diff --git a/app/download_manager.py b/app/download_manager.py
index 30f79af..b223cc3 100644
--- a/app/download_manager.py
+++ b/app/download_manager.py
@@ -76,7 +76,7 @@ class DownloadManager:
                 os.remove(task.file_path)
 
     async def delete_task(self, task_id: str):
-        """Completely remove a task from the task list"""
+        """Completely remove a task from the task list (keeps completed files)"""
         task = self.tasks.get(task_id)
         if task:
             # Cancel if downloading
@@ -84,9 +84,10 @@ class DownloadManager:
                 self.active_downloads[task_id].cancel()
                 del self.active_downloads[task_id]
 
-            # Delete file if exists
-            if task.file_path and os.path.exists(task.file_path):
-                os.remove(task.file_path)
+            # Delete partial file ONLY if download is not completed
+            if task.status != DownloadStatus.COMPLETED:
+                if task.file_path and os.path.exists(task.file_path):
+                    os.remove(task.file_path)
 
             # Remove from tasks dict
             del self.tasks[task_id]