.NET: Add shell support to the HarnessAgent (#6005)

* Add shell support to the HarnessAgent

* Address PR comments

* Address PR comments

dotnet/src/Microsoft.Agents.AI.Harness/HarnessAgent.cs

@@ -6,6 +6,9 @@ using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using Microsoft.Agents.AI.Compaction;
+#if NET
+using Microsoft.Agents.AI.Tools.Shell;
+#endif
 using Microsoft.Extensions.AI;
 using Microsoft.Shared.DiagnosticIds;
 using Microsoft.Shared.Diagnostics;
@@ -201,6 +204,14 @@ public sealed class HarnessAgent : DelegatingAIAgent
             result.Tools.Add(new HostedWebSearchTool());
         }
 
+#if NET
+        if (options?.ShellExecutor is ShellExecutor shellExecutor)
+        {
+            result.Tools ??= [];
+            result.Tools.Add(shellExecutor.AsAIFunction());
+        }
+#endif
+
         return result;
     }
 
@@ -259,6 +270,13 @@ public sealed class HarnessAgent : DelegatingAIAgent
             }
         }
 
+#if NET
+        if (options?.ShellExecutor is ShellExecutor shellExecutor)
+        {
+            providers.Add(new ShellEnvironmentProvider(shellExecutor, options.ShellEnvironmentProviderOptions));
+        }
+#endif
+
         if (options?.AIContextProviders is IEnumerable<AIContextProvider> userProviders)
         {
             providers.AddRange(userProviders);

dotnet/src/Microsoft.Agents.AI.Harness/HarnessAgentOptions.cs

@@ -2,6 +2,9 @@
 
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+#if NET
+using Microsoft.Agents.AI.Tools.Shell;
+#endif
 using Microsoft.Extensions.AI;
 using Microsoft.Shared.DiagnosticIds;
 
@@ -240,4 +243,27 @@ public sealed class HarnessAgentOptions
     /// This property is ignored when <see cref="BackgroundAgents"/> is <see langword="null"/> or empty.
     /// </remarks>
     public BackgroundAgentsProviderOptions? BackgroundAgentsProviderOptions { get; set; }
+
+#if NET
+    /// <summary>
+    /// Gets or sets the shell executor used to enable shell tool and environment probing via <see cref="ShellEnvironmentProvider"/>.
+    /// </summary>
+    /// <remarks>
+    /// When non-null, a <see cref="ShellEnvironmentProvider"/> is automatically included in the agent's context
+    /// providers (injecting OS/shell/CWD information into the system prompt), and the executor's
+    /// <see cref="ShellExecutor.AsAIFunction"/> is registered as a callable tool.
+    /// When <see langword="null"/> (the default), no shell features are enabled.
+    /// </remarks>
+    public ShellExecutor? ShellExecutor { get; set; }
+
+    /// <summary>
+    /// Gets or sets optional configuration for the <see cref="ShellEnvironmentProvider"/>.
+    /// </summary>
+    /// <remarks>
+    /// Use this to customize which tools are probed, the probe timeout, shell family override,
+    /// or the instructions formatter.
+    /// This property is ignored when <see cref="ShellExecutor"/> is <see langword="null"/>.
+    /// </remarks>
+    public ShellEnvironmentProviderOptions? ShellEnvironmentProviderOptions { get; set; }
+#endif
 }

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

@@ -15,6 +15,10 @@
     <ProjectReference Include="..\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
   </ItemGroup>
 
+  <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
+    <ProjectReference Include="..\Microsoft.Agents.AI.Tools.Shell\Microsoft.Agents.AI.Tools.Shell.csproj" />
+  </ItemGroup>
+
   <PropertyGroup>
     <!-- NuGet Package Settings -->
     <Title>Microsoft Agent Framework Harness</Title>

