diff --git a/dotnet/src/Types.cs b/dotnet/src/Types.cs
index 664b35d9..d024071d 100644
--- a/dotnet/src/Types.cs
+++ b/dotnet/src/Types.cs
@@ -24,6 +24,34 @@ public enum ConnectionState
 
 public class CopilotClientOptions
 {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CopilotClientOptions"/> class.
+    /// </summary>
+    public CopilotClientOptions() { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CopilotClientOptions"/> class
+    /// by copying the properties of the specified instance.
+    /// </summary>
+    protected CopilotClientOptions(CopilotClientOptions? other)
+    {
+        if (other is null) return;
+
+        AutoRestart = other.AutoRestart;
+        AutoStart = other.AutoStart;
+        CliArgs = (string[]?)other.CliArgs?.Clone();
+        CliPath = other.CliPath;
+        CliUrl = other.CliUrl;
+        Cwd = other.Cwd;
+        Environment = other.Environment;
+        GithubToken = other.GithubToken;
+        Logger = other.Logger;
+        LogLevel = other.LogLevel;
+        Port = other.Port;
+        UseLoggedInUser = other.UseLoggedInUser;
+        UseStdio = other.UseStdio;
+    }
+
     /// <summary>
     /// Path to the Copilot CLI executable. If not specified, uses the bundled CLI from the SDK.
     /// </summary>
@@ -53,6 +81,17 @@ public class CopilotClientOptions
     /// Default: true (but defaults to false when GithubToken is provided).
     /// </summary>
     public bool? UseLoggedInUser { get; set; }
+
+    /// <summary>
+    /// Creates a shallow clone of this <see cref="CopilotClientOptions"/> instance.
+    /// </summary>
+    /// <remarks>
+    /// Mutable collection properties are copied into new collection instances so that modifications
+    /// to those collections on the clone do not affect the original.
+    /// Other reference-type properties (for example delegates and the logger) are not
+    /// deep-cloned; the original and the clone will share those objects.
+    /// </remarks>
+    public virtual CopilotClientOptions Clone() => new(this);
 }
 
 public class ToolBinaryResult
@@ -692,6 +731,42 @@ public class InfiniteSessionConfig
 
 public class SessionConfig
 {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SessionConfig"/> class.
+    /// </summary>
+    public SessionConfig() { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SessionConfig"/> class
+    /// by copying the properties of the specified instance.
+    /// </summary>
+    protected SessionConfig(SessionConfig? other)
+    {
+        if (other is null) return;
+
+        AvailableTools = other.AvailableTools is not null ? [.. other.AvailableTools] : null;
+        ConfigDir = other.ConfigDir;
+        CustomAgents = other.CustomAgents is not null ? [.. other.CustomAgents] : null;
+        DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
+        ExcludedTools = other.ExcludedTools is not null ? [.. other.ExcludedTools] : null;
+        Hooks = other.Hooks;
+        InfiniteSessions = other.InfiniteSessions;
+        McpServers = other.McpServers is not null
+            ? new Dictionary<string, object>(other.McpServers, other.McpServers.Comparer)
+            : null;
+        Model = other.Model;
+        OnPermissionRequest = other.OnPermissionRequest;
+        OnUserInputRequest = other.OnUserInputRequest;
+        Provider = other.Provider;
+        ReasoningEffort = other.ReasoningEffort;
+        SessionId = other.SessionId;
+        SkillDirectories = other.SkillDirectories is not null ? [.. other.SkillDirectories] : null;
+        Streaming = other.Streaming;
+        SystemMessage = other.SystemMessage;
+        Tools = other.Tools is not null ? [.. other.Tools] : null;
+        WorkingDirectory = other.WorkingDirectory;
+    }
+
     public string? SessionId { get; set; }
     public string? Model { get; set; }
 
