Cohort residual slice 7: PCDB override routes separate_dhw_tests∈{2,3} through Table 3c

Renames `_pcdb_table_3b_combi_loss_override` → `pcdb_combi_loss_override`
(drop the underscore now that it has a unit-testable contract; helper
is now a public boundary of cert_to_inputs). The gate routes on PCDF
Spec Rev 6b field 48:

    = 1 → Table 3b row 1 (profile M only)         — existing
    = 2 → Table 3c row 1 with DVF branch "M+L"    — new (schedules 2+3)
    = 3 → Table 3c row 1 with DVF branch "M+S"    — new (schedules 2+1)
    other / missing factors → None (Table 3a)

Storage-FGHRS (subsidiary_type ∈ {1, 2, 3}) and storage-combi
(store_type ∈ {1, 2, 3}) configurations stay rejected — they gate
Rows 2-5 of both Tables 3b and 3c, deferred until a fixture exercises
them.

Tests (4 new):
  - PCDB 18118 (Vaillant ecoTEC sustain 24, sep_dhw=2) routes through
    Table 3c with M+L. Element-wise match at abs=1e-12 against direct
    Table 3c invocation with the same inputs.
  - PCDB 16952 (Fondital Itaca KC 24, sep_dhw=3 — the M+S branch) routes
    through Table 3c with M+S. No Elmhurst fixture lodges this record;
    borrow 000477's monthly inputs as the deterministic vehicle.
  - PCDB 16839 (sep_dhw=1) preserves the existing Table 3b row 1 path —
    regression guard.
  - Synthetic skeleton record exercises None-returning branches:
    null record, sep_dhw=0, integral FGHRS subsidiary_type=1, primary
    store store_type=1, missing F2.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

packages/domain/src/domain/sap/rdsap/cert_to_inputs.py

@@ -37,7 +37,7 @@ Reference: RdSAP 10 specification (10-06-2025); SAP 10.3 specification
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import Callable, Final, Optional
+from typing import Callable, Final, Literal, Optional
 
 from datatypes.epc.domain.epc_property_data import (
     EpcPropertyData,
@@ -100,6 +100,7 @@ from domain.sap.worksheet.water_heating import (
     TABLE_J1_TCOLD_FROM_MAINS_C,
     WaterHeatingResult,
     combi_loss_monthly_kwh_table_3b_row_1_instantaneous,
+    combi_loss_monthly_kwh_table_3c_two_profile_instantaneous,
     water_efficiency_monthly_via_equation_d1,
     water_heating_from_cert,
 )
@@ -722,38 +723,68 @@ def _has_bath_from_cert(epc: EpcPropertyData) -> bool:
     return n is None or n >= 1
 
 
-def _pcdb_table_3b_combi_loss_override(
+def pcdb_combi_loss_override(
     pcdb_record: Optional[GasOilBoilerRecord],
     *,
     energy_content_monthly_kwh: tuple[float, ...],
     daily_hot_water_monthly_l_per_day: tuple[float, ...],
 ) -> Optional[tuple[float, ...]]:
-    """Build a Table 3b row-1 combi-loss override when the PCDB record
-    lodges single-profile (Profile M only) test data for an instantaneous
-    combi with non-storage FGHRS or without FGHRS. Returns None for
-    every other PCDB combi configuration so the worksheet falls back to
-    the Table 3a default. Other Table 3b/3c rows (storage variants,
-    integral FGHRS, two-profile Table 3c) are deferred until a fixture
-    exercises them — defaulting to Table 3a is safe (matches the pre-
-    §4 behaviour) but loses spec accuracy for those configurations."""
+    """Route a PCDB combi record to the matching SAP10.2 Appendix J row.
+
+    PCDF Spec Rev 6b field 48 (`separate_dhw_tests`) encodes which EN
+    13203-2 / OPS 26 schedules the lab tested under, and that selects
+    the SAP Table:
+      = 1 → schedule 2 only (profile M)           → Table 3b row 1
+      = 2 → schedules 2 and 3 (profiles M + L)    → Table 3c, DVF = M+L
+      = 3 → schedules 2 and 1 (profiles M + S)    → Table 3c, DVF = M+S
+    Any other value (0, None, or insufficient r1/F factors lodged)
+    returns None so the worksheet falls back to the Table 3a default.
+
+    Storage-FGHRS and storage-combi variants (`subsidiary_type` ∈ {1, 2,
+    3} → integral FGHRS / HP+boiler combinations; `store_type` ∈ {1, 2,
+    3} → primary / secondary store / CPSU) gate Rows 2-5 of both Tables
+    3b and 3c. Those rows are deferred until a fixture exercises them
+    — defaulting to Table 3a is safe (matches the pre-§4 behaviour) but
+    loses spec accuracy for those configurations.
+    """
     if pcdb_record is None:
         return None
-    if pcdb_record.separate_dhw_tests != 1:
-        return None
     if pcdb_record.subsidiary_type not in (None, 0):
         return None
     if pcdb_record.store_type not in (None, 0):
         return None
     r1 = pcdb_record.rejected_energy_proportion_r1
-    f1 = pcdb_record.loss_factor_f1_kwh_per_day
-    if r1 is None or f1 is None:
+    if r1 is None:
         return None
-    return combi_loss_monthly_kwh_table_3b_row_1_instantaneous(
-        rejected_energy_proportion_r1=r1,
-        loss_factor_f1_kwh_per_day=f1,
-        energy_content_monthly_kwh=energy_content_monthly_kwh,
-        daily_hot_water_monthly_l_per_day=daily_hot_water_monthly_l_per_day,
-    )
+    match pcdb_record.separate_dhw_tests:
+        case 1:
+            f1 = pcdb_record.loss_factor_f1_kwh_per_day
+            if f1 is None:
+                return None
+            return combi_loss_monthly_kwh_table_3b_row_1_instantaneous(
+                rejected_energy_proportion_r1=r1,
+                loss_factor_f1_kwh_per_day=f1,
+                energy_content_monthly_kwh=energy_content_monthly_kwh,
+                daily_hot_water_monthly_l_per_day=daily_hot_water_monthly_l_per_day,
+            )
+        case 2 | 3:
+            f2 = pcdb_record.loss_factor_f2_kwh_per_day
+            f3 = pcdb_record.rejected_factor_f3_per_litre
+            if f2 is None or f3 is None:
+                return None
+            profile_pair: Literal["M+L", "M+S"] = (
+                "M+L" if pcdb_record.separate_dhw_tests == 2 else "M+S"
+            )
+            return combi_loss_monthly_kwh_table_3c_two_profile_instantaneous(
+                rejected_energy_proportion_r1=r1,
+                loss_factor_f2_kwh_per_day=f2,
+                rejected_factor_f3_per_litre=f3,
+                profile_pair=profile_pair,
+                energy_content_monthly_kwh=energy_content_monthly_kwh,
+                daily_hot_water_monthly_l_per_day=daily_hot_water_monthly_l_per_day,
+            )
+        case _:
+            return None
 
 
 def _water_heating_worksheet_and_gains(
@@ -781,7 +812,7 @@ def _water_heating_worksheet_and_gains(
         cold_water_temps_c=TABLE_J1_TCOLD_FROM_MAINS_C,
         low_water_use=False,
     )
-    combi_loss_override = _pcdb_table_3b_combi_loss_override(
+    combi_loss_override = pcdb_combi_loss_override(
         pcdb_record,
         energy_content_monthly_kwh=bootstrap.energy_content_monthly_kwh,
         daily_hot_water_monthly_l_per_day=bootstrap.daily_hot_water_l_per_day_monthly,

packages/domain/src/domain/sap/rdsap/tests/test_cert_to_inputs.py

@@ -28,7 +28,13 @@ from domain.ml.tests._fixtures import (
     make_window,
 )
 from domain.sap.calculator import Sap10Calculator, SapResult
-from domain.sap.rdsap.cert_to_inputs import cert_to_inputs
+from domain.sap.rdsap.cert_to_inputs import pcdb_combi_loss_override, cert_to_inputs
+from domain.sap.tables.pcdb import GasOilBoilerRecord, gas_oil_boiler_record
+from domain.sap.worksheet.tests import _elmhurst_worksheet_000477 as _w000477
+from domain.sap.worksheet.water_heating import (
+    combi_loss_monthly_kwh_table_3b_row_1_instantaneous,
+    combi_loss_monthly_kwh_table_3c_two_profile_instantaneous,
+)
 
 
 def _gas_boiler_detail(sap_main_heating_code: int = 102) -> MainHeatingDetail:
@@ -720,3 +726,197 @@ def test_detached_house_dwelling_type_keeps_full_envelope_exposed() -> None:
     # Assert
     assert inputs.heat_transmission.floor_w_per_k > 0
     assert inputs.heat_transmission.roof_w_per_k > 0
+
+
+def test_pcdb_combi_loss_override_routes_separate_dhw_tests_2_through_table_3c_m_plus_l() -> None:
+    """PCDF Spec Rev 6b (12 May 2021) field 48 = 2 encodes EN 13203-2 /
+    OPS 26 testing under schedules 2 and 3 = profiles M and L. The
+    override gate must route those PCDB records through SAP10.2 Appendix
+    J Table 3c with the M+L DVF branch — not the existing Table 3b row
+    1 path (which is profile M only)."""
+    # Arrange — PCDB 18118 (Vaillant ecoTEC sustain 24) lodges
+    # separate_dhw_tests=2, r1=0.015, F2=0.0, F3=0.00014; 000477 ships
+    # the matching (44)m / (45)m worksheet inputs.
+    pcdb = gas_oil_boiler_record(18118)
+    assert pcdb is not None
+    assert pcdb.separate_dhw_tests == 2
+    energy_content = _w000477.LINE_45_M_HW_ENERGY_CONTENT_KWH
+    daily_hw = _w000477.LINE_44_M_DAILY_HW_USAGE_L
+
+    # Act
+    override = pcdb_combi_loss_override(
+        pcdb,
+        energy_content_monthly_kwh=energy_content,
+        daily_hot_water_monthly_l_per_day=daily_hw,
+    )
+
+    # Assert — override is exactly the Table 3c M+L output (no
+    # double-rounding, no transposed F1↔F2). Element-wise.
+    expected = combi_loss_monthly_kwh_table_3c_two_profile_instantaneous(
+        rejected_energy_proportion_r1=0.015,
+        loss_factor_f2_kwh_per_day=0.0,
+        rejected_factor_f3_per_litre=0.00014,
+        profile_pair="M+L",
+        energy_content_monthly_kwh=energy_content,
+        daily_hot_water_monthly_l_per_day=daily_hw,
+    )
+    assert override is not None
+    for month_idx, (got, want) in enumerate(zip(override, expected)):
+        assert got == pytest.approx(want, abs=1e-12), (
+            f"month {month_idx}: got {got!r}, want {want!r}"
+        )
+
+
+def test_pcdb_combi_loss_override_routes_separate_dhw_tests_3_through_table_3c_m_plus_s() -> None:
+    """PCDF Spec Rev 6b field 48 = 3 encodes EN 13203-2 / OPS 26 testing
+    under schedules 2 and 1 = profiles M and S. The override gate must
+    route those PCDB records through Table 3c with the M+S DVF branch.
+    """
+    # Arrange — PCDB 16952 (Fondital Itaca KC 24) is one of the three
+    # boilers in pcdb10.dat with separate_dhw_tests=3. Borrow 000477's
+    # monthly inputs purely as a deterministic vehicle for the formula —
+    # there is no Elmhurst fixture lodging this PCDB record.
+    pcdb = gas_oil_boiler_record(16952)
+    assert pcdb is not None
+    assert pcdb.separate_dhw_tests == 3
+    energy_content = _w000477.LINE_45_M_HW_ENERGY_CONTENT_KWH
+    daily_hw = _w000477.LINE_44_M_DAILY_HW_USAGE_L
+
+    # Act
+    override = pcdb_combi_loss_override(
+        pcdb,
+        energy_content_monthly_kwh=energy_content,
+        daily_hot_water_monthly_l_per_day=daily_hw,
+    )
+
+    # Assert — override matches Table 3c with profile_pair="M+S".
+    assert pcdb.rejected_energy_proportion_r1 is not None
+    assert pcdb.loss_factor_f2_kwh_per_day is not None
+    assert pcdb.rejected_factor_f3_per_litre is not None
+    expected = combi_loss_monthly_kwh_table_3c_two_profile_instantaneous(
+        rejected_energy_proportion_r1=pcdb.rejected_energy_proportion_r1,
+        loss_factor_f2_kwh_per_day=pcdb.loss_factor_f2_kwh_per_day,
+        rejected_factor_f3_per_litre=pcdb.rejected_factor_f3_per_litre,
+        profile_pair="M+S",
+        energy_content_monthly_kwh=energy_content,
+        daily_hot_water_monthly_l_per_day=daily_hw,
+    )
+    assert override is not None
+    for month_idx, (got, want) in enumerate(zip(override, expected)):
+        assert got == pytest.approx(want, abs=1e-12), (
+            f"month {month_idx}: got {got!r}, want {want!r}"
+        )
+
+
+def test_pcdb_combi_loss_override_preserves_separate_dhw_tests_1_routing_to_table_3b() -> None:
+    """Regression guard: separate_dhw_tests=1 (profile M only) must
+    continue to route through Table 3b row 1 — same path that closes
+    000474 to delta=0 today. The Slice 6+7 Table 3c work must not
+    perturb this branch."""
+    # Arrange — PCDB 16839 (Vaillant ecoTEC pro 28, used by 000474).
