Classify the landlord Main Fuel column into a fuel category 🟩

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

applications/landlord_description_overrides/handler.py

@@ -8,6 +8,7 @@ from applications.landlord_description_overrides.landlord_description_overrides_
     LandlordDescriptionOverridesTriggerBody,
 )
 from domain.epc.built_form_type import BuiltFormType
+from domain.epc.main_fuel_type import MainFuelType
 from domain.epc.property_type import PropertyType
 from domain.epc.roof_type import RoofType
 from domain.epc.wall_type import WallType
@@ -24,6 +25,9 @@ from infrastructure.postgres.engine import commit_scope, make_engine, make_sessi
 from infrastructure.postgres.landlord_built_form_type_override_table import (
     LandlordBuiltFormTypeOverrideRow,
 )
+from infrastructure.postgres.landlord_main_fuel_override_table import (
+    LandlordMainFuelOverrideRow,
+)
 from infrastructure.postgres.landlord_property_type_override_table import (
     LandlordPropertyTypeOverrideRow,
 )
@@ -102,6 +106,16 @@ def _build_columns(
                 session, LandlordRoofTypeOverrideRow
             ),
         ),
+        "main_fuel": lambda src: ClassifiableColumn(
+            name="main_fuel",
+            source_column=src,
+            classifier=ChatGptColumnClassifier(
+                chat_gpt, MainFuelType, MainFuelType.UNKNOWN
+            ),
+            repo=LandlordOverridesRepository[MainFuelType](
+                session, LandlordMainFuelOverrideRow
+            ),
+        ),
     }
 
     columns: list[ClassifiableColumn[Any]] = []

domain/epc/main_fuel_type.py

@@ -0,0 +1,23 @@
+from enum import Enum
+
+
+class MainFuelType(Enum):
+    """A landlord-supplied main-fuel description, as resolved by the
+    landlord-description-overrides context.
+
+    Each member's value is the canonical fuel description that the main-fuel
+    Simulation Overlay (``domain/epc/property_overlays/main_fuel_overlay.py``)
+    decomposes into the RdSAP ``main_fuel`` int code the calculator reads — so
+    the member values here MUST stay in lock-step with that overlay's
+    ``_FUEL_CODES`` keys. ``UNKNOWN`` covers values the classifier cannot
+    resolve, and also any fuel not yet given a verified overlay code (it leaves
+    the lodged cert's fuel untouched rather than guessing).
+    """
+
+    MAINS_GAS = "mains gas"
+    MAINS_GAS_COMMUNITY = "mains gas (community)"
+    ELECTRICITY = "electricity"
+    LPG_BULK = "LPG (bulk)"
+    OIL = "oil"
+    HOUSE_COAL = "house coal"
+    UNKNOWN = "Unknown"

infrastructure/postgres/landlord_main_fuel_override_table.py

@@ -0,0 +1,69 @@
+"""SQLModel mirror of the ``landlord_main_fuel_overrides`` Drizzle table.
+
+The schema source of truth lives in the ``assessment-model`` TS repo
+(`src/app/db/schema/landlord_overrides.ts`). The migrations are owned there;
+this row class only mirrors the columns so the Python lambda can read/write.
+See ADR-0003. Shape mirrors ``LandlordWallTypeOverrideRow`` -- the only
+differences are the table name, the ``main_fuel`` pgEnum on ``value``, and
+the unique-constraint name.
+"""
+
+from datetime import datetime, timezone
+from typing import ClassVar
+from uuid import UUID, uuid4
+
+from sqlalchemy import BigInteger, Column, UniqueConstraint
+from sqlalchemy import Enum as SAEnum
+from sqlmodel import Field, SQLModel
+
+from domain.epc.main_fuel_type import MainFuelType
+from infrastructure.postgres.landlord_override_enums import override_source_sa_enum
+
+
+class LandlordMainFuelOverrideRow(SQLModel, table=True):
+    __tablename__: ClassVar[str] = "landlord_main_fuel_overrides"  # pyright: ignore[reportIncompatibleVariableOverride]
+    __table_args__: ClassVar[tuple[UniqueConstraint, ...]] = (  # pyright: ignore[reportIncompatibleVariableOverride]
+        UniqueConstraint(
+            "portfolio_id",
+            "description",
+            name="landlord_main_fuel_overrides_portfolio_description_unique",
+        ),
+    )
+
+    id: UUID = Field(default_factory=uuid4, primary_key=True)
+
+    # bigint to match the Drizzle ``portfolio_id`` FK; SQLModel's default int
+    # mapping is 32-bit Integer and would overflow once portfolio IDs exceed
+    # 2^31. The FK to ``portfolio.id`` is enforced by the Drizzle migration,
+    # not declared here -- the ``portfolio`` table is not modelled in Python.
+    portfolio_id: int = Field(
+        sa_column=Column(BigInteger, nullable=False, index=True),
+    )
+
+    description: str = Field(nullable=False)
+
+    value: MainFuelType = Field(
+        sa_column=Column(
+            SAEnum(
+                MainFuelType,
+                name="main_fuel",
+                values_callable=lambda cls: [m.value for m in cls],  # pyright: ignore[reportUnknownLambdaType, reportUnknownMemberType, reportUnknownVariableType]
+            ),
+            nullable=False,
+        ),
+    )
+
+    # Shared SAEnum -- see ``landlord_override_enums`` for why this single
+    # instance is reused by every ``landlord_*_overrides`` row class.
+    source: str = Field(
+        sa_column=Column(override_source_sa_enum, nullable=False),
+    )
+
+    created_at: datetime = Field(
+        default_factory=lambda: datetime.now(timezone.utc),
+        nullable=False,
+    )
+    updated_at: datetime = Field(
+        default_factory=lambda: datetime.now(timezone.utc),
+        nullable=False,
+    )