Load the off-peak day/night rate from the committed snapshot 🟩

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

repositories/fuel_rates/fuel_rates_static_file_repository.py

@@ -5,7 +5,7 @@ from pathlib import Path
 from typing import Any, Optional
 
 from domain.fuel_rates.fuel import Fuel
-from domain.fuel_rates.fuel_rates import FuelRate, FuelRates
+from domain.fuel_rates.fuel_rates import FuelRate, FuelRates, OffPeakRate
 from repositories.fuel_rates.fuel_rates_repository import FuelRatesRepository
 
 _DEFAULT_SNAPSHOT = Path(__file__).parent / "data" / "fuel_rates_2026_q2.json"
@@ -14,10 +14,12 @@ _DEFAULT_SNAPSHOT = Path(__file__).parent / "data" / "fuel_rates_2026_q2.json"
 class FuelRatesStaticFileRepository(FuelRatesRepository):
     """Reads Fuel Rates from a committed JSON snapshot (ADR-0014).
 
-    Only **single-rate** fuels (those lodging a ``unit_rate_p_per_kwh``) are
-    exposed. Off-peak (day/night) and the unpriced gaps (null entries — house
-    coal, heat network) are skipped, so pricing them raises ``UnpricedFuel``.
-    The day/night accessor for off-peak lands in a later slice.
+    **Single-rate** fuels (those lodging a ``unit_rate_p_per_kwh``) populate the
+    ``rates`` map. The **off-peak** entry — a dual-rate meter lodging
+    ``day_p_per_kwh`` / ``night_p_per_kwh`` — loads as an ``OffPeakRate`` (each
+    end use blends day/night by its own High-Rate Fraction). The unpriced gaps
+    (null entries — house coal, heat network) are skipped, so pricing them
+    raises ``UnpricedFuel``.
     """
 
     def __init__(self, snapshot_path: Optional[Path] = None) -> None:
@@ -27,11 +29,19 @@ class FuelRatesStaticFileRepository(FuelRatesRepository):
         payload: dict[str, Any] = json.loads(self._snapshot_path.read_text())
         fuels: dict[str, Any] = payload["fuels"]
         rates: dict[Fuel, FuelRate] = {}
+        off_peak: Optional[OffPeakRate] = None
         for name, entry in fuels.items():
             if entry is None:
                 continue  # an unpriced gap (house coal / heat network)
+            if name == Fuel.ELECTRICITY_OFF_PEAK.name:
+                off_peak = OffPeakRate(
+                    day_p_per_kwh=float(entry["day_p_per_kwh"]),
+                    night_p_per_kwh=float(entry["night_p_per_kwh"]),
+                    standing_charge_p_per_day=float(entry["standing_charge_p_per_day"]),
+                )
+                continue
             if "unit_rate_p_per_kwh" not in entry:
-                continue  # off-peak day/night — priced in a later slice
+                continue  # an unpriced gap with no single rate
             rates[Fuel[name]] = FuelRate(
                 unit_rate_p_per_kwh=float(entry["unit_rate_p_per_kwh"]),
                 standing_charge_p_per_day=float(entry["standing_charge_p_per_day"]),
@@ -40,4 +50,5 @@ class FuelRatesStaticFileRepository(FuelRatesRepository):
             period=str(payload["period"]),
             seg_export_p_per_kwh=float(payload["seg_export_p_per_kwh"]),
             rates=rates,
+            off_peak=off_peak,
         )

tests/repositories/fuel_rates/test_fuel_rates_static_file_repository.py

@@ -55,8 +55,21 @@ def test_dual_fuel_carries_a_derived_midpoint_rate() -> None:
     assert rates.standing_charge_p_per_day(Fuel.DUAL_FUEL_MINERAL_AND_WOOD) == 0.0
 
 
-def test_off_peak_remains_unpriced_pending_the_day_night_accessor() -> None:
-    # Arrange — off-peak still needs the day/night split a later slice adds (ADR-0014).
+def test_off_peak_meter_prices_day_night_from_the_snapshot() -> None:
+    # Arrange — the committed snapshot's off-peak entry carries a day/night
+    # split (ADR-0014 2026-06-24 amendment); the repo loads it as an OffPeakRate.
+    rates = FuelRatesStaticFileRepository().get_current()
+
+    # Act / Assert — an all-night load bills at the night rate, an all-day load
+    # at the day rate, and the off-peak meter carries its own standing charge.
+    assert rates.off_peak_blended_p_per_kwh(high_rate_fraction=0.0) == 13.89
+    assert rates.off_peak_blended_p_per_kwh(high_rate_fraction=1.0) == 29.73
+    assert rates.standing_charge_p_per_day(Fuel.ELECTRICITY_OFF_PEAK) == 56.99
+
+
+def test_off_peak_has_no_single_unit_rate() -> None:
+    # Arrange — off-peak has no single blended unit rate; callers must price it
+    # day/night via a High-Rate Fraction, so unit_rate_p_per_kwh still raises.
     rates = FuelRatesStaticFileRepository().get_current()
 
     # Act / Assert