Upgrade MCP C# SDK to v1.2.0 and re-enable InMemoryMcpTaskStore

DotNetMcp.Tests/DotNetMcp.Tests.csproj

@@ -14,7 +14,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.5" />
     <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" Version="10.4.0" />
     <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.5.2" />
-    <PackageReference Include="ModelContextProtocol" Version="1.1.0" />
+    <PackageReference Include="ModelContextProtocol" Version="1.2.0" />
     <PackageReference Include="xunit.v3.mtp-v2" Version="3.2.2" />
   </ItemGroup>
 

DotNetMcp.Tests/Server/McpConformanceTests.cs

@@ -713,22 +713,21 @@ public async Task Server_CompleteHandler_ShouldReturnConfigurationSuggestions()
 
     #endregion
 
-    #region MCP Task Support Tests (Graceful Degradation)
+    #region MCP Task Support Tests
 
-    // Task support is intentionally disabled: MCP SDK v1.1.0's ExecuteToolAsTaskAsync
-    // disposes the DI scope before the background task resolves services, causing
-    // ObjectDisposedException on every tool call. Without InMemoryMcpTaskStore,
-    // the server runs tools synchronously and does not advertise task capabilities.
+    // Task support is enabled: MCP SDK v1.2.0 fixed the DI scope lifetime bug (#1430).
+    // InMemoryMcpTaskStore is registered, so tool calls with TaskSupport = Optional
+    // can run as background tasks.
 
     [Fact]
-    public void Server_ShouldNotAdvertiseTasksCapability_WhenTaskStoreNotRegistered()
+    public void Server_ShouldAdvertiseTasksCapability_WhenTaskStoreRegistered()
     {
         // Arrange
         Assert.NotNull(_client);
 
-        // Assert - no task store means no tasks capability advertised
+        // Assert - task store is registered so tasks capability is advertised
         Assert.NotNull(_client.ServerCapabilities);
-        Assert.Null(_client.ServerCapabilities.Tasks);
+        Assert.NotNull(_client.ServerCapabilities.Tasks);
     }
 
     [Fact]
@@ -741,23 +740,20 @@ public async Task Server_DotnetProject_ShouldDeclareTaskSupportOptional()
         var tools = await _client.ListToolsAsync(cancellationToken: TestContext.Current.CancellationToken);
         var projectTool = tools.FirstOrDefault(t => t.Name == "dotnet_project");
 
-        // Assert - the tool attribute declares TaskSupport = Optional so it's ready when
-        // task support is re-enabled by un-commenting the IMcpTaskStore registration in Program.cs
-        // (pending fix of https://github.com/modelcontextprotocol/csharp-sdk/issues/1430).
-        // Without a task store registered, the SDK runs it synchronously inline (graceful degradation).
+        // Assert - the tool attribute declares TaskSupport = Optional
         Assert.NotNull(projectTool);
         var execution = projectTool.ProtocolTool.Execution;
         Assert.NotNull(execution);
         Assert.Equal(ModelContextProtocol.Protocol.ToolTaskSupport.Optional, execution.TaskSupport);
     }
 
     [Fact]
-    public async Task Server_DotnetProject_ShouldWorkSynchronously()
+    public async Task Server_DotnetProject_ShouldWorkWithTaskStore()
     {
-        // Arrange - verify tools work reliably via normal tools/call (no tasks)
+        // Arrange - verify tools work reliably with task store registered
         Assert.NotNull(_client);
 
-        // Act - standard synchronous tool call
+        // Act - tool call (task store is present; SDK may run as task or inline)
         var result = await _client.CallToolAsync(
             "dotnet_project",
             new Dictionary<string, object?>

DotNetMcp.Tests/Server/ServerCapabilitiesTests.cs

@@ -2,6 +2,7 @@
 using DotNetMcp;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using ModelContextProtocol;
 using Xunit;
 
 namespace DotNetMcp.Tests;
@@ -16,7 +17,7 @@ public ServerCapabilitiesTests()
     {
         _logger = NullLogger<DotNetCliTools>.Instance;
         _concurrencyManager = new ConcurrencyManager();
-        _tools = new DotNetCliTools(_logger, _concurrencyManager, new ProcessSessionManager());
+        _tools = new DotNetCliTools(_logger, _concurrencyManager, new ProcessSessionManager(), taskStore: new InMemoryMcpTaskStore());
     }
 
     [Fact]
@@ -210,7 +211,7 @@ public async Task DotnetServerCapabilities_SdkVersions_Lts_IsNet100()
     }
 
