mode this is built directly from the project root derived from the
+    /// supplied agent endpoint; in project-endpoint mode it is the cached client returned by
+    /// <see cref="AIProjectClient"/>.
+    /// </summary>
+    private readonly ProjectOpenAIClient _projectOpenAIClient;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="FoundryAgent"/> class using the direct Responses API path.
@@ -72,30 +94,49 @@ public sealed class FoundryAgent : DelegatingAIAgent
             out var aiProjectClient))
     {
         this._aiProjectClient = aiProjectClient;
+        this._projectOpenAIClient = aiProjectClient.GetProjectOpenAIClient();
     }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="FoundryAgent"/> class from an agent-specific endpoint.
     /// </summary>
-    /// <param name="agentEndpoint">The agent-specific endpoint URI (must contain the agent name in the path).</param>
+    /// <param name="agentEndpoint">
+    /// The agent-specific endpoint URI. Must be of the shape
+    /// <c>https://&lt;host&gt;/.../projects/&lt;project&gt;/agents/&lt;agentName&gt;/endpoint/protocols/openai</c>.
+    /// </param>
     /// <param name="credential">The authentication credential.</param>
-    /// <param name="clientOptions">Optional configuration options for the <see cref="AIProjectClient"/>.</param>
+    /// <param name="clientOptions">
+    /// Optional configuration for the underlying <see cref="ProjectOpenAIClient"/>. When supplied:
+    /// <list type="bullet">
+    ///   <item><description>The instance is passed through to the per-agent client; pipeline policies added via <c>AddPolicy(...)</c> on it execute on the per-agent traffic.</description></item>
+    ///   <item><description><c>Endpoint</c> and <see cref="ProjectOpenAIClientOptions.AgentName"/> are owned by this constructor and are overwritten with values derived from <paramref name="agentEndpoint"/>; any caller value is replaced.</description></item>
+    ///   <item><description>For the project-level conversations client a separate fresh options bag is built that copies only <see cref="ClientPipelineOptions.RetryPolicy"/>, <see cref="ClientPipelineOptions.NetworkTimeout"/>, <see cref="ClientPipelineOptions.Transport"/>, and <c>UserAgentApplicationId</c>; pipeline policies added via <c>AddPolicy(...)</c> do <strong>not</strong> propagate to the conversations pipeline.</description></item>
+    /// </list>
+    /// </param>
     /// <param name="tools">Optional tools to use when interacting with the agent.</param>
     /// <param name="clientFactory">Provides a way to customize the creation of the underlying <see cref="IChatClient"/>.</param>
     /// <param name="services">Optional service provider for resolving dependencies required by AI functions.</param>
+    /// <exception cref="ArgumentNullException"><paramref name="agentEndpoint"/> or <paramref name="credential"/> is null.</exception>
+    /// <exception cref="ArgumentException"><paramref name="agentEndpoint"/> does not match the expected agent-endpoint shape.</exception>
+    /// <remarks>
+    /// This is the lightweight constructor for invoking an existing Foundry hosted agent when the
+    /// caller already has the per-agent endpoint URL. It populates <see cref="ChatClientAgentOptions.Id"/>
+    /// and <see cref="ChatClientAgentOptions.Name"/> from the agent name parsed out of the endpoint
+    /// path; <c>Description</c>, <c>Instructions</c>, <c>Temperature</c>, and <c>TopP</c> are not
+    /// populated. Callers that need those fields hydrated from server-side state should use
+    /// <c>AIProjectClient.AsAIAgent(ProjectsAgentVersion)</c> or
+    /// <c>AIProjectClient.AsAIAgent(ProjectsAgentRecord)</c> instead.
+    /// </remarks>
     public FoundryAgent(
         Uri agentEndpoint,
         AuthenticationTokenProvider credential,
-        AIProjectClientOptions? clientOptions = null,
+        ProjectOpenAIClientOptions? clientOptions = null,
         IList<AITool>? tools = null,
         Func<IChatClient, IChatClient>? clientFactory = null,
         IServiceProvider? services = null)
-        : base(CreateInnerAgentFromEndpoint(
-            CreateProjectClient(agentEndpoint, credential, clientOptions),
-            agentEndpoint, tools, clientFactory, services,
-            out var aiProjectClient))
+        : base(CreateInnerAgentFromAgentEndpoint(agentEndpoint, credential, clientOptions, tools, clientFactory, services))
     {
-        this._aiProjectClient = aiProjectClient;
+        this._projectOpenAIClient = CreateProjectLevelOpenAIClientFromAgentEndpoint(agentEndpoint, credential, clientOptions);
     }
 
     /// <summary>
@@ -105,6 +146,7 @@ public sealed class FoundryAgent : DelegatingAIAgent
         : base(WireClientHeaders(Throw.IfNull(innerAgent)))
     {
         this._aiProjectClient = Throw.IfNull(aiProjectClient);
+        this._projectOpenAIClient = aiProjectClient.GetProjectOpenAIClient();
     }
 
     #region Convenience methods
@@ -137,9 +179,7 @@ public sealed class FoundryAgent : DelegatingAIAgent
     /// <returns>A <see cref="ChatClientAgentSession"/> linked to the newly created server-side conversation.</returns>
     public async Task<ChatClientAgentSession> CreateConversationSessionAsync(CancellationToken cancellationToken = default)
     {
-        var conversationsClient = this._aiProjectClient
-            .GetProjectOpenAIClient()
-            .GetProjectConversationsClient();
+        var conversationsClient = this._projectOpenAIClient.GetProjectConversationsClient();
 
         var conversation = (await conversationsClient.CreateProjectConversationAsync(options: null, cancellationToken).ConfigureAwait(false)).Value;
 
@@ -161,6 +201,11 @@ public sealed class FoundryAgent : DelegatingAIAgent
             return this._aiProjectClient;
         }
 
+        if (serviceKey is null && serviceType == typeof(ProjectOpenAIClient))
+        {
+            return this._projectOpenAIClient;
+        }
+
         return base.GetService(serviceType, serviceKey);
     }
 
@@ -238,47 +283,181 @@ public sealed class FoundryAgent : DelegatingAIAgent
             OpenAIRequestPoliciesReflection.AddPolicyIfMissing(
                 policies,
                 ClientHeadersPolicy.Instance,
-                System.ClientModel.Primitives.PipelinePosition.PerCall);
+                PipelinePosition.PerCall);
         }
 
         return new ClientHeadersAgent(innerAgent);
     }
 
-    private static AIAgent CreateInnerAgentFromEndpoint(
-        AIProjectClient aiProjectClient,
+    /// <summary>
+    /// Builds the inner <see cref="ChatClientAgent"/> for the agent-endpoint constructor by
+    /// constructing a per-agent <see cref="ProjectOpenAIClient"/> via the
+    /// <c>ProjectOpenAIClient(AuthenticationPolicy, ProjectOpenAIClientOptions)</c>
+    /// constructor with <see cref="ProjectOpenAIClientOptions.AgentName"/> set. This routes the
+    /// outbound URL through the per-agent endpoint shape that the Foundry service expects for
+    /// hosted agents and lets the SDK auto-append the <c>api-version</c> query string.
+    /// Caller-supplied <paramref name="clientOptions"/> are passed through to the per-agent
+    /// client with <c>Endpoint</c> and
+    /// <see cref="ProjectOpenAIClientOptions.AgentName"/> overridden by values derived from
+    /// <paramref name="agentEndpoint"/>; any policies the caller added via <c>AddPolicy</c>
+    /// remain in effect on the per-agent pipeline. The MEAI user-agent policy is appended last.
+    /// </summary>
+    private static AIAgent CreateInnerAgentFromAgentEndpoint(
         Uri agentEndpoint,
+        AuthenticationTokenProvider credential,
+        ProjectOpenAIClientOptions? clientOptions,
         IList<AITool>? tools,
         Func<IChatClient, IChatClient>? clientFactory,
-        IServiceProvider? services,
-        out AIProjectClient outClient)
+        IServiceProvider? services)
     {
-        outClient = aiProjectClient;
+        Throw.IfNull(agentEndpoint);
+        Throw.IfNull(credential);
 
-        AgentReference agentReference = agentEndpoint.Segments[^1].TrimEnd('/');
+        var (agentName, _) = ParseAgentEndpoint(agentEndpoint);
 
