fix: keep legacy 200/400 codes for older clients in schedule-related endpoints

documentation/changelog.rst

@@ -21,7 +21,7 @@ Bugfixes
 v1.0.0 | August 14, 2026
 ============================
 
-.. warning:: As of this release we standardize asynchronous job responses to use the ``job`` field and return HTTP ``202 Accepted`` while a background job is queued or running. See :ref:`api_background_jobs` for the response format and polling flow. Legacy response fields such as ``schedule`` and ``forecast`` will be deprecated; clients should migrate to ``job`` (see the Infrastructure / Support section below for migration details).
+.. warning:: As of this release we standardize asynchronous job responses to use the ``job`` field and return HTTP ``202 Accepted`` while a background job is queued or running. See :ref:`api_background_jobs` for the response format and polling flow. Legacy response fields such as ``schedule`` and ``forecast`` will be deprecated; clients should migrate to ``job`` (see the Infrastructure / Support section below for migration details). To receive legacy status codes (e.g. for older clients), hosts can use :ref:`legacy-schedule-client-config`.
 
 .. warning:: Upgrading to this version requires running ``flexmeasures db upgrade`` (you can create a backup first with ``flexmeasures db-ops dump``).
 
@@ -87,7 +87,7 @@ Infrastructure / Support
 -------------------------
 
 * Support storing encrypted connection secrets on organisations and assets, including utility functions, encryption key configuration, CLI commands to set and delete secrets, and UI tables that show stored secret names and optional expiration times without exposing their values [see `PR #2236 <https://www.github.com/FlexMeasures/flexmeasures/pull/2236>`_]
-* Standardize job-trigger API responses to return ``202 Accepted`` and a canonical ``job`` field; legacy response fields such as ``schedule`` and ``forecast`` are preserved for backward-compatibility but marked deprecated with migration guidance in :ref:`api_background_jobs` [see `PR #2224 <https://github.com/FlexMeasures/flexmeasures/pull/2224>`_].
+* Standardize job-trigger API responses to return ``202 Accepted`` and a canonical ``job`` field; legacy response fields such as ``schedule`` and ``forecast`` are preserved for backward-compatibility but marked deprecated with migration guidance in :ref:`api_background_jobs` [see `PR #2224 <https://github.com/FlexMeasures/flexmeasures/pull/2224>`_ and `PR #2429 <https://github.com/FlexMeasures/flexmeasures/pull/2429>`_].
 * Warn on startup when ``TRUSTED_HOSTS`` is unset, as that lets clients poison the URLs FlexMeasures generates, such as password reset links; the setting can now also be given as a comma-separated environment variable, and the ``development`` environment trusts loopback hosts by default (so reaching a development server by its LAN address or through a tunnel now means listing that host) [see `PR #2389 <https://www.github.com/FlexMeasures/flexmeasures/pull/2389>`_]
 * Upgraded dependencies [see `PR #1485 <https://www.github.com/FlexMeasures/flexmeasures/pull/1485>`_, `PR #2215 <https://www.github.com/FlexMeasures/flexmeasures/pull/2215>`_, `PR #2243 <https://www.github.com/FlexMeasures/flexmeasures/pull/2243>`_, `PR #2348 <https://www.github.com/FlexMeasures/flexmeasures/pull/2348>`_ and `PR #2388 <https://www.github.com/FlexMeasures/flexmeasures/pull/2388>`_]
 * Add a ``FLEXMEASURES_SENTRY_DAILY_RATE_LIMIT`` setting for spreading a host's Sentry error allowance across the month with a fail-open daily Redis counter, and send the startup error about the database schema not being at the Alembic head revision to Sentry at most once per UTC calendar day per pair of current and expected revisions (it is still logged in full on every start) [see `PR #2366 <https://www.github.com/FlexMeasures/flexmeasures/pull/2366>`_]

documentation/configuration.rst

@@ -1024,6 +1024,31 @@ If ``False``, the API transparently follows the fallback job and returns the fal
 
 Default: ``False``
 
+
+.. _legacy-schedule-client-config:
+
+FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_CLIENT_VERSION_ATTRIBUTE
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Backwards-compatibility switch for scheduling-related endpoints in API v3.
+
+Name of a version-valued asset attribute used to identify clients that still expect schedule trigger requests to return ``HTTP status 200 (OK)`` and unfinished schedule requests to return ``HTTP status 400`` with a message about the scheduling job "waiting to be processed".
+FlexMeasures checks the scheduled asset itself, its parent asset, and its grandparent asset for this attribute.
+When unset, all clients receive the standard ``202 Accepted`` response for accepted trigger requests and unfinished schedule requests.
+
+For example: "v2g-liberty-version"
+
+Default: ``None``
+
+FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_MAX_INCOMPATIBLE_CLIENT_VERSION
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Maximum client version that receives the legacy schedule responses.
+Assets whose configured client-version attribute contains this version or a lower version receive the legacy schedule responses.
+
+Default: ``"0.9.1"``
+
+
 .. _reporters-config:
 
