diff --git a/app/static/js/chat.js b/app/static/js/chat.js
index 9fac14c..256f4f5 100644
--- a/app/static/js/chat.js
+++ b/app/static/js/chat.js
@@ -3,7 +3,7 @@
 
 let chatSessionId = sessionStorage.getItem('chat_session');
 if (!chatSessionId) {
-    chatSessionId = crypto.randomUUID();
+    chatSessionId = 'sess-' + Date.now().toString(36) + '-' + Math.random().toString(36).slice(2, 10);
     sessionStorage.setItem('chat_session', chatSessionId);
 }