dotnet/src/Microsoft.Agents.AI.Tools.Shell/DockerShellExecutor.cs

@@ -248,7 +248,7 @@ public sealed class DockerShellExecutor : ShellExecutor
     /// Build the AIFunction for this tool.
     /// </summary>
     /// <remarks>
-    /// When <paramref name="requireApproval"/> is <see langword="null"/>
+    /// When <paramref name="requireApproval"/> is <see langword="true"/>
     /// (the default), the returned function is wrapped in
     /// <see cref="ApprovalRequiredAIFunction"/>. The caller must
     /// explicitly pass <see langword="false"/> to opt out of approval
@@ -259,14 +259,12 @@ public sealed class DockerShellExecutor : ShellExecutor
     /// <param name="name">Function name surfaced to the model.</param>
     /// <param name="description">Function description for the model.</param>
     /// <param name="requireApproval">
-    /// <see langword="true"/> or <see langword="null"/> (the default)
-    /// wraps the function in <see cref="ApprovalRequiredAIFunction"/>;
+    /// <see langword="true"/> (the default) wraps the function in
+    /// <see cref="ApprovalRequiredAIFunction"/>;
     /// <see langword="false"/> opts out and returns the raw function.
     /// </param>
-    public AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool? requireApproval = null)
+    public override AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true)
     {
-        var effectiveRequireApproval = requireApproval ?? true;
-
         description ??=
             "Execute a single shell command inside an isolated Docker container and return its " +
             "stdout, stderr, and exit code. The container has no network, no host filesystem access " +
@@ -292,7 +290,7 @@ public sealed class DockerShellExecutor : ShellExecutor
             },
             new AIFunctionFactoryOptions { Name = name, Description = description });
 
-        return effectiveRequireApproval ? new ApprovalRequiredAIFunction(fn) : fn;
+        return requireApproval ? new ApprovalRequiredAIFunction(fn) : fn;
     }
 
     /// <summary>

dotnet/src/Microsoft.Agents.AI.Tools.Shell/LocalShellExecutor.cs

@@ -325,7 +325,7 @@ public sealed class LocalShellExecutor : ShellExecutor
     /// container where the tool itself is the boundary).
     /// </param>
     /// <returns>An <see cref="AIFunction"/> wrapping <see cref="RunAsync"/>.</returns>
-    public AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true)
+    public override AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true)
     {
         if (!requireApproval && !this._acknowledgeUnsafe)
         {

dotnet/src/Microsoft.Agents.AI.Tools.Shell/ShellExecutor.cs

@@ -3,6 +3,7 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
 
 namespace Microsoft.Agents.AI.Tools.Shell;
 
@@ -65,6 +66,20 @@ public abstract class ShellExecutor : IAsyncDisposable
     /// <param name="cancellationToken">Cancellation token.</param>
     public abstract Task<ShellResult> RunAsync(string command, CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// Build an <see cref="AIFunction"/> bound to this executor, suitable for
+    /// registering with an agent as a callable tool.
+    /// </summary>
+    /// <param name="name">Function name visible to the model.</param>
+    /// <param name="description">Function description for the model.</param>
+    /// <param name="requireApproval">
+    /// When <see langword="true"/> (the default), wraps the function in
+    /// <see cref="ApprovalRequiredAIFunction"/> so every invocation requires
+    /// explicit user approval before executing.
+    /// </param>
+    /// <returns>An <see cref="AIFunction"/> wrapping <see cref="RunAsync"/>.</returns>
+    public abstract AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true);
+
     /// <inheritdoc />
     public abstract ValueTask DisposeAsync();
 }

dotnet/tests/Microsoft.Agents.AI.Harness.UnitTests/HarnessAgentOptionsTests.cs

@@ -1,6 +1,9 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using Moq;
+#if NET
+using Microsoft.Agents.AI.Tools.Shell;
+#endif
 
 namespace Microsoft.Agents.AI.UnitTests;
 
@@ -39,6 +42,10 @@ public class HarnessAgentOptionsTests
         Assert.Null(options.AgentSkillsSource);
         Assert.Null(options.BackgroundAgents);
         Assert.Null(options.BackgroundAgentsProviderOptions);
+#if NET
+        Assert.Null(options.ShellExecutor);
+        Assert.Null(options.ShellEnvironmentProviderOptions);
+#endif
     }
 
     /// <summary>
@@ -56,6 +63,10 @@ public class HarnessAgentOptionsTests
         var skillsSource = new Mock<AgentSkillsSource>().Object;
         var backgroundAgents = new AIAgent[] { new Mock<AIAgent>().Object };
         var backgroundAgentsOptions = new BackgroundAgentsProviderOptions();
+#if NET
+        var shellExecutor = new Mock<ShellExecutor>().Object;
+        var shellEnvOptions = new ShellEnvironmentProviderOptions();
+#endif
 