 Reporters

flexmeasures/api/common/responses.py

@@ -387,6 +387,7 @@ def request_accepted_for_processing(
     message: str = "Request has been accepted for processing.",
     legacy_key: str | None = None,
     job_results_url: str | None = None,
+    status_code: int = 202,
 ) -> ResponseTuple:
     """
     Standard 202 response when a background job is accepted.
@@ -414,7 +415,7 @@ def request_accepted_for_processing(
         # keep legacy key for backwards compatibility; not (yet) deprecated, see docstring
         resp[legacy_key] = job_id
 
-    return resp, 202
+    return resp, status_code
 
 
 def request_too_large(message: str) -> ResponseTuple:

flexmeasures/api/common/utils/api_utils.py

@@ -3,6 +3,7 @@
 from copy import deepcopy
 import json
 import re
+from packaging.version import InvalidVersion, Version
 from timely_beliefs.beliefs.classes import BeliefsDataFrame
 from timely_beliefs.sensors.func_store import knowledge_horizons
 from typing import Sequence
@@ -62,6 +63,48 @@ def upsample_values(
     return value_groups
 
 
+def use_legacy_schedule_accepted_status(asset: GenericAsset) -> bool:
+    version_attribute = current_app.config.get(
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_CLIENT_VERSION_ATTRIBUTE"
+    )
+    if not version_attribute:
+        return False
+
+    client_version, attribute_asset = _get_asset_attribute_from_nearby_hierarchy(
+        asset, version_attribute
+    )
+    if client_version is None or attribute_asset is None:
+        return False
+    try:
+        return Version(str(client_version)) <= Version(
+            str(
+                current_app.config[
+                    "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_MAX_INCOMPATIBLE_CLIENT_VERSION"
+                ]
+            )
+        )
+    except InvalidVersion:
+        current_app.logger.warning(
+            "Ignoring invalid schedule client version %r on asset %s.",
+            client_version,
+            attribute_asset.id,
+        )
+        return False
+
+
+def _get_asset_attribute_from_nearby_hierarchy(
+    asset: GenericAsset, attribute: str, max_parent_depth: int = 2
+) -> tuple[object | None, GenericAsset | None]:
+    current_asset = asset
+    for _ in range(max_parent_depth + 1):
+        if attribute in (current_asset.attributes or {}):
+            return current_asset.attributes[attribute], current_asset
+        if current_asset.parent_asset is None:
+            break
+        current_asset = current_asset.parent_asset
+    return None, None
+
+
 def unique_ever_seen(iterable: Sequence, selector: Sequence):
     """
     Return unique iterable elements with corresponding lists of selector elements, preserving order.

flexmeasures/api/v3_0/assets.py

@@ -72,6 +72,7 @@
 from flexmeasures.api.common.utils.api_utils import (
     get_accessible_accounts,
     copy_asset,
+    use_legacy_schedule_accepted_status,
 )
 from flexmeasures.api.common.responses import (
     unprocessable_entity,
@@ -1794,6 +1795,7 @@ def trigger_schedule(
         return request_accepted_for_processing(
             job.id,
             legacy_key="schedule",
+            status_code=200 if use_legacy_schedule_accepted_status(asset) else 202,
         )
 
     @route("/<id>/kpis", methods=["GET"])

flexmeasures/api/v3_0/sensors.py

@@ -41,7 +41,10 @@
 from flexmeasures.api.common.schemas.sensors import SensorId  # noqa F401
 from flexmeasures.api.common.schemas.users import AccountIdField
 from flexmeasures.api.common.rate_limiting import limit_triggers
-from flexmeasures.api.common.utils.api_utils import process_sensor_data_ingestion
+from flexmeasures.api.common.utils.api_utils import (
+    process_sensor_data_ingestion,
+    use_legacy_schedule_accepted_status,
+)
 from flexmeasures.data.services.utils import job_status_description
 from flexmeasures.api.common.utils.deprecation_utils import (
     _add_headers as add_deprecation_header,
@@ -1090,6 +1093,11 @@ def trigger_schedule(
             job_results_url=url_for(
                 "SensorAPI:get_schedule", id=sensor.id, uuid=job.id
             ),
+            status_code=(
+                200
+                if use_legacy_schedule_accepted_status(sensor.generic_asset)
+                else 202
+            ),
         )
 
