Wrap each request in a service scope (#276)

* Wrap each request in a service scope

* Change request/notification delegates to return ValueTask

* Address feedback

src/ModelContextProtocol/Server/RequestContext.cs

@@ -1,9 +1,10 @@
 using Microsoft.Extensions.DependencyInjection;
+using ModelContextProtocol.Utils;
 
 namespace ModelContextProtocol.Server;
 
 /// <summary>
-/// Provides a context container that provides access to both the server instance and the client request parameters.
+/// Provides a context container that provides access to the client request parameters and resources for the request.
 /// </summary>
 /// <typeparam name="TParams">Type of the request parameters specific to each MCP operation.</typeparam>
 /// <remarks>
@@ -11,4 +12,43 @@ namespace ModelContextProtocol.Server;
 /// This type is typically received as a parameter in handler delegates registered with <see cref="IMcpServerBuilder"/>,
 /// and may be injected as parameters into <see cref="McpServerTool"/>s.
 /// </remarks>
-public record RequestContext<TParams>(IMcpServer Server, TParams? Params);
+public sealed class RequestContext<TParams>
+{
+    /// <summary>The server with which this instance is associated.</summary>
+    private IMcpServer _server;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="RequestContext{TParams}"/> class with the specified server.
+    /// </summary>
+    /// <param name="server">The server with which this instance is associated.</param>
+    public RequestContext(IMcpServer server)
+    {
+        Throw.IfNull(server);
+
+        _server = server;
+        Services = server.Services;
+    }
+
+    /// <summary>Gets or sets the server with which this instance is associated.</summary>
+    public IMcpServer Server 
+    {
+        get => _server;
+        set
+        {
+            Throw.IfNull(value);
+            _server = value;
+        }
+    }
+
+    /// <summary>Gets or sets the services associated with this request.</summary>
+    /// <remarks>
+    /// This may not be the same instance stored in <see cref="IMcpServer.Services"/>
+    /// if <see cref="McpServerOptions.ScopeRequests"/> was true, in which case this
+    /// might be a scoped <see cref="IServiceProvider"/> derived from the server's
+    /// <see cref="IMcpServer.Services"/>.
+    /// </remarks>
+    public IServiceProvider? Services { get; set; }
+
+    /// <summary>Gets or sets the parameters associated with this request.</summary>
+    public TParams? Params { get; set; }
+}