Classify the landlord Age column into a construction-age-band 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.construction_age_band import ConstructionAgeBand
 from domain.epc.glazing_type import GlazingType
 from domain.epc.main_fuel_type import MainFuelType
 from domain.epc.property_type import PropertyType
@@ -26,6 +27,9 @@ 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_construction_age_band_override_table import (
+    LandlordConstructionAgeBandOverrideRow,
+)
 from infrastructure.postgres.landlord_glazing_override_table import (
     LandlordGlazingOverrideRow,
 )
@@ -130,6 +134,16 @@ def _build_columns(
                 session, LandlordGlazingOverrideRow
             ),
         ),
+        "construction_age_band": lambda src: ClassifiableColumn(
+            name="construction_age_band",
+            source_column=src,
+            classifier=ChatGptColumnClassifier(
+                chat_gpt, ConstructionAgeBand, ConstructionAgeBand.UNKNOWN
+            ),
+            repo=LandlordOverridesRepository[ConstructionAgeBand](
+                session, LandlordConstructionAgeBandOverrideRow
+            ),
+        ),
     }
 
     columns: list[ClassifiableColumn[Any]] = []

domain/epc/construction_age_band.py

@@ -0,0 +1,31 @@
+from enum import Enum
+
+
+class ConstructionAgeBand(Enum):
+    """A landlord-supplied construction age band, as resolved by the
+    landlord-description-overrides context.
+
+    Each member's value is the RdSAP England-&-Wales age-band **letter code**
+    (A..M) the calculator's U-value cascades read from
+    `SapBuildingPart.construction_age_band` — the same representation the gov-EPC
+    API lodges. The construction-age-band Simulation Overlay
+    (``domain/epc/property_overlays/construction_age_band_overlay.py``) sets the
+    letter directly, so these values MUST stay the bare letter codes. Member
+    names carry the year ranges for readability. ``UNKNOWN`` covers values the
+    classifier cannot resolve (it leaves the lodged cert's age band untouched).
+    """
+
+    A_BEFORE_1900 = "A"
+    B_1900_1929 = "B"
+    C_1930_1949 = "C"
+    D_1950_1966 = "D"
+    E_1967_1975 = "E"
+    F_1976_1982 = "F"
+    G_1983_1990 = "G"
+    H_1991_1995 = "H"
+    I_1996_2002 = "I"
+    J_2003_2006 = "J"
+    K_2007_2011 = "K"
+    L_2012_2022 = "L"
+    M_2023_ONWARDS = "M"
+    UNKNOWN = "Unknown"

infrastructure/postgres/landlord_construction_age_band_override_table.py

@@ -0,0 +1,69 @@
+"""SQLModel mirror of the ``landlord_construction_age_band_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 ``construction_age_band`` 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.construction_age_band import ConstructionAgeBand
+from infrastructure.postgres.landlord_override_enums import override_source_sa_enum
+
+
+class LandlordConstructionAgeBandOverrideRow(SQLModel, table=True):
+    __tablename__: ClassVar[str] = "landlord_construction_age_band_overrides"  # pyright: ignore[reportIncompatibleVariableOverride]
+    __table_args__: ClassVar[tuple[UniqueConstraint, ...]] = (  # pyright: ignore[reportIncompatibleVariableOverride]
+        UniqueConstraint(
+            "portfolio_id",
+            "description",
+            name="landlord_construction_age_band_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: ConstructionAgeBand = Field(
+        sa_column=Column(
+            SAEnum(
+                ConstructionAgeBand,
+                name="construction_age_band",
+                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,
+    )