diff --git a/dotnet/Directory.Packages.props b/dotnet/Directory.Packages.props
index d0227c1dbe..de0efb2eb5 100644
--- a/dotnet/Directory.Packages.props
+++ b/dotnet/Directory.Packages.props
@@ -89,7 +89,7 @@
     <PackageVersion Include="Microsoft.SemanticKernel.Agents.AzureAI" Version="1.67.0-preview" />
     <PackageVersion Include="Microsoft.SemanticKernel.Plugins.OpenApi" Version="1.67.0" />
     <!-- Agent SDKs -->
-    <PackageVersion Include="GitHub.Copilot.SDK" Version="0.1.18" />
+    <PackageVersion Include="GitHub.Copilot.SDK" Version="0.1.23" />
     <PackageVersion Include="Microsoft.Agents.CopilotStudio.Client" Version="1.3.171-beta" />
     <!-- M365 Agents SDK -->
     <PackageVersion Include="AdaptiveCards" Version="3.1.0" />
diff --git a/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs b/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs
index ed1f1a32ac..8319832613 100644
--- a/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs
+++ b/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs
@@ -147,21 +147,7 @@ public sealed class GitHubCopilotAgent : AIAgent, IAsyncDisposable
 
         // Create or resume a session with streaming enabled
         SessionConfig sessionConfig = this._sessionConfig != null
-            ? new SessionConfig
-            {
-                Model = this._sessionConfig.Model,
-                Tools = this._sessionConfig.Tools,
-                SystemMessage = this._sessionConfig.SystemMessage,
-                AvailableTools = this._sessionConfig.AvailableTools,
-                ExcludedTools = this._sessionConfig.ExcludedTools,
-                Provider = this._sessionConfig.Provider,
-                OnPermissionRequest = this._sessionConfig.OnPermissionRequest,
-                McpServers = this._sessionConfig.McpServers,
-                CustomAgents = this._sessionConfig.CustomAgents,
-                SkillDirectories = this._sessionConfig.SkillDirectories,
-                DisabledSkills = this._sessionConfig.DisabledSkills,
-                Streaming = true
-            }
+            ? CopySessionConfig(this._sessionConfig)
             : new SessionConfig { Streaming = true };
 
         CopilotSession copilotSession;
@@ -283,16 +269,64 @@ public sealed class GitHubCopilotAgent : AIAgent, IAsyncDisposable
     }
 
     private ResumeSessionConfig CreateResumeConfig()
+    {
+        return CopyResumeSessionConfig(this._sessionConfig);
+    }
+
+    /// <summary>
+    /// Copies all supported properties from a source <see cref="SessionConfig"/> into a new instance
+    /// with <see cref="SessionConfig.Streaming"/> set to <c>true</c>.
+    /// </summary>
+    internal static SessionConfig CopySessionConfig(SessionConfig source)
+    {
+        return new SessionConfig
+        {
+            Model = source.Model,
+            ReasoningEffort = source.ReasoningEffort,
+            Tools = source.Tools,
+            SystemMessage = source.SystemMessage,
+            AvailableTools = source.AvailableTools,
+            ExcludedTools = source.ExcludedTools,
+            Provider = source.Provider,
+            OnPermissionRequest = source.OnPermissionRequest,
+            OnUserInputRequest = source.OnUserInputRequest,
+            Hooks = source.Hooks,
+            WorkingDirectory = source.WorkingDirectory,
+            ConfigDir = source.ConfigDir,
+            McpServers = source.McpServers,
+            CustomAgents = source.CustomAgents,
+            SkillDirectories = source.SkillDirectories,
+            DisabledSkills = source.DisabledSkills,
+            InfiniteSessions = source.InfiniteSessions,
+            Streaming = true
+        };
+    }
+
+    /// <summary>
+    /// Copies all supported properties from a source <see cref="SessionConfig"/> into a new
+    /// <see cref="ResumeSessionConfig"/> with <see cref="ResumeSessionConfig.Streaming"/> set to <c>true</c>.
