feat(epc-prediction): ±1-band age scoring + window_count cosmetic (#1222)

Measurement honesty so we optimise SAP-relevant accuracy, not SAP-neutral
misses (ADR-0030 Component Accuracy):
- Add construction_age_band_pm1: an exact-or-adjacent-band hit. Adjacent
  RdSAP age bands carry near-identical U-values, so an off-by-one is
  ~SAP-neutral. Full corpus: exact 78.5% but ±1-band 91.7% (fixture
  63.9% -> 83.3%) — most age misses are adjacent.
- Drop window_count from the gate's residual ceilings (cosmetic): the
  predicted picture clusters at a mapper-default 4 windows vs actuals 1-21,
  but total_window_area (the SAP-relevant signal) stays tight at ~3.4 m2.

Gate: + construction_age_band_pm1 floor 0.8333; window_count no longer gated.

Closes #1222

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

domain/epc_prediction/prediction_comparison.py

@@ -59,6 +59,32 @@ def _classify(predicted: object, actual: object) -> Optional[bool]:
     return predicted == actual
 
 
+# RdSAP construction age bands, oldest → newest. Adjacent bands carry near-
+# identical U-values, so an off-by-one is treated as a (SAP-neutral) ±1 hit.
+_AGE_BAND_ORDER: str = "ABCDEFGHIJKL"
+
+
+def _age_band_within_one(predicted: object, actual: object) -> Optional[bool]:
+    """A ±1-band age hit: None when the actual is absent, True on an exact or
+    adjacent-band match, else False (issue #1222 — exact match overstates the
+    SAP impact of age-band misses)."""
+    if actual is None:
+        return None
+    if predicted == actual:
+        return True
+    if (
+        isinstance(predicted, str)
+        and isinstance(actual, str)
+        and predicted in _AGE_BAND_ORDER
+        and actual in _AGE_BAND_ORDER
+    ):
+        return (
+            abs(_AGE_BAND_ORDER.index(predicted) - _AGE_BAND_ORDER.index(actual))
+            <= 1
+        )
+    return False
+
+
 def _main_heating_detail(epc: EpcPropertyData) -> Optional[MainHeatingDetail]:
     """The primary heating system's detail row, or None when none is lodged."""
     details = epc.sap_heating.main_heating_details
@@ -179,6 +205,10 @@ def compare_prediction(
             _main(predicted).construction_age_band,
             _main(actual).construction_age_band,
         ),
+        "construction_age_band_pm1": _age_band_within_one(
+            _main(predicted).construction_age_band,
+            _main(actual).construction_age_band,
+        ),
         "roof_construction": _classify(
             _main(predicted).roof_construction,
             _main(actual).roof_construction,

tests/domain/epc_prediction/test_component_accuracy_gate.py

@@ -33,6 +33,7 @@ _RATE_FLOORS: dict[str, float] = {
     "wall_construction": 0.8889,
     "wall_insulation_type": 0.7778,
     "construction_age_band": 0.6389,
+    "construction_age_band_pm1": 0.8333,
     "roof_construction": 0.7222,
     "floor_construction": 0.7500,
     "heating_main_fuel": 0.9722,
@@ -52,9 +53,11 @@ _RATE_FLOORS: dict[str, float] = {
 }
 
 # Maximum mean absolute residual per numeric component (ratchet ceilings).
+# window_count is deliberately excluded — it is cosmetic for SAP (issue #1222):
+# the predicted picture clusters at a mapper-default 4 windows while actuals
+# spread 1-21, yet total_window_area (the SAP-relevant signal) stays tight.
 _RESIDUAL_CEILINGS: dict[str, float] = {
     "floor_area": 12.2175,
-    "window_count": 3.8889,
     "total_window_area": 4.4067,
     "building_parts": 0.3333,
     "door_count": 0.6389,

tests/domain/epc_prediction/test_prediction_comparison.py

@@ -97,6 +97,34 @@ def _epc(
     return epc
 
 
+def test_scores_age_band_within_one_band() -> None:
+    # Arrange — predicted age band K, actual J (adjacent). Adjacent RdSAP age
+    # bands carry near-identical U-values, so an off-by-one is ~SAP-neutral: it
+    # misses the exact hit but counts as a ±1-band hit (issue #1222).
+    predicted = _epc(construction_age_band="K")
+    actual = _epc(construction_age_band="J")
+
+    # Act
+    hits = compare_prediction(predicted, actual).categorical_hits
+
+    # Assert
+    assert hits["construction_age_band"] is False
+    assert hits["construction_age_band_pm1"] is True
+
+
+def test_age_band_two_apart_misses_both() -> None:
+    # Arrange — predicted K, actual H (three bands apart): a real miss on both.
+    predicted = _epc(construction_age_band="K")
+    actual = _epc(construction_age_band="H")
+
+    # Act
+    hits = compare_prediction(predicted, actual).categorical_hits
+
+    # Assert
+    assert hits["construction_age_band"] is False
+    assert hits["construction_age_band_pm1"] is False
+
+
 def test_flags_a_correct_main_wall_construction_classification() -> None:
     # Arrange — predicted and actual agree on cavity (1).
     predicted = _epc(wall_construction=1)