@@ -769,10 +844,58 @@ public class SessionConfig
     /// When enabled (default), sessions automatically manage context limits and persist state.
     /// </summary>
     public InfiniteSessionConfig? InfiniteSessions { get; set; }
+
+    /// <summary>
+    /// Creates a shallow clone of this <see cref="SessionConfig"/> instance.
+    /// </summary>
+    /// <remarks>
+    /// Mutable collection properties are copied into new collection instances so that modifications
+    /// to those collections on the clone do not affect the original.
+    /// Other reference-type properties (for example provider configuration, system messages,
+    /// hooks, infinite session configuration, and delegates) are not deep-cloned; the original
+    /// and the clone will share those nested objects, and changes to them may affect both.
+    /// </remarks>
+    public virtual SessionConfig Clone() => new(this);
 }
 
 public class ResumeSessionConfig
 {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ResumeSessionConfig"/> class.
+    /// </summary>
+    public ResumeSessionConfig() { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ResumeSessionConfig"/> class
+    /// by copying the properties of the specified instance.
+    /// </summary>
+    protected ResumeSessionConfig(ResumeSessionConfig? other)
+    {
+        if (other is null) return;
+
+        AvailableTools = other.AvailableTools is not null ? [.. other.AvailableTools] : null;
+        ConfigDir = other.ConfigDir;
+        CustomAgents = other.CustomAgents is not null ? [.. other.CustomAgents] : null;
+        DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
+        DisableResume = other.DisableResume;
+        ExcludedTools = other.ExcludedTools is not null ? [.. other.ExcludedTools] : null;
+        Hooks = other.Hooks;
+        InfiniteSessions = other.InfiniteSessions;
+        McpServers = other.McpServers is not null
+            ? new Dictionary<string, object>(other.McpServers, other.McpServers.Comparer)
+            : null;
+        Model = other.Model;
+        OnPermissionRequest = other.OnPermissionRequest;
+        OnUserInputRequest = other.OnUserInputRequest;
+        Provider = other.Provider;
+        ReasoningEffort = other.ReasoningEffort;
+        SkillDirectories = other.SkillDirectories is not null ? [.. other.SkillDirectories] : null;
+        Streaming = other.Streaming;
+        SystemMessage = other.SystemMessage;
+        Tools = other.Tools is not null ? [.. other.Tools] : null;
+        WorkingDirectory = other.WorkingDirectory;
+    }
+
     /// <summary>
     /// Model to use for this session. Can change the model when resuming.
     /// </summary>
@@ -870,13 +993,54 @@ public class ResumeSessionConfig
     /// Infinite session configuration for persistent workspaces and automatic compaction.
     /// </summary>
     public InfiniteSessionConfig? InfiniteSessions { get; set; }
+
+    /// <summary>
+    /// Creates a shallow clone of this <see cref="ResumeSessionConfig"/> instance.
+    /// </summary>
+    /// <remarks>
+    /// Mutable collection properties are copied into new collection instances so that modifications
+    /// to those collections on the clone do not affect the original.
+    /// Other reference-type properties (for example provider configuration, system messages,
+    /// hooks, infinite session configuration, and delegates) are not deep-cloned; the original
+    /// and the clone will share those nested objects, and changes to them may affect both.
+    /// </remarks>
+    public virtual ResumeSessionConfig Clone() => new(this);
 }
 
 public class MessageOptions
 {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MessageOptions"/> class.
+    /// </summary>
+    public MessageOptions() { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MessageOptions"/> class
+    /// by copying the properties of the specified instance.
+    /// </summary>
+    protected MessageOptions(MessageOptions? other)
+    {
+        if (other is null) return;
+
+        Attachments = other.Attachments is not null ? [.. other.Attachments] : null;
+        Mode = other.Mode;
+        Prompt = other.Prompt;
+    }
+
     public string Prompt { get; set; } = string.Empty;
     public List<UserMessageDataAttachmentsItem>? Attachments { get; set; }
     public string? Mode { get; set; }
+
+    /// <summary>
+    /// Creates a shallow clone of this <see cref="MessageOptions"/> instance.
+    /// </summary>
+    /// <remarks>
+    /// Mutable collection properties are copied into new collection instances so that modifications
+    /// to those collections on the clone do not affect the original.
+    /// Other reference-type properties (for example attachment items) are not deep-cloned;
+    /// the original and the clone will share those nested objects.
+    /// </remarks>
+    public virtual MessageOptions Clone() => new(this);
 }
 