-        ChatClientAgentOptions agentOptions = new()
-        {
-            Name = agentReference.Name,
-            ChatOptions = new() { Tools = tools },
-        };
+        var perAgentOptions = clientOptions ?? new ProjectOpenAIClientOptions();
+        perAgentOptions.Endpoint = agentEndpoint;
+        perAgentOptions.AgentName = agentName;
+        perAgentOptions.AddPolicy(RequestOptionsExtensions.UserAgentPolicy, PipelinePosition.PerCall);
 
-        IChatClient chatClient = new AzureAIProjectChatClient(aiProjectClient, agentReference, defaultModelId: null, agentOptions.ChatOptions);
+        var authPolicy = new BearerTokenPolicy(credential, AzureAiResourceScope);
+        var perAgentClient = new ProjectOpenAIClient(authPolicy, perAgentOptions);
 
+        IChatClient chatClient = perAgentClient.GetProjectResponsesClient().AsIChatClient();
         if (clientFactory is not null)
         {
             chatClient = clientFactory(chatClient);
         }
 
+        ChatClientAgentOptions agentOptions = new()
+        {
+            Id = agentName,
+            Name = agentName,
+            ChatOptions = new() { Tools = tools },
+        };
+
         return WireClientHeaders(new ChatClientAgent(chatClient, agentOptions, services: services));
     }
 
+    /// <summary>
+    /// Builds the project-scoped <see cref="ProjectOpenAIClient"/> for the agent-endpoint
+    /// constructor by deriving the project root from the supplied agent endpoint and constructing
+    /// a fresh client without <see cref="ProjectOpenAIClientOptions.AgentName"/> so the SDK
+    /// appends the standard <c>/openai/v1</c> suffix expected for project-level surfaces such as
+    /// conversations.
+    /// </summary>
+    /// <remarks>
+    /// Only the four observable primitive properties (<see cref="ClientPipelineOptions.RetryPolicy"/>,
+    /// <see cref="ClientPipelineOptions.NetworkTimeout"/>, <see cref="ClientPipelineOptions.Transport"/>,
+    /// and <c>UserAgentApplicationId</c>) are copied from the caller's options bag. Pipeline
+    /// policies added via <c>AddPolicy</c> on the caller bag do not propagate because
+    /// <see cref="ClientPipelineOptions"/> does not publicly enumerate its policies. The MEAI
+    /// user-agent policy is appended last.
+    /// </remarks>
+    private static ProjectOpenAIClient CreateProjectLevelOpenAIClientFromAgentEndpoint(
+        Uri agentEndpoint,
+        AuthenticationTokenProvider credential,
+        ProjectOpenAIClientOptions? clientOptions)
+    {
+        var (_, projectRoot) = ParseAgentEndpoint(agentEndpoint);
+
+        var projectOptions = new ProjectOpenAIClientOptions();
+        if (clientOptions is not null)
+        {
+            if (clientOptions.RetryPolicy is not null)
+            {
+                projectOptions.RetryPolicy = clientOptions.RetryPolicy;
+            }
+
+            if (clientOptions.NetworkTimeout is not null)
+            {
+                projectOptions.NetworkTimeout = clientOptions.NetworkTimeout;
+            }
+
+            if (clientOptions.Transport is not null)
+            {
+                projectOptions.Transport = clientOptions.Transport;
+            }
+
+            if (!string.IsNullOrEmpty(clientOptions.UserAgentApplicationId))
+            {
+                projectOptions.UserAgentApplicationId = clientOptions.UserAgentApplicationId;
+            }
+        }
+
+        projectOptions.AddPolicy(RequestOptionsExtensions.UserAgentPolicy, PipelinePosition.PerCall);
+
+        return new ProjectOpenAIClient(projectRoot, credential, projectOptions);
+    }
+
+    /// <summary>
+    /// Parses an agent endpoint URI of shape
+    /// <c>https://&lt;host&gt;/.../projects/&lt;project&gt;/agents/&lt;agentName&gt;/endpoint/protocols/openai</c>
+    /// and returns the agent name and the derived project-root URI.
+    /// </summary>
+    /// <remarks>
+    /// Single source of truth for both agent-name extraction and project-root derivation.
+    /// Tolerates trailing slash, casing variants on <c>/agents/</c> and the suffix segment, and
+    /// strips query string and fragment. Throws <see cref="ArgumentException"/> for inputs that
+    /// do not match the expected shape.
+    /// </remarks>
+    /// <exception cref="ArgumentException">
+    /// The endpoint is missing the <c>/agents/</c> segment, has an empty agent name, or has a
+    /// suffix other than <c>/endpoint/protocols/openai</c>.
+    /// </exception>
+    internal static (string AgentName, Uri ProjectRoot) ParseAgentEndpoint(Uri agentEndpoint)
+    {
+        Throw.IfNull(agentEndpoint);
+
+        const string AgentsSegment = "/agents/";
+        const string ExpectedSuffix = "/endpoint/protocols/openai";
+
+        var path = agentEndpoint.AbsolutePath.TrimEnd('/');
+        var idx = path.IndexOf(AgentsSegment, StringComparison.OrdinalIgnoreCase);
+        if (idx < 0)
+        {
+            throw new ArgumentException(
+                $"Expected an agent endpoint of shape 'https://<host>/.../projects/<project>/agents/<agentName>/endpoint/protocols/openai' but got '{agentEndpoint}'. " +
+                "If you want to construct a FoundryAgent against a project endpoint, use the (Uri projectEndpoint, AuthenticationTokenProvider credential, string model, string instructions, ...) constructor instead.",
+                nameof(agentEndpoint));
+        }
+
+        var afterAgents = path.Substring(idx + AgentsSegment.Length);
+        var nextSlash = afterAgents.IndexOf('/');
+        if (nextSlash <= 0)
+        {
+            throw new ArgumentException(
+                $"Agent endpoint '{agentEndpoint}' is missing the '<agentName>{ExpectedSuffix}' suffix.",
+                nameof(agentEndpoint));
+        }
+
+        var agentName = afterAgents.Substring(0, nextSlash);
+        var suffix = afterAgents.Substring(nextSlash);
+        if (!string.Equals(suffix, ExpectedSuffix, StringComparison.OrdinalIgnoreCase))
+        {
+            throw new ArgumentException(
+                $"Agent endpoint '{agentEndpoint}' has an unexpected suffix '{suffix}'. Expected '{ExpectedSuffix}'.",
+                nameof(agentEndpoint));
+        }
+
+        var rootPath = path.Substring(0, idx);
+        var projectRoot = new UriBuilder(agentEndpoint)
+        {
+            Path = rootPath,
+            Query = string.Empty,
+            Fragment = string.Empty,
+        }.Uri;
+
+        return (agentName, projectRoot);
+    }
+
     private static AIProjectClient CreateProjectClient(Uri endpoint, AuthenticationTokenProvider credential, AIProjectClientOptions? clientOptions = null)
     {
         Throw.IfNull(endpoint);
         Throw.IfNull(credential);
 
         clientOptions ??= new AIProjectClientOptions();
-        clientOptions.AddPolicy(RequestOptionsExtensions.UserAgentPolicy, System.ClientModel.Primitives.PipelinePosition.PerCall);
+        clientOptions.AddPolicy(RequestOptionsExtensions.UserAgentPolicy, PipelinePosition.PerCall);
         return new AIProjectClient(endpoint, credential, clientOptions);
     }
 

dotnet/src/Microsoft.Agents.AI.Foundry/Microsoft.Agents.AI.Foundry.csproj

@@ -1,7 +1,10 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <IsReleased>true</IsReleased>
+    <!-- Preview while we depend on Azure.AI.Projects 2.1.0-beta.1 for hosted-agent routing
+         (ProjectOpenAIClientOptions.AgentName, the (AuthenticationPolicy, options) ctor, and
+         related per-agent endpoint surface). Flip back to IsReleased=true once Azure.AI.Projects
+         ships a stable 2.1.0. -->
     <InjectSharedThrow>true</InjectSharedThrow>
     <NoWarn>$(NoWarn);OPENAI001</NoWarn>
   </PropertyGroup>

dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgentOptions.cs

@@ -151,6 +151,36 @@ public sealed class ChatClientAgentOptions
     [Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
     public bool RequirePerServiceCallChatHistoryPersistence { get; set; }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether to include a <see cref="MessageInjectingChatClient"/>
+    /// in the chat client pipeline.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// When set to <see langword="true"/>, a <see cref="MessageInjectingChatClient"/> is added to the pipeline
+    /// between the <see cref="FunctionInvokingChatClient"/> and the inner client. This enables external code
+    /// (such as tool delegates) to inject messages into the function execution loop via the
+    /// <see cref="MessageInjectingChatClient"/> class, which can be resolved from the chat client using
+    /// <c>GetService&lt;MessageInjectingChatClient&gt;()</c>.
+    /// </para>
+    /// <para>
+    /// This setting can be used independently of <see cref="RequirePerServiceCallChatHistoryPersistence"/>,
+    /// however it is recommended to also enable per-service-call persistence when using message injection
+    /// so that injected messages are persisted to chat history between service calls.
+    /// </para>
+    /// <para>
+    /// When setting the <see cref="UseProvidedChatClientAsIs"/> setting to <see langword="true"/> and
+    /// <see cref="EnableMessageInjection"/> to <see langword="true"/>, ensure that your custom chat client stack
+    /// includes a <see cref="MessageInjectingChatClient"/>. You can add one manually via the
+    /// <see cref="ChatClientBuilderExtensions.UseMessageInjection"/> extension method.
+    /// </para>
+    /// </remarks>
+    /// <value>
+    /// Default is <see langword="false"/>.
+    /// </value>
+    [Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+    public bool EnableMessageInjection { get; set; }
+
     /// <summary>
     /// Creates a new instance of <see cref="ChatClientAgentOptions"/> with the same values as this instance.
     /// </summary>
@@ -168,5 +198,6 @@ public sealed class ChatClientAgentOptions
             WarnOnChatHistoryProviderConflict = this.WarnOnChatHistoryProviderConflict,
             ThrowOnChatHistoryProviderConflict = this.ThrowOnChatHistoryProviderConflict,
             RequirePerServiceCallChatHistoryPersistence = this.RequirePerServiceCallChatHistoryPersistence,
+            EnableMessageInjection = this.EnableMessageInjection,
         };
 }

dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientBuilderExtensions.cs

@@ -114,4 +114,38 @@ public static class ChatClientBuilderExtensions
     {
         return builder.Use(innerClient => new PerServiceCallChatHistoryPersistingChatClient(innerClient));
     }
+
+    /// <summary>
+    /// Adds a <see cref="MessageInjectingChatClient"/> to the chat client pipeline.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// This decorator enables external code (such as tool delegates) to inject messages into the function
+    /// execution loop. It should be positioned between the <see cref="FunctionInvokingChatClient"/> and
+    /// the <see cref="PerServiceCallChatHistoryPersistingChatClient"/> (or the leaf <see cref="IChatClient"/>)
+    /// in the pipeline.
+    /// </para>
+    /// <para>
+    /// The <see cref="MessageInjectingChatClient"/> can be retrieved from the chat client via
+    /// <c>GetService&lt;MessageInjectingChatClient&gt;</c> to enqueue messages from tool delegates or other code.
+    /// </para>
+    /// <para>
+    /// This extension method is intended for use with custom chat client stacks when
+    /// <see cref="ChatClientAgentOptions.UseProvidedChatClientAsIs"/> is <see langword="true"/>.
+    /// When <see cref="ChatClientAgentOptions.UseProvidedChatClientAsIs"/> is <see langword="false"/> (the default),
+    /// the <see cref="ChatClientAgent"/> automatically includes this decorator in the pipeline when
+    /// <see cref="ChatClientAgentOptions.RequirePerServiceCallChatHistoryPersistence"/> is <see langword="true"/>.
+    /// </para>
+    /// <para>
+    /// This decorator only works within the context of a running <see cref="ChatClientAgent"/> and will throw an
+    /// exception if used in any other stack.
+    /// </para>
+    /// </remarks>
+    /// <param name="builder">The <see cref="ChatClientBuilder"/> to add the decorator to.</param>
+    /// <returns>The <paramref name="builder"/> for chaining.</returns>
+    [Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+    public static ChatClientBuilder UseMessageInjection(this ChatClientBuilder builder)
+    {
+        return builder.Use(innerClient => new MessageInjectingChatClient(innerClient));
+    }
 }

dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientExtensions.cs

@@ -63,13 +63,21 @@ public static class ChatClientExtensions
             });
         }
 
-        // PerServiceCallChatHistoryPersistingChatClient is only injected when RequirePerServiceCallChatHistoryPersistence is enabled.
-        // It is registered after FunctionInvokingChatClient so that it sits between FIC and the leaf client.
+        // MessageInjectingChatClient is injected when EnableMessageInjection is enabled.
+        // It is registered after FunctionInvokingChatClient so that it sits between FIC and the inner client.
         // ChatClientBuilder.Build applies factories in reverse order, making the first Use() call outermost.
-        // By adding our decorator second, the resulting pipeline is:
-        //   FunctionInvokingChatClient → PerServiceCallChatHistoryPersistingChatClient → leaf IChatClient
-        // This allows the decorator to simulate service-stored chat history by loading history before
-        // each service call, persisting after each call, and returning a sentinel ConversationId.
+        // MessageInjectingChatClient enables injecting messages during the function loop and looping when needed.
+        if (options?.EnableMessageInjection is true)
+        {
+            chatBuilder.Use(innerClient => new MessageInjectingChatClient(innerClient));
+        }
+
+        // PerServiceCallChatHistoryPersistingChatClient is injected when RequirePerServiceCallChatHistoryPersistence is enabled.
+        // It is registered after MessageInjectingChatClient (if present) so it sits closest to the leaf client.
+        // The resulting pipeline is:
+        //   FunctionInvokingChatClient → [MessageInjectingChatClient] → [PerServiceCallChatHistoryPersistingChatClient] → leaf IChatClient
+        // PerServiceCallChatHistoryPersistingChatClient simulates service-stored chat history by loading history
+        // before each service call, persisting after each call, and returning a sentinel ConversationId.
         if (options?.RequirePerServiceCallChatHistoryPersistence is true)
         {
             chatBuilder.Use(innerClient => new PerServiceCallChatHistoryPersistingChatClient(innerClient));

