From 82ac8c341b04f81110ed25c8e3caf4c491e936b8 Mon Sep 17 00:00:00 2001
From: Khalim Conn-Kowlessar <kconnkowlessar@gmail.com>
Date: Thu, 23 Jul 2026 13:50:13 +0000
Subject: [PATCH] =?UTF-8?q?Compose=20the=20party-ceiling=20and=20sloping-c?=
 =?UTF-8?q?eiling=20roof=20guards=20ahead=20of=20the=20LLM=20=F0=9F=9F=A5?=
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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 domain/epc/property_overrides/roof_guard.py |  9 +++++
 tests/domain/epc/test_roof_guard.py         | 37 +++++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 domain/epc/property_overrides/roof_guard.py
 create mode 100644 tests/domain/epc/test_roof_guard.py

diff --git a/domain/epc/property_overrides/roof_guard.py b/domain/epc/property_overrides/roof_guard.py
new file mode 100644
index 000000000..e3203e950
--- /dev/null
+++ b/domain/epc/property_overrides/roof_guard.py
@@ -0,0 +1,9 @@
+from __future__ import annotations
+
+from typing import Optional
+
+from domain.epc.property_overrides.roof_type import RoofType
+
+
+def roof_guard(description: str) -> Optional[RoofType]:
+    raise NotImplementedError
diff --git a/tests/domain/epc/test_roof_guard.py b/tests/domain/epc/test_roof_guard.py
new file mode 100644
index 000000000..afb86923b
--- /dev/null
+++ b/tests/domain/epc/test_roof_guard.py
@@ -0,0 +1,37 @@
+"""The composed roof guard wired into the roof `GuardedColumnClassifier`.
+
+Two deterministic roof guards compose ahead of the LLM fallback: the
+party-ceiling guard (#1376) and the sloping-ceiling guard (ADR-0066). A roof
+description that neither recognises returns None and reaches the LLM.
+"""
+
+from __future__ import annotations
+
+from domain.epc.property_overrides.roof_guard import roof_guard
+from domain.epc.property_overrides.roof_type import RoofType
+
+
+def test_party_ceiling_marker_resolves_to_its_party_member() -> None:
+    # Act
+    member = roof_guard("another dwelling above")
+
+    # Assert
+    assert member is RoofType.ADJACENT_ANOTHER_DWELLING_ABOVE
+
+
+def test_sloping_ceiling_marker_resolves_to_the_sloping_family() -> None:
+    # Act
+    member = roof_guard("PitchedWithSlopingCeiling: 150mm")
+
+    # Assert
+    assert member is RoofType.PITCHED_SLOPING_CEILING_150MM
+
+
+def test_a_plain_loft_description_is_left_for_the_llm() -> None:
+    # Neither deterministic guard recognises a loft depth, so it reaches the LLM.
+
+    # Act
+    member = roof_guard("Pitched, 150 mm loft insulation")
+
+    # Assert
+    assert member is None