Add ITestOutputHelper logging to scenario and conformance test harness

DotNetMcp.Tests/ReleaseScenarios/ColdCacheProjectLifecycleReleaseScenarioTests.cs

@@ -7,6 +7,13 @@ namespace DotNetMcp.Tests.ReleaseScenarios;
 [Collection("ProcessWideStateTests")]
 public class ColdCacheProjectLifecycleReleaseScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public ColdCacheProjectLifecycleReleaseScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ReleaseScenarioFact]
     public async Task ReleaseScenario_ColdNuGetCache_Console_AddPackage_Restore_Build_Publish()
     {
@@ -38,7 +45,7 @@ public async Task ReleaseScenario_ColdNuGetCache_Console_AddPackage_Restore_Buil
             var projectPath = Path.Join(tempRoot.Path, "App.csproj");
             Assert.True(File.Exists(projectPath), $"Expected App.csproj to exist at {projectPath}");
 
-            await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+            await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
             // Add a small public package to force a real restore against NuGet.
             var addPackageText = await client.CallToolTextAsync(

DotNetMcp.Tests/ReleaseScenarios/EfCoreSqliteMigrationsReleaseScenarioTests.cs

@@ -7,6 +7,13 @@ namespace DotNetMcp.Tests.ReleaseScenarios;
 [Collection("ProcessWideStateTests")]
 public class EfCoreSqliteMigrationsReleaseScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public EfCoreSqliteMigrationsReleaseScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ReleaseScenarioFact]
     public async Task ReleaseScenario_EfCoreSqlite_MigrationsAdd_And_DatabaseUpdate()
     {
@@ -38,7 +45,7 @@ public async Task ReleaseScenario_EfCoreSqlite_MigrationsAdd_And_DatabaseUpdate(
             Assert.True(File.Exists(projectPath), $"Expected EfApp.csproj to exist at {projectPath}");
 
             // Add EF Core packages via MCP.
-            await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+            await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
             var addSqliteText = await client.CallToolTextAsync(
                 toolName: "dotnet_package",

DotNetMcp.Tests/ReleaseScenarios/LocalToolManifestReleaseScenarioTests.cs

@@ -6,13 +6,20 @@ namespace DotNetMcp.Tests.ReleaseScenarios;
 
 public class LocalToolManifestReleaseScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public LocalToolManifestReleaseScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ReleaseScenarioFact]
     public async Task ReleaseScenario_DotnetTool_CreateManifest_Install_Restore_List()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
         using var tempRoot = ScenarioHelpers.CreateTempDirectory(nameof(ReleaseScenario_DotnetTool_CreateManifest_Install_Restore_List));
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         var createManifestText = await client.CallToolTextAsync(
             toolName: "dotnet_tool",

DotNetMcp.Tests/ReleaseScenarios/ServerConcurrencyStressReleaseScenarioTests.cs

@@ -6,12 +6,19 @@ namespace DotNetMcp.Tests.ReleaseScenarios;
 
 public class ServerConcurrencyStressReleaseScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public ServerConcurrencyStressReleaseScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ReleaseScenarioFact]
     public async Task ReleaseScenario_ServerConcurrency_ManyParallelSdkInfoCalls()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         const int callCount = 64;
 

DotNetMcp.Tests/Scenarios/BackgroundRunScenarioTests.cs

@@ -6,6 +6,13 @@ namespace DotNetMcp.Tests.Scenarios;
 
 public class BackgroundRunScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public BackgroundRunScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     private static async Task<string> WaitForLogsContainingAsync(
         McpScenarioClient client,
         string sessionId,
@@ -77,7 +84,7 @@ public async Task Scenario_BackgroundRun_StartStopProcess_Success()
 ";
         File.WriteAllText(programPath, programContent);
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         // Build the project
         var buildText = await client.CallToolTextAsync(
@@ -180,7 +187,7 @@ public async Task Scenario_BackgroundRun_RetrieveLogs_Success()
 ";
         File.WriteAllText(programPath, programContent);
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         // Build the project
         var buildText = await client.CallToolTextAsync(
@@ -265,7 +272,7 @@ await client.CallToolTextAsync(
     public async Task Scenario_BackgroundRun_Logs_InvalidSessionId_ReturnsError()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         // Try to retrieve logs for a non-existent session
         var logsText = await client.CallToolTextAsync(

DotNetMcp.Tests/Scenarios/BuildErrorScenarioTests.cs

@@ -6,6 +6,13 @@ namespace DotNetMcp.Tests.Scenarios;
 
 public class BuildErrorScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public BuildErrorScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ScenarioFact]
     public async Task Scenario_DotnetProject_Build_WithCompileError_ReturnsMachineReadableError()
     {
@@ -32,7 +39,7 @@ public async Task Scenario_DotnetProject_Build_WithCompileError_ReturnsMachineRe
         Assert.True(File.Exists(programPath), "Expected Program.cs to exist");
         await File.WriteAllTextAsync(programPath, "IAmABogusType bogus = new IAmABogusType();\n", cancellationToken);
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         var result = await client.CallToolAsync(
             toolName: "dotnet_project",

