fix

app/main.py

@@ -20,6 +20,7 @@ middleware = [
 
 app = FastAPI(middleware=middleware)
 
+files_dir = os.path.expanduser("~/wtp_be_files/")
 session_assistant = ChatPDF()
 session_messages = []
 
@@ -37,14 +38,14 @@ def process_input(text: str):
 def upload(files: list[UploadFile]):
     session_assistant.clear()
     session_messages = []
-    files_dir = os.path.expanduser("~/wtp_be_files/")
     
     try:
         os.makedirs(files_dir)
         for file in files:
             try:
+                path = f"{files_dir}/{file.filename}"
                 file.file.seek(0)
-                with Path(files_dir).open("wb") as destination:
+                with open(path, 'wb') as destination:
                     shutil.copyfileobj(file.file, destination)
             finally:
                 file.file.close()