dotnet/src/Microsoft.Agents.AI/ChatClient/MessageInjectingChatClient.cs

@@ -0,0 +1,320 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// A delegating chat client that supports injecting messages into the function execution loop.
+/// </summary>
+/// <remarks>
+/// <para>
+/// This decorator enables external code (such as tool delegates) to enqueue messages that will be
+/// sent to the underlying model at the next opportunity. It sits between the <see cref="FunctionInvokingChatClient"/>
+/// and the <see cref="PerServiceCallChatHistoryPersistingChatClient"/> (or the leaf <see cref="IChatClient"/>)
+/// in a <see cref="ChatClientAgent"/> pipeline.
+/// </para>
+/// <para>
+/// The injected messages queue is stored per-session in the <see cref="AgentSession.StateBag"/>, ensuring
+/// isolation between concurrent sessions.
+/// </para>
+/// <para>
+/// After each service call, if no actionable <see cref="FunctionCallContent"/> is returned but injected
+/// messages are pending, the decorator loops internally and calls the inner client again with the new
+/// messages. When actionable function calls are present, control returns to the parent
+/// <see cref="FunctionInvokingChatClient"/> loop.
+/// </para>
+/// <para>
+/// This chat client must be used within the context of a running <see cref="ChatClientAgent"/>. It retrieves the
+/// current session from <see cref="AIAgent.CurrentRunContext"/>, which is set automatically when an agent's
+/// <see cref="AIAgent.RunAsync(IEnumerable{ChatMessage}, AgentSession?, AgentRunOptions?, CancellationToken)"/> or
+/// <see cref="AIAgent.RunStreamingAsync(IEnumerable{ChatMessage}, AgentSession?, AgentRunOptions?, CancellationToken)"/>
+/// method is called.
+/// </para>
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed class MessageInjectingChatClient : DelegatingChatClient
+{
+    /// <summary>
+    /// The key used to store the pending injected messages queue in the session's <see cref="AgentSessionStateBag"/>.
+    /// </summary>
+    internal const string PendingMessagesStateKey = "MessageInjectingChatClient.PendingInjectedMessages";
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MessageInjectingChatClient"/> class.
+    /// </summary>
+    /// <param name="innerClient">The underlying chat client that will handle the core operations.</param>
+    public MessageInjectingChatClient(IChatClient innerClient)
+        : base(innerClient)
+    {
+    }
+
+    /// <inheritdoc/>
+    public override async Task<ChatResponse> GetResponseAsync(
+        IEnumerable<ChatMessage> messages,
+        ChatOptions? options = null,
+        CancellationToken cancellationToken = default)
+    {
+        var session = GetRequiredSession();
+        var queue = GetOrCreateQueue(session);
+
+        var newMessages = DrainInjectedMessages(queue, messages as IList<ChatMessage> ?? messages.ToList());
+
+        // Loop to process injected messages: after each service call, if no actionable function calls
+        // are pending but new messages have been injected into the queue, we call the service again
+        // so the model can process them. The loop exits when the response contains actionable
+        // function calls (handed off to the parent FunctionInvokingChatClient) or the queue is empty.
+        while (true)
+        {
+            var response = await base.GetResponseAsync(newMessages, options, cancellationToken).ConfigureAwait(false);
+
+            // If the response contains actionable function calls, the parent FunctionInvokingChatClient
+            // loop will iterate — return immediately so it can process them.
+            if (HasActionableFunctionCalls(response.Messages))
+            {
+                return response;
+            }
+
+            // No actionable function calls. If there are pending injected messages, loop again
+            // to send them to the service. Otherwise, we're done.
+            bool queueEmpty;
+            lock (queue)
+            {
+                queueEmpty = queue.Count == 0;
+            }
+
+            if (queueEmpty)
+            {
+                return response;
+            }
+
+            // Propagate any ConversationId returned by the service so subsequent iterations
+            // continue within the same conversation.
+            UpdateOptionsForNextIteration(ref options, response.ConversationId);
+
+            newMessages = DrainInjectedMessages(queue, Array.Empty<ChatMessage>());
+        }
+    }
+
+    /// <inheritdoc/>
+    public override async IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseAsync(
+        IEnumerable<ChatMessage> messages,
+        ChatOptions? options = null,
+        [EnumeratorCancellation] CancellationToken cancellationToken = default)
+    {
+        var session = GetRequiredSession();
+        var queue = GetOrCreateQueue(session);
+
+        var newMessages = DrainInjectedMessages(queue, messages as IList<ChatMessage> ?? messages.ToList());
+
+        // Loop to process injected messages: after each service call, if no actionable function calls
+        // are pending but new messages have been injected into the queue, we call the service again
+        // so the model can process them. The loop exits when the response contains actionable
+        // function calls (handed off to the parent FunctionInvokingChatClient) or the queue is empty.
+        while (true)
+        {
+            bool hasActionableFunctionCalls = false;
+            string? lastConversationId = null;
+
+            var enumerator = base.GetStreamingResponseAsync(newMessages, options, cancellationToken).GetAsyncEnumerator(cancellationToken);
+            try
+            {
+                while (await enumerator.MoveNextAsync().ConfigureAwait(false))
+                {
+                    var update = enumerator.Current;
+
+                    // Check each update for actionable function call content as it streams through.
+                    if (!hasActionableFunctionCalls && HasActionableFunctionCalls(update))
+                    {
+                        hasActionableFunctionCalls = true;
+                    }
+
+                    // Track the latest ConversationId from the stream.
+                    if (update.ConversationId is not null)
+                    {
+                        lastConversationId = update.ConversationId;
+                    }
+
+                    yield return update;
+                }
+            }
+            finally
+            {
+                await enumerator.DisposeAsync().ConfigureAwait(false);
+            }
+
+            // If the response contains actionable function calls, the parent FunctionInvokingChatClient
+            // loop will iterate — return immediately so it can process them.
+            if (hasActionableFunctionCalls)
+            {
+                yield break;
+            }
+
+            // No actionable function calls. If there are pending injected messages, loop again
+            // to send them to the service. Otherwise, we're done.
+            bool queueEmpty;
+            lock (queue)
+            {
+                queueEmpty = queue.Count == 0;
+            }
+
+            if (queueEmpty)
+            {
+                yield break;
+            }
+
+            // Propagate any ConversationId returned by the service so subsequent iterations
+            // continue within the same conversation.
+            UpdateOptionsForNextIteration(ref options, lastConversationId);
+
+            newMessages = DrainInjectedMessages(queue, Array.Empty<ChatMessage>());
+        }
+    }
+
+    /// <summary>
+    /// Enqueues one or more messages to be used at the next opportunity.
+    /// </summary>
+    /// <remarks>
+    /// This method is thread-safe and can be called concurrently from tool delegates or other code
+    /// while the function execution loop is in progress. The enqueued messages will be picked up
+    /// at the next opportunity.
+    /// </remarks>
+    /// <param name="session">The agent session to enqueue messages for.</param>
+    /// <param name="messages">The messages to enqueue.</param>
+    public void EnqueueMessages(AgentSession session, IEnumerable<ChatMessage> messages)
+    {
+        Throw.IfNull(session);
+        Throw.IfNull(messages);
+
+        var queue = GetOrCreateQueue(session);
+
+        lock (queue)
+        {
+            foreach (var message in messages)
+            {
+                queue.Add(message);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Gets or creates the pending injected messages queue from the session's <see cref="AgentSessionStateBag"/>.
+    /// </summary>
+    private static List<ChatMessage> GetOrCreateQueue(AgentSession session)
+    {
+        if (session.StateBag.TryGetValue<List<ChatMessage>>(PendingMessagesStateKey, out var queue))
+        {
+            return queue!;
+        }
+
+        var newQueue = new List<ChatMessage>();
+        session.StateBag.SetValue(PendingMessagesStateKey, newQueue);
+        return newQueue;
+    }
+
+    /// <summary>
+    /// Gets the current <see cref="AgentSession"/> from the run context.
+    /// </summary>
+    private static AgentSession GetRequiredSession()
+    {
+        var runContext = AIAgent.CurrentRunContext
+            ?? throw new InvalidOperationException(
+                $"{nameof(MessageInjectingChatClient)} can only be used within the context of a running AIAgent. " +
+                "Ensure that the chat client is being invoked as part of an AIAgent.RunAsync or AIAgent.RunStreamingAsync call.");
+
+        return runContext.Session
+            ?? throw new InvalidOperationException(
+                $"{nameof(MessageInjectingChatClient)} requires a session. " +
+                "The current run context does not have a session.");
+    }
+
+    /// <summary>
+    /// Drains all pending injected messages from the queue and returns a new list combining
+    /// the original messages with the drained messages. The original list is never modified.
+    /// </summary>
+    private static IList<ChatMessage> DrainInjectedMessages(List<ChatMessage> queue, IList<ChatMessage> newMessages)
+    {
+        lock (queue)
+        {
+            if (queue.Count == 0)
+            {
+                return newMessages;
+            }
+
+            var combined = new List<ChatMessage>(newMessages);
+            combined.AddRange(queue);
+            queue.Clear();
+            return combined;
+        }
+    }
+
+    /// <summary>
+    /// Determines whether any message in the list contains a <see cref="FunctionCallContent"/>
+    /// that is not marked as <see cref="FunctionCallContent.InformationalOnly"/>.
+    /// </summary>
+    private static bool HasActionableFunctionCalls(IList<ChatMessage> responseMessages)
+    {
+        for (int i = 0; i < responseMessages.Count; i++)
+        {
+            var contents = responseMessages[i].Contents;
+            for (int j = 0; j < contents.Count; j++)
+            {
+                if (contents[j] is FunctionCallContent fcc && !fcc.InformationalOnly)
+                {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+    /// <summary>
+    /// Determines whether a streaming update contains a <see cref="FunctionCallContent"/>
+    /// that is not marked as <see cref="FunctionCallContent.InformationalOnly"/>.
+    /// </summary>
+    private static bool HasActionableFunctionCalls(ChatResponseUpdate update)
+    {
+        var contents = update.Contents;
+        for (int i = 0; i < contents.Count; i++)
+        {
+            if (contents[i] is FunctionCallContent fcc && !fcc.InformationalOnly)
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /// <summary>
+    /// Propagates the <paramref name="conversationId"/> from the service response into
+    /// <paramref name="options"/> so that subsequent loop iterations continue within the
+    /// same conversation. Clones <paramref name="options"/> before mutating to avoid
+    /// affecting the caller's instance.
+    /// </summary>
+    private static void UpdateOptionsForNextIteration(ref ChatOptions? options, string? conversationId)
+    {
+        if (options is null)
+        {
+            if (conversationId is not null)
+            {
+                options = new() { ConversationId = conversationId };
+            }
+        }
+        else if (options.ConversationId != conversationId)
+        {
+            options = options.Clone();
+            options.ConversationId = conversationId;
+        }
+    }
+}

dotnet/tests/Microsoft.Agents.AI.Foundry.Hosting.UnitTests/Microsoft.Agents.AI.Foundry.Hosting.UnitTests.csproj

