diff --git a/src/worker.py b/src/worker.py
index bf344bf..8fe6263 100644
--- a/src/worker.py
+++ b/src/worker.py
@@ -6527,13 +6527,22 @@ async def on_fetch(self, request):
         user_param = (qs.get("user_id") or [None])[0]
         display_param = (qs.get("display_name") or [None])[0]
 
+        allow_anon_raw = getattr(self.env, "ALLOW_ANON_PRESENCE", "true")
+        allow_anon = str(allow_anon_raw).strip().lower() in ("true", "1", "yes")
+
         authenticated_user = verify_token(token_param or "", self.env.JWT_SECRET) if token_param else None
-        can_interact = authenticated_user is not None
 
         if authenticated_user:
             user_id = str(authenticated_user.get("id", ""))
             display_name = str(authenticated_user.get("username") or user_id)
+            can_interact = True
         else:
+            if not allow_anon:
+                return Response(
+                    json.dumps({"error": "Authentication required"}),
+                    status=401,
+                    headers={"Content-Type": "application/json"},
+                )
             if token_param or not user_param:
                 return Response(
                     json.dumps({"error": "Authentication required"}),
@@ -6542,6 +6551,7 @@ async def on_fetch(self, request):
                 )
             user_id = str(user_param)
             display_name = str(display_param or user_id)
+            can_interact = True
 
         user_id = user_id[:64]
         display_name = display_name[:64]