Thread the off-peak meter flag and high-rate fractions onto SapResult 🟩

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

domain/sap10_calculator/calculator.py

@@ -355,6 +355,21 @@ class CalculatorInputs:
     main_2_heating_fuel_code: Optional[int] = None
     secondary_heating_fuel_code: Optional[int] = None
     hot_water_fuel_code: Optional[int] = None
+    # Off-Peak Meter day/night billing metadata for ADR-0014 Bill Derivation —
+    # output-only (NOT fed into cost / CO2 / PE / sap_score, already priced via
+    # the per-end-use cost factor fields above). `is_off_peak_meter` routes every
+    # electric end use to the off-peak carrier; the per-end-use High-Rate
+    # Fractions (SAP 10.2 Table 12a) drive the day/night split. cert_to_inputs
+    # supplies them from the same Table-12a helpers the cost cascade uses;
+    # defaults (`False` + 1.0) keep synthetic / standard-tariff constructions a
+    # no-op. They thread byte-identical onto `SapResult`.
+    is_off_peak_meter: bool = False
+    main_heating_high_rate_fraction: float = 1.0
+    main_2_heating_high_rate_fraction: float = 1.0
+    secondary_heating_high_rate_fraction: float = 1.0
+    hot_water_high_rate_fraction: float = 1.0
+    pumps_fans_high_rate_fraction: float = 1.0
+    other_electricity_high_rate_fraction: float = 1.0
 
 
 @dataclass(frozen=True)
@@ -875,6 +890,13 @@ def calculate_sap_from_inputs(inputs: CalculatorInputs) -> SapResult:
         primary_energy_kwh_per_m2=primary_energy_per_m2,
         monthly=monthly,
         intermediate=intermediate,
+        is_off_peak_meter=inputs.is_off_peak_meter,
+        main_heating_high_rate_fraction=inputs.main_heating_high_rate_fraction,
+        main_2_heating_high_rate_fraction=inputs.main_2_heating_high_rate_fraction,
+        secondary_heating_high_rate_fraction=inputs.secondary_heating_high_rate_fraction,
+        hot_water_high_rate_fraction=inputs.hot_water_high_rate_fraction,
+        pumps_fans_high_rate_fraction=inputs.pumps_fans_high_rate_fraction,
+        other_electricity_high_rate_fraction=inputs.other_electricity_high_rate_fraction,
     )
 
 

tests/domain/sap10_calculator/test_calculator.py

@@ -165,6 +165,37 @@ def test_fuel_codes_and_pv_export_thread_unchanged_onto_sap_result() -> None:
     assert abs(result.pv_exported_kwh_per_yr - 850.0) <= 1e-9
 
 
+def test_off_peak_meter_flag_and_high_rate_fractions_thread_onto_sap_result() -> None:
+    """The Off-Peak Meter flag + per-end-use High-Rate Fractions surface on
+    SapResult unchanged (ADR-0014). Output-only metadata for Bill Derivation's
+    day/night split — they must thread byte-identical from CalculatorInputs
+    through `calculate_sap_from_inputs` and NOT perturb the SAP cost/score."""
+    # Arrange — an off-peak dwelling: storage heating all-night (0.0), HW immersion
+    # all-night (0.0), other uses 0.90 / pumps 0.71 (7-hour Grid-2 fractions).
+    inputs = replace(
+        _baseline_inputs(),
+        is_off_peak_meter=True,
+        main_heating_high_rate_fraction=0.0,
+        main_2_heating_high_rate_fraction=0.5,
+        secondary_heating_high_rate_fraction=1.0,
+        hot_water_high_rate_fraction=0.0,
+        pumps_fans_high_rate_fraction=0.71,
+        other_electricity_high_rate_fraction=0.90,
+    )
+
+    # Act
+    result = calculate_sap_from_inputs(inputs)
+
+    # Assert — threaded unchanged.
+    assert result.is_off_peak_meter is True
+    assert result.main_heating_high_rate_fraction == 0.0
+    assert result.main_2_heating_high_rate_fraction == 0.5
+    assert result.secondary_heating_high_rate_fraction == 1.0
+    assert result.hot_water_high_rate_fraction == 0.0
+    assert result.pumps_fans_high_rate_fraction == 0.71
+    assert result.other_electricity_high_rate_fraction == 0.90
+
+
 def test_pv_export_collapses_none_input_to_zero_on_sap_result() -> None:
     """`pv_exported_kwh_per_yr` is 0.0 (not None) on SapResult for no-PV.