@@ -9,7 +9,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging" />
     <PackageReference Include="Azure.AI.AgentServer.Responses" />
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Microsoft.AspNetCore.TestHost" />
     <PackageReference Include="OpenTelemetry" />
     <PackageReference Include="OpenTelemetry.Exporter.InMemory" />

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

@@ -7,6 +7,7 @@ using System.Net.Http;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using Azure.AI.Extensions.OpenAI;
 using Azure.AI.Projects;
 using Microsoft.Extensions.AI;
 
@@ -184,7 +185,7 @@ public class FoundryAgentTests
 
         // Act: this AsAIAgent path constructs FoundryAgent via its internal
         // (AIProjectClient, ChatClientAgent) constructor, which previously bypassed pre-wiring.
-        var agent = projectClient.AsAIAgent(new Azure.AI.Extensions.OpenAI.AgentReference("agent-name"));
+        var agent = projectClient.AsAIAgent(new AgentReference("agent-name"));
 
         // Assert
         Assert.NotNull(agent.GetService<ClientHeadersAgent>());
@@ -398,4 +399,379 @@ public class FoundryAgentTests
     }
 
     #endregion
+
+    #region Agent-endpoint constructor tests
+
+    private const string TestAgentEndpoint = "https://test.services.ai.azure.com/api/projects/test-project/agents/it-happy-path/endpoint/protocols/openai";
+    private static readonly Uri s_testAgentEndpoint = new(TestAgentEndpoint);
+
+    [Fact]
+    public void AgentEndpointConstructor_NullEndpoint_ThrowsArgumentNullException()
+    {
+        ArgumentNullException ex = Assert.Throws<ArgumentNullException>(() =>
+            new FoundryAgent(agentEndpoint: null!, credential: new FakeAuthenticationTokenProvider()));
+        Assert.Equal("agentEndpoint", ex.ParamName);
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_NullCredential_ThrowsArgumentNullException()
+    {
+        ArgumentNullException ex = Assert.Throws<ArgumentNullException>(() =>
+            new FoundryAgent(agentEndpoint: s_testAgentEndpoint, credential: null!));
+        Assert.Equal("credential", ex.ParamName);
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_PopulatesNameAndIdFromEndpointSlug()
+    {
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider());
+
+        Assert.Equal("it-happy-path", agent.Name);
+        Assert.Equal("it-happy-path", agent.Id);
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_GetServiceProjectOpenAIClient_ReturnsNonNull()
+    {
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider());
+
+        Assert.NotNull(agent.GetService<ProjectOpenAIClient>());
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_GetServiceAIProjectClient_ReturnsNull()
+    {
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider());
+
+        Assert.Null(agent.GetService<AIProjectClient>());
+    }
+
+    [Fact]
+    public void ProjectEndpointConstructor_GetServiceProjectOpenAIClient_ReturnsNonNull()
+    {
+        FoundryAgent agent = new(
+            s_testEndpoint,
+            new FakeAuthenticationTokenProvider(),
+            model: "gpt-4o-mini",
+            instructions: "Test");
+
+        Assert.NotNull(agent.GetService<ProjectOpenAIClient>());
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_AppliesClientFactoryOnce()
+    {
+        int count = 0;
+        FoundryAgent agent = new(
+            s_testAgentEndpoint,
+            new FakeAuthenticationTokenProvider(),
+            clientFactory: c => { count++; return c; });
+
+        Assert.Equal(1, count);
+        Assert.NotNull(agent);
+    }
+
+    [Fact]
+    public async Task AgentEndpointConstructor_RunAsync_RoutesThroughPerAgentResponsesUrlAsync()
+    {
+        Uri? capturedUri = null;
+        using HttpHandlerAssert handler = new(req =>
+        {
+            capturedUri = req.RequestUri;
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(TestDataUtil.GetOpenAIDefaultResponseJson(), Encoding.UTF8, "application/json"),
+            };
+        });
+#pragma warning disable CA5399
+        using HttpClient http = new(handler);
+#pragma warning restore CA5399
+        ProjectOpenAIClientOptions opts = new() { Transport = new HttpClientPipelineTransport(http) };
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+        await agent.RunAsync("Hello");
+
+        Assert.NotNull(capturedUri);
+        string path = capturedUri!.AbsolutePath;
+        Assert.Contains("/agents/it-happy-path/endpoint/protocols/openai/responses", path, StringComparison.OrdinalIgnoreCase);
+        Assert.DoesNotContain("/openai/v1/responses", path, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("api-version=v1", capturedUri.Query, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public async Task AgentEndpointConstructor_RunStreamingAsync_RoutesThroughPerAgentResponsesUrlAsync()
+    {
+        Uri? capturedUri = null;
+        bool sawStreamTrue = false;
+        using HttpHandlerAssert handler = new(async req =>
+        {
+            capturedUri = req.RequestUri;
+            if (req.Content is not null)
+            {
+                string body = await req.Content.ReadAsStringAsync().ConfigureAwait(false);
+                if (body.Contains("\"stream\":true", StringComparison.Ordinal))
+                {
+                    sawStreamTrue = true;
+                }
+            }
+
+            // Minimal SSE response; xUnit assertion only cares about the URL/body shape.
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("data: [DONE]\n\n", Encoding.UTF8, "text/event-stream"),
+            };
+        });
+#pragma warning disable CA5399
+        using HttpClient http = new(handler);
+#pragma warning restore CA5399
+        ProjectOpenAIClientOptions opts = new() { Transport = new HttpClientPipelineTransport(http) };
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+        try
+        {
+            await foreach (var _ in agent.RunStreamingAsync("Hello"))
+            {
+                // drain
+            }
+        }
+        catch
+        {
+            // SSE parse errors are acceptable; we only assert the request shape.
+        }
+
+        Assert.NotNull(capturedUri);
+        Assert.Contains("/agents/it-happy-path/endpoint/protocols/openai/responses", capturedUri!.AbsolutePath, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("api-version=v1", capturedUri.Query, StringComparison.OrdinalIgnoreCase);
+        Assert.True(sawStreamTrue, "Expected request body to include \"stream\":true.");
+    }
+
+    [Fact]
+    public async Task AgentEndpointConstructor_CreateConversationSessionAsync_RoutesThroughProjectLevelUrlAsync()
+    {
+        Uri? capturedUri = null;
+        using HttpHandlerAssert handler = new(req =>
+        {
+            capturedUri = req.RequestUri;
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("{\"id\":\"conv_123\"}", Encoding.UTF8, "application/json"),
+            };
+        });
+#pragma warning disable CA5399
+        using HttpClient http = new(handler);
+#pragma warning restore CA5399
+        ProjectOpenAIClientOptions opts = new() { Transport = new HttpClientPipelineTransport(http) };
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+        try
+        {
+            _ = await agent.CreateConversationSessionAsync();
+        }
+        catch
+        {
+            // Underlying SDK may attempt extra parsing on the minimal response. We only assert URL routing.
+        }
+
+        Assert.NotNull(capturedUri);
+        string path = capturedUri!.AbsolutePath;
+        Assert.Contains("/api/projects/test-project/openai/v1/conversations", path, StringComparison.OrdinalIgnoreCase);
+        Assert.DoesNotContain("/agents/", path, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public async Task AgentEndpointConstructor_StampsMeaiUserAgentHeaderAsync()
+    {
+        bool meaiSeen = false;
