Work around SocketsHttpHandler bug where it doesn't call DispseAsync on the stream returned by the ConnectCallback

- Move workaround to KestrelInMemoryConnection instead of SseClientSessionTransport which is product code

Author: halter73

src/ModelContextProtocol/Protocol/Transport/SseClientSessionTransport.cs

@@ -204,15 +204,8 @@ private async Task ReceiveMessagesAsync(CancellationToken cancellationToken)
 
                 using var stream = await response.Content.ReadAsStreamAsync(cancellationToken).ConfigureAwait(false);
 
-                // A lot of methods in HttpClient, including HttpConnection.FillAsync, do not currently respect any
-                // cancellation tokens so we have to cancel awaiting ourselves.
-                // I tried disposing the HttpRequestMessage and HttpResponseMessage instead, but neither of these canceled
-                // the ongoing body read, and we don't want to dispose an HttpClient we may not own.
-                var sseEventEnumerator = SseParser.Create(stream).EnumerateAsync(cancellationToken).GetAsyncEnumerator();
-                while (await sseEventEnumerator.MoveNextAsync().AsTask().WaitAsync(cancellationToken).ConfigureAwait(false))
+                await foreach (SseItem<string> sseEvent in SseParser.Create(stream).EnumerateAsync(cancellationToken).ConfigureAwait(false))
                 {
-                    SseItem<string> sseEvent = sseEventEnumerator.Current;
-
                     switch (sseEvent.EventType)
                     {
                         case "endpoint":

tests/ModelContextProtocol.Tests/Utils/KestrelInMemoryConnection.cs

@@ -77,13 +77,12 @@ public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationTo
         public override Task FlushAsync(CancellationToken cancellationToken)
             => _writeStream.FlushAsync(cancellationToken);
 
-        public override async ValueTask DisposeAsync()
+        protected override void Dispose(bool disposing)
         {
             // Signal to the server the the client has closed the connection, and dispose the client-half of the Pipes.
-            await connectionClosedCts.CancelAsync();
+            connectionClosedCts.Cancel();
             duplexPipe.Input.Complete();
             duplexPipe.Output.Complete();
-            await base.DisposeAsync();
         }
 
         // Unsupported stuff