Lodge the heat-network SAP code and Table 12 community fuel for PasHub community heating 🟥

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

datatypes/epc/domain/tests/test_from_site_notes.py

@@ -122,6 +122,54 @@ class TestPhotovoltaicArrayMapping:
         assert result.sap_energy_source.photovoltaic_arrays is None
 
 
+class TestCommunityHeatingMapping:
+    """A "Community heating system" dwelling must lodge the Table 4a
+    heat-network SAP code and the Table 12 community fuel — with
+    `sap_main_heating_code=None`, `is_heat_network_main()` is False and the
+    calculator's whole heat-network branch (DLF, £120 standing charge, 80%
+    heat-source efficiency, Table 4c(3) charging) never fires; the dwelling is
+    priced as an ordinary mains-gas boiler (issue #1590 follow-up; fixture
+    507644414148 over-rates +14.3, −8.6 of it from these two fields).
+    """
+
+    def test_community_boilers_lodge_heat_network_code_and_fuel(self) -> None:
+        # Arrange — the cohort's community lodgement (verbatim survey labels).
+        data = load("pashub_rdsap_site_notes_example1.json")
+        mh = data["heating_and_hot_water"]["main_heating"]
+        mh["system_type"] = "Community heating system"
+        mh["community_heat_source"] = "Community heating - boilers only"
+        mh["fuel"] = "Mains Gas"
+        mh["controls"] = (
+            "Charging system linked to use of community heating, room thermostat only"
+        )
+        mh["product_id"] = 0  # heat networks lodge no PCDB boiler
+        survey = from_dict(PasHubRdSapSiteNotes, data)
+
+        # Act
+        main = EpcPropertyDataMapper.from_site_notes(
+            survey
+        ).sap_heating.main_heating_details[0]
+
+        # Assert — Table 4a code 301 (community boilers) routes
+        # is_heat_network_main; Table 12 code 51 (community boilers,
+        # mains gas) prices/factors the heat correctly.
+        assert main.sap_main_heating_code == 301
+        assert main.main_fuel_type == 51
+
+    def test_unknown_heat_source_strict_raises(self) -> None:
+        # Arrange
+        data = load("pashub_rdsap_site_notes_example1.json")
+        mh = data["heating_and_hot_water"]["main_heating"]
+        mh["system_type"] = "Community heating system"
+        mh["community_heat_source"] = "Some novel scheme"
+        mh["controls"] = ""
+        survey = from_dict(PasHubRdSapSiteNotes, data)
+
+        # Act / Assert
+        with pytest.raises(UnmappedPasHubLabel, match="community heat source"):
+            EpcPropertyDataMapper.from_site_notes(survey)
+
+
 class TestRoomInRoofMapping:
     """A surveyed room-in-roof block (RdSAP §3.10 detailed measurement) must
     reach `sap_building_parts[*].sap_room_in_roof` — left None, ~32 m² of

datatypes/epc/surveys/pashub_rdsap_site_notes.py

@@ -202,6 +202,10 @@ class MainHeating:
     weather_compensator: bool
     emitter: str
     emitter_temperature: str
+    # §Heating "Heating System (Other)" — the community heat-source label
+    # (e.g. "Community heating - boilers only") lodged only by heat-network
+    # dwellings; blank elsewhere.
+    community_heat_source: str = ""
 
 
 @dataclass