Restructure IMcpEndpoint, IMcpClient, and IMcpServer (#723)

* Remove `McpEndpoint` & `IMcpClient`

* Revise naming, add abstract classes

* Fix missing renames

* Move extension methods to instance methods

* Add back old API, but obsoleted

* Add back obsoleted factory classes

* Move deprecation attributes

* `SseClientTransport` -> `HttpClientTransport`

* Update src/ModelContextProtocol.Core/Server/AugmentedServiceProvider.cs

Co-authored-by: Stephen Halter <halter73@gmail.com>

* PR feedback

* PR feedback

* Add back dispose lock

* Fix docs projects

* PR feedback

* Undo `docs/*.md` changes

---------

Co-authored-by: Stephen Halter <halter73@gmail.com>

src/ModelContextProtocol.AspNetCore/AuthorizationFilterSetup.cs

@@ -292,7 +292,7 @@ internal sealed class AuthorizationFilterSetup(IAuthorizationPolicyProvider? pol
         if (requestServices is null)
         {
             // The IAuthorizationPolicyProvider service must be non-null to get to this line, so it's very unexpected for RequestContext.Services to not be set.
-            throw new InvalidOperationException("RequestContext.Services is not set! The IMcpServer must be initialized with a non-null IServiceProvider.");
+            throw new InvalidOperationException("RequestContext.Services is not set! The McpServer must be initialized with a non-null IServiceProvider.");
         }
 
         // ASP.NET Core's AuthorizationMiddleware resolves the IAuthorizationService from scoped request services, so we do the same.

src/ModelContextProtocol.AspNetCore/HttpServerTransportOptions.cs

@@ -20,7 +20,7 @@ public class HttpServerTransportOptions
     /// Gets or sets an optional asynchronous callback for running new MCP sessions manually.
     /// This is useful for running logic before a sessions starts and after it completes.
     /// </summary>
-    public Func<HttpContext, IMcpServer, CancellationToken, Task>? RunSessionHandler { get; set; }
+    public Func<HttpContext, McpServer, CancellationToken, Task>? RunSessionHandler { get; set; }
 
     /// <summary>
     /// Gets or sets whether the server should run in a stateless mode that does not require all requests for a given session

src/ModelContextProtocol.AspNetCore/SseHandler.cs

@@ -53,7 +53,7 @@ internal sealed class SseHandler(
 
             try
             {
-                await using var mcpServer = McpServerFactory.Create(transport, mcpServerOptions, loggerFactory, context.RequestServices);
+                await using var mcpServer = McpServer.Create(transport, mcpServerOptions, loggerFactory, context.RequestServices);
                 context.Features.Set(mcpServer);
 
                 var runSessionAsync = httpMcpServerOptions.Value.RunSessionHandler ?? StreamableHttpHandler.RunSessionAsync;

src/ModelContextProtocol.AspNetCore/StreamableHttpHandler.cs

@@ -232,7 +232,7 @@ internal sealed class StreamableHttpHandler(
             }
         }
 
-        var server = McpServerFactory.Create(transport, mcpServerOptions, loggerFactory, mcpServerServices);
+        var server = McpServer.Create(transport, mcpServerOptions, loggerFactory, mcpServerServices);
         context.Features.Set(server);
 
         var userIdClaim = statelessId?.UserIdClaim ?? GetUserIdClaim(context.User);
@@ -307,7 +307,7 @@ internal sealed class StreamableHttpHandler(
         };
     }
 
-    internal static Task RunSessionAsync(HttpContext httpContext, IMcpServer session, CancellationToken requestAborted)
+    internal static Task RunSessionAsync(HttpContext httpContext, McpServer session, CancellationToken requestAborted)
         => session.RunAsync(requestAborted);
 
     // SignalR only checks for ClaimTypes.NameIdentifier in HttpConnectionDispatcher, but AspNetCore.Antiforgery checks that plus the sub and UPN claims.

src/ModelContextProtocol.AspNetCore/StreamableHttpSession.cs

@@ -7,7 +7,7 @@ namespace ModelContextProtocol.AspNetCore;
 internal sealed class StreamableHttpSession(
     string sessionId,
     StreamableHttpServerTransport transport,
-    IMcpServer server,
+    McpServer server,
     UserIdClaim? userId,
     StatefulSessionManager sessionManager) : IAsyncDisposable
 {
@@ -20,7 +20,7 @@ internal sealed class StreamableHttpSession(
 
     public string Id => sessionId;
     public StreamableHttpServerTransport Transport => transport;
-    public IMcpServer Server => server;
+    public McpServer Server => server;
     private StatefulSessionManager SessionManager => sessionManager;
 
     public CancellationToken SessionClosed => _disposeCts.Token;