 public delegate void SessionEventHandler(SessionEvent sessionEvent);
diff --git a/dotnet/test/CloneTests.cs b/dotnet/test/CloneTests.cs
new file mode 100644
index 00000000..10ad0205
--- /dev/null
+++ b/dotnet/test/CloneTests.cs
@@ -0,0 +1,243 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
+using Microsoft.Extensions.AI;
+using Xunit;
+
+namespace GitHub.Copilot.SDK.Test;
+
+public class CloneTests
+{
+    [Fact]
+    public void CopilotClientOptions_Clone_CopiesAllProperties()
+    {
+        var original = new CopilotClientOptions
+        {
+            CliPath = "/usr/bin/copilot",
+            CliArgs = ["--verbose", "--debug"],
+            Cwd = "/home/user",
+            Port = 8080,
+            UseStdio = false,
+            CliUrl = "http://localhost:8080",
+            LogLevel = "debug",
+            AutoStart = false,
+            AutoRestart = false,
+            Environment = new Dictionary<string, string> { ["KEY"] = "value" },
+            GithubToken = "ghp_test",
+            UseLoggedInUser = false,
+        };
+
+        var clone = original.Clone();
+
+        Assert.Equal(original.CliPath, clone.CliPath);
+        Assert.Equal(original.CliArgs, clone.CliArgs);
+        Assert.Equal(original.Cwd, clone.Cwd);
+        Assert.Equal(original.Port, clone.Port);
+        Assert.Equal(original.UseStdio, clone.UseStdio);
+        Assert.Equal(original.CliUrl, clone.CliUrl);
+        Assert.Equal(original.LogLevel, clone.LogLevel);
+        Assert.Equal(original.AutoStart, clone.AutoStart);
+        Assert.Equal(original.AutoRestart, clone.AutoRestart);
+        Assert.Equal(original.Environment, clone.Environment);
+        Assert.Equal(original.GithubToken, clone.GithubToken);
+        Assert.Equal(original.UseLoggedInUser, clone.UseLoggedInUser);
+    }
+
+    [Fact]
+    public void CopilotClientOptions_Clone_CollectionsAreIndependent()
+    {
+        var original = new CopilotClientOptions
+        {
+            CliArgs = ["--verbose"],
+        };
+
+        var clone = original.Clone();
+
+        // Mutate clone array
+        clone.CliArgs![0] = "--quiet";
+
+        // Original is unaffected
+        Assert.Equal("--verbose", original.CliArgs![0]);
+    }
+
+    [Fact]
+    public void CopilotClientOptions_Clone_EnvironmentIsShared()
+    {
+        var env = new Dictionary<string, string> { ["key"] = "value" };
+        var original = new CopilotClientOptions { Environment = env };
+
+        var clone = original.Clone();
+
+        Assert.Same(original.Environment, clone.Environment);
+    }
+
+    [Fact]
+    public void SessionConfig_Clone_CopiesAllProperties()
+    {
+        var original = new SessionConfig
+        {
+            SessionId = "test-session",
+            Model = "gpt-4",
+            ReasoningEffort = "high",
+            ConfigDir = "/config",
+            AvailableTools = ["tool1", "tool2"],
+            ExcludedTools = ["tool3"],
+            WorkingDirectory = "/workspace",
+            Streaming = true,
+            McpServers = new Dictionary<string, object> { ["server1"] = new object() },
+            CustomAgents = [new CustomAgentConfig { Name = "agent1" }],
+            SkillDirectories = ["/skills"],
+            DisabledSkills = ["skill1"],
+        };
+
+        var clone = original.Clone();
+
+        Assert.Equal(original.SessionId, clone.SessionId);
+        Assert.Equal(original.Model, clone.Model);
+        Assert.Equal(original.ReasoningEffort, clone.ReasoningEffort);
+        Assert.Equal(original.ConfigDir, clone.ConfigDir);
+        Assert.Equal(original.AvailableTools, clone.AvailableTools);
+        Assert.Equal(original.ExcludedTools, clone.ExcludedTools);
+        Assert.Equal(original.WorkingDirectory, clone.WorkingDirectory);
+        Assert.Equal(original.Streaming, clone.Streaming);
+        Assert.Equal(original.McpServers.Count, clone.McpServers!.Count);
+        Assert.Equal(original.CustomAgents.Count, clone.CustomAgents!.Count);
+        Assert.Equal(original.SkillDirectories, clone.SkillDirectories);
+        Assert.Equal(original.DisabledSkills, clone.DisabledSkills);
+    }
+
+    [Fact]
+    public void SessionConfig_Clone_CollectionsAreIndependent()
+    {
+        var original = new SessionConfig
+        {
+            AvailableTools = ["tool1"],
+            ExcludedTools = ["tool2"],
+            McpServers = new Dictionary<string, object> { ["s1"] = new object() },