     [Fact]
-    public async Task DotnetServerCapabilities_Supports_AsyncTasks_IsFalse()
+    public async Task DotnetServerCapabilities_Supports_AsyncTasks_IsTrue()
     {
         // Act
         var result = (await _tools.DotnetServerCapabilities()).GetText();
@@ -220,8 +221,8 @@ public async Task DotnetServerCapabilities_Supports_AsyncTasks_IsFalse()
             .GetProperty("asyncTasks")
             .GetBoolean();
 
-        // Assert - MCP Task support disabled due to SDK v1.1.0 DI scope lifetime bug
-        Assert.False(asyncTasks);
+        // Assert - MCP Task support enabled with MCP SDK v1.2.0 fix for DI scope lifetime bug
+        Assert.True(asyncTasks);
     }
 
     [Fact]
@@ -262,7 +263,7 @@ public async Task DotnetServerCapabilities_JsonSchema_MatchesExpectedStructure()
         Assert.True(capabilities.Supports.MachineReadable);
         Assert.True(capabilities.Supports.Cancellation);
         Assert.True(capabilities.Supports.Telemetry);
-        Assert.False(capabilities.Supports.AsyncTasks);
+        Assert.True(capabilities.Supports.AsyncTasks);
         Assert.True(capabilities.Supports.Prompts);
         Assert.True(capabilities.Supports.Elicitation);
         Assert.True(capabilities.Supports.Completions);

DotNetMcp/DotNetMcp.csproj

@@ -51,7 +51,7 @@
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.5" />
     <PackageReference Include="Microsoft.TemplateEngine.Abstractions" Version="10.0.201" />
     <PackageReference Include="Microsoft.TemplateEngine.Edge" Version="10.0.201" />
-    <PackageReference Include="ModelContextProtocol" Version="1.1.0" />
+    <PackageReference Include="ModelContextProtocol" Version="1.2.0" />
     <PackageReference Include="MinVer" Version="7.0.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

DotNetMcp/Program.cs

@@ -21,12 +21,8 @@
 // Register ProcessSessionManager as a singleton
 builder.Services.AddSingleton<ProcessSessionManager>();
 
-// TODO: Re-enable InMemoryMcpTaskStore once the MCP SDK fixes the DI scope lifetime bug.
-// Upstream issue: https://github.com/modelcontextprotocol/csharp-sdk/issues/1430
-// MCP SDK v1.1.0's ExecuteToolAsTaskAsync disposes the request-scoped IServiceProvider
-// before the background task resolves services, causing ObjectDisposedException on every
-// tool call. Without a task store, the SDK runs tools synchronously inline.
-// builder.Services.AddSingleton<IMcpTaskStore, InMemoryMcpTaskStore>();
+// Register InMemoryMcpTaskStore for async task support (MCP SDK v1.2.0 fixed #1430).
+builder.Services.AddSingleton<IMcpTaskStore, InMemoryMcpTaskStore>();
 
 // Register ToolMetricsAccumulator for in-memory telemetry collection.
 // The accumulator is also captured by the telemetry filter added below.

DotNetMcp/Tools/Cli/DotNetCliTools.Misc.cs

@@ -71,7 +71,7 @@ public async partial Task<CallToolResult> DotnetServerCapabilities()
                 Cancellation = true,
                 Telemetry = true,  // SDK v0.6+ supports request duration logging and OpenTelemetry semantic conventions
                 Metrics = true,    // In-memory per-tool metrics via MCP message filter (dotnet_server_metrics tool)
-                AsyncTasks = _taskStore != null, // Derived from DI: true when IMcpTaskStore is registered; currently false (MCP SDK DI scope bug https://github.com/modelcontextprotocol/csharp-sdk/issues/1430)
+                AsyncTasks = _taskStore != null, // Derived from DI: true when IMcpTaskStore is registered
                 Prompts = true,     // Predefined prompt catalog: create_new_webapi, add_package_and_restore, run_tests_with_coverage
                 Elicitation = true,  // Elicitation for confirmation before destructive ops (Clean, solution Remove)
                 McpLogging = true,   // MCP log notifications sent to client during key operations (build, test, publish, restore, package add/update)

README.md

@@ -1096,7 +1096,7 @@ Key files to start with:
 - 📖 [Concurrency Safety](doc/concurrency.md) - Parallel execution guidance for AI orchestrators
 - 📖 [Testing](doc/testing.md) - How to run tests (including opt-in interactive tests)
 - 📖 [Model Context Protocol](https://modelcontextprotocol.io/) - Official MCP specification
-- 📖 [MCP C# SDK Docs](https://modelcontextprotocol.github.io/csharp-sdk/) - SDK documentation
+- 📖 [MCP C# SDK Docs](https://csharp.sdk.modelcontextprotocol.io/) - SDK documentation
 
 ## Interoperability