Fix rescheduled sensors hanging before poke

[hkc-8010]

Rescheduled tasks currently fetch their first task reschedule start date from the supervisor when RuntimeTaskInstance.get_first_reschedule_date() is called. For sensors, this can happen before poke() starts, which means a worker can block on the supervisor/API round trip before emitting the sensor's usual poke log line.

This PR includes the first task reschedule start date in the task instance run context returned by the Execution API. The Task SDK uses that value directly when present, while keeping the existing supervisor request as a compatibility fallback for older API responses.

closes: #68010

Tests:

• breeze testing task-sdk-tests --python 3.10 -- task-sdk/tests/task_sdk/execution_time/test_task_runner.py -k get_first_reschedule_date -q
• breeze testing core-tests --python 3.10 --db-reset -- airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_task_instances.py airflow-core/tests/unit/api_fastapi/execution_api/versions/v2026_06_30/test_task_instances.py -q
• breeze testing core-tests --backend postgres --python 3.10 --db-reset -- airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_task_instances.py airflow-core/tests/unit/api_fastapi/execution_api/versions/v2026_06_30/test_task_instances.py -q
• breeze testing task-sdk-tests --python 3.10
• prek run --files <changed-files>
• prek run --files <changed-files> --stage manual

---

Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-by: OpenAI Codex following the guidelines

---

• Read the Pull Request Guidelines for more information. Note: commit author/co-author name and email in commits become permanently public when merged.
• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
• When adding dependency, check compliance with the ASF 3rd Party License Policy.
• For significant user-facing changes create newsfragment: {pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.

[potiuk]

@hkc-8010 A few things need addressing before review — see our Pull Request quality criteria.

• ❌ Merge conflicts with main. See docs.

No rush.

Note: This comment was drafted by an AI-assisted triage tool and may contain mistakes. Once you have addressed the points above, an Apache Airflow maintainer — a real person — will take the next look at your PR. We use this two-stage triage process so that our maintainers' limited time is spent where it matters most: the conversation with you.

[hkc-8010]

@potiuk thanks for the heads up. I rebased the branch on current main, resolved the conflicts, and force-pushed the updated commit (f3bd4aae0da6ad23a2b06500b6c9354dec140a77).

The local pre-push hooks are passing now, including the supervisor schema snapshot/version checks that caught one missing generated snapshot update during the rebase. GitHub checks have restarted on the updated commit.

Could you please take another look when you get a chance?

[Copilot]

Pull request overview

This PR aims to prevent rescheduled sensors from blocking before poke() by including the first TaskReschedule.start_date in the Execution API’s TIRunContext, and teaching the Task SDK to use that value when present (with a supervisor/API fallback for older server responses).

Changes:

• Add first_task_reschedule_start_date to TIRunContext (core + Task SDK generated models/schema) and expose it from the /execution/task-instances/{id}/run response.
• Update RuntimeTaskInstance.get_first_reschedule_date() to use the server-provided context value before falling back to GetTaskRescheduleStartDate.
• Add/adjust backward-compat and Task SDK tests covering presence/absence of the new field.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
task-sdk/tests/task_sdk/execution_time/test_task_runner.py	Adds a test ensuring the server-provided first reschedule date avoids a supervisor request.
task-sdk/tests/conftest.py	Extends test context factory helpers to support first_task_reschedule_start_date.
task-sdk/src/airflow/sdk/execution_time/task_runner.py	Uses first_task_reschedule_start_date from server context when available.
task-sdk/src/airflow/sdk/execution_time/schema/versions/init.py	Adjusts schema version bundle/lazy import plumbing (currently broken as written).
task-sdk/src/airflow/sdk/execution_time/schema/schema.json	Adds first_task_reschedule_start_date to the Task SDK schema.
task-sdk/src/airflow/sdk/api/datamodels/_generated.py	Regenerates Task SDK datamodels to include first_task_reschedule_start_date.
airflow-core/tests/unit/api_fastapi/execution_api/versions/v2026_06_30/test_task_instances.py	Adds a backward-compat test for stripping the new field for older API versions (currently has duplicated fixture/import block).
airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_task_instances.py	Adds a head-version test asserting the run context includes the first reschedule start date.
airflow-core/src/airflow/api_fastapi/execution_api/versions/v2026_06_30.py	Adds a Cadwyn version change for the new response field.
airflow-core/src/airflow/api_fastapi/execution_api/versions/init.py	Registers the new version change in the 2026-06-30 bundle.
airflow-core/src/airflow/api_fastapi/execution_api/routes/task_instances.py	Populates first_task_reschedule_start_date from TaskReschedule rows during ti_run.
airflow-core/src/airflow/api_fastapi/execution_api/datamodels/taskinstance.py	Adds the new field to the server-side TIRunContext datamodel.

Comments suppressed due to low confidence (1)

airflow-core/tests/unit/api_fastapi/execution_api/versions/v2026_06_30/test_task_instances.py:43

• This file now contains a duplicate old_ver_client fixture plus a second block of repeated imports/pytestmark. The first fixture has no body beyond a docstring, and the redefinition will be flagged by linters (and is easy to miss in review). Remove the duplicate block so there is only one old_ver_client fixture and a single import section.

@pytest.fixture
def old_ver_client(client):
    """Last released execution API before first_task_reschedule_start_date was added."""
import pytest

from airflow._shared.timezones import timezone
from airflow.utils.state import DagRunState, State

from tests_common.test_utils.db import clear_db_runs

pytestmark = pytest.mark.db_test

[nailo2c]

Brilliant! I have a small suggestion that might be helpful :)