Drag a solid-fuel room heater's coherent room-heater companions 🟥

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

tests/domain/epc/test_main_heating_system_overlay.py

@@ -399,3 +399,23 @@ def test_solid_fuel_room_heater_decodes_to_the_closed_room_heater_code() -> None
     assert simulation is not None
     assert simulation.heating is not None
     assert simulation.heating.sap_main_heating_code == 633
+
+
+def test_solid_fuel_room_heater_drags_its_coherent_room_heater_companions() -> None:
+    # The landlord names the system, not its category/control/meter. A solid-fuel
+    # room heater is a room-heater system (Table 4a category 10) on a single-rate
+    # meter (not off-peak storage), under the conservative room-heater control
+    # real certs lodge (Table 4e Group 6 code 2601 — "no thermostatic control",
+    # the lowest-SAP room-heater control, so it never over-credits an unobserved
+    # control, mirroring the storage manual-charge default). ADR-0035.
+
+    # Act
+    simulation = main_heating_overlay_for("Solid fuel room heater, closed", 0)
+
+    # Assert
+    assert simulation is not None
+    assert simulation.heating is not None
+    heating = simulation.heating
+    assert heating.main_heating_category == 10
+    assert heating.main_heating_control == 2601
+    assert heating.meter_type == "Single"