Roll up each Property's SAP points and savings across its measures 🟥

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

tests/domain/scenario_export/test_scenario_sheet.py

@@ -4,6 +4,8 @@ Property, and the Plan's post-works figures."""
 
 from typing import Optional, Sequence
 
+import pytest
+
 from domain.scenario_export.scenario_sheet import (
     MEASURE_COLUMNS,
     ExportMeasure,
@@ -86,3 +88,41 @@ def test_every_measure_column_is_present_and_blank_where_the_property_lacks_it()
     assert row["cavity_wall_insulation"] == 800.0
     assert row["loft_insulation"] == ""
     assert row["solar_pv"] == ""
+
+
+def test_savings_and_sap_points_are_summed_across_a_propertys_measures() -> None:
+    # arrange — two measures, each pivoting to its own cost column and each
+    # contributing SAP points and carbon / energy / bill savings.
+    prop = _property(
+        measures=[
+            _measure(
+                measure_type="loft_insulation",
+                estimated_cost=1000.0,
+                sap_points=3.0,
+                co2_equivalent_savings=0.4,
+                kwh_savings=900.0,
+                energy_cost_savings=120.0,
+            ),
+            _measure(
+                measure_type="solar_pv",
+                estimated_cost=5000.0,
+                sap_points=5.0,
+                co2_equivalent_savings=1.1,
+                kwh_savings=2500.0,
+                energy_cost_savings=300.0,
+            ),
+        ]
+    )
+
+    # act
+    sheet = shape_scenario_sheet([prop])
+
+    # assert — each cost pivots to its own column, and the savings roll up to the
+    # Property's totals.
+    row = sheet.rows[0]
+    assert row["loft_insulation"] == 1000.0
+    assert row["solar_pv"] == 5000.0
+    assert row["sap_points"] == 8.0
+    assert row["co2_equivalent_savings"] == pytest.approx(1.5)
+    assert row["kwh_savings"] == 3400.0
+    assert row["energy_cost_savings"] == 420.0