+        using HttpHandlerAssert handler = new(req =>
+        {
+            if (req.Headers.TryGetValues("User-Agent", out var values))
+            {
+                foreach (string v in values)
+                {
+                    if (v.IndexOf("MEAI/", StringComparison.OrdinalIgnoreCase) >= 0)
+                    {
+                        meaiSeen = true;
+                    }
+                }
+            }
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(TestDataUtil.GetOpenAIDefaultResponseJson(), Encoding.UTF8, "application/json"),
+            };
+        });
+#pragma warning disable CA5399
+        using HttpClient http = new(handler);
+#pragma warning restore CA5399
+        ProjectOpenAIClientOptions opts = new() { Transport = new HttpClientPipelineTransport(http) };
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+        await agent.RunAsync("Hello");
+
+        Assert.True(meaiSeen, "Expected MEAI/x.y.z to appear in the User-Agent header on the agent-endpoint pipeline.");
+    }
+
+    [Fact]
+    public async Task AgentEndpointConstructor_PassesThroughCallerPolicyOnPerAgentPipelineAsync()
+    {
+        // Direct switch to ProjectOpenAIClientOptions means caller-supplied pipeline policies
+        // (added via AddPolicy) actually flow through to the per-agent traffic. Assert that a
+        // tag-stamping policy executes on each outbound per-agent request.
+        bool tagSeen = false;
+        using HttpHandlerAssert handler = new(req =>
+        {
+            if (req.Headers.TryGetValues("X-Test-Tag", out var values))
+            {
+                foreach (string v in values)
+                {
+                    if (v == "tag-1")
+                    {
+                        tagSeen = true;
+                    }
+                }
+            }
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(TestDataUtil.GetOpenAIDefaultResponseJson(), Encoding.UTF8, "application/json"),
+            };
+        });
+#pragma warning disable CA5399
+        using HttpClient http = new(handler);
+#pragma warning restore CA5399
+        ProjectOpenAIClientOptions opts = new() { Transport = new HttpClientPipelineTransport(http) };
+        opts.AddPolicy(new HeaderStampPolicy("X-Test-Tag", "tag-1"), PipelinePosition.PerCall);
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+        await agent.RunAsync("Hello");
+
+        Assert.True(tagSeen, "Expected caller-supplied per-call policy to execute on the per-agent pipeline.");
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_OverridesCallerEndpointAndAgentName()
+    {
+        // The caller may set Endpoint/AgentName on the options bag; we must override both with
+        // values derived from agentEndpoint so the URL routing is correct regardless.
+        ProjectOpenAIClientOptions opts = new()
+        {
+            Endpoint = new Uri("https://wrong.example.com/openai/v1"),
+            AgentName = "wrong-agent",
+        };
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+
+        Assert.Equal("it-happy-path", agent.Name);
+        Assert.Equal(s_testAgentEndpoint, opts.Endpoint);
+        Assert.Equal("it-happy-path", opts.AgentName);
+    }
+
+    [Fact]
+    public void AgentEndpointConstructor_PropagatesUserAgentApplicationId_ToProjectLevelClient()
+    {
+        // The MEAI policy adds its own User-Agent header so we cannot reliably observe the OpenAI SDK's
+        // application-id stamp in the outbound request. Verify the value is propagated onto the
+        // project-level client's options via the public ProjectOpenAIClient surface.
+        ProjectOpenAIClientOptions opts = new() { UserAgentApplicationId = "my-app-id" };
+
+        FoundryAgent agent = new(s_testAgentEndpoint, new FakeAuthenticationTokenProvider(), clientOptions: opts);
+
+        ProjectOpenAIClient? projectClient = agent.GetService<ProjectOpenAIClient>();
+        Assert.NotNull(projectClient);
+        // Caller's UserAgentApplicationId is preserved on the per-agent options bag verbatim.
+        Assert.Equal("my-app-id", opts.UserAgentApplicationId);
+    }
+
+    #endregion
+
+    #region ParseAgentEndpoint tests
+
+    [Fact]
+    public void ParseAgentEndpoint_StandardShape_Parses()
+    {
+        var (name, root) = FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p1/agents/a1/endpoint/protocols/openai"));
+        Assert.Equal("a1", name);
+        Assert.Equal("https://h.example.com/api/projects/p1", root.AbsoluteUri.TrimEnd('/'));
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_TrailingSlash_Parses()
+    {
+        var (name, root) = FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p1/agents/a1/endpoint/protocols/openai/"));
+        Assert.Equal("a1", name);
+        Assert.Equal("https://h.example.com/api/projects/p1", root.AbsoluteUri.TrimEnd('/'));
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_UppercaseAgentsSegment_Parses()
+    {
+        var (name, _) = FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p1/Agents/a1/endpoint/protocols/openai"));
+        Assert.Equal("a1", name);
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_SpecialCharsInName_Parses()
+    {
+        var (name, _) = FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p/agents/it-happy_path-1/endpoint/protocols/openai"));
+        Assert.Equal("it-happy_path-1", name);
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_QueryAndFragmentStripped()
+    {
+        var (_, root) = FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p/agents/a/endpoint/protocols/openai?x=1#frag"));
+        Assert.Equal(string.Empty, root.Query);
+        Assert.Equal(string.Empty, root.Fragment);
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_SovereignCloudHostNoApiPrefix_Parses()
+    {
+        var (name, root) = FoundryAgent.ParseAgentEndpoint(new Uri("https://h.cognitive.microsoft.us/projects/p/agents/a1/endpoint/protocols/openai"));
+        Assert.Equal("a1", name);
+        Assert.Equal("https://h.cognitive.microsoft.us/projects/p", root.AbsoluteUri.TrimEnd('/'));
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_MissingAgentsSegment_Throws()
+    {
+        ArgumentException ex = Assert.Throws<ArgumentException>(() =>
+            FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p1/openai/v1")));
+        Assert.Equal("agentEndpoint", ex.ParamName);
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_WrongSuffix_Throws()
+    {
+        ArgumentException ex = Assert.Throws<ArgumentException>(() =>
+            FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p/agents/a1/openai/v1")));
+        Assert.Equal("agentEndpoint", ex.ParamName);
+    }
+
+    [Fact]
+    public void ParseAgentEndpoint_EmptyAgentName_Throws()
+    {
+        ArgumentException ex = Assert.Throws<ArgumentException>(() =>
+            FoundryAgent.ParseAgentEndpoint(new Uri("https://h.example.com/api/projects/p/agents//endpoint/protocols/openai")));
+        Assert.Equal("agentEndpoint", ex.ParamName);
+    }
+
+    #endregion
+
+    private sealed class HeaderStampPolicy : PipelinePolicy
+    {
+        private readonly string _name;
+        private readonly string _value;
+        public HeaderStampPolicy(string name, string value) { this._name = name; this._value = value; }
+
+        public override void Process(PipelineMessage message, System.Collections.Generic.IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
+        {
+            message.Request.Headers.Set(this._name, this._value);
+            ProcessNext(message, pipeline, currentIndex);
+        }
+
+        public override ValueTask ProcessAsync(PipelineMessage message, System.Collections.Generic.IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
+        {
+            message.Request.Headers.Set(this._name, this._value);
+            return ProcessNextAsync(message, pipeline, currentIndex);
+        }
+    }
 }