+    /// </summary>
+    internal static ResumeSessionConfig CopyResumeSessionConfig(SessionConfig? source)
     {
         return new ResumeSessionConfig
         {
-            Tools = this._sessionConfig?.Tools,
-            Provider = this._sessionConfig?.Provider,
-            OnPermissionRequest = this._sessionConfig?.OnPermissionRequest,
-            McpServers = this._sessionConfig?.McpServers,
-            CustomAgents = this._sessionConfig?.CustomAgents,
-            SkillDirectories = this._sessionConfig?.SkillDirectories,
-            DisabledSkills = this._sessionConfig?.DisabledSkills,
+            Model = source?.Model,
+            ReasoningEffort = source?.ReasoningEffort,
+            Tools = source?.Tools,
+            SystemMessage = source?.SystemMessage,
+            AvailableTools = source?.AvailableTools,
+            ExcludedTools = source?.ExcludedTools,
+            Provider = source?.Provider,
+            OnPermissionRequest = source?.OnPermissionRequest,
+            OnUserInputRequest = source?.OnUserInputRequest,
+            Hooks = source?.Hooks,
+            WorkingDirectory = source?.WorkingDirectory,
+            ConfigDir = source?.ConfigDir,
+            McpServers = source?.McpServers,
+            CustomAgents = source?.CustomAgents,
+            SkillDirectories = source?.SkillDirectories,
+            DisabledSkills = source?.DisabledSkills,
+            InfiniteSessions = source?.InfiniteSessions,
             Streaming = true
         };
     }
@@ -427,9 +461,8 @@ public sealed class GitHubCopilotAgent : AIAgent, IAsyncDisposable
                     string tempFilePath = await dataContent.SaveToAsync(tempDir, cancellationToken).ConfigureAwait(false);
 
                     attachments ??= [];
-                    attachments.Add(new UserMessageDataAttachmentsItem
+                    attachments.Add(new UserMessageDataAttachmentsItemFile
                     {
-                        Type = UserMessageDataAttachmentsItemType.File,
                         Path = tempFilePath,
                         DisplayName = Path.GetFileName(tempFilePath)
                     });
diff --git a/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/Microsoft.Agents.AI.GitHub.Copilot.csproj b/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/Microsoft.Agents.AI.GitHub.Copilot.csproj
index f4f79c27bd..4c436263c1 100644
--- a/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/Microsoft.Agents.AI.GitHub.Copilot.csproj
+++ b/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/Microsoft.Agents.AI.GitHub.Copilot.csproj
@@ -17,6 +17,10 @@
     <ProjectReference Include="..\Microsoft.Agents.AI.Abstractions\Microsoft.Agents.AI.Abstractions.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <InternalsVisibleTo Include="Microsoft.Agents.AI.GitHub.Copilot.UnitTests" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="GitHub.Copilot.SDK" />
   </ItemGroup>
diff --git a/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs b/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs
index e80990de1b..8a4d3c1068 100644
--- a/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs
+++ b/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs
@@ -100,4 +100,125 @@ public sealed class GitHubCopilotAgentTests
         Assert.NotNull(agent);
         Assert.NotNull(agent.Id);
     }
+
+    [Fact]
+    public void CopySessionConfig_CopiesAllProperties()
+    {
+        // Arrange
+        List<AIFunction> tools = [AIFunctionFactory.Create(() => "test", "TestFunc", "Test function")];
+        var hooks = new SessionHooks();
+        var infiniteSessions = new InfiniteSessionConfig();
+        var systemMessage = new SystemMessageConfig { Mode = SystemMessageMode.Append, Content = "Be helpful" };
+        PermissionHandler permissionHandler = (_, _) => Task.FromResult(new PermissionRequestResult());
+        UserInputHandler userInputHandler = (_, _) => Task.FromResult(new UserInputResponse { Answer = "input" });
+        var mcpServers = new Dictionary<string, object> { ["server1"] = new McpLocalServerConfig() };
+
+        var source = new SessionConfig
+        {
+            Model = "gpt-4o",
+            ReasoningEffort = "high",
+            Tools = tools,
+            SystemMessage = systemMessage,
+            AvailableTools = ["tool1", "tool2"],
+            ExcludedTools = ["tool3"],
+            WorkingDirectory = "/workspace",