+            CustomAgents = [new CustomAgentConfig { Name = "a1" }],
+            SkillDirectories = ["/skills"],
+            DisabledSkills = ["skill1"],
+        };
+
+        var clone = original.Clone();
+
+        // Mutate clone collections
+        clone.AvailableTools!.Add("tool99");
+        clone.ExcludedTools!.Add("tool99");
+        clone.McpServers!["s2"] = new object();
+        clone.CustomAgents!.Add(new CustomAgentConfig { Name = "a2" });
+        clone.SkillDirectories!.Add("/more");
+        clone.DisabledSkills!.Add("skill99");
+
+        // Original is unaffected
+        Assert.Single(original.AvailableTools!);
+        Assert.Single(original.ExcludedTools!);
+        Assert.Single(original.McpServers!);
+        Assert.Single(original.CustomAgents!);
+        Assert.Single(original.SkillDirectories!);
+        Assert.Single(original.DisabledSkills!);
+    }
+
+    [Fact]
+    public void SessionConfig_Clone_PreservesMcpServersComparer()
+    {
+        var servers = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase) { ["server"] = new object() };
+        var original = new SessionConfig { McpServers = servers };
+
+        var clone = original.Clone();
+
+        Assert.True(clone.McpServers!.ContainsKey("SERVER")); // case-insensitive lookup works
+    }
+
+    [Fact]
+    public void ResumeSessionConfig_Clone_CollectionsAreIndependent()
+    {
+        var original = new ResumeSessionConfig
+        {
+            AvailableTools = ["tool1"],
+            ExcludedTools = ["tool2"],
+            McpServers = new Dictionary<string, object> { ["s1"] = new object() },
+            CustomAgents = [new CustomAgentConfig { Name = "a1" }],
+            SkillDirectories = ["/skills"],
+            DisabledSkills = ["skill1"],
+        };
+
+        var clone = original.Clone();
+
+        // Mutate clone collections
+        clone.AvailableTools!.Add("tool99");
+        clone.ExcludedTools!.Add("tool99");
+        clone.McpServers!["s2"] = new object();
+        clone.CustomAgents!.Add(new CustomAgentConfig { Name = "a2" });
+        clone.SkillDirectories!.Add("/more");
+        clone.DisabledSkills!.Add("skill99");
+
+        // Original is unaffected
+        Assert.Single(original.AvailableTools!);
+        Assert.Single(original.ExcludedTools!);
+        Assert.Single(original.McpServers!);
+        Assert.Single(original.CustomAgents!);
+        Assert.Single(original.SkillDirectories!);
+        Assert.Single(original.DisabledSkills!);
+    }
+
+    [Fact]
+    public void ResumeSessionConfig_Clone_PreservesMcpServersComparer()
+    {
+        var servers = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase) { ["server"] = new object() };
+        var original = new ResumeSessionConfig { McpServers = servers };
+
+        var clone = original.Clone();
+
+        Assert.True(clone.McpServers!.ContainsKey("SERVER"));
+    }
+
+    [Fact]
+    public void MessageOptions_Clone_CopiesAllProperties()
+    {
+        var original = new MessageOptions
+        {
+            Prompt = "Hello",
+            Attachments = [new UserMessageDataAttachmentsItemFile { Path = "/test.txt", DisplayName = "test.txt" }],
+            Mode = "chat",
+        };
+
+        var clone = original.Clone();
+
+        Assert.Equal(original.Prompt, clone.Prompt);
+        Assert.Equal(original.Mode, clone.Mode);
+        Assert.Single(clone.Attachments!);
+    }
+
+    [Fact]
+    public void MessageOptions_Clone_AttachmentsAreIndependent()
+    {
+        var original = new MessageOptions
+        {
+            Attachments = [new UserMessageDataAttachmentsItemFile { Path = "/test.txt", DisplayName = "test.txt" }],
+        };
+
+        var clone = original.Clone();
+
+        clone.Attachments!.Add(new UserMessageDataAttachmentsItemFile { Path = "/other.txt", DisplayName = "other.txt" });
+
+        Assert.Single(original.Attachments!);
+    }
+
+    [Fact]
+    public void Clone_WithNullCollections_ReturnsNullCollections()
+    {
+        var original = new SessionConfig();
+
+        var clone = original.Clone();
+
+        Assert.Null(clone.AvailableTools);
+        Assert.Null(clone.ExcludedTools);
+        Assert.Null(clone.McpServers);
+        Assert.Null(clone.CustomAgents);
+        Assert.Null(clone.SkillDirectories);
+        Assert.Null(clone.DisabledSkills);
+        Assert.Null(clone.Tools);
+    }
+}