diff --git a/backend/packages/harness/deerflow/uploads/manager.py b/backend/packages/harness/deerflow/uploads/manager.py
index 4f3334c62..3b4046d18 100644
--- a/backend/packages/harness/deerflow/uploads/manager.py
+++ b/backend/packages/harness/deerflow/uploads/manager.py
@@ -387,7 +387,12 @@ def delete_file_safe(base_dir: Path, filename: str) -> dict:
     safe_name = normalize_filename(filename)
     if safe_name != filename:
         raise PathTraversalError("Path traversal detected")
-    base_dir = _validate_upload_directory(Path(base_dir))
+    try:
+        base_dir = _validate_upload_directory(Path(base_dir))
+    except UnsafeUploadPathError as exc:
+        if isinstance(exc.__cause__, FileNotFoundError):
+            raise FileNotFoundError(f"File not found: {filename}") from exc
+        raise
     file_path = base_dir / safe_name
     try:
         file_stat = os.lstat(file_path)
diff --git a/backend/tests/test_uploads_manager.py b/backend/tests/test_uploads_manager.py
index 04af37de2..6f2612233 100644
--- a/backend/tests/test_uploads_manager.py
+++ b/backend/tests/test_uploads_manager.py
@@ -362,6 +362,10 @@ class TestDeleteFileSafe:
         with pytest.raises(FileNotFoundError):
             delete_file_safe(tmp_path, "nope.txt")
 
+    def test_delete_from_nonexistent_directory_raises_file_not_found(self, tmp_path):
+        with pytest.raises(FileNotFoundError, match="ghost.txt"):
+            delete_file_safe(tmp_path / "missing-uploads", "ghost.txt")
+
     def test_delete_traversal_raises(self, tmp_path):
         with pytest.raises(PathTraversalError, match="traversal"):
             delete_file_safe(tmp_path, "../outside.txt")