Split Foundry into stable V1 and preview Hosting package

Extract hosted agent functionality from Microsoft.Agents.AI.Foundry into a
new Microsoft.Agents.AI.Foundry.Hosting preview package. This resolves NU5104
build errors caused by the stable Foundry package depending on prerelease
Azure SDK packages (Azure.AI.AgentServer.Responses, Azure.AI.Projects beta).

Changes:
- Create Microsoft.Agents.AI.Foundry.Hosting with VersionSuffix=preview,
  targeting .NET Core only (net8.0/9.0/10.0)
- Move all Hosting/ source files to the new project
- Move ToolboxRecord/ToolboxVersion overloads to FoundryAIToolExtensions
- Revert Azure.AI.Projects to 2.0.0 in Directory.Packages.props;
  Hosting uses VersionOverride for 2.1.0-beta.1
- Clean V1 Foundry csproj: remove beta deps, ASP.NET Core ref, hosting conditionals
- Update 8 hosted agent sample projects to reference Foundry.Hosting
- Split unit tests: ToolboxRecord/ToolboxVersion tests moved to Hosting/
- Add Foundry.Hosting to solution file

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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

@@ -0,0 +1,48 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using Azure.AI.Projects.Agents;
+using Microsoft.Extensions.AI;
+
+namespace Microsoft.Agents.AI.Foundry.Hosting;
+
+/// <summary>
+/// Extension methods for <see cref="FoundryAITool"/> that require Azure.AI.Projects 2.1.0-beta.1+
+/// types (e.g. <see cref="ToolboxRecord"/>, <see cref="ToolboxVersion"/>).
+/// </summary>
+public static class FoundryAIToolExtensions
+{
+    /// <summary>
+    /// Creates an <see cref="AITool"/> marker from a <see cref="ToolboxRecord"/> retrieved
+    /// from <c>AIProjectClient</c>. Uses <see cref="ToolboxRecord.Name"/> and
+    /// <see cref="ToolboxRecord.DefaultVersion"/>.
+    /// </summary>
+    /// <param name="toolbox">The toolbox record.</param>
+    /// <returns>An <see cref="AITool"/> marker backed by <see cref="HostedMcpToolboxAITool"/>.</returns>
+    public static AITool CreateHostedMcpToolbox(ToolboxRecord toolbox)
+    {
+        if (toolbox is null)
+        {
+            throw new ArgumentNullException(nameof(toolbox));
+        }
+
+        return new HostedMcpToolboxAITool(toolbox.Name, toolbox.DefaultVersion);
+    }
+
+    /// <summary>
+    /// Creates an <see cref="AITool"/> marker from a specific <see cref="ToolboxVersion"/>
+    /// retrieved from <c>AIProjectClient</c>. Uses <see cref="ToolboxVersion.Name"/> and
+    /// <see cref="ToolboxVersion.Version"/>.
+    /// </summary>
+    /// <param name="toolboxVersion">The toolbox version.</param>
+    /// <returns>An <see cref="AITool"/> marker backed by <see cref="HostedMcpToolboxAITool"/>.</returns>
+    public static AITool CreateHostedMcpToolbox(ToolboxVersion toolboxVersion)
+    {
+        if (toolboxVersion is null)
+        {
+            throw new ArgumentNullException(nameof(toolboxVersion));
+        }
+
+        return new HostedMcpToolboxAITool(toolboxVersion.Name, toolboxVersion.Version);
+    }
+}

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

@@ -0,0 +1,50 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>$(TargetFrameworksCore)</TargetFrameworks>
+    <RootNamespace>Microsoft.Agents.AI.Foundry.Hosting</RootNamespace>
+    <VersionSuffix>preview</VersionSuffix>
+    <Title>Microsoft Agent Framework for Foundry Hosted Agents</Title>
+    <Description>Provides Microsoft Agent Framework support for hosting Foundry Agents with the Azure AI Agent Service.</Description>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <InjectSharedThrow>true</InjectSharedThrow>
+    <InjectSharedDiagnosticIds>true</InjectSharedDiagnosticIds>
+    <InjectExperimentalAttributeOnLegacy>true</InjectExperimentalAttributeOnLegacy>
+    <InjectSharedRedaction>true</InjectSharedRedaction>
+    <NoWarn>$(NoWarn);OPENAI001;MEAI001;NU1903</NoWarn> <!-- NU1903: Microsoft.Bcl.Memory 9.0.4 transitive vulnerability via Azure SDK; awaiting upstream fix -->
+    <CentralPackageTransitivePinningEnabled>false</CentralPackageTransitivePinningEnabled>
+  </PropertyGroup>
+
+  <Import Project="$(RepoRoot)/dotnet/nuget/nuget-package.props" />
+
+  <!-- Disable package validation baseline until the first release -->
+  <PropertyGroup>
+    <PackageValidationBaselineVersion />
+    <EnablePackageValidation>false</EnablePackageValidation>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.AgentServer.Responses" />
+    <PackageReference Include="Azure.AI.Projects" VersionOverride="2.1.0-beta.1" />
+    <PackageReference Include="Azure.Identity" />
+    <PackageReference Include="ModelContextProtocol" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Microsoft.Agents.AI.Foundry\Microsoft.Agents.AI.Foundry.csproj" />
+    <ProjectReference Include="..\Microsoft.Agents.AI.Abstractions\Microsoft.Agents.AI.Abstractions.csproj" />
+    <ProjectReference Include="..\Microsoft.Agents.AI.Workflows\Microsoft.Agents.AI.Workflows.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <InternalsVisibleTo Include="Microsoft.Agents.AI.Foundry.UnitTests" />
+    <InternalsVisibleTo Include="DynamicProxyGenAssembly2" />
+  </ItemGroup>
+
+</Project>

