feat(modelling): wire the lighting generator into the candidate pool

Slice 4 of the lighting generator (ADR-0023): run recommend_lighting in
_candidate_recommendations (no planning gate). Price low_energy_lighting in the
offline catalogue + contingency table (0.26, the legacy rate); the
_GENERATOR_MEASURE_TYPES forcing test enforces both. A run_modelling test pins
the wiring end-to-end (an incandescent-lit dwelling gets the LED upgrade in the
optimised package).

Downstream updates, all because lighting now fires on any cert with non-LED
bulbs: report.py gains the low_energy_lighting trigger (the non-LED counts); the
two golden-cert report tests and the multi-measure integration test now expect
low_energy_lighting alongside the fabric measures (the sample/golden EPCs lodge
low-energy-unknown bulbs); first-run integration seeds a low_energy_lighting
MaterialRow.

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

domain/modelling/contingencies.py

@@ -17,6 +17,7 @@ _CONTINGENCY_RATES: dict[str, float] = {
     "internal_wall_insulation": 0.26,
     "double_glazing": 0.15,
     "secondary_glazing": 0.15,
+    "low_energy_lighting": 0.26,
 }
 
 

harness/report.py

@@ -123,6 +123,17 @@ def _triggers_for(epc: EpcPropertyData, measure_type: str) -> dict[str, Any]:
             else epc.sap_ventilation.mechanical_ventilation_kind
         )
         return {"mechanical_ventilation_kind": kind}
+    if measure_type == "low_energy_lighting":
+        # lighting_recommendation.py fires on any non-LED bulb.
+        return {
+            "incandescent_fixed_lighting_bulbs_count": (
+                epc.incandescent_fixed_lighting_bulbs_count
+            ),
+            "cfl_fixed_lighting_bulbs_count": epc.cfl_fixed_lighting_bulbs_count,
+            "low_energy_fixed_lighting_bulbs_count": (
+                epc.low_energy_fixed_lighting_bulbs_count
+            ),
+        }
     return {}
 
 

harness/sample_catalogue.json

@@ -9,5 +9,6 @@
   "external_wall_insulation": { "unit_cost_per_m2": 100.0 },
   "internal_wall_insulation": { "unit_cost_per_m2": 90.0 },
   "double_glazing": { "unit_cost_per_m2": 600.0 },
-  "secondary_glazing": { "unit_cost_per_m2": 510.0 }
+  "secondary_glazing": { "unit_cost_per_m2": 510.0 },
+  "low_energy_lighting": { "unit_cost_per_m2": 8.0 }
 }

orchestration/modelling_orchestrator.py

@@ -29,6 +29,7 @@ from domain.modelling.scoring.scoring import (
 from domain.modelling.generators.wall_recommendation import recommend_cavity_wall
 from domain.modelling.generators.solid_wall_recommendation import recommend_solid_wall
 from domain.modelling.generators.glazing_recommendation import recommend_glazing
+from domain.modelling.generators.lighting_recommendation import recommend_lighting
 from domain.geospatial.planning_restrictions import PlanningRestrictions
 from domain.sap10_calculator.calculator import SapCalculator
 from repositories.fuel_rates.fuel_rates_repository import FuelRatesRepository
@@ -207,6 +208,7 @@ def _candidate_recommendations(
         recommend_roof_insulation(effective_epc, products),
         recommend_floor_insulation(effective_epc, products),
         recommend_glazing(effective_epc, products, planning_restrictions),
+        recommend_lighting(effective_epc, products),
     )
     return [recommendation for recommendation in found if recommendation is not None]
 

tests/harness/test_console.py

@@ -33,6 +33,7 @@ _GENERATOR_MEASURE_TYPES = (
     "mechanical_ventilation",
     "double_glazing",
     "secondary_glazing",
+    "low_energy_lighting",
 )
 
 
@@ -151,6 +152,30 @@ def test_run_modelling_protected_dwelling_yields_secondary_glazing() -> None:
     # Assert — the picked glazing Measure is secondary, never double.
     measure_types = {measure.measure_type for measure in plan.measures}
     assert "secondary_glazing" in measure_types
+
+
+def _incandescent_lit_epc() -> EpcPropertyData:
+    """The cavity/floor dwelling lit entirely by incandescent bulbs — the
+    lighting generator's trigger, sized so the LED upgrade reaches the package."""
+    epc: EpcPropertyData = _build_uninsulated_cavity_and_floor_epc()
+    epc.led_fixed_lighting_bulbs_count = 0
+    epc.cfl_fixed_lighting_bulbs_count = 0
+    epc.incandescent_fixed_lighting_bulbs_count = 10
+    epc.low_energy_fixed_lighting_bulbs_count = 0
+    return epc
+
+
+def test_run_modelling_recommends_low_energy_lighting_for_non_led_bulbs() -> None:
+    # Arrange — a dwelling lit by incandescent bulbs; the lighting generator is
+    # wired into the candidate pool.
+    epc: EpcPropertyData = _incandescent_lit_epc()
+
+    # Act — Modelling only, no database.
+    plan = run_modelling(epc, goal_band="C", print_table=False)
+
+    # Assert — the LED upgrade reaches the optimised package.
+    measure_types = {measure.measure_type for measure in plan.measures}
+    assert "low_energy_lighting" in measure_types
     assert "double_glazing" not in measure_types
 
