fix(backend): always cleanup uploaded temp files

backend/Generator/main.py

@@ -20,6 +20,7 @@
 from typing import Any, List, Mapping, Tuple
 import re
 import os
+import uuid
 import fitz 
 import mammoth
 
@@ -368,20 +369,28 @@
             return result.value
 
     def process_file(self, file):
-        file_path = os.path.join(self.upload_folder, file.filename)
-        file.save(file_path)
+        original_filename = os.path.basename(file.filename or "")
+        _, ext = os.path.splitext(original_filename)
+        lower_ext = ext.lower()
+        safe_filename = f"{uuid.uuid4().hex}{lower_ext}"
+        file_path = os.path.join(self.upload_folder, safe_filename)
         content = ""
 
-        if file.filename.endswith('.txt'):
-            with open(file_path, 'r') as f:
-                content = f.read()
-        elif file.filename.endswith('.pdf'):
-            content = self.extract_text_from_pdf(file_path)
-        elif file.filename.endswith('.docx'):
-            content = self.extract_text_from_docx(file_path)
-
-        os.remove(file_path)
-        return content
+        try:
+            file.save(file_path)
+            if lower_ext == '.txt':
+                with open(file_path, 'r') as f:
+                    content = f.read()
+            elif lower_ext == '.pdf':
+                content = self.extract_text_from_pdf(file_path)
+            elif lower_ext == '.docx':
+                content = self.extract_text_from_docx(file_path)
+            return content
+        finally:
+            try:
+                os.remove(file_path)
+            except FileNotFoundError:
+                pass
 
 class QuestionGenerator:
     """A transformer-based NLP system for generating reading comprehension-style questions from