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

@@ -122,40 +122,6 @@ public static class FoundryAITool
     public static AITool CreateHostedMcpToolbox(string toolboxName, string? version = null)
         => new HostedMcpToolboxAITool(toolboxName, version);
 
-    /// <summary>
-    /// Creates an <see cref="AITool"/> marker from a <see cref="ToolboxRecord"/> retrieved
-    /// from <c>AIProjectClient</c>. Uses <see cref="ToolboxRecord.Name"/> and
-    /// <see cref="ToolboxRecord.DefaultVersion"/>.
-    /// </summary>
-    /// <param name="toolbox">The toolbox record.</param>
-    /// <returns>An <see cref="AITool"/> marker backed by <see cref="HostedMcpToolboxAITool"/>.</returns>
-    public static AITool CreateHostedMcpToolbox(ToolboxRecord toolbox)
-    {
-        if (toolbox is null)
-        {
-            throw new ArgumentNullException(nameof(toolbox));
-        }
-
-        return new HostedMcpToolboxAITool(toolbox.Name, toolbox.DefaultVersion);
-    }
-
-    /// <summary>
-    /// Creates an <see cref="AITool"/> marker from a specific <see cref="ToolboxVersion"/>
-    /// retrieved from <c>AIProjectClient</c>. Uses <see cref="ToolboxVersion.Name"/> and
-    /// <see cref="ToolboxVersion.Version"/>.
-    /// </summary>
-    /// <param name="toolboxVersion">The toolbox version.</param>
-    /// <returns>An <see cref="AITool"/> marker backed by <see cref="HostedMcpToolboxAITool"/>.</returns>
-    public static AITool CreateHostedMcpToolbox(ToolboxVersion toolboxVersion)
-    {
-        if (toolboxVersion is null)
-        {
-            throw new ArgumentNullException(nameof(toolboxVersion));
-        }
-
-        return new HostedMcpToolboxAITool(toolboxVersion.Name, toolboxVersion.Version);
-    }
-
     // --- OpenAI SDK ResponseTool factories ---
 
     /// <summary>

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

@@ -3,8 +3,7 @@
   <PropertyGroup>
     <IsReleased>true</IsReleased>
     <InjectSharedThrow>true</InjectSharedThrow>
-    <NoWarn>$(NoWarn);OPENAI001;MEAI001;NU1903</NoWarn> <!-- NU1903: Microsoft.Bcl.Memory 9.0.4 transitive vulnerability via Azure SDK; awaiting upstream fix -->
-    <CentralPackageTransitivePinningEnabled>false</CentralPackageTransitivePinningEnabled>
+    <NoWarn>$(NoWarn);OPENAI001;MEAI001</NoWarn>
   </PropertyGroup>
 
   <Import Project="$(RepoRoot)/dotnet/nuget/nuget-package.props" />
@@ -21,10 +20,6 @@
     <InjectSharedRedaction>true</InjectSharedRedaction>
   </PropertyGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
-    <FrameworkReference Include="Microsoft.AspNetCore.App" />
-  </ItemGroup>
-
   <ItemGroup>
     <PackageReference Include="Azure.AI.Projects" />
     <PackageReference Include="Microsoft.Extensions.AI" />
@@ -34,12 +29,6 @@
     <PackageReference Include="OpenAI" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
-    <PackageReference Include="Azure.AI.AgentServer.Responses" />
-    <PackageReference Include="Azure.Identity" />
-    <PackageReference Include="ModelContextProtocol" />
-  </ItemGroup>
-
   <!-- Evaluation support requires net8.0+ (MEAI.Evaluation does not support legacy TFMs) -->
   <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
     <PackageReference Include="Microsoft.Extensions.AI.Evaluation" />
@@ -56,11 +45,6 @@
     <ProjectReference Include="..\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
-    <ProjectReference Include="..\Microsoft.Agents.AI.Abstractions\Microsoft.Agents.AI.Abstractions.csproj" />
-    <ProjectReference Include="..\Microsoft.Agents.AI.Workflows\Microsoft.Agents.AI.Workflows.csproj" />
-  </ItemGroup>
-
   <PropertyGroup>
     <!-- NuGet Package Settings -->
     <Title>Microsoft Agent Framework for Foundry Agents</Title>
@@ -72,9 +56,4 @@
     <InternalsVisibleTo Include="DynamicProxyGenAssembly2" />
   </ItemGroup>
 
-  <!-- Hosting code requires .NET Core (ASP.NET Core + Azure.AI.AgentServer.Responses) -->
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
-    <Compile Remove="Hosting\**" />
-  </ItemGroup>
-
 </Project>