Pass request _meta to request handlers extra param

src/shared/protocol.ts

@@ -21,6 +21,7 @@ import {
   RequestId,
   Result,
   ServerCapabilities,
+  RequestMeta,
 } from "../types.js";
 import { Transport, TransportSendOptions } from "./transport.js";
 import { AuthInfo } from "../server/auth/types.js";
@@ -115,6 +116,11 @@ export type RequestHandlerExtra<SendRequestT extends Request,
      */
     sessionId?: string;
 
+    /**
+     * Metadata from the original request.
+     */
+    _meta?: RequestMeta;
+
     /**
      * The JSON-RPC ID of the request being handled.
      * This can be useful for tracking or logging purposes.
@@ -361,6 +367,7 @@ export abstract class Protocol<
     const fullExtra: RequestHandlerExtra<SendRequestT, SendNotificationT> = {
       signal: abortController.signal,
       sessionId: this._transport?.sessionId,
+      _meta: request.params?._meta,
       sendNotification:
         (notification) =>
           this.notification(notification, { relatedRequestId: request.id }),