feat(epc): persist renewable_heat_incentive — full round-trip equality (#1137)

Add epc_renewable_heat_incentive table (space_heating_kwh, water_heating_kwh +
the three insulation-impact kWh fields), wired into EpcPostgresRepository
save/get. This is the P0 gap: RenewableHeatIncentive carries the baseline
space-heating/hot-water kWh that EPC Energy Derivation consumes.

The round-trip test now asserts full deep-equality (dropped the
renewable_heat_incentive exclusion) and passes for RdSAP 21.0.0 + 21.0.1.
DB migration for the new table documented in
docs/migrations/epc-property-round-trip-fidelity.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/migrations/epc-property-round-trip-fidelity.md

@@ -44,11 +44,14 @@ and **still require the matching DB migration** wherever the physical tables liv
   `ventilation_has_draught_lobby`, `ventilation_air_permeability_ap4_m3_h_m2`,
   `ventilation_mechanical_ventilation_kind`; `epc_building_part`: `roof_construction_type`,
   `curtain_wall_age`.
+- **§2.1 `epc_renewable_heat_incentive` table** (#1137) — now created on the SQLModel and wired
+  into save/get; the round-trip test asserts **full deep-equality** (no exclusion). DB migration
+  still required.
 
-**Still open (follow-up issues):** §2.1 `epc_renewable_heat_incentive` (P0, #1137 — excluded from the
-slice-1 assertion via `dataclasses.replace(..., renewable_heat_incentive=None)` until landed), and
-the remaining §2 structural tables (room-in-roof detail, PV arrays, roof windows) + §3 nested-wall
-fields (`SapAlternativeWall.u_value`/`wall_thickness_mm`) + `SapFloorDimension` exposed-floor flags.
+**Still open (follow-up issues):** the remaining §2 structural tables (room-in-roof detail, PV
+arrays, roof windows) + §3 nested-wall fields (`SapAlternativeWall.u_value`/`wall_thickness_mm`) +
+`SapFloorDimension` exposed-floor flags — none populated in the 21.0.0/21.0.1 fixtures, so latent
+until a richer fixture exercises them.
 
 ---
 

infrastructure/postgres/epc_property_table.py

@@ -9,6 +9,7 @@ from datatypes.epc.domain.epc_property_data import (
     EpcPropertyData,
     EnergyElement,
     MainHeatingDetail,
+    RenewableHeatIncentive,
     SapBuildingPart,
     SapFloorDimension,
     SapFlatDetails,
@@ -413,6 +414,34 @@ class EpcPropertyEnergyPerformanceModel(SQLModel, table=True):
         )
 
 
+class EpcRenewableHeatIncentiveModel(SQLModel, table=True):
+    __tablename__: ClassVar[str] = "epc_renewable_heat_incentive"  # pyright: ignore[reportIncompatibleVariableOverride]
+
+    id: Optional[int] = Field(default=None, primary_key=True)
+    epc_property_id: int = Field(
+        foreign_key="epc_property.id", nullable=False, unique=True
+    )
+
+    space_heating_kwh: float
+    water_heating_kwh: float
+    impact_of_loft_insulation_kwh: Optional[float] = Field(default=None)
+    impact_of_cavity_insulation_kwh: Optional[float] = Field(default=None)
+    impact_of_solid_wall_insulation_kwh: Optional[float] = Field(default=None)
+
+    @classmethod
+    def from_domain(
+        cls, rhi: RenewableHeatIncentive, epc_property_id: int
+    ) -> EpcRenewableHeatIncentiveModel:
+        return cls(
+            epc_property_id=epc_property_id,
+            space_heating_kwh=rhi.space_heating_kwh,
+            water_heating_kwh=rhi.water_heating_kwh,
+            impact_of_loft_insulation_kwh=rhi.impact_of_loft_insulation_kwh,
+            impact_of_cavity_insulation_kwh=rhi.impact_of_cavity_insulation_kwh,
+            impact_of_solid_wall_insulation_kwh=rhi.impact_of_solid_wall_insulation_kwh,
+        )
+
+
 class EpcFlatDetailsModel(SQLModel, table=True):
     __tablename__: ClassVar[str] = "epc_flat_details"  # pyright: ignore[reportIncompatibleVariableOverride]
 

