diff --git a/gadget-code/src/controllers/api/v1/chat-session.ts b/gadget-code/src/controllers/api/v1/chat-session.ts
index 4d14ef8..51e7a3a 100644
--- a/gadget-code/src/controllers/api/v1/chat-session.ts
+++ b/gadget-code/src/controllers/api/v1/chat-session.ts
@@ -190,8 +190,11 @@ class ChatSessionController extends DtpController {
         allowedUpdates.selectedModel = updates.selectedModel;
       }
       if (updates.mode !== undefined) {
-        allowedUpdates.mode =
-          ChatSessionMode[updates.mode as keyof typeof ChatSessionMode];
+        if (Object.values(ChatSessionMode).includes(updates.mode as ChatSessionMode)) {
+          allowedUpdates.mode = updates.mode as ChatSessionMode;
+        } else {
+          throw new Error(`Invalid mode: ${updates.mode}`);
+        }
       }
 
       const session = await ChatSessionService.update(