diff --git a/tests/domain/sap10_calculator/worksheet/_elmhurst_worksheet_001431_case6.py b/tests/domain/sap10_calculator/worksheet/_elmhurst_worksheet_001431_case6.py
index 0ef2714e..71f19cbf 100644
--- a/tests/domain/sap10_calculator/worksheet/_elmhurst_worksheet_001431_case6.py
+++ b/tests/domain/sap10_calculator/worksheet/_elmhurst_worksheet_001431_case6.py
@@ -23,14 +23,24 @@ This cert surfaced two site-notes gaps fixed in S0380.199:
   already-inclined "Double between 2002 and 2021" → 2.30 (so the
   inclination adjustment isn't double-applied).
 
-SCOPE: this fixture pins only the §3 heat-transmission WINDOW line refs
-(27)/(27a)/(31) — NOT the full SapResult. Case 6 has a DUAL main heating
-system (51% radiators + 49% underfloor, oil), and `SapResult`'s
-`main_heating_fuel_kwh_per_yr` / `pumps_fans_kwh_per_yr` aggregate the
-two systems differently from the worksheet's per-system (211)/(231)
-lines, so a full SapResult pin isn't apples-to-apples. Heating is also
-SAP code 127 here vs 0240's code 130 condensing combi — so case 6 pins
-to its OWN worksheet, not 0240's register.
+SCOPE: promoted to a FULL SapResult e2e fixture (S0380.207) once the dual
+main heating system was fully modelled. Case 6 has Main 1 radiators (51%,
+control 2106) + Main 2 underfloor (49%, control 2110) heating different
+parts. Closing every line ref took: Table 4f note c) two circulation
+pumps (231) S0380.201; Table 5a note a) two pump gains (70) S0380.202;
+RdSAP §3.7 "Roof of Room" rooflights → §3.10.1 RR residual (30) S0380.203;
+SAP 10.2 p.186 two-systems-different-parts MIT — weighted responsiveness
+0.8775 + elsewhere two-control blend — (87)/(90)/(98c) S0380.205 (with
+the Main 2 emitter/control extractor fix S0380.204); and Eq D1 per-boiler
+(204) space share (219) S0380.206. SapResult pins (Block 1 energy rating)
+live in `test_e2e_elmhurst_sap_score.py::_FIXTURE_PINS["001431_case6"]`;
+`main_heating_fuel_kwh_per_yr` is the (211)+(213) two-system sum. Heating
+is SAP code 127 (vs 0240's 130 condensing combi) — case 6 pins to its OWN
+worksheet, the spec authority for this dual-oil archetype.
+
+The §3 window line refs (27)/(27a)/(31), the roof (30), the pumps (231),
+the pump gains (70), the per-system fuel (211)/(213), and HW (219) also
+have dedicated section pins in `test_section_cascade_pins.py`.
 
 Source: user-simulated PDFs at `sap worksheets/golden fixture
 debugging/simulated case 6/`. Summary mirrored into the tracked
diff --git a/tests/domain/sap10_calculator/worksheet/test_e2e_elmhurst_sap_score.py b/tests/domain/sap10_calculator/worksheet/test_e2e_elmhurst_sap_score.py
index 1dbee580..93df288e 100644
--- a/tests/domain/sap10_calculator/worksheet/test_e2e_elmhurst_sap_score.py
+++ b/tests/domain/sap10_calculator/worksheet/test_e2e_elmhurst_sap_score.py
@@ -42,6 +42,7 @@ from tests.domain.sap10_calculator.worksheet import (
     _elmhurst_worksheet_001431_rr8 as _w001431_rr8,
     _elmhurst_worksheet_001431_6035 as _w001431_6035,
     _elmhurst_worksheet_001431_case5 as _w001431_case5,
+    _elmhurst_worksheet_001431_case6 as _w001431_case6,
 )
 from tests.domain.sap10_calculator.worksheet._elmhurst_fixtures import (
     ALL_FIXTURES as _ELMHURST_FIXTURES,
@@ -237,6 +238,27 @@ _FIXTURE_PINS: Final[dict[str, FixtureCascadePins]] = {
         lighting_kwh_per_yr=381.4601,
         pumps_fans_kwh_per_yr=141.0,
     ),
+    # Mapper-driven cohort entry — Summary_001431_case6.pdf → extractor →
+    # mapper → calculator. DETACHED dual-oil cousin of case 5: Main 1
+    # radiators (control 2106) + Main 2 underfloor (control 2110) heating
+    # DIFFERENT parts (51% / 49%), 6 "Roof of Room" rooflights, no boiler
+    # interlock (cyl stat No → −5pp on Main 1). Promoted to a full
+    # SapResult fixture once S0380.201-206 closed every line ref: Table 4f
+    # note c) two-pump electricity (231), Table 5a note a) two-pump gain
+    # (70), §3.7 rooflight→RR-residual (30), SAP 10.2 p.186 two-systems-
+    # different-parts MIT (87)/(90)/(98c), and Eq D1 per-boiler (204)
+    # space share (219). Pins are worksheet Block 1 (energy rating) line
+    # refs; main_heating_fuel_kwh_per_yr is the (211)+(213) two-system sum.
+    "001431_case6": FixtureCascadePins(
+        sap_score=72, sap_score_continuous=71.6597, ecf=2.0316,
+        total_fuel_cost_gbp=1162.5374, co2_kg_per_yr=5953.6679,
+        space_heating_kwh_per_yr=11991.9611,
+        main_heating_fuel_kwh_per_yr=14736.9564,
+        secondary_heating_fuel_kwh_per_yr=0.0,
+        hot_water_kwh_per_yr=4902.8601,
+        lighting_kwh_per_yr=357.6571,
+        pumps_fans_kwh_per_yr=356.0,
+    ),
 }
 
 
@@ -253,6 +275,7 @@ _FIXTURE_MODULES: Final[dict[str, ModuleType]] = {
     "001431_rr8": _w001431_rr8,
     "001431_6035": _w001431_6035,
     "001431_case5": _w001431_case5,
+    "001431_case6": _w001431_case6,
 }