repositories/epc/epc_postgres_repository.py

@@ -17,6 +17,7 @@ from datatypes.epc.domain.epc_property_data import (
     PhotovoltaicSupplyNoneOrNoDetails,
     PvBatteries,
     PvBattery,
+    RenewableHeatIncentive,
     SapAlternativeWall,
     SapBuildingPart,
     SapEnergySource,
@@ -40,6 +41,7 @@ from infrastructure.postgres.epc_property_table import (
     EpcMainHeatingDetailModel,
     EpcPropertyEnergyPerformanceModel,
     EpcPropertyModel,
+    EpcRenewableHeatIncentiveModel,
     EpcWindowModel,
 )
 from repositories.epc.epc_repository import EpcRepository
@@ -124,6 +126,12 @@ class EpcPostgresRepository(EpcRepository):
             self._session.add(
                 EpcFlatDetailsModel.from_domain(data.sap_flat_details, epc_property_id)
             )
+        if data.renewable_heat_incentive is not None:
+            self._session.add(
+                EpcRenewableHeatIncentiveModel.from_domain(
+                    data.renewable_heat_incentive, epc_property_id
+                )
+            )
         return epc_property_id
 
     def get(self, epc_property_id: int) -> EpcPropertyData:
@@ -161,6 +169,11 @@ class EpcPostgresRepository(EpcRepository):
                 EpcFlatDetailsModel.epc_property_id == epc_property_id
             )
         ).first()
+        rhi_row = self._session.exec(
+            select(EpcRenewableHeatIncentiveModel).where(
+                EpcRenewableHeatIncentiveModel.epc_property_id == epc_property_id
+            )
+        ).first()
 
         def _elements(element_type: str) -> list[EnergyElement]:
             return [self._to_energy_element(e) for e in elements if e.element_type == element_type]
@@ -308,6 +321,17 @@ class EpcPostgresRepository(EpcRepository):
             waste_water_heat_recovery=p.waste_water_heat_recovery,
             hydro=p.hydro,
             photovoltaic_array=p.photovoltaic_array,
+            renewable_heat_incentive=(
+                RenewableHeatIncentive(
+                    space_heating_kwh=rhi_row.space_heating_kwh,
+                    water_heating_kwh=rhi_row.water_heating_kwh,
+                    impact_of_loft_insulation_kwh=rhi_row.impact_of_loft_insulation_kwh,
+                    impact_of_cavity_insulation_kwh=rhi_row.impact_of_cavity_insulation_kwh,
+                    impact_of_solid_wall_insulation_kwh=rhi_row.impact_of_solid_wall_insulation_kwh,
+                )
+                if rhi_row is not None
+                else None
+            ),
             mechanical_vent_duct_insulation_level=p.mechanical_vent_duct_insulation_level,
             addendum=(
                 Addendum(

tests/repositories/epc/test_epc_round_trip.py

@@ -9,7 +9,6 @@ inside First Run, rather than be deferred to a later Refresh.
 
 from __future__ import annotations
 
-import dataclasses
 import json
 from pathlib import Path
 from typing import Any
@@ -48,9 +47,4 @@ def test_epc_property_data_round_trips(schema_dir: str, db_engine: Engine) -> No
         reloaded = EpcPostgresRepository(session).get(epc_property_id)
 
     # Assert
-    # Slice 1 pins round-trip fidelity over the persisted projection. The only
-    # field not yet stored is `renewable_heat_incentive` (the P0 structural gap
-    # tracked in #1137 — a new table); exclude it here and drop this `replace`
-    # once that table lands.
-    projected = dataclasses.replace(original, renewable_heat_incentive=None)
-    assert reloaded == projected
+    assert reloaded == original