From ffbef2d0475a2700f32e3a83015c852e69bdebc5 Mon Sep 17 00:00:00 2001
From: Khalim Conn-Kowlessar <kconnkowlessar@gmail.com>
Date: Wed, 1 Jul 2026 13:58:39 +0000
Subject: [PATCH] =?UTF-8?q?Re-map=20house-coal=20water-heating=20overrides?=
 =?UTF-8?q?=20onto=20faithful=20biomass=20and=20immersion=20archetypes=20?=
 =?UTF-8?q?=F0=9F=9F=A5?=
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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 scripts/reclassify_water_heating.py           | 12 ++++
 .../scripts/test_reclassify_water_heating.py  | 68 +++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 scripts/reclassify_water_heating.py
 create mode 100644 tests/scripts/test_reclassify_water_heating.py

diff --git a/scripts/reclassify_water_heating.py b/scripts/reclassify_water_heating.py
new file mode 100644
index 000000000..b79463ad6
--- /dev/null
+++ b/scripts/reclassify_water_heating.py
@@ -0,0 +1,12 @@
+"""One-time re-classification of water-heating overrides funnelled into house coal.
+
+Placeholder — decision function stubbed; filled in GREEN.
+"""
+
+from __future__ import annotations
+
+from collections.abc import Iterable
+
+
+def water_heating_corrections(stored: Iterable[tuple[str, str]]) -> dict[str, str]:
+    raise NotImplementedError
diff --git a/tests/scripts/test_reclassify_water_heating.py b/tests/scripts/test_reclassify_water_heating.py
new file mode 100644
index 000000000..f59e6d200
--- /dev/null
+++ b/tests/scripts/test_reclassify_water_heating.py
@@ -0,0 +1,68 @@
+"""The water-heating reclassify maps the house-coal dumping ground onto faithful
+biomass / wood / dual-fuel / biodiesel / immersion archetypes, leaves genuine coal
+and already-correct rows alone, and is idempotent (#1376 / ADR-0043)."""
+
+from __future__ import annotations
+
+from scripts.reclassify_water_heating import water_heating_corrections
+
+
+def test_house_coal_bucket_rows_are_remapped_to_faithful_fuels() -> None:
+    # Arrange — the biomass/wood family + the "no system / immersion assumed" case
+    # all funnelled into house coal, plus a genuinely-coal row and a correctly-
+    # classified mains-gas row (descriptions arrive lower-cased from the query).
+    stored = [
+        ("from main heating system: wood logs", "From main system, house coal"),
+        (
+            "from main heating system: dual fuel: mineral and wood",
+            "From main system, house coal",
+        ),
+        (
+            "hot-water only community scheme - boilers: biomass (community)",
+            "From main system, house coal",
+        ),
+        (
+            "hot-water only community scheme - boilers: heat from boilers using "
+            "biodiesel from any source (community)",
+            "From main system, house coal",
+        ),
+        (
+            "no hot water system present - electric immersion assumed: "
+            "no heating or hot water",
+            "From main system, house coal",
+        ),
+        # Genuinely coal — stays (guard resolves house coal, value unchanged).
+        ("from main heating system: house coal", "From main system, house coal"),
+        # Already correct — the guard does not claim it.
+        ("from main heating system: mains gas", "From main system, mains gas"),
+    ]
+
+    # Act
+    corrections = water_heating_corrections(stored)
+
+    # Assert — only the mis-scored rows move, each to its faithful archetype.
+    assert corrections == {
+        "from main heating system: wood logs": "From main system, wood logs",
+        "from main heating system: dual fuel: mineral and wood": (
+            "From main system, dual fuel (mineral and wood)"
+        ),
+        "hot-water only community scheme - boilers: biomass (community)": (
+            "From main system, biomass (community)"
+        ),
+        "hot-water only community scheme - boilers: heat from boilers using "
+        "biodiesel from any source (community)": (
+            "From main system, biodiesel (community)"
+        ),
+        "no hot water system present - electric immersion assumed: "
+        "no heating or hot water": "Electric immersion, electricity",
+    }
+
+
+def test_already_corrected_rows_need_no_change() -> None:
+    # Act / Assert — idempotent: a re-run against corrected data is a no-op.
+    assert (
+        water_heating_corrections(
+            [("from main heating system: wood logs", "From main system, wood logs")]
+        )
+        == {}
+    )