(airflow) 01/01: Update the stale cycle-detection comment on SerializedTaskGroup.topological_sort

[pi...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

pierrejeambrun pushed a commit to branch pierrejeambrun/lang-sdk-e2e/cycle-comment-fix
in repository https://gitbox.apache.org/repos/asf/airflow.git

commit db1aa687741a6fda96907a93b6ff7e3bbf6f0619
Author: pierrejeambrun <pi...@gmail.com>
AuthorDate: Fri Oct 2 11:23:33 2026 +0200

    Update the stale cycle-detection comment on SerializedTaskGroup.topological_sort
    
    DAG.check_cycle was the only guard this comment named, but a Lang-SDK Dag
    never runs it: it has no Python DAG object to call it on. The Dag processor
    now rejects a cyclic Lang-SDK Dag of its own accord, through
    DagSerialization.validate_serialized_dag, so the comment should name both
    guards rather than the one that does not cover every author.
---
 airflow-core/src/airflow/serialization/definitions/taskgroup.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/airflow-core/src/airflow/serialization/definitions/taskgroup.py b/airflow-core/src/airflow/serialization/definitions/taskgroup.py
index b82e1c0b933..8e9fe75e6b2 100644
--- a/airflow-core/src/airflow/serialization/definitions/taskgroup.py
+++ b/airflow-core/src/airflow/serialization/definitions/taskgroup.py
@@ -237,9 +237,12 @@ class SerializedTaskGroup(TaskGroupMixin, DAGNode):
         Sort children topologically — a task always comes after its upstream dependencies.
 
         See ``TaskGroup.topological_sort`` in task-sdk for the algorithm. Cycles are
-        treated as corrupt input: ``DAG.check_cycle`` rejects cyclic Dags before
-        serialization, so a cycle reaching this code indicates malformed serialized data,
-        and we raise ``ValueError`` rather than silently looping forever.
+        treated as corrupt input: a Python Dag's cycle is rejected by ``DAG.check_cycle``
+        before serialization, and a Lang-SDK Dag's cycle is rejected by
+        ``DagSerialization.validate_serialized_dag`` when the Dag processor receives it
+        (both call the shared ``detect_cycle``). A cycle reaching this code indicates
+        malformed serialized data, and we raise ``ValueError`` rather than silently
+        looping forever.
         """
         children = self.children
         if not children: