Phase-2 candidates are valued against the post-fabric dwelling 🟩