Fix explicit taskbadger_parent=None and __getattr__ recursion

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: snopoke

taskbadger/celery.py

@@ -334,8 +334,9 @@ def _maybe_create_task(signal_sender):
         "external_id": external_id,
         # eager and canvas tasks are created here rather than at publish time, but
         # still run inside whatever task invoked them. An explicit
-        # `taskbadger_parent` wins, as it does at publish time.
-        "parent": header_kwargs.get("parent") or parent_id(),
+        # `taskbadger_parent` wins, as it does at publish time — including an
+        # explicit `None`, which asks for a root task.
+        "parent": header_kwargs["parent"] if "parent" in header_kwargs else parent_id(),
     }
     heartbeat_interval, stale_timeout = resolve_heartbeat_options(
         header_kwargs.get("heartbeat_interval", getattr(signal_sender, TB_HEARTBEAT_INTERVAL, None)),

taskbadger/sdk.py

@@ -554,6 +554,11 @@ def tags(self):
         return self._task.tags.to_dict()
 
     def __getattr__(self, item):
+        if item.startswith("_"):
+            # don't delegate private / dunder lookups: `copy` and `pickle` probe
+            # for e.g. `__setstate__` on an instance that has no `_task` yet,
+            # which would recurse until the stack blows up.
+            raise AttributeError(item)
         return getattr(self._task, item)
 
     def safe_update(self, **kwargs):
@@ -606,6 +611,11 @@ def __len__(self):
         return len(self._results)
 
     def __getattr__(self, item):
+        if item.startswith("_"):
+            # don't delegate private / dunder lookups: `copy` and `pickle` probe
+            # for e.g. `__setstate__` on an instance that has no `_task_list` yet,
+            # which would recurse until the stack blows up.
+            raise AttributeError(item)
         return getattr(self._task_list, item)
 
 

tests/test_parents.py

@@ -5,6 +5,7 @@
 is attached to the same root rather than to the child.
 """
 
+import copy
 import logging
 from unittest import mock
 
@@ -148,6 +149,9 @@ def test_list_tasks_filters_by_parent(httpx_mock):
     assert child.parent == "parent_id"
     assert list(tasks) == tasks.results
     assert len(tasks) == 1
+    # a TaskList must survive copy / pickle: both probe for dunders that
+    # `__getattr__` must not try to delegate
+    assert len(copy.deepcopy(tasks)) == 1
 
 
 @pytest.mark.usefixtures("_bind_settings")
@@ -406,6 +410,26 @@ def test_celery_eager_nests_under_the_running_task():
     assert create.call_args.kwargs["parent"] == "root_id"
 
 
+@pytest.mark.usefixtures("_bind_settings")
+def test_celery_eager_explicit_none_parent_makes_a_root_task():
+    """`taskbadger_parent=None` asks for a root task, as it does at publish time."""
+    add = _celery_app(task_always_eager=True, task_eager_propagates=True)
+
+    with (
+        mock.patch("taskbadger.celery.create_task_safe") as create,
+        mock.patch("taskbadger.celery.update_task_safe"),
+        mock.patch("taskbadger.sdk.get_task"),
+    ):
+        create.return_value = task_for_test()
+        token = enter_task("root_id")
+        try:
+            add.apply_async((2, 2), taskbadger_parent=None)
+        finally:
+            exit_task(token)
+
+    assert create.call_args.kwargs["parent"] is None
+
+
 # --- Procrastinate ------------------------------------------------------------