     # mark endpoint as deprecated
@@ -1326,21 +1334,20 @@ def get_schedule(  # noqa: C901
         elif job.is_failed:
             return unknown_schedule(job_status_description(job, scheduler_info_msg))
         else:
-            if current_app.config.get("FLEXMEASURES_API_SUNSET_ACTIVE"):
-                job_status = job.get_status()
-                job_status_name = (
-                    job_status.upper()
-                    if isinstance(job_status, str)
-                    else job_status.name
-                )
-                return (
-                    dict(
-                        status=job_status_name,
-                        message=job_status_description(job, scheduler_info_msg),
-                    ),
-                    202,
-                )
-            return unknown_schedule(job_status_description(job, scheduler_info_msg))
+            job_status = job.get_status()
+            job_status_name = (
+                job_status.upper() if isinstance(job_status, str) else job_status.name
+            )
+            response = dict(
+                status=job_status_name,
+                message=job_status_description(job, scheduler_info_msg),
+            )
+            if use_legacy_schedule_accepted_status(sensor.generic_asset):
+                return response, 400
+            return (
+                response,
+                202,
+            )
         schedule_start = job.kwargs["start"]
 
         data_source = get_data_source_for_job(job)

flexmeasures/api/v3_0/tests/test_sensor_schedules.py

@@ -12,16 +12,18 @@
     unknown_schedule,
     unrecognized_event,
 )
+from flexmeasures.api.common.utils.api_utils import use_legacy_schedule_accepted_status
 from flexmeasures.api.tests.utils import check_deprecation
 from flexmeasures.api.v3_0.tests.utils import (
     get_sensor_by_name,
     message_for_trigger_schedule,
 )
 from flexmeasures.data.models.data_sources import DataSource
+from flexmeasures.data.models.generic_assets import GenericAsset
 from flexmeasures.data.models.time_series import Sensor
-from flexmeasures.utils.job_utils import work_on_rq
 from flexmeasures.data.services.scheduling import handle_scheduling_exception
 from flexmeasures.tests.utils import get_test_sensor
+from flexmeasures.utils.job_utils import work_on_rq
 from flexmeasures.utils.unit_utils import ur
 
 
@@ -343,18 +345,118 @@ def test_trigger_and_get_schedule_with_unknown_prices(
     assert "prices unknown" in get_schedule_response.json["message"].lower()
 
