fix check to skip session validation for stateless mode

Author: ihrpr

src/server/streamableHttp.test.ts

@@ -288,7 +288,7 @@ describe("StreamableHTTPServerTransport", () => {
     });
   });
 
-  it("should reject requests without a valid session ID", async () => {
+  it.only("should reject requests without a valid session ID", async () => {
     const response = await sendPostRequest(baseUrl, TEST_MESSAGES.toolsList);
 
     expect(response.status).toBe(400);

src/server/streamableHttp.ts

@@ -463,8 +463,8 @@ export class StreamableHTTPServerTransport implements Transport {
    * Returns true if the session is valid, false otherwise
    */
   private validateSession(req: IncomingMessage, res: ServerResponse): boolean {
-    if (this.sessionId === undefined) {
-      // If the session ID is not set, the session management is disabled
+    if (this.sessionIdGenerator === undefined) {
+      // If the sessionIdGenerator ID is not set, the session management is disabled
       // and we don't need to validate the session ID
       return true;
     }