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/Microsoft.Agents.AI.Foundry.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <CentralPackageTransitivePinningEnabled>false</CentralPackageTransitivePinningEnabled>
@@ -7,7 +7,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging" />
-    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.AI.Projects" />
   </ItemGroup>
 
   <ItemGroup>

dotnet/tests/Microsoft.Agents.AI.UnitTests/ChatClient/MessageInjectingChatClientTests.cs

@@ -0,0 +1,493 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.DependencyInjection;
+using Moq;
+using Moq.Protected;
+
+namespace Microsoft.Agents.AI.UnitTests;
+
+/// <summary>
+/// Unit tests for <see cref="MessageInjectingChatClient"/>.
+/// </summary>
+public class MessageInjectingChatClientTests
+{
+    /// <summary>
+    /// Verifies that <see cref="MessageInjectingChatClient"/> is resolvable via GetService when the decorator is active.
+    /// </summary>
+    [Fact]
+    public void GetService_ReturnsMessageInjectingChatClient_WhenDecoratorActive()
+    {
+        // Arrange
+        Mock<IChatClient> mockService = new();
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            EnableMessageInjection = true,
+        });
+
+        // Act
+        var injector = agent.ChatClient.GetService<MessageInjectingChatClient>();
+
+        // Assert
+        Assert.NotNull(injector);
+    }
+
+    /// <summary>
+    /// Verifies that <see cref="MessageInjectingChatClient"/> is null when the decorator is not active.
+    /// </summary>
+    [Fact]
+    public void GetService_ReturnsNull_WhenDecoratorNotActive()
+    {
+        // Arrange
+        Mock<IChatClient> mockService = new();
+        ChatClientAgent agent = new(mockService.Object, options: new());
+
+        // Act
+        var injector = agent.ChatClient.GetService<MessageInjectingChatClient>();
+
+        // Assert
+        Assert.Null(injector);
+    }
+
+    /// <summary>
+    /// Verifies that messages enqueued on the session before RunAsync are included in the service call messages.
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_IncludesInjectedMessages_WhenEnqueuedBeforeCallAsync()
+    {
+        // Arrange
+        List<ChatMessage> capturedMessages = [];
+        Mock<IChatClient> mockService = new();
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Callback((IEnumerable<ChatMessage> msgs, ChatOptions? _, CancellationToken _) =>
+                capturedMessages.AddRange(msgs))
+            .ReturnsAsync(new ChatResponse([new(ChatRole.Assistant, "response")]));
+
+        Mock<ChatHistoryProvider> mockChatHistoryProvider = new(null, null, null);
+        mockChatHistoryProvider.SetupGet(p => p.StateKeys).Returns(["TestChatHistoryProvider"]);
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask<IEnumerable<ChatMessage>>>("InvokingCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokingContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns((ChatHistoryProvider.InvokingContext ctx, CancellationToken _) =>
+                new ValueTask<IEnumerable<ChatMessage>>(ctx.RequestMessages.ToList()));
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask>("InvokedCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokedContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns(new ValueTask());
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatHistoryProvider = mockChatHistoryProvider.Object,
+            RequirePerServiceCallChatHistoryPersistence = true,
+            EnableMessageInjection = true,
+        });
+
+        // Create session and enqueue a message directly onto the session's StateBag queue before calling RunAsync
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        var queue = new List<ChatMessage>();
+        queue.Add(new ChatMessage(ChatRole.User, "injected message"));
+        session!.StateBag.SetValue("MessageInjectingChatClient.PendingInjectedMessages", queue);
+
+        // Act
+        await agent.RunAsync([new(ChatRole.User, "original")], session);
+
+        // Assert — the service should have received both the original and injected messages
+        Assert.Contains(capturedMessages, m => m.Text == "original");
+        Assert.Contains(capturedMessages, m => m.Text == "injected message");
+    }
+
+    /// <summary>
+    /// Verifies that the queue is drained after a call (messages are not re-delivered on subsequent calls).
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_DrainsQueue_MessagesNotRedeliveredAsync()
+    {
+        // Arrange
+        List<ChatMessage> capturedMessages = [];
+        Mock<IChatClient> mockService = new();
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Callback((IEnumerable<ChatMessage> msgs, ChatOptions? _, CancellationToken _) =>
+                capturedMessages.AddRange(msgs))
+            .ReturnsAsync(new ChatResponse([new(ChatRole.Assistant, "response")]));
+
+        Mock<ChatHistoryProvider> mockChatHistoryProvider = new(null, null, null);
+        mockChatHistoryProvider.SetupGet(p => p.StateKeys).Returns(["TestChatHistoryProvider"]);
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask<IEnumerable<ChatMessage>>>("InvokingCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokingContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns((ChatHistoryProvider.InvokingContext ctx, CancellationToken _) =>
+                new ValueTask<IEnumerable<ChatMessage>>(ctx.RequestMessages.ToList()));
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask>("InvokedCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokedContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns(new ValueTask());
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatHistoryProvider = mockChatHistoryProvider.Object,
+            RequirePerServiceCallChatHistoryPersistence = true,
+            EnableMessageInjection = true,
+        });
+
+        // Create session and enqueue a message directly onto the session's StateBag queue
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        var queue = new List<ChatMessage>();
+        queue.Add(new ChatMessage(ChatRole.User, "injected once"));
+        session!.StateBag.SetValue("MessageInjectingChatClient.PendingInjectedMessages", queue);
+
+        // Act
+        await agent.RunAsync([new(ChatRole.User, "first call")], session);
+
+        // Assert — the injected message was included in the service call
+        Assert.Contains(capturedMessages, m => m.Text == "injected once");
+
+        // Assert — the session's queue is now empty (drained)
+        Assert.Empty(queue);
+    }
+
+    /// <summary>
+    /// Verifies that the internal loop fires when no actionable FunctionCallContent is returned
+    /// but there are pending injected messages in the queue.
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_LoopsInternally_WhenNoActionableFCCButPendingMessagesAsync()
+    {
+        // Arrange
+        int serviceCallCount = 0;
+        Mock<IChatClient> mockService = new();
+        MessageInjectingChatClient? injectorRef = null;
+        ChatClientAgentSession? sessionRef = null;
+
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Returns((IEnumerable<ChatMessage> msgs, ChatOptions? _, CancellationToken _) =>
+            {
+                serviceCallCount++;
+                if (serviceCallCount == 1)
+                {
+                    // First call — simulate that something enqueues a message (e.g., a provider or background task)
+                    injectorRef!.EnqueueMessages(sessionRef!, [new ChatMessage(ChatRole.User, "injected during first call")]);
+                }
+
+                // Return a plain text response (no FunctionCallContent) to trigger the internal loop
+                return Task.FromResult(new ChatResponse([new(ChatRole.Assistant, $"response {serviceCallCount}")]));
+            });
+
+        Mock<ChatHistoryProvider> mockChatHistoryProvider = new(null, null, null);
+        mockChatHistoryProvider.SetupGet(p => p.StateKeys).Returns(["TestChatHistoryProvider"]);
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask<IEnumerable<ChatMessage>>>("InvokingCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokingContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns((ChatHistoryProvider.InvokingContext ctx, CancellationToken _) =>
+                new ValueTask<IEnumerable<ChatMessage>>(ctx.RequestMessages.ToList()));
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask>("InvokedCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokedContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns(new ValueTask());
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatHistoryProvider = mockChatHistoryProvider.Object,
+            RequirePerServiceCallChatHistoryPersistence = true,
+            EnableMessageInjection = true,
+        });
+
+        injectorRef = agent.ChatClient.GetService<MessageInjectingChatClient>()!;
+
+        // Act
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        sessionRef = session;
+        await agent.RunAsync([new(ChatRole.User, "original")], session);
+
+        // Assert — should have made 2 service calls (internal loop triggered by the injected message)
+        Assert.Equal(2, serviceCallCount);
+    }
+
+    /// <summary>
+    /// Verifies that the internal loop does NOT fire when the response contains actionable
+    /// FunctionCallContent, even if there are pending injected messages.
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_DoesNotLoopInternally_WhenActionableFCCPresentAsync()
+    {
+        // Arrange
+        int serviceCallCount = 0;
+        Mock<IChatClient> mockService = new();
+        MessageInjectingChatClient? injectorRef = null;
+        ChatClientAgentSession? sessionRef = null;
+
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Returns((IEnumerable<ChatMessage> msgs, ChatOptions? _, CancellationToken _) =>
+            {
+                serviceCallCount++;
+                if (serviceCallCount == 1)
+                {
+                    // Enqueue a message during the first call
+                    injectorRef!.EnqueueMessages(sessionRef!, [new ChatMessage(ChatRole.User, "injected")]);
+                    // Return a response with an actionable FunctionCallContent
+                    return Task.FromResult(new ChatResponse([new(ChatRole.Assistant,
+                        [new FunctionCallContent("call1", "myTool", new Dictionary<string, object?>())])]));
+                }
+
+                // Subsequent calls return plain text (the FCC loop will call back after tool execution)
+                return Task.FromResult(new ChatResponse([new(ChatRole.Assistant, "final")]));
+            });
+
+        Mock<ChatHistoryProvider> mockChatHistoryProvider = new(null, null, null);
+        mockChatHistoryProvider.SetupGet(p => p.StateKeys).Returns(["TestChatHistoryProvider"]);