 
+@pytest.mark.parametrize("version_attribute_level", ["asset", "parent", "grandparent"])
+def test_legacy_schedule_accepted_status_checks_nearby_asset_hierarchy(
+    app,
+    add_battery_assets,
+    monkeypatch,
+    version_attribute_level,
+):
+    battery = add_battery_assets["Test battery"]
+    building = add_battery_assets["Test building"]
+    version_attribute = "flexmeasures-client-version"
+    monkeypatch.setitem(
+        app.config,
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_CLIENT_VERSION_ATTRIBUTE",
+        version_attribute,
+    )
+    monkeypatch.setitem(
+        app.config,
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_MAX_INCOMPATIBLE_CLIENT_VERSION",
+        "0.9.1",
+    )
+    battery.attributes = {
+        key: value
+        for key, value in (battery.attributes or {}).items()
+        if key != version_attribute
+    }
+    building.attributes = {
+        key: value
+        for key, value in (building.attributes or {}).items()
+        if key != version_attribute
+    }
+
+    if version_attribute_level == "asset":
+        battery.attributes = {**(battery.attributes or {}), version_attribute: "0.7.0"}
+    elif version_attribute_level == "parent":
+        building.attributes = {
+            **(building.attributes or {}),
+            version_attribute: "0.7.0",
+        }
+    else:
+        site = GenericAsset(
+            name="schedule client version site",
+            generic_asset_type=building.generic_asset_type,
+            owner=building.owner,
+            attributes={version_attribute: "0.7.0"},
+        )
+        monkeypatch.setattr(building, "parent_asset", site)
+
+    assert use_legacy_schedule_accepted_status(battery)
+
+
+@pytest.mark.parametrize("trigger_endpoint", ["sensor", "asset"])
 @pytest.mark.parametrize(
     "requesting_user", ["test_prosumer_user@seita.nl"], indirect=True
 )
-def test_get_schedule_unfinished_job_returns_202_when_sunset_active(
+def test_trigger_schedule_returns_200_for_legacy_schedule_accepted_status(
     app,
+    db,
     add_battery_assets,
     keep_scheduling_queue_empty,
+    monkeypatch,
     requesting_user,
+    trigger_endpoint,
 ):
     sensor = add_battery_assets["Test battery"].sensors[0]
-    original_sunset_active = app.config.get("FLEXMEASURES_API_SUNSET_ACTIVE")
-    app.config["FLEXMEASURES_API_SUNSET_ACTIVE"] = True
+    version_attribute = "flexmeasures-client-version"
+    monkeypatch.setitem(
+        app.config,
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_CLIENT_VERSION_ATTRIBUTE",
+        version_attribute,
+    )
+    monkeypatch.setitem(
+        app.config,
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_MAX_INCOMPATIBLE_CLIENT_VERSION",
+        "0.9.1",
+    )
+    sensor.generic_asset.attributes = {
+        **(sensor.generic_asset.attributes or {}),
+        version_attribute: "0.7.0",
+    }
+    db.session.commit()
+
+    message = message_for_trigger_schedule()
+    if trigger_endpoint == "asset":
+        message["flex-model"] = [{**message["flex-model"], "sensor": sensor.id}]
+        url = url_for("AssetAPI:trigger_schedule", id=sensor.generic_asset.id)
+    else:
+        url = url_for("SensorAPI:trigger_schedule", id=sensor.id)
+
+    with app.test_client() as client:
+        trigger_schedule_response = client.post(url, json=message)
+
+    assert trigger_schedule_response.status_code == 200
+    assert (
+        trigger_schedule_response.json["job"]
+        == trigger_schedule_response.json["schedule"]
+    )
+    assert len(app.queues["scheduling"]) == 1
+
+
+@pytest.mark.parametrize(
+    "requesting_user", ["test_prosumer_user@seita.nl"], indirect=True
+)
+def test_get_schedule_unfinished_job_returns_202_by_default(
+    app,
+    db,
+    add_battery_assets,
+    keep_scheduling_queue_empty,
+    monkeypatch,
+    requesting_user,
+):
+    sensor = add_battery_assets["Test battery"].sensors[0]
+    monkeypatch.setitem(app.config, "FLEXMEASURES_API_SUNSET_ACTIVE", False)
 
     with app.test_client() as client:
         trigger_schedule_response = client.post(
@@ -372,16 +474,52 @@ def test_get_schedule_unfinished_job_returns_202_when_sunset_active(
     assert get_schedule_response.json["status"] in {"QUEUED", "STARTED", "DEFERRED"}
     assert "message" in get_schedule_response.json
 
-    app.config["FLEXMEASURES_API_SUNSET_ACTIVE"] = False
+    version_attribute = "flexmeasures-client-version"
+    monkeypatch.setitem(
+        app.config,
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_CLIENT_VERSION_ATTRIBUTE",
+        version_attribute,
+    )
+    monkeypatch.setitem(
+        app.config,
+        "FLEXMEASURES_LEGACY_SCHEDULEACCEPTED_STATUS_MAX_INCOMPATIBLE_CLIENT_VERSION",
+        "0.9.1",
+    )
+    sensor.generic_asset.attributes = {
+        **(sensor.generic_asset.attributes or {}),
+        version_attribute: "0.9.1",
+    }
+    db.session.commit()
+
     with app.test_client() as client:
-        get_schedule_response_old = client.get(
+        get_schedule_response_legacy_client = client.get(
             url_for("SensorAPI:get_schedule", id=sensor.id, uuid=job_id),
         )
 
-    app.config["FLEXMEASURES_API_SUNSET_ACTIVE"] = original_sunset_active
+    assert get_schedule_response_legacy_client.status_code == 400
+    # Legacy flexmeasures-client releases retry HTTP 400 responses whose
+    # message contains this exact, long-standing substring.
+    assert (
+        "Scheduling job waiting" in get_schedule_response_legacy_client.json["message"]
+    )
+    assert get_schedule_response_legacy_client.json["status"] in {
+        "QUEUED",
+        "STARTED",
+        "DEFERRED",
+    }
+
+    sensor.generic_asset.attributes = {
+        **(sensor.generic_asset.attributes or {}),
+        version_attribute: "0.9.2",
+    }
+    db.session.commit()
+
+    with app.test_client() as client:
+        get_schedule_response_compatible_client = client.get(
+            url_for("SensorAPI:get_schedule", id=sensor.id, uuid=job_id),
+        )
 
-    assert get_schedule_response_old.status_code == 400
-    assert get_schedule_response_old.json["status"] == unknown_schedule()[0]["status"]
+    assert get_schedule_response_compatible_client.status_code == 202
 
 
 @pytest.mark.parametrize(