         // Act
         var options = new HarnessAgentOptions
@@ -83,6 +94,10 @@ public class HarnessAgentOptionsTests
             OpenTelemetrySourceName = "custom-source",
             BackgroundAgents = backgroundAgents,
             BackgroundAgentsProviderOptions = backgroundAgentsOptions,
+#if NET
+            ShellExecutor = shellExecutor,
+            ShellEnvironmentProviderOptions = shellEnvOptions,
+#endif
         };
 
         // Assert
@@ -111,5 +126,9 @@ public class HarnessAgentOptionsTests
         Assert.Equal("custom-source", options.OpenTelemetrySourceName);
         Assert.Same(backgroundAgents, options.BackgroundAgents);
         Assert.Same(backgroundAgentsOptions, options.BackgroundAgentsProviderOptions);
+#if NET
+        Assert.Same(shellExecutor, options.ShellExecutor);
+        Assert.Same(shellEnvOptions, options.ShellEnvironmentProviderOptions);
+#endif
     }
 }

dotnet/tests/Microsoft.Agents.AI.Harness.UnitTests/HarnessAgentTests.cs

@@ -5,6 +5,9 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+#if NET
+using Microsoft.Agents.AI.Tools.Shell;
+#endif
 using Microsoft.Extensions.AI;
 using Moq;
 
