Revert TimeProvider NuGet dependency, use conditional compilation for test-only TimeProvider support

Co-authored-by: eiriktsarpalis <2813363+eiriktsarpalis@users.noreply.github.com>

Author: Copilot

Directory.Packages.props

@@ -26,7 +26,6 @@
   <!-- Product dependencies .NET Standard -->
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageVersion Include="Microsoft.Bcl.Memory" Version="$(System10Version)" />
-    <PackageVersion Include="Microsoft.Bcl.TimeProvider" Version="$(System10Version)" />
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="$(System10Version)" />
     <PackageVersion Include="System.IO.Pipelines" Version="$(System10Version)" />
     <PackageVersion Include="System.Text.Json" Version="$(System10Version)" />

src/ModelContextProtocol.Core/ModelContextProtocol.Core.csproj

@@ -33,7 +33,6 @@
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <Compile Include="..\Common\CancellableStreamReader\**\*.cs" />
     <PackageReference Include="Microsoft.Bcl.Memory" />
-    <PackageReference Include="Microsoft.Bcl.TimeProvider" />
     <PackageReference Include="System.Diagnostics.DiagnosticSource" />
     <PackageReference Include="System.Text.Json" />
     <PackageReference Include="System.Threading.Channels" />

src/ModelContextProtocol.Core/Server/InMemoryMcpTaskStore.cs

@@ -35,7 +35,9 @@ public sealed class InMemoryMcpTaskStore : IMcpTaskStore, IDisposable
     private readonly int _pageSize;
     private readonly int? _maxTasks;
     private readonly int? _maxTasksPerSession;
+#if MCP_TEST_TIME_PROVIDER
     private readonly TimeProvider _timeProvider;
+#endif
 
     /// <summary>
     /// Initializes a new instance of the <see cref="InMemoryMcpTaskStore"/> class.
@@ -66,19 +68,14 @@ public sealed class InMemoryMcpTaskStore : IMcpTaskStore, IDisposable
     /// Maximum number of tasks allowed per session. Null means unlimited.
     /// When the limit is reached for a session, <see cref="CreateTaskAsync"/> will throw <see cref="InvalidOperationException"/>.
     /// </param>
-    /// <param name="timeProvider">
-    /// Time provider for getting the current time. Defaults to <see cref="TimeProvider.System"/>.
-    /// This parameter is primarily useful for testing scenarios where you need to control time.
-    /// </param>
     public InMemoryMcpTaskStore(
         TimeSpan? defaultTtl = null,
         TimeSpan? maxTtl = null,
         TimeSpan? pollInterval = null,
         TimeSpan? cleanupInterval = null,
         int pageSize = 100,
         int? maxTasks = null,
-        int? maxTasksPerSession = null,
-        TimeProvider? timeProvider = null)
+        int? maxTasksPerSession = null)
     {
         if (defaultTtl.HasValue && maxTtl.HasValue && defaultTtl.Value > maxTtl.Value)
         {
@@ -126,7 +123,9 @@ public InMemoryMcpTaskStore(
         _pageSize = pageSize;
         _maxTasks = maxTasks;
         _maxTasksPerSession = maxTasksPerSession;
-        _timeProvider = timeProvider ?? TimeProvider.System;
+#if MCP_TEST_TIME_PROVIDER
+        _timeProvider = TimeProvider.System;
+#endif
 
         cleanupInterval ??= TimeSpan.FromMinutes(1);
         if (cleanupInterval.Value != Timeout.InfiniteTimeSpan)
@@ -135,6 +134,26 @@ public InMemoryMcpTaskStore(
         }
     }
 
+#if MCP_TEST_TIME_PROVIDER
+    /// <summary>
+    /// Initializes a new instance of the <see cref="InMemoryMcpTaskStore"/> class with a custom time provider.
+    /// This constructor is only available for testing purposes.
+    /// </summary>
+    internal InMemoryMcpTaskStore(
+        TimeSpan? defaultTtl,
+        TimeSpan? maxTtl,
+        TimeSpan? pollInterval,
+        TimeSpan? cleanupInterval,
+        int pageSize,
+        int? maxTasks,
+        int? maxTasksPerSession,
+        TimeProvider timeProvider)
+        : this(defaultTtl, maxTtl, pollInterval, cleanupInterval, pageSize, maxTasks, maxTasksPerSession)
+    {
+        _timeProvider = timeProvider ?? TimeProvider.System;
+    }
+#endif
+
     /// <inheritdoc/>
     public Task<McpTask> CreateTaskAsync(
         McpTaskMetadata taskParams,
@@ -162,7 +181,7 @@ public Task<McpTask> CreateTaskAsync(
         }
 
         var taskId = GenerateTaskId();
-        var now = _timeProvider.GetUtcNow();
+        var now = GetUtcNow();
 
