Update app.py

app.py

@@ -55,7 +55,7 @@ def navigate(screenshot, task: str, platform: str, history):
     else:
         messages = history
 
-    if messages is None:
+    if messages is None or len(messages)==0:
         prompt_header = (
             "You are a GUI agent. You are given a task and your action history, with screenshots." 
             " You need to perform the next action to complete the task. \n\n## Output Format\n```\nThought: ...\nAction: ...\n```\n\n## Action Space\n\nclick(start_box='<|box_start|>(x1, y1)<|box_end|>')\nleft_double(start_box='<|box_start|>(x1, y1)<|box_end|>')\nright_single(start_box='<|box_start|>(x1, y1)<|box_end|>')\ndrag(start_box='<|box_start|>(x1, y1)<|box_end|>', end_box='<|box_start|>(x3, y3)<|box_end|>')\nhotkey(key='')\ntype(content='') #If you want to submit your input, use \"\\n\" at the end of `content`.\nscroll(start_box='<|box_start|>(x1, y1)<|box_end|>', direction='down or up or right or left')\nwait() #Sleep for 5s and take a screenshot to check for any changes.\nfinished(content='xxx') # Use escape characters \\', \\\", and \\n in content part to ensure we can parse the content in normal python string format.\n\n\n## Note\n- Use Chinese in `Thought` part.\n- Write a small plan and finally summarize your next action (with its target element) in one sentence in `Thought` part.\n\n"