DotNetMcp.Tests/Scenarios/ConsoleScenarioTests.cs

@@ -5,6 +5,13 @@ namespace DotNetMcp.Tests.Scenarios;
 
 public class ConsoleScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public ConsoleScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ScenarioFact]
     public async Task Scenario_ConsoleProject_AddPackageAndBuild_Release()
     {
@@ -22,7 +29,7 @@ public async Task Scenario_ConsoleProject_AddPackageAndBuild_Release()
         var projectPath = Path.Join(tempRoot.Path, "ConsoleApp.csproj");
         Assert.True(File.Exists(projectPath), $"Expected ConsoleApp.csproj to exist at {projectPath}");
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         // Add a package via MCP.
         var addPackageText = await client.CallToolTextAsync(

DotNetMcp.Tests/Scenarios/McpScenarioClient.cs

@@ -11,27 +11,39 @@ namespace DotNetMcp.Tests.Scenarios;
 /// over stdio for end-to-end integration tests.
 /// </summary>
 /// <remarks>
-/// Use <see cref="CreateAsync(CancellationToken)"/> to create an instance, which will launch
-/// the MCP server process and connect an <see cref="McpClient"/> over stdio. Call
-/// <see cref="DisposeAsync"/> when finished to shut down the underlying client and release
+/// Use <see cref="CreateAsync(CancellationToken, ITestOutputHelper?)"/> to create an instance,
+/// which will launch the MCP server process and connect an <see cref="McpClient"/> over stdio.
+/// Pass an <see cref="ITestOutputHelper"/> to capture diagnostic output (server command, tool
+/// calls, and response snippets) tied to the individual test in CI logs.
+/// Call <see cref="DisposeAsync"/> when finished to shut down the underlying client and release
 /// associated resources, including the logger factory and server process.
 /// </remarks>
 internal sealed class McpScenarioClient : IAsyncDisposable
 {
+    private const int MaxResponseLogLength = 500;
+
     private readonly ILoggerFactory _loggerFactory;
+    private readonly ITestOutputHelper? _output;
     private McpClient? _client;
 
-    private McpScenarioClient(ILoggerFactory loggerFactory)
+    private McpScenarioClient(ILoggerFactory loggerFactory, ITestOutputHelper? output)
     {
         _loggerFactory = loggerFactory;
+        _output = output;
     }
 
     /// <summary>
     /// Creates and starts a new MCP scenario client connected to the dotnet-mcp server.
     /// </summary>
     /// <param name="cancellationToken">A cancellation token to cancel the operation.</param>
+    /// <param name="output">
+    /// Optional xUnit output helper. When provided, diagnostic information (server start
+    /// command, tool calls, and response snippets) is written to the per-test output channel
+    /// so that CI logs for failing tests include actionable context. Arg values are never
+    /// logged to avoid inadvertently printing secrets.
+    /// </param>
     /// <returns>A connected McpScenarioClient instance.</returns>
-    public static async Task<McpScenarioClient> CreateAsync(CancellationToken cancellationToken)
+    public static async Task<McpScenarioClient> CreateAsync(CancellationToken cancellationToken, ITestOutputHelper? output = null)
     {
         var loggerFactory = LoggerFactory.Create(builder =>
         {
@@ -42,7 +54,7 @@ public static async Task<McpScenarioClient> CreateAsync(CancellationToken cancel
             builder.SetMinimumLevel(LogLevel.Warning);
         });
 
-        var host = new McpScenarioClient(loggerFactory);
+        var host = new McpScenarioClient(loggerFactory, output);
         await host.StartAsync(cancellationToken);
         return host;
     }
@@ -51,6 +63,8 @@ private async Task StartAsync(CancellationToken cancellationToken)
     {
         var serverPath = GetServerExecutablePath();
 
+        _output?.WriteLine($"[MCP] Server command: {serverPath.command} {string.Join(" ", serverPath.arguments)}");
+
         var transportOptions = new StdioClientTransportOptions
         {
             Command = serverPath.command,
@@ -64,6 +78,8 @@ private async Task StartAsync(CancellationToken cancellationToken)
             transport,
             loggerFactory: _loggerFactory,
             cancellationToken: cancellationToken);
+
+        _output?.WriteLine("[MCP] Server connected.");
     }
 
     /// <summary>
@@ -80,9 +96,14 @@ public async Task<string> CallToolTextAsync(string toolName, Dictionary<string,
             throw new InvalidOperationException("MCP client not initialized.");
         }
 
+        LogToolCall(toolName, args);
+
         var result = await _client.CallToolAsync(toolName, args, cancellationToken: cancellationToken);
-        var text = result.Content.OfType<TextContentBlock>().FirstOrDefault()?.Text;
-        return text ?? string.Empty;
+        var text = result.Content.OfType<TextContentBlock>().FirstOrDefault()?.Text ?? string.Empty;
+
+        LogToolResponse(toolName, text);
+
+        return text;
     }
 
