handler creates one child SubTask per property ID in the batch 🟥

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

applications/modelling_e2e/handler.py

@@ -56,6 +56,7 @@ from domain.property_baseline.calculator_rebaseliner import CalculatorRebaseline
 from domain.sap10_calculator.calculator import Sap10Calculator
 from domain.tasks.tasks import Source
 from harness.console import run_modelling
+from orchestration.task_orchestrator import TaskOrchestrator
 from orchestration.property_baseline_orchestrator import (
     PropertyBaselineOrchestrator,
 )
@@ -97,6 +98,7 @@ from repositories.scenario.scenario_postgres_repository import (
 )
 from repositories.solar.solar_postgres_repository import SolarPostgresRepository
 from utilities.aws_lambda.task_handler import task_handler
+from uuid import UUID
 from utilities.logger import setup_logger
 
 _engine: Optional[Engine] = None
@@ -212,8 +214,8 @@ def _predict_epc(
     return predicted
 
 
-@task_handler(task_source="modelling_e2e", source=Source.PROPERTY)
-def handler(body: dict[str, Any], context: Any) -> Optional[dict[str, Any]]:
+@task_handler(task_source="modelling_e2e", source=Source.PROPERTY, pass_task_orchestrator=True)
+def handler(body: dict[str, Any], context: Any, orchestrator: TaskOrchestrator, task_id: UUID) -> None:
     trigger = ModellingE2ETriggerBody.model_validate(body)
     property_ids = trigger.property_ids
     portfolio_id = trigger.portfolio_id

tests/applications/modelling_e2e/test_handler.py

@@ -8,8 +8,9 @@ is needed. One test per distinct behaviour path.
 from __future__ import annotations
 
 from contextlib import ExitStack
-from typing import Any, Iterator
+from typing import Any, Iterator, Optional
 from unittest.mock import MagicMock, call, patch
+from uuid import UUID, uuid4
 
 import pytest
 from pydantic import ValidationError
@@ -39,10 +40,22 @@ _BODY = {
 }
 
 
-def _call_handler(body: dict[str, Any]) -> Any:
+def _mock_orchestrator() -> MagicMock:
+    mock = MagicMock()
+    mock.run_subtask.side_effect = lambda subtask_id, work, **kwargs: work()
+    child = MagicMock()
+    child.id = uuid4()
+    mock.create_child_subtask.return_value = child
+    return mock
+
+
+def _call_handler(
+    body: dict[str, Any], orchestrator: Optional[MagicMock] = None
+) -> Any:
     from applications.modelling_e2e.handler import handler
 
-    return handler.__wrapped__(body, None)  # type: ignore[attr-defined]
+    orch = orchestrator if orchestrator is not None else _mock_orchestrator()
+    return handler.__wrapped__(body, None, orch, uuid4())  # type: ignore[attr-defined]
 
 
 def _engine_mock(
@@ -122,6 +135,72 @@ def test_trigger_body_rejects_missing_property_ids() -> None:
         )
 
 
+# ---------------------------------------------------------------------------
+# Child SubTask creation
+# ---------------------------------------------------------------------------
+
+
+def test_handler_creates_one_child_subtask_per_property_id() -> None:
+    """Handler creates exactly N child SubTasks, one per property in the batch,
+    each recording its property_id in inputs."""
+    # Arrange
+    pid1, pid2, pid3 = 111, 222, 333
+    mock_engine = _engine_mock(
+        [pid1, pid2, pid3], [1001, 1002, 1003], [POSTCODE, POSTCODE, POSTCODE]
+    )
+    mock_orch = _mock_orchestrator()
+    task_id = uuid4()
+
+    with ExitStack() as stack:
+        stack.enter_context(patch("applications.modelling_e2e.handler.os.environ", _ENV))
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler._get_engine", return_value=mock_engine)
+        )
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler.EpcClientService")
+        ).return_value.get_by_uprn.return_value = MagicMock()
+        stack.enter_context(patch("applications.modelling_e2e.handler.GeospatialS3Repository"))
+        stack.enter_context(patch("applications.modelling_e2e.handler.GoogleSolarApiClient"))
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler._spatial_for", return_value=None)
+        )
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler._solar_insights_for", return_value=None)
+        )
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler.overlays_from", return_value=[])
+        )
+        stack.enter_context(patch("applications.modelling_e2e.handler.PropertyOverridesPostgresReader"))
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler.ScenarioPostgresRepository")
+        ).return_value.get_many.return_value = [MagicMock()]
+        stack.enter_context(patch("applications.modelling_e2e.handler.catalogue_with_off_catalogue_overrides"))
+        stack.enter_context(patch("applications.modelling_e2e.handler.Session"))
+        stack.enter_context(
+            patch("applications.modelling_e2e.handler.run_modelling", return_value=_plan_mock())
+        )
+        MockUoW = stack.enter_context(patch("applications.modelling_e2e.handler.PostgresUnitOfWork"))
+        mock_uow = MagicMock()
+        MockUoW.return_value.__enter__.return_value = mock_uow
+        MockUoW.return_value.__exit__.return_value = False
+
+        # Act
+        from applications.modelling_e2e.handler import handler
+        handler.__wrapped__(  # type: ignore[attr-defined]
+            {"property_ids": [pid1, pid2, pid3], "portfolio_id": PORTFOLIO_ID,
+             "scenario_id": SCENARIO_ID, "no_solar": True, "dry_run": False},
+            None, mock_orch, task_id,
+        )
+
+    # Assert — one child SubTask per property, inputs record the property_id
+    assert mock_orch.create_child_subtask.call_count == 3
+    calls = mock_orch.create_child_subtask.call_args_list
+    recorded_ids = [c.kwargs["inputs"]["property_id"] for c in calls]
+    assert recorded_ids == [pid1, pid2, pid3]
+    # All three calls used the same task_id
+    assert all(c.args[0] == task_id for c in calls)
+
+
 # ---------------------------------------------------------------------------
 # Lodged EPC path
 # ---------------------------------------------------------------------------