From 450ecfb9b4aea3915b0dcb1fbfb3f3aafdc3f39d Mon Sep 17 00:00:00 2001
From: Khalim Conn-Kowlessar <kconnkowlessar@gmail.com>
Date: Mon, 29 Jun 2026 22:58:35 +0000
Subject: [PATCH] =?UTF-8?q?Lock=20full-SAP=2016.x=20tariff=20translation?=
 =?UTF-8?q?=20via=20the=20assessment=5Ftype=20gate=20=F0=9F=9F=A9?=
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Confirming regression test for the prime-lead suspicion (SAP-16.x meter
over-rating). A full-SAP-shaped 16.x cert lodges the SAP energy_tariff code
space; the assessment_type=SAP gate routes it to the full-SAP mapper, which
translates the code (1=standard → STANDARD) rather than raw-passing it to the
RdSAP normaliser (where 1="dual" → SEVEN_HOUR, the over-rating bug). No fix
needed — the gate already prevents the drop; this pins that behaviour.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../epc/domain/tests/test_from_sap_schema.py  | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/datatypes/epc/domain/tests/test_from_sap_schema.py b/datatypes/epc/domain/tests/test_from_sap_schema.py
index ec9981009..957cc4a44 100644
--- a/datatypes/epc/domain/tests/test_from_sap_schema.py
+++ b/datatypes/epc/domain/tests/test_from_sap_schema.py
@@ -870,6 +870,27 @@ class TestFullSapSchema16xRouting:
         assert epc.door_count == 1
         assert epc.dwelling_type == "Detached house"
 
+    def test_full_sap_16_x_electricity_tariff_is_translated_not_passed_through(
+        self,
+    ) -> None:
+        # A full-SAP 16.x cert lodges the SAP `energy_tariff` code space, not the
+        # RdSAP `meter_type` one. Routing it through the full-SAP mapper (via the
+        # assessment_type=SAP gate) must apply `_sap_17_1_meter_type`: tariff 1 =
+        # standard → STANDARD. Were it raw-passed to the RdSAP normaliser, code 1
+        # = "dual" → SEVEN_HOUR (the prime-lead over-rating bug this guards).
+        from domain.sap10_calculator.tables.table_12a import (
+            Tariff,
+            tariff_from_meter_type,
+        )
+
+        data = load("sap_16_0_full.json")  # electricity_tariff = 1 (standard)
+
+        epc = EpcPropertyDataMapper.from_api_response(data)
+
+        assert tariff_from_meter_type(epc.sap_energy_source.meter_type) is (
+            Tariff.STANDARD
+        )
+
     def test_reduced_16_x_cert_unaffected_by_full_sap_routing(self) -> None:
         # Arrange — a reduced 16.2 cert (assessment_type RdSAP) must stay on the
         # RdSAP path, keeping its top-level property_type.