+            ConfigDir = "/config",
+            Hooks = hooks,
+            InfiniteSessions = infiniteSessions,
+            OnPermissionRequest = permissionHandler,
+            OnUserInputRequest = userInputHandler,
+            McpServers = mcpServers,
+            DisabledSkills = ["skill1"],
+        };
+
+        // Act
+        SessionConfig result = GitHubCopilotAgent.CopySessionConfig(source);
+
+        // Assert
+        Assert.Equal("gpt-4o", result.Model);
+        Assert.Equal("high", result.ReasoningEffort);
+        Assert.Same(tools, result.Tools);
+        Assert.Same(systemMessage, result.SystemMessage);
+        Assert.Equal(new List<string> { "tool1", "tool2" }, result.AvailableTools);
+        Assert.Equal(new List<string> { "tool3" }, result.ExcludedTools);
+        Assert.Equal("/workspace", result.WorkingDirectory);
+        Assert.Equal("/config", result.ConfigDir);
+        Assert.Same(hooks, result.Hooks);
+        Assert.Same(infiniteSessions, result.InfiniteSessions);
+        Assert.Same(permissionHandler, result.OnPermissionRequest);
+        Assert.Same(userInputHandler, result.OnUserInputRequest);
+        Assert.Same(mcpServers, result.McpServers);
+        Assert.Equal(new List<string> { "skill1" }, result.DisabledSkills);
+        Assert.True(result.Streaming);
+    }
+
+    [Fact]
+    public void CopyResumeSessionConfig_CopiesAllProperties()
+    {
+        // Arrange
+        List<AIFunction> tools = [AIFunctionFactory.Create(() => "test", "TestFunc", "Test function")];
+        var hooks = new SessionHooks();
+        var infiniteSessions = new InfiniteSessionConfig();
+        var systemMessage = new SystemMessageConfig { Mode = SystemMessageMode.Append, Content = "Be helpful" };
+        PermissionHandler permissionHandler = (_, _) => Task.FromResult(new PermissionRequestResult());
+        UserInputHandler userInputHandler = (_, _) => Task.FromResult(new UserInputResponse { Answer = "input" });
+        var mcpServers = new Dictionary<string, object> { ["server1"] = new McpLocalServerConfig() };
+
+        var source = new SessionConfig
+        {
+            Model = "gpt-4o",
+            ReasoningEffort = "high",
+            Tools = tools,
+            SystemMessage = systemMessage,
+            AvailableTools = ["tool1", "tool2"],
+            ExcludedTools = ["tool3"],
+            WorkingDirectory = "/workspace",
+            ConfigDir = "/config",
+            Hooks = hooks,
+            InfiniteSessions = infiniteSessions,
+            OnPermissionRequest = permissionHandler,
+            OnUserInputRequest = userInputHandler,
+            McpServers = mcpServers,
+            DisabledSkills = ["skill1"],
+        };
+
+        // Act
+        ResumeSessionConfig result = GitHubCopilotAgent.CopyResumeSessionConfig(source);
+
+        // Assert
+        Assert.Equal("gpt-4o", result.Model);
+        Assert.Equal("high", result.ReasoningEffort);
+        Assert.Same(tools, result.Tools);
+        Assert.Same(systemMessage, result.SystemMessage);
+        Assert.Equal(new List<string> { "tool1", "tool2" }, result.AvailableTools);
+        Assert.Equal(new List<string> { "tool3" }, result.ExcludedTools);
+        Assert.Equal("/workspace", result.WorkingDirectory);
+        Assert.Equal("/config", result.ConfigDir);
+        Assert.Same(hooks, result.Hooks);
+        Assert.Same(infiniteSessions, result.InfiniteSessions);
+        Assert.Same(permissionHandler, result.OnPermissionRequest);
+        Assert.Same(userInputHandler, result.OnUserInputRequest);
+        Assert.Same(mcpServers, result.McpServers);
+        Assert.Equal(new List<string> { "skill1" }, result.DisabledSkills);
+        Assert.True(result.Streaming);
+    }
+
+    [Fact]
+    public void CopyResumeSessionConfig_WithNullSource_ReturnsDefaults()
+    {
+        // Act
+        ResumeSessionConfig result = GitHubCopilotAgent.CopyResumeSessionConfig(null);
+
+        // Assert
+        Assert.Null(result.Model);
+        Assert.Null(result.ReasoningEffort);
+        Assert.Null(result.Tools);
+        Assert.Null(result.SystemMessage);
+        Assert.Null(result.OnPermissionRequest);
+        Assert.Null(result.OnUserInputRequest);
+        Assert.Null(result.Hooks);
+        Assert.Null(result.WorkingDirectory);
+        Assert.Null(result.ConfigDir);
+        Assert.True(result.Streaming);
+    }
 }