Update app.py

app.py

@@ -39,7 +39,7 @@ def navigate(screenshot, task: str, platform: str, history):
         history (list | str | None): Previous messages list. Accepts either an
             actual Python list (via gr.JSON) or a JSON/Python‑literal string.
     """
-
+    global _MODEL, _PROCESSOR 
      # ------- on-demand model / processor load -------------------------
     if _MODEL is None:
         from transformers import BitsAndBytesConfig