 

tests/harness/test_report.py

@@ -82,6 +82,7 @@ def test_each_fired_measure_carries_the_attributes_that_triggered_it() -> None:
         "cavity_wall_insulation",
         "mechanical_ventilation",
         "solid_floor_insulation",
+        "low_energy_lighting",
     }
     # Cavity fill fired because the main wall is an uninsulated cavity.
     assert triggers["cavity_wall_insulation"].triggers == {
@@ -97,22 +98,34 @@ def test_each_fired_measure_carries_the_attributes_that_triggered_it() -> None:
         "floor_insulation_thickness": None,
         "floor_construction_type": "Solid",
     }
+    # The LED upgrade fired because the dwelling lodges 10 low-energy-unknown bulbs.
+    assert triggers["low_energy_lighting"].triggers == {
+        "incandescent_fixed_lighting_bulbs_count": 0,
+        "cfl_fixed_lighting_bulbs_count": None,
+        "low_energy_fixed_lighting_bulbs_count": 10,
+    }
 
 
-def test_single_measure_cert_surfaces_only_that_measures_trigger() -> None:
+def test_few_measure_cert_surfaces_only_its_fired_measures_triggers() -> None:
     # Arrange
     path: Path = _GOLDEN / f"{_WITHIN_TOLERANCE}.json"
 
     # Act
     report: PropertyReport = build_property_report(path)
 
-    # Assert — 0036 fires the solid-floor measure alone.
+    # Assert — 0036 fires solid-floor insulation and the LED upgrade (it lodges
+    # 7 low-energy-unknown bulbs), and nothing else.
     triggers: dict[str, MeasureTrigger] = _triggers_by_measure(report)
-    assert set(triggers) == {"solid_floor_insulation"}
+    assert set(triggers) == {"solid_floor_insulation", "low_energy_lighting"}
     assert triggers["solid_floor_insulation"].triggers == {
         "floor_insulation_thickness": None,
         "floor_construction_type": "Solid",
     }
+    assert triggers["low_energy_lighting"].triggers == {
+        "incandescent_fixed_lighting_bulbs_count": 0,
+        "cfl_fixed_lighting_bulbs_count": None,
+        "low_energy_fixed_lighting_bulbs_count": 7,
+    }
 
 
 def test_cohort_builder_models_each_path_capturing_errors(tmp_path: Path) -> None:

tests/orchestration/test_ara_first_run_pipeline_integration.py

@@ -152,6 +152,14 @@ def test_first_run_baselines_through_repos_and_is_idempotent_on_rerun(
                     is_active=True,
                     description="Double glazing",
                 ),
+                MaterialRow(
+                    id=4,
+                    type="low_energy_lighting",
+                    total_cost=8.0,
+                    cost_unit="gbp_per_unit",
+                    is_active=True,
+                    description="LED bulb",
+                ),
             ]
         )
         session.commit()
@@ -260,6 +268,14 @@ def test_modelling_optimises_and_persists_a_multi_measure_plan(
                     is_active=True,
                     description="Mechanical extract ventilation unit",
                 ),
+                MaterialRow(
+                    id=4,
+                    type="low_energy_lighting",
+                    total_cost=8.0,
+                    cost_unit="gbp_per_unit",
+                    is_active=True,
+                    description="LED bulb",
+                ),
             ]
         )
         session.commit()
@@ -316,6 +332,9 @@ def test_modelling_optimises_and_persists_a_multi_measure_plan(
         "cavity_wall_insulation",
         "suspended_floor_insulation",
         "mechanical_ventilation",
+        # The sample EPC lodges 8 low-energy-unknown bulbs, so the LED upgrade is
+        # a cheap positive-SAP candidate the Optimiser also keeps (ADR-0023).
+        "low_energy_lighting",
     }
     # Each persisted measure carries the catalogue id of the Product it installs
     # (the MaterialRow ids seeded above), replacing the retired
@@ -323,6 +342,7 @@ def test_modelling_optimises_and_persists_a_multi_measure_plan(
     assert by_type["cavity_wall_insulation"].material_id == 1
     assert by_type["suspended_floor_insulation"].material_id == 2
     assert by_type["mechanical_ventilation"].material_id == 3
+    assert by_type["low_energy_lighting"].material_id == 4
     for rec in rec_rows:
         assert rec.default is True
         assert rec.already_installed is False
@@ -411,6 +431,14 @@ def test_modelling_recommends_nothing_when_already_at_the_target_band(
                     is_active=True,
                     description="Mechanical extract ventilation unit",
                 ),
+                MaterialRow(
+                    id=13,
+                    type="low_energy_lighting",
+                    total_cost=8.0,
+                    cost_unit="gbp_per_unit",
+                    is_active=True,
+                    description="LED bulb",
+                ),
             ]
         )
         session.commit()