diff --git a/tests/domain/modelling/test_solar_config_selection.py b/tests/domain/modelling/test_solar_config_selection.py
index 01dba8533..eb4f7f757 100644
--- a/tests/domain/modelling/test_solar_config_selection.py
+++ b/tests/domain/modelling/test_solar_config_selection.py
@@ -373,3 +373,20 @@ def test_roof_capped_below_two_panels_still_yields_no_configs() -> None:
 
     # Assert
     assert configs == ()
+
+
+def test_dwelling_roof_cap_bounds_the_sub_ladder_too() -> None:
+    # ADR-0058 — the cap regime is unchanged: when the Dwelling-Roof Cap
+    # (ADR-0038) resolves BELOW the 0.7×Google cap, it bounds the Sub-Ladder
+    # rungs as well — a conflated Google roof can't inflate even a small array.
+
+    # Arrange — max 6 (0.7 cap = 4.2) with Google's ladder starting at 4;
+    # a ~8.5 m² dwelling roof caps at ≈2.5 panels → only the 2-panel rung.
+    potential = _potential_with_panel_dims(max_panels=6, panel_counts=(4,))
+
+    # Act
+    configs = select_conservative_configs(potential, dwelling_roof_area_m2=8.5)
+
+    # Assert — one rung at 2 panels, pro-rata off the 4-panel rung's 400.
+    assert [c.panels_count for c in configs] == [2]
+    assert [c.yearly_energy_dc_kwh for c in configs] == [200.0]