@@ -1347,4 +1350,114 @@ public class HarnessAgentTests
     }
 
     #endregion
+
+#if NET
+    #region Feature: ShellEnvironmentProvider
+
+    /// <summary>
+    /// Verify that ShellEnvironmentProvider is included when ShellExecutor is provided.
+    /// </summary>
+    [Fact]
+    public void ShellEnvironmentProvider_IncludedWhenExecutorProvided()
+    {
+        // Arrange
+        var chatClient = new Mock<IChatClient>().Object;
+        var executorMock = new Mock<ShellExecutor>();
+        executorMock.Setup(e => e.AsAIFunction(It.IsAny<string>(), It.IsAny<string?>(), It.IsAny<bool>()))
+            .Returns(AIFunctionFactory.Create(() => "test", "run_shell"));
+        var options = CreateAllDisabledOptions();
+        options.ShellExecutor = executorMock.Object;
+
+        // Act
+        var agent = new HarnessAgent(chatClient, TestMaxContextWindowTokens, TestMaxOutputTokens, options);
+        var innerAgent = agent.GetService<ChatClientAgent>();
+
+        // Assert
+        Assert.NotNull(innerAgent?.AIContextProviders);
+        Assert.Contains(innerAgent!.AIContextProviders!, p => p is ShellEnvironmentProvider);
+    }
+
+    /// <summary>
+    /// Verify that ShellEnvironmentProvider is not included when ShellExecutor is null.
+    /// </summary>
+    [Fact]
+    public void ShellEnvironmentProvider_ExcludedWhenExecutorNull()
+    {
+        // Arrange
+        var chatClient = new Mock<IChatClient>().Object;
+        var options = CreateAllDisabledOptions();
+        options.ShellExecutor = null;
+
+        // Act
+        var agent = new HarnessAgent(chatClient, TestMaxContextWindowTokens, TestMaxOutputTokens, options);
+        var innerAgent = agent.GetService<ChatClientAgent>();
+
+        // Assert
+        Assert.NotNull(innerAgent);
+        Assert.NotNull(innerAgent!.AIContextProviders);
+        Assert.DoesNotContain(innerAgent.AIContextProviders!, p => p is ShellEnvironmentProvider);
+    }
+
+    /// <summary>
+    /// Verify that the shell tool AIFunction is added to ChatOptions.Tools when ShellExecutor is provided.
+    /// </summary>
+    [Fact]
+    public async Task ShellExecutor_ToolAddedToChatOptionsAsync()
+    {
+        // Arrange
+        ChatOptions? capturedOptions = null;
+        var chatClientMock = new Mock<IChatClient>();
+        chatClientMock
+            .Setup(c => c.GetResponseAsync(It.IsAny<IEnumerable<ChatMessage>>(), It.IsAny<ChatOptions>(), It.IsAny<CancellationToken>()))
+            .Callback<IEnumerable<ChatMessage>, ChatOptions?, CancellationToken>((_, opts, _) => capturedOptions = opts)
+            .ReturnsAsync(new ChatResponse(new ChatMessage(ChatRole.Assistant, "done")));
+
+        var executorMock = new Mock<ShellExecutor>();
+        executorMock.Setup(e => e.AsAIFunction(It.IsAny<string>(), It.IsAny<string?>(), It.IsAny<bool>()))
+            .Returns(AIFunctionFactory.Create(() => "shell output", "run_shell"));
+
+        var options = CreateAllDisabledOptions();
+        options.DisableWebSearch = true;
+        options.ShellExecutor = executorMock.Object;
+
+        // Act
+        var agent = new HarnessAgent(chatClientMock.Object, TestMaxContextWindowTokens, TestMaxOutputTokens, options);
+        var session = await agent.CreateSessionAsync();
+        await agent.RunAsync([new ChatMessage(ChatRole.User, "Hi")], session);
+
+        // Assert — the shell tool should be present
+        Assert.NotNull(capturedOptions?.Tools);
+        Assert.Contains(capturedOptions!.Tools!, t => t is AIFunction f && f.Name == "run_shell");
+    }
+
+    /// <summary>
+    /// Verify that ShellEnvironmentProvider is present when ShellEnvironmentProviderOptions is also specified.
+    /// </summary>
+    [Fact]
+    public void ShellEnvironmentProvider_PresentWhenOptionsProvided()
+    {
+        // Arrange
+        var chatClient = new Mock<IChatClient>().Object;
+        var executorMock = new Mock<ShellExecutor>();
+        executorMock.Setup(e => e.AsAIFunction(It.IsAny<string>(), It.IsAny<string?>(), It.IsAny<bool>()))
+            .Returns(AIFunctionFactory.Create(() => "test", "run_shell"));
+        var envOptions = new ShellEnvironmentProviderOptions
+        {
+            ProbeTools = ["git", "python"],
+        };
+        var options = CreateAllDisabledOptions();
+        options.ShellExecutor = executorMock.Object;
+        options.ShellEnvironmentProviderOptions = envOptions;
+
+        // Act
+        var agent = new HarnessAgent(chatClient, TestMaxContextWindowTokens, TestMaxOutputTokens, options);
+        var innerAgent = agent.GetService<ChatClientAgent>();
+
+        // Assert — provider should exist (options wiring is validated by the provider's behavior)
+        Assert.NotNull(innerAgent?.AIContextProviders);
+        Assert.Contains(innerAgent!.AIContextProviders!, p => p is ShellEnvironmentProvider);
+    }
+
+    #endregion
+#endif
 }

dotnet/tests/Microsoft.Agents.AI.Tools.Shell.UnitTests/ShellEnvironmentProviderTests.cs

@@ -6,6 +6,7 @@ using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
 
 namespace Microsoft.Agents.AI.Tools.Shell.UnitTests;
 
@@ -226,6 +227,8 @@ public sealed class ShellEnvironmentProviderTests
         public override Task InitializeAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
         public override Task<ShellResult> RunAsync(string command, CancellationToken cancellationToken = default) =>
             Task.FromResult(this.Responses.Dequeue());
+        public override AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true) =>
+            throw new NotSupportedException();
         public override ValueTask DisposeAsync() => default;
     }
 
@@ -280,6 +283,8 @@ public sealed class ShellEnvironmentProviderTests
         public override Task InitializeAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
         public override Task<ShellResult> RunAsync(string command, CancellationToken cancellationToken = default) =>
             Task.FromResult(this._factory(cancellationToken));
+        public override AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true) =>
+            throw new NotSupportedException();
         public override ValueTask DisposeAsync() => default;
     }
 
@@ -372,6 +377,8 @@ public sealed class ShellEnvironmentProviderTests
             this.RunCount++;
             return Task.FromResult(this.NextResult);
         }
+        public override AIFunction AsAIFunction(string name = "run_shell", string? description = null, bool requireApproval = true) =>
+            throw new NotSupportedException();
         public override ValueTask DisposeAsync() => default;
     }
 }