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask<IEnumerable<ChatMessage>>>("InvokingCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokingContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns((ChatHistoryProvider.InvokingContext ctx, CancellationToken _) =>
+                new ValueTask<IEnumerable<ChatMessage>>(ctx.RequestMessages.ToList()));
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask>("InvokedCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokedContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns(new ValueTask());
+
+        var tool = AIFunctionFactory.Create(() => "tool result", "myTool", "A test tool");
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatOptions = new() { Tools = [tool] },
+            ChatHistoryProvider = mockChatHistoryProvider.Object,
+            RequirePerServiceCallChatHistoryPersistence = true,
+            EnableMessageInjection = true,
+        }, services: new ServiceCollection().BuildServiceProvider());
+
+        injectorRef = agent.ChatClient.GetService<MessageInjectingChatClient>()!;
+
+        // Act
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        sessionRef = session;
+        await agent.RunAsync([new(ChatRole.User, "original")], session);
+
+        // Assert — The first service call returned actionable FCC, so no internal injected-message loop
+        // occurred there. The FCC loop invokes the tool and calls the service again (second call).
+        // The injected message should be picked up by the second service call (drained at start of
+        // GetResponseAsync), but no extra internal loop should fire. Exactly 2 service calls expected.
+        Assert.Equal(2, serviceCallCount);
+    }
+
+    /// <summary>
+    /// Verifies that the internal loop fires when the response contains only InformationalOnly
+    /// FunctionCallContent (which are not actionable) and there are pending injected messages.
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_LoopsInternally_WhenOnlyInformationalOnlyFCCAndPendingMessagesAsync()
+    {
+        // Arrange
+        int serviceCallCount = 0;
+        Mock<IChatClient> mockService = new();
+        MessageInjectingChatClient? injectorRef = null;
+        ChatClientAgentSession? sessionRef = null;
+
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Returns((IEnumerable<ChatMessage> msgs, ChatOptions? _, CancellationToken _) =>
+            {
+                serviceCallCount++;
+                if (serviceCallCount == 1)
+                {
+                    // Enqueue a message during the first call
+                    injectorRef!.EnqueueMessages(sessionRef!, [new ChatMessage(ChatRole.User, "injected")]);
+                    // Return a response with InformationalOnly FCC (not actionable)
+                    return Task.FromResult(new ChatResponse([new(ChatRole.Assistant,
+                        [new FunctionCallContent("call1", "myTool", new Dictionary<string, object?>()) { InformationalOnly = true }])]));
+                }
+
+                return Task.FromResult(new ChatResponse([new(ChatRole.Assistant, "final")]));
+            });
+
+        Mock<ChatHistoryProvider> mockChatHistoryProvider = new(null, null, null);
+        mockChatHistoryProvider.SetupGet(p => p.StateKeys).Returns(["TestChatHistoryProvider"]);
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask<IEnumerable<ChatMessage>>>("InvokingCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokingContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns((ChatHistoryProvider.InvokingContext ctx, CancellationToken _) =>
+                new ValueTask<IEnumerable<ChatMessage>>(ctx.RequestMessages.ToList()));
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask>("InvokedCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokedContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns(new ValueTask());
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatHistoryProvider = mockChatHistoryProvider.Object,
+            RequirePerServiceCallChatHistoryPersistence = true,
+            EnableMessageInjection = true,
+        });
+
+        injectorRef = agent.ChatClient.GetService<MessageInjectingChatClient>()!;
+
+        // Act
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        sessionRef = session;
+        await agent.RunAsync([new(ChatRole.User, "original")], session);
+
+        // Assert — InformationalOnly FCC is NOT actionable, so internal loop should trigger
+        Assert.Equal(2, serviceCallCount);
+    }
+
+    /// <summary>
+    /// Verifies that when the inner client returns a ConversationId on the first call, the
+    /// MessageInjectingChatClient propagates it to options on subsequent loop iterations.
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_PropagatesConversationId_AcrossInternalLoopIterationsAsync()
+    {
+        // Arrange
+        int serviceCallCount = 0;
+        List<string?> capturedConversationIds = [];
+        MessageInjectingChatClient? injectorRef = null;
+        ChatClientAgentSession? sessionRef = null;
+
+        Mock<IChatClient> mockService = new();
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Returns((IEnumerable<ChatMessage> _, ChatOptions? opts, CancellationToken _) =>
+            {
+                serviceCallCount++;
+                capturedConversationIds.Add(opts?.ConversationId);
+
+                if (serviceCallCount == 1)
+                {
+                    // First call: inject a message and return a ConversationId
+                    injectorRef!.EnqueueMessages(sessionRef!, [new ChatMessage(ChatRole.User, "injected")]);
+                    return Task.FromResult(new ChatResponse([new(ChatRole.Assistant, "first response")])
+                    {
+                        ConversationId = "conv-123",
+                    });
+                }
+
+                // Second call (from loop): should have the propagated ConversationId
+                return Task.FromResult(new ChatResponse([new(ChatRole.Assistant, "second response")]));
+            });
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            EnableMessageInjection = true,
+        }, services: new ServiceCollection().BuildServiceProvider());
+
+        injectorRef = agent.ChatClient.GetService<MessageInjectingChatClient>()!;
+
+        // Act
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        sessionRef = session;
+        await agent.RunAsync([new(ChatRole.User, "hello")], session);
+
+        // Assert — The second call should have received the ConversationId propagated from the first response
+        Assert.Equal(2, serviceCallCount);
+        Assert.Null(capturedConversationIds[0]); // First call: no ConversationId yet
+        Assert.Equal("conv-123", capturedConversationIds[1]); // Second call: propagated from first response
+    }
+
+    /// <summary>
+    /// Verifies that a session with pending injected messages can be serialized and deserialized,
+    /// and that the deserialized session correctly delivers the injected messages on the next run.
+    /// </summary>
+    [Fact]
+    public async Task RunAsync_DeliversInjectedMessages_AfterSessionSerializationRoundTripAsync()
+    {
+        // Arrange
+        List<ChatMessage> capturedMessagesFirstRun = [];
+        List<ChatMessage> capturedMessagesSecondRun = [];
+        int runCount = 0;
+        Mock<IChatClient> mockService = new();
+        MessageInjectingChatClient? injectorRef = null;
+        ChatClientAgentSession? sessionRef = null;
+
+        mockService.Setup(
+            s => s.GetResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Returns((IEnumerable<ChatMessage> msgs, ChatOptions? _, CancellationToken _) =>
+            {
+                if (runCount == 1)
+                {
+                    capturedMessagesFirstRun.AddRange(msgs);
+
+                    // Inject a message during the first run — this will remain pending (not drained)
+                    // because we return an actionable FCC that causes the parent loop to take over.
+                    injectorRef!.EnqueueMessages(sessionRef!, [new ChatMessage(ChatRole.User, "injected before serialization")]);
+
+                    // Return actionable FCC so the injection loop does NOT drain the message
+                    return Task.FromResult(new ChatResponse([new(ChatRole.Assistant,
+                        [new FunctionCallContent("call1", "myTool", new Dictionary<string, object?>())])]));
+                }
+
+                // Second run (after deserialization) — capture what messages come through
+                capturedMessagesSecondRun.AddRange(msgs);
+                return Task.FromResult(new ChatResponse([new(ChatRole.Assistant, "final response")]));
+            });
+
+        Mock<ChatHistoryProvider> mockChatHistoryProvider = new(null, null, null);
+        mockChatHistoryProvider.SetupGet(p => p.StateKeys).Returns(["TestChatHistoryProvider"]);
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask<IEnumerable<ChatMessage>>>("InvokingCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokingContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns((ChatHistoryProvider.InvokingContext ctx, CancellationToken _) =>
+                new ValueTask<IEnumerable<ChatMessage>>(ctx.RequestMessages.ToList()));
+        mockChatHistoryProvider
+            .Protected()
+            .Setup<ValueTask>("InvokedCoreAsync", ItExpr.IsAny<ChatHistoryProvider.InvokedContext>(), ItExpr.IsAny<CancellationToken>())
+            .Returns(new ValueTask());
+
+        var tool = AIFunctionFactory.Create(() => "tool result", "myTool", "A test tool");
+
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatOptions = new() { Tools = [tool] },
+            ChatHistoryProvider = mockChatHistoryProvider.Object,
+            RequirePerServiceCallChatHistoryPersistence = true,
+            EnableMessageInjection = true,
+        }, services: new ServiceCollection().BuildServiceProvider());
+
+        injectorRef = agent.ChatClient.GetService<MessageInjectingChatClient>()!;
+
+        // Act — First run: inject a message that stays pending
+        var session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        sessionRef = session;
+        runCount = 1;
+        await agent.RunAsync([new(ChatRole.User, "first run message")], session);
+
+        // Serialize the session and deserialize into a new instance
+        var serialized = await agent.SerializeSessionAsync(session!);
+        var deserializedSession = await agent.DeserializeSessionAsync(serialized) as ChatClientAgentSession;
+
+        // Second run on the deserialized session — the injected message should be delivered
+        runCount = 2;
+        sessionRef = deserializedSession;
+        await agent.RunAsync([new(ChatRole.User, "second run message")], deserializedSession);
+
+        // Assert — the second run should include the injected message from before serialization
+        Assert.Contains(capturedMessagesSecondRun, m => m.Text == "injected before serialization");
+        Assert.Contains(capturedMessagesSecondRun, m => m.Text == "second run message");
+    }
+}