Guarantee every measure column on every scenario sheet 🟥

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

tests/domain/scenario_export/test_scenario_sheet.py

@@ -5,6 +5,7 @@ Property, and the Plan's post-works figures."""
 from typing import Optional, Sequence
 
 from domain.scenario_export.scenario_sheet import (
+    MEASURE_COLUMNS,
     ExportMeasure,
     PropertyScenarioData,
     shape_scenario_sheet,
@@ -65,3 +66,23 @@ def test_a_measures_cost_lands_in_its_own_column_with_the_property_identity() ->
     assert row["property_id"] == 42
     assert row["landlord_property_id"] == "LP42"
     assert row["loft_insulation"] == 1200.0
+
+
+def test_every_measure_column_is_present_and_blank_where_the_property_lacks_it() -> None:
+    # arrange — a Property with a single measure. Every other measure column
+    # must still appear on the sheet (the frozen contract, ADR-0065), blank for
+    # this Property, so all scenario sheets share one column set.
+    prop = _property(
+        measures=[_measure(measure_type="cavity_wall_insulation", estimated_cost=800.0)]
+    )
+
+    # act
+    sheet = shape_scenario_sheet([prop])
+
+    # assert — the full frozen measure contract is present; the one selected
+    # measure carries its cost, every other measure column is blank.
+    assert set(MEASURE_COLUMNS).issubset(set(sheet.columns))
+    row = sheet.rows[0]
+    assert row["cavity_wall_insulation"] == 800.0
+    assert row["loft_insulation"] == ""
+    assert row["solar_pv"] == ""