Remove support for re-serializing a Serialized Operator

airflow-core/src/airflow/serialization/serialized_objects.py

@@ -717,8 +717,6 @@ def serialize(
 
         :meta private:
         """
-        from airflow.models.mappedoperator import MappedOperator as SchedulerMappedOperator
-
         if cls._is_primitive(var):
             # enum.IntEnum is an int instance, it causes json dumps error so we use its value.
             if isinstance(var, enum.Enum):
@@ -758,9 +756,9 @@ def serialize(
             return cls._encode(DeadlineAlert.serialize_deadline_alert(var), type_=DAT.DEADLINE_ALERT)
         elif isinstance(var, Resources):
             return var.to_dict()
-        elif isinstance(var, (MappedOperator, SchedulerMappedOperator)):
+        elif isinstance(var, MappedOperator):
             return cls._encode(SerializedBaseOperator.serialize_mapped_operator(var), type_=DAT.OP)
-        elif isinstance(var, (BaseOperator, SerializedBaseOperator)):
+        elif isinstance(var, BaseOperator):
             var._needs_expansion = var.get_needs_expansion()
             return cls._encode(SerializedBaseOperator.serialize_operator(var), type_=DAT.OP)
         elif isinstance(var, cls._datetime_types):
@@ -1358,7 +1356,7 @@ def __getattr__(self, name):
         raise AttributeError(f"'{self.task_type}' object has no attribute '{name}'")
 
     @classmethod
-    def serialize_mapped_operator(cls, op: MappedOperator | SchedulerMappedOperator) -> dict[str, Any]:
+    def serialize_mapped_operator(cls, op: MappedOperator) -> dict[str, Any]:
         serialized_op = cls._serialize_node(op)
         # Handle expand_input and op_kwargs_expand_input.
         expansion_kwargs = op._get_specified_expand_input()
@@ -1384,11 +1382,11 @@ def serialize_mapped_operator(cls, op: MappedOperator | SchedulerMappedOperator)
         return serialized_op
 
     @classmethod
-    def serialize_operator(cls, op: SdkOperator | SchedulerOperator) -> dict[str, Any]:
+    def serialize_operator(cls, op: SdkOperator) -> dict[str, Any]:
         return cls._serialize_node(op)
 
     @classmethod
-    def _serialize_node(cls, op: SdkOperator | SchedulerOperator) -> dict[str, Any]:
+    def _serialize_node(cls, op: SdkOperator) -> dict[str, Any]:
         """Serialize operator into a JSON object."""
         serialize_op = cls.serialize_to_json(op, cls._decorated_fields)
 

airflow-core/tests/unit/models/test_cleartasks.py

@@ -713,7 +713,6 @@ def test_clear_task_instances_with_run_on_latest_version(self, run_on_latest_ver
             bundle_version="v2",
         ) as dag:
             EmptyOperator(task_id="0")
-        SerializedDagModel.write_dag(dag=dag, bundle_name="dag_maker", bundle_version="v2")
         new_dag_version = DagVersion.get_latest_version(dag.dag_id)
 
         assert old_dag_version.id != new_dag_version.id

airflow-core/tests/unit/serialization/test_serialized_objects.py

@@ -159,6 +159,16 @@ class Test:
         BaseSerialization.serialize(obj, strict=True)  # now raises
 
 
+def test_prevent_re_serialization_of_serialized_operators():
+    """SerializedBaseOperator should not be re-serializable."""
+    from airflow.serialization.serialized_objects import BaseSerialization, SerializedBaseOperator
+
+    serialized_op = SerializedBaseOperator(task_id="test_task")
+
+    with pytest.raises(SerializationError, match="Encountered unexpected type"):
+        BaseSerialization.serialize(serialized_op, strict=True)
+
+
 def test_validate_schema():
     from airflow.serialization.serialized_objects import BaseSerialization