diff --git a/docs/sap-spec/SPEC_COVERAGE.md b/docs/sap-spec/SPEC_COVERAGE.md
index 6c9d01a9..e0a9b737 100644
--- a/docs/sap-spec/SPEC_COVERAGE.md
+++ b/docs/sap-spec/SPEC_COVERAGE.md
@@ -53,12 +53,13 @@ The canonical SAP10.2 algorithm lives in [`2026-05-19-17-18 RdSap10Worksheet.xls
 
 ## Prioritised gap list (by likely MAE impact)
 
-1. **Table 11 Secondary heating allocation** — most boiler-main certs allocate 10% of space heating to a secondary system (often a less-efficient room heater on a different fuel). We model 0%. Likely +1-2 SAP-point bias on affected certs.
-2. **Wind-shelter factor on infiltration** (§2 worksheet lines 19-21) — multiplies infiltration by `1 - 0.075 × sheltered_sides`. We have no shelter input; assume 2 sheltered sides default. Net effect on infiltration ACH probably ~10%.
-3. **Table 12a high-rate fraction for off-peak dwellings** — we currently bill 100% of E7 space heating at the low rate. Real spec says e.g. heat pumps on 7h tariff at 80% high-rate. Affects ~5% of certs.
-4. **Cylinder-loss factor cascade** — currently uses simplified buckets in `domain.ml.demand._STORAGE_LOSS_FACTOR`. Spec has more precise interpolation rules from cylinder volume + insulation thickness.
-5. **Standing charges in cost** — Table 12 note (a) gives the rule for when standing charges are included (energy use vs rating). May affect bias.
-6. **Per-junction thermal bridging (Table R2)** — only relevant when assessor lodged junction-count data, otherwise global y is the spec answer for RdSAP-driven assessments.
+1. **Boiler / heat-pump efficiency Manufacturer override (PCDB integration)** — `MainHeatingDetail` lodges the PCDB pointer (`main_heating_index_number`) but no scalar efficiency. With `NoOpPcdbLookup` (ADR-0009 grill outcome #1) still in place, `cert_to_inputs` falls back to the SAP10 Table 4a category default (typically 0.80 for gas boilers, SCOP 2.30 for heat pumps) on every cert. Per [ADR-0010 §4](../adr/0010-sap10-calculator-spec-target-and-validation.md#4-pcdb-integration-is-promoted-from-session-c-to-a-prerequisite) this accounts for ~19 SAP points of MAE on heat-pump certs and most per-cert variance on the 78 % of gas-boiler certs lodging `main_heating_data_source=1` (PCDB-typical 0.88–0.94 vs 0.80 default). Directly visible on 000490 e2e: `inputs.main_heating_efficiency = 0.80` vs PDF Vaillant Ecotec Pro Manufacturer-declared 0.882 — drives +3 SAP overshoot via the `q_useful / η` cascade in both space heating and HW. Closing requires a real PCDB CSV ingest + `PcdbLookup` Protocol impl + precedence wiring in `cert_to_inputs._main_heating_efficiency` and `_water_efficiency_with_category_inherit`. Promoted to prerequisite under ADR-0010, not a section-sweep slice.
+2. **Table 11 Secondary heating allocation** — most boiler-main certs allocate 10% of space heating to a secondary system (often a less-efficient room heater on a different fuel). We model 0%. Likely +1-2 SAP-point bias on affected certs.
+3. **Wind-shelter factor on infiltration** (§2 worksheet lines 19-21) — multiplies infiltration by `1 - 0.075 × sheltered_sides`. We have no shelter input; assume 2 sheltered sides default. Net effect on infiltration ACH probably ~10%.
+4. **Table 12a high-rate fraction for off-peak dwellings** — we currently bill 100% of E7 space heating at the low rate. Real spec says e.g. heat pumps on 7h tariff at 80% high-rate. Affects ~5% of certs.
+5. **Cylinder-loss factor cascade** — currently uses simplified buckets in `domain.ml.demand._STORAGE_LOSS_FACTOR`. Spec has more precise interpolation rules from cylinder volume + insulation thickness.
+6. **Standing charges in cost** — Table 12 note (a) gives the rule for when standing charges are included (energy use vs rating). May affect bias.
+7. **Per-junction thermal bridging (Table R2)** — only relevant when assessor lodged junction-count data, otherwise global y is the spec answer for RdSAP-driven assessments.
 
 Status now: 100-cert MAE 4.49, 300-cert MAE 5.45, bias near zero (±0.2). Worksheet-driven phase begins with **Secondary heating Table 11** as the next slice.