Add sessionIdGenerator config (#121)

* add sessionIdGenerator config

* Changeset

---------

Co-authored-by: Andrew Qu <qual1337@gmail.com>

Author: chulkilee

.changeset/wide-points-search.md

@@ -0,0 +1,5 @@
+---
+"mcp-handler": patch
+---
+
+Allow passing in sessionIdGenerator for stateful sessions

src/handler/mcp-api-handler.ts

@@ -126,6 +126,11 @@ export type Config = {
    * @default false
    */
   disableSse?: boolean;
+
+  /**
+   * sessionIdGenerator for the streamable HTTP transport
+   */
+  sessionIdGenerator?: undefined;
 };
 
 /**
@@ -248,6 +253,7 @@ export function initializeMcpApiHandler(
     maxDuration,
     verboseLogs,
     disableSse,
+    sessionIdGenerator,
   } = config;
 
   const {
@@ -273,7 +279,7 @@ export function initializeMcpApiHandler(
 
   let statelessServer: McpServer;
   const statelessTransport = new StreamableHTTPServerTransport({
-    sessionIdGenerator: undefined,
+    sessionIdGenerator: sessionIdGenerator,
   });
 
   // Start periodic cleanup if not already running