     /// <summary>
@@ -99,7 +120,36 @@ public async Task<CallToolResult> CallToolAsync(string toolName, Dictionary<stri
             throw new InvalidOperationException("MCP client not initialized.");
         }
 
-        return await _client.CallToolAsync(toolName, args, cancellationToken: cancellationToken);
+        LogToolCall(toolName, args);
+
+        var result = await _client.CallToolAsync(toolName, args, cancellationToken: cancellationToken);
+
+        var text = result.Content.OfType<TextContentBlock>().FirstOrDefault()?.Text ?? string.Empty;
+        LogToolResponse(toolName, text);
+
+        return result;
+    }
+
+    /// <summary>
+    /// Logs the tool call with its name and argument keys (values are omitted to avoid leaking secrets).
+    /// </summary>
+    private void LogToolCall(string toolName, Dictionary<string, object?> args)
+    {
+        if (_output is null) return;
+        var keys = string.Join(", ", args.Keys);
+        _output.WriteLine($"[MCP] → {toolName} (args: {{{keys}}})");
+    }
+
+    /// <summary>
+    /// Logs a truncated snippet of the tool response.
+    /// </summary>
+    private void LogToolResponse(string toolName, string text)
+    {
+        if (_output is null) return;
+        var snippet = text.Length <= MaxResponseLogLength
+            ? text
+            : string.Concat(text.AsSpan(0, MaxResponseLogLength), $"... [{text.Length - MaxResponseLogLength} chars truncated]");
+        _output.WriteLine($"[MCP] ← {toolName}: {snippet}");
     }
 
     /// <summary>

DotNetMcp.Tests/Scenarios/PackageAndReferenceScenarioTests.cs

@@ -5,6 +5,13 @@ namespace DotNetMcp.Tests.Scenarios;
 
 public class PackageAndReferenceScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public PackageAndReferenceScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ScenarioFact]
     public async Task Scenario_DotnetPackage_AddInvalidPackage_ReturnsMachineReadableError()
     {
@@ -22,7 +29,7 @@ public async Task Scenario_DotnetPackage_AddInvalidPackage_ReturnsMachineReadabl
         var projectPath = Path.Join(tempRoot.Path, "TempProj.csproj");
         Assert.True(File.Exists(projectPath), $"Expected TempProj.csproj to exist at {projectPath}");
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         var text = await client.CallToolTextAsync(
             toolName: "dotnet_package",
@@ -64,7 +71,7 @@ public async Task Scenario_ProjectReferenceFlow_AddReferenceAndBuildSolution_Rel
         Assert.True(File.Exists(libAProj));
         Assert.True(File.Exists(libBProj));
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         // Create solution via MCP.
         var slnCreateText = await client.CallToolTextAsync(

DotNetMcp.Tests/Scenarios/SdkContractScenarioTests.cs

@@ -5,12 +5,19 @@ namespace DotNetMcp.Tests.Scenarios;
 
 public class SdkContractScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public SdkContractScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ScenarioFact]
     public async Task Scenario_DotnetSdk_ListSdks_MachineReadable_Success()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         var text = await client.CallToolTextAsync(
             toolName: "dotnet_sdk",
@@ -30,7 +37,7 @@ public async Task Scenario_DotnetSdk_SearchTemplates_MissingSearchTerm_ReturnsVa
     {
         var cancellationToken = TestContext.Current.CancellationToken;
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         var text = await client.CallToolTextAsync(
             toolName: "dotnet_sdk",
@@ -49,7 +56,7 @@ public async Task Scenario_DotnetSdk_ListTemplatePacks_MachineReadable_Success()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         var text = await client.CallToolTextAsync(
             toolName: "dotnet_sdk",

DotNetMcp.Tests/Scenarios/SecretsRedactionScenarioTests.cs

@@ -5,6 +5,13 @@ namespace DotNetMcp.Tests.Scenarios;
 
 public class SecretsRedactionScenarioTests
 {
+    private readonly ITestOutputHelper _output;
+
+    public SecretsRedactionScenarioTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
     [ScenarioFact]
     public async Task Scenario_UserSecrets_NoSecretLeak_InOtherToolOutputs()
     {
@@ -24,7 +31,7 @@ public async Task Scenario_UserSecrets_NoSecretLeak_InOtherToolOutputs()
         var projectPath = Path.Join(tempRoot.Path, "SecretsProj.csproj");
         Assert.True(File.Exists(projectPath), $"Expected SecretsProj.csproj to exist at {projectPath}");
 
-        await using var client = await McpScenarioClient.CreateAsync(cancellationToken);
+        await using var client = await McpScenarioClient.CreateAsync(cancellationToken, _output);
 
         // Initialize + set a secret for the main project.
         var initText = await client.CallToolTextAsync(