Carry donor's display heating + control into predicted EPC 🟥

_apply_heating_donor copies the donor's calc sap_heating but leaves the
display rows (main_heating, main_heating_controls) on the structural template
— incoherent, and 'Heating Control: Unknown' when the template lodged no
control (predicted property 721167, ADR-0029 follow-up).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/domain/epc_prediction/test_epc_prediction.py

@@ -10,6 +10,7 @@ from typing import Optional, Union
 
 from datatypes.epc.domain.epc_property_data import (
     BuildingPartIdentifier,
+    EnergyElement,
     EpcPropertyData,
     MainHeatingDetail,
     SapBuildingPart,
@@ -51,6 +52,8 @@ def _epc(
     has_hot_water_cylinder: bool = True,
     solar_water_heating: bool = False,
     meter_type: str = "2",
+    main_heating_label: str = "Boiler and radiators, mains gas",
+    main_heating_controls_label: Optional[str] = None,
 ) -> EpcPropertyData:
     epc: EpcPropertyData = object.__new__(EpcPropertyData)
     epc.property_type = "2"
@@ -87,6 +90,22 @@ def _epc(
     heating.cylinder_insulation_type = 1
     heating.secondary_heating_type = None
     epc.sap_heating = heating
+    epc.main_heating = [
+        EnergyElement(
+            description=main_heating_label,
+            energy_efficiency_rating=4,
+            environmental_efficiency_rating=4,
+        )
+    ]
+    epc.main_heating_controls = (
+        EnergyElement(
+            description=main_heating_controls_label,
+            energy_efficiency_rating=4,
+            environmental_efficiency_rating=4,
+        )
+        if main_heating_controls_label is not None
+        else None
+    )
     epc.has_hot_water_cylinder = has_hot_water_cylinder
     epc.solar_water_heating = solar_water_heating
     energy: SapEnergySource = object.__new__(SapEnergySource)
@@ -637,3 +656,32 @@ def test_heating_donor_carries_the_donors_off_peak_meter() -> None:
     donor = _epc(meter_type="Dual", main_fuel_type=29)  # the cohort's heating
     EpcPrediction._apply_heating_donor(predicted, _cohort(donor))
     assert predicted.sap_energy_source.meter_type == "Dual"
+
+
+def test_heating_donor_carries_the_donors_display_heating_and_control() -> None:
+    # The displayed heating panel (Main Heating + Heating Control rows) describes
+    # the same system as the calc cluster, so it must travel with the donor — not
+    # be left on the size-representative structural template. Two failures
+    # otherwise: (1) the displayed heating is incoherent with the donated calc
+    # system, and (2) "Heating Control: Unknown" whenever the template lodged no
+    # control row (the donor's is dropped). Predicted property 721167 (ADR-0029
+    # follow-up): the template carried no main_heating_controls, so its passport
+    # showed Heating Control = Unknown despite a coherent gas-boiler donor.
+    predicted = _epc(
+        main_heating_label="Room heaters, electric",
+        main_heating_controls_label=None,  # template lodged no control
+    )
+    donor = _epc(
+        main_fuel_type=29,
+        main_heating_label="Boiler and radiators, mains gas",
+        main_heating_controls_label="Programmer, room thermostat and TRVs",
+    )
+
+    EpcPrediction._apply_heating_donor(predicted, _cohort(donor))
+
+    assert predicted.main_heating[0].description == "Boiler and radiators, mains gas"
+    assert predicted.main_heating_controls is not None
+    assert (
+        predicted.main_heating_controls.description
+        == "Programmer, room thermostat and TRVs"
+    )