Normalize RdSAP lighting mapping on the degraded 17.0/19.0 paths

PRD #1385, lighting family. The 17.0 and 19.0 API mappers hardcoded every
fixed-lighting bulb count to 0, dropping the lodged lighting mix that the
reference-complete 17.1/18.0/20.0 paths read. The schema lodges total +
low-energy OUTLET counts (ADR-0028); mirror the reference split — low-energy
outlets → low_energy bulbs, the remainder → incandescent — so the SAP
lighting-energy calc sees the real low-energy credit instead of assuming none.

led/cfl stay 0 (reduced-field certs don't split those); 21.0.x use a different
bulb-based lighting schema and are out of scope. The `total - low_energy`
subtraction is safe: all 37 local 17.0/19.0 fixtures have low_energy <= total
(no negative incandescent), matching the reference paths that already do this
unclamped.

Verification: new test 2 passed; test_mapper_corpus 6002 passed; SAP-accuracy /
RealCertExpectation regressions 56 passed (no pinned shifts); pyright unchanged
(39 -> 39, pre-existing).

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

datatypes/epc/domain/mapper.py

@@ -603,9 +603,18 @@ class EpcPropertyDataMapper:
             insulated_door_count=schema.insulated_door_count,
             draughtproofed_door_count=None,
             percent_draughtproofed=schema.percent_draughtproofed,
+            # ADR-0028: the schema lodges total + low-energy OUTLET counts, not a
+            # bulb split — mirror the 17.1/18.0/20.0 paths (low-energy outlets →
+            # low_energy bulbs; the remainder → incandescent). Hardcoding all
+            # bulb counts to 0 dropped the lodged lighting mix, understating the
+            # low-energy lighting credit in the SAP lighting-energy calc.
             led_fixed_lighting_bulbs_count=0,
             cfl_fixed_lighting_bulbs_count=0,
-            incandescent_fixed_lighting_bulbs_count=0,
+            incandescent_fixed_lighting_bulbs_count=(
+                schema.fixed_lighting_outlets_count
+                - schema.low_energy_fixed_lighting_outlets_count
+            ),
+            low_energy_fixed_lighting_bulbs_count=schema.low_energy_fixed_lighting_outlets_count,
             roofs=EpcPropertyDataMapper._map_energy_elements(schema.roofs),
             walls=EpcPropertyDataMapper._map_energy_elements(schema.walls),
             floors=EpcPropertyDataMapper._map_energy_elements(schema.floors),
@@ -1577,9 +1586,18 @@ class EpcPropertyDataMapper:
             insulated_door_count=schema.insulated_door_count,
             draughtproofed_door_count=None,
             percent_draughtproofed=schema.percent_draughtproofed,
+            # ADR-0028: the schema lodges total + low-energy OUTLET counts, not a
+            # bulb split — mirror the 17.1/18.0/20.0 paths (low-energy outlets →
+            # low_energy bulbs; the remainder → incandescent). Hardcoding all
+            # bulb counts to 0 dropped the lodged lighting mix, understating the
+            # low-energy lighting credit in the SAP lighting-energy calc.
             led_fixed_lighting_bulbs_count=0,
             cfl_fixed_lighting_bulbs_count=0,
-            incandescent_fixed_lighting_bulbs_count=0,
+            incandescent_fixed_lighting_bulbs_count=(
+                schema.fixed_lighting_outlets_count
+                - schema.low_energy_fixed_lighting_outlets_count
+            ),
+            low_energy_fixed_lighting_bulbs_count=schema.low_energy_fixed_lighting_outlets_count,
             roofs=EpcPropertyDataMapper._map_energy_elements(schema.roofs),
             walls=EpcPropertyDataMapper._map_energy_elements(schema.walls),
             floors=EpcPropertyDataMapper._map_energy_elements(schema.floors),

tests/datatypes/epc/domain/test_mapper_lighting_parity.py

@@ -0,0 +1,57 @@
+"""Regression: the degraded RdSAP paths (17.0, 19.0) must carry the lodged
+fixed-lighting outlet counts, like the reference-complete 17.1/18.0/20.0 paths.
+
+PRD #1385 (mapper normalization), lighting family. Both paths hardcoded every
+bulb count to 0, dropping the lodged lighting mix. The schema lodges total +
+low-energy OUTLET counts (ADR-0028); the reference paths split them as
+low-energy → low_energy bulbs and the remainder → incandescent, feeding the SAP
+lighting-energy calc. (21.0.x use a different bulb-based lighting schema and are
+out of scope for this slice.)
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import Any
+
+from datatypes.epc.domain.mapper import EpcPropertyDataMapper
+
+# 17.0 cert: fixed_lighting_outlets_count=10, low_energy=5 → incandescent 5.
+_FIXTURE_17_0 = Path("tests/fixtures/epc_prediction/PE71NT/cert-26619d8e7f8e.json")
+# 19.0 cert: fixed_lighting_outlets_count=8, low_energy=5 → incandescent 3.
+_FIXTURE_19_0 = Path("tests/fixtures/epc_prediction/PE71NT/cert-21b634bc4b59.json")
+
+
+def _load(path: Path, schema_type: str) -> dict[str, Any]:
+    data: dict[str, Any] = json.loads(path.read_text())
+    assert data["schema_type"] == schema_type
+    return data
+
+
+def test_17_0_path_carries_lighting_outlet_counts() -> None:
+    data = _load(_FIXTURE_17_0, "RdSAP-Schema-17.0")
+    assert data["fixed_lighting_outlets_count"] == 10
+    assert data["low_energy_fixed_lighting_outlets_count"] == 5
+
+    epc = EpcPropertyDataMapper.from_api_response(data)
+
+    # Was hardcoded 0/0/0. Low-energy outlets carry through; the remainder is
+    # incandescent; led/cfl stay 0 (reduced-field certs don't split those).
+    assert epc.low_energy_fixed_lighting_bulbs_count == 5
+    assert epc.incandescent_fixed_lighting_bulbs_count == 5
+    assert epc.led_fixed_lighting_bulbs_count == 0
+    assert epc.cfl_fixed_lighting_bulbs_count == 0
+
+
+def test_19_0_path_carries_lighting_outlet_counts() -> None:
+    data = _load(_FIXTURE_19_0, "RdSAP-Schema-19.0")
+    assert data["fixed_lighting_outlets_count"] == 8
+    assert data["low_energy_fixed_lighting_outlets_count"] == 5
+
+    epc = EpcPropertyDataMapper.from_api_response(data)
+
+    assert epc.low_energy_fixed_lighting_bulbs_count == 5
+    assert epc.incandescent_fixed_lighting_bulbs_count == 3
+    assert epc.led_fixed_lighting_bulbs_count == 0
+    assert epc.cfl_fixed_lighting_bulbs_count == 0