From 163a0410a5a465edcd4b12147a7e9c9ca5c6e784 Mon Sep 17 00:00:00 2001
From: Fabio Kayser <f.kayser@oraylis.de>
Date: Wed, 11 Nov 2026 17:24:58 +0100
Subject: [PATCH] Remove empty parent directories after cleaning their children

---
 docs/backend-contract.md     |  2 ++
 src/datam8/utils/__init__.py |  4 ++--
 tests/test_020_helper.py     | 27 +++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/docs/backend-contract.md b/docs/backend-contract.md
index 63ccac5..29b83a7 100644
--- a/docs/backend-contract.md
+++ b/docs/backend-contract.md
@@ -116,6 +116,8 @@ editor. Runtime configuration changes and process failure may require a restart.
   unrelated files keep their source directories in place.
   Function-directory moves are preflighted and rolled back if
   the model move fails. Saving a deleted folder also removes child functions.
+  Empty directory cleanup checks each directory after removing its children, so
+  a deleted folder does not remain solely because it contained empty subdirectories.
 - Function source paths are relative to their model entity. Absolute/drive-qualified
   paths, traversal, empty segments and symlink escapes are rejected.
 - A bare function filename first resolves beside the entity JSON, then in its
diff --git a/src/datam8/utils/__init__.py b/src/datam8/utils/__init__.py
index 2074401..e0599ad 100644
--- a/src/datam8/utils/__init__.py
+++ b/src/datam8/utils/__init__.py
@@ -139,8 +139,8 @@ def cleanup_directory(path: Path, up_to: Path) -> None:
     """
 
     # remove children
-    for dir_path, dir_names, file_names in path.walk(top_down=False):
-        if len(dir_names) == 0 and len(file_names) == 0:
+    for dir_path, _, _ in path.walk(top_down=False):
+        if not any(dir_path.iterdir()):
             delete_path(dir_path)
 
     # remove empty parents
diff --git a/tests/test_020_helper.py b/tests/test_020_helper.py
index 50deb6c..ef29425 100644
--- a/tests/test_020_helper.py
+++ b/tests/test_020_helper.py
@@ -24,9 +24,36 @@
     UuidCases,
 )
 
+from datam8.utils import cleanup_directory
 from datam8.utils import hasher as hashutils
 
 
+@pytest.mark.parametrize("folder", ["Root", "Core/Nested"])
+def test_cleanup_removes_parent_after_empty_descendants(tmp_path, folder):
+    target = tmp_path / "Model" / folder
+    (target / "Empty" / "Nested").mkdir(parents=True)
+    retained = tmp_path / "Model" / "Neighbour" / "keep.txt"
+    retained.parent.mkdir(parents=True)
+    retained.write_text("keep", encoding="utf-8")
+
+    cleanup_directory(target, tmp_path)
+
+    assert not target.exists()
+    assert retained.read_text(encoding="utf-8") == "keep"
+
+
+def test_cleanup_preserves_directories_with_remaining_files(tmp_path):
+    target = tmp_path / "Model" / "Root"
+    (target / "Empty" / "Nested").mkdir(parents=True)
+    retained = target / "keep.txt"
+    retained.write_text("keep", encoding="utf-8")
+
+    cleanup_directory(target, tmp_path)
+
+    assert not (target / "Empty").exists()
+    assert retained.read_text(encoding="utf-8") == "keep"
+
+
 @parametrize_with_cases("algorithm", cases=AlgorithmCases, glob="*_valid")
 @parametrize_with_cases("input", cases=HashCases, glob="*_valid")
 def test_hasher_hash(input, algorithm):