Fix backward compatibility for workloads TaskInstance import (#62714)

Re-export TaskInstance from airflow.executors.workloads as an alias to TaskInstanceDTO so integrations using the legacy import path continue to work. Add a regression test that verifies the alias remains available.

Author: kaxil

airflow-core/src/airflow/executors/workloads/__init__.py

@@ -24,12 +24,23 @@
 
 from airflow.executors.workloads.base import BaseWorkload, BundleInfo
 from airflow.executors.workloads.callback import CallbackFetchMethod, ExecuteCallback
-from airflow.executors.workloads.task import ExecuteTask
+from airflow.executors.workloads.task import ExecuteTask, TaskInstanceDTO
 from airflow.executors.workloads.trigger import RunTrigger
 
 All = Annotated[
     ExecuteTask | ExecuteCallback | RunTrigger,
     Field(discriminator="type"),
 ]
 
-__all__ = ["All", "BaseWorkload", "BundleInfo", "CallbackFetchMethod", "ExecuteCallback", "ExecuteTask"]
+TaskInstance = TaskInstanceDTO
+
+__all__ = [
+    "All",
+    "BaseWorkload",
+    "BundleInfo",
+    "CallbackFetchMethod",
+    "ExecuteCallback",
+    "ExecuteTask",
+    "TaskInstance",
+    "TaskInstanceDTO",
+]

airflow-core/tests/unit/executors/test_workloads.py

@@ -0,0 +1,27 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+from airflow.executors import workloads
+from airflow.executors.workloads import TaskInstance, TaskInstanceDTO
+
+
+def test_task_instance_alias_keeps_backwards_compat():
+    assert TaskInstance is TaskInstanceDTO
+    assert workloads.TaskInstance is TaskInstanceDTO
+    assert workloads.TaskInstanceDTO is TaskInstanceDTO