         // Determine TTL: use requested, fall back to default, respect max limit
         var ttl = taskParams.TimeToLive ?? _defaultTtl;
@@ -249,7 +268,7 @@ public Task<McpTask> StoreTaskResultAsync(
             var updatedEntry = new TaskEntry(entry)
             {
                 Status = status,
-                LastUpdatedAt = _timeProvider.GetUtcNow(),
+                LastUpdatedAt = GetUtcNow(),
                 StoredResult = result
             };
 
@@ -310,7 +329,7 @@ public Task<McpTask> UpdateTaskStatusAsync(
             {
                 Status = status,
                 StatusMessage = statusMessage,
-                LastUpdatedAt = _timeProvider.GetUtcNow(),
+                LastUpdatedAt = GetUtcNow(),
             };
 
             if (_tasks.TryUpdate(taskId, updatedEntry, entry))
@@ -405,7 +424,7 @@ public Task<McpTask> CancelTaskAsync(string taskId, string? sessionId = null, Ca
             var updatedEntry = new TaskEntry(entry)
             {
                 Status = McpTaskStatus.Cancelled,
-                LastUpdatedAt = _timeProvider.GetUtcNow(),
+                LastUpdatedAt = GetUtcNow(),
             };
 
             if (_tasks.TryUpdate(taskId, updatedEntry, entry))
@@ -430,15 +449,25 @@ public void Dispose()
     private static bool IsTerminalStatus(McpTaskStatus status) =>
         status is McpTaskStatus.Completed or McpTaskStatus.Failed or McpTaskStatus.Cancelled;
 
+#if MCP_TEST_TIME_PROVIDER
+    private DateTimeOffset GetUtcNow() => _timeProvider.GetUtcNow();
+#else
+    private static DateTimeOffset GetUtcNow() => DateTimeOffset.UtcNow;
+#endif
+
+#if MCP_TEST_TIME_PROVIDER
     private bool IsExpired(TaskEntry entry)
+#else
+    private static bool IsExpired(TaskEntry entry)
+#endif
     {
         if (entry.TimeToLive == null)
         {
             return false; // Unlimited lifetime
         }
 
         var expirationTime = entry.CreatedAt + entry.TimeToLive.Value;
-        return _timeProvider.GetUtcNow() >= expirationTime;
+        return GetUtcNow() >= expirationTime;
     }
 
     private void CleanupExpiredTasks(object? state)

tests/ModelContextProtocol.Tests/ModelContextProtocol.Tests.csproj

@@ -10,7 +10,9 @@
     <IsTestProject>true</IsTestProject>
     <RootNamespace>ModelContextProtocol.Tests</RootNamespace>
     <!-- https://github.com/dotnet/sdk/issues/51060 -->
-    <NoWarn>$(NoWarn);NU1903;NU1902</NoWarn>
+    <NoWarn>$(NoWarn);NU1903;NU1902;CS0436</NoWarn>
+    <!-- Define for conditional TimeProvider support in InMemoryMcpTaskStore -->
+    <DefineConstants>$(DefineConstants);MCP_TEST_TIME_PROVIDER</DefineConstants>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(TargetFramework)' == 'net9.0'">
@@ -27,6 +29,10 @@
 
   <ItemGroup>
     <Compile Include="..\Common\**\*.cs" />
+    <!-- Link InMemoryMcpTaskStore.cs for testing with TimeProvider support -->
+    <Compile Include="..\..\src\ModelContextProtocol.Core\Server\InMemoryMcpTaskStore.cs" Link="Server\InMemoryMcpTaskStore.cs" />
+    <!-- Include dependencies for the linked InMemoryMcpTaskStore.cs -->
+    <Compile Include="..\..\src\Common\Experimentals.cs" Link="Experimentals.cs" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net472'">

tests/ModelContextProtocol.Tests/Server/InMemoryMcpTaskStoreTests.cs

@@ -1038,7 +1038,15 @@ public async Task ListTasksAsync_KeysetPaginationWorksWithIdenticalTimestamps()
     {
         // Arrange - Use a fake time provider to create tasks with identical timestamps
         var fakeTime = new FakeTimeProvider(DateTimeOffset.UtcNow);
-        using var store = new InMemoryMcpTaskStore(pageSize: 5, timeProvider: fakeTime);
+        using var store = new InMemoryMcpTaskStore(
+            defaultTtl: null,
+            maxTtl: null,
+            pollInterval: null,
+            cleanupInterval: Timeout.InfiniteTimeSpan,
+            pageSize: 5,
+            maxTasks: null,
+            maxTasksPerSession: null,
+            timeProvider: fakeTime);
 
         // Create 10 tasks - all with the EXACT same timestamp
         var createdTasks = new List<McpTask>();