+    pcdb = gas_oil_boiler_record(16839)
+    assert pcdb is not None
+    assert pcdb.separate_dhw_tests == 1
+    energy_content = _w000477.LINE_45_M_HW_ENERGY_CONTENT_KWH
+    daily_hw = _w000477.LINE_44_M_DAILY_HW_USAGE_L
+
+    # Act
+    override = pcdb_combi_loss_override(
+        pcdb,
+        energy_content_monthly_kwh=energy_content,
+        daily_hot_water_monthly_l_per_day=daily_hw,
+    )
+
+    # Assert — override matches Table 3b row 1.
+    assert pcdb.rejected_energy_proportion_r1 is not None
+    assert pcdb.loss_factor_f1_kwh_per_day is not None
+    expected = combi_loss_monthly_kwh_table_3b_row_1_instantaneous(
+        rejected_energy_proportion_r1=pcdb.rejected_energy_proportion_r1,
+        loss_factor_f1_kwh_per_day=pcdb.loss_factor_f1_kwh_per_day,
+        energy_content_monthly_kwh=energy_content,
+        daily_hot_water_monthly_l_per_day=daily_hw,
+    )
+    assert override is not None
+    for month_idx, (got, want) in enumerate(zip(override, expected)):
+        assert got == pytest.approx(want, abs=1e-12), (
+            f"month {month_idx}: got {got!r}, want {want!r}"
+        )
+
+
+def test_pcdb_combi_loss_override_returns_none_for_untested_or_storage_combis() -> None:
+    """The override gate returns None — letting the worksheet fall back
+    to Table 3a — whenever the PCDB record is missing test data (field
+    48 ∈ {0, None}), lodges insufficient lab factors, or sits in a
+    storage / FGHRS row (Table 3b/3c rows 2-5, deferred until a fixture
+    exercises them)."""
+    # Arrange — a minimal record skeleton, mutated per scenario via
+    # dataclasses.replace.
+    from dataclasses import replace
+
+    energy_content = _w000477.LINE_45_M_HW_ENERGY_CONTENT_KWH
+    daily_hw = _w000477.LINE_44_M_DAILY_HW_USAGE_L
+    base = GasOilBoilerRecord(
+        pcdb_id=99999,
+        brand_name="X",
+        model_name="Y",
+        model_qualifier="",
+        winter_efficiency_pct=88.0,
+        summer_efficiency_pct=80.0,
+        comparative_hot_water_efficiency_pct=75.0,
+        output_kw_max=24.0,
+        final_year_of_manufacture=None,
+        subsidiary_type=0,
+        store_type=0,
+        separate_dhw_tests=2,
+        rejected_energy_proportion_r1=0.015,
+        loss_factor_f1_kwh_per_day=0.5,
+        loss_factor_f2_kwh_per_day=0.001,
+        rejected_factor_f3_per_litre=0.00014,
+        raw=(),
+    )
+
+    # Act / Assert — None record → None.
+    assert (
+        pcdb_combi_loss_override(
+            None,
+            energy_content_monthly_kwh=energy_content,
+            daily_hot_water_monthly_l_per_day=daily_hw,
+        )
+        is None
+    )
+    # separate_dhw_tests=0 → None (no PCDB test data).
+    assert (
+        pcdb_combi_loss_override(
+            replace(base, separate_dhw_tests=0),
+            energy_content_monthly_kwh=energy_content,
+            daily_hot_water_monthly_l_per_day=daily_hw,
+        )
+        is None
+    )
+    # Integral FGHRS (subsidiary_type=1) → row 2/3 deferred → None.
+    assert (
+        pcdb_combi_loss_override(
+            replace(base, subsidiary_type=1),
+            energy_content_monthly_kwh=energy_content,
+            daily_hot_water_monthly_l_per_day=daily_hw,
+        )
+        is None
+    )
+    # Storage combi (store_type=1 primary store) → row 4/5 deferred → None.
+    assert (
+        pcdb_combi_loss_override(
+            replace(base, store_type=1),
+            energy_content_monthly_kwh=energy_content,
+            daily_hot_water_monthly_l_per_day=daily_hw,
+        )
+        is None
+    )
+    # separate_dhw_tests=2 with F2 missing → insufficient lab data → None.
+    assert (
+        pcdb_combi_loss_override(
+            replace(base, loss_factor_f2_kwh_per_day=None),
+            energy_content_monthly_kwh=energy_content,
+            daily_hot_water_monthly_l_per_day=daily_hw,
+        )
+        is None
+    )

packages/domain/src/domain/sap/worksheet/water_heating.py

@@ -399,7 +399,7 @@ def combi_loss_monthly_kwh_table_3c_two_profile_instantaneous(
 
     Storage-FGHRS / storage-combi variants (Table 3c rows 2-5) are
     deferred until a fixture exercises them — mirrors the row-1-only
-    coverage of Table 3b (see `_pcdb_combi_loss_override`).
+    coverage of Table 3b (see `pcdb_combi_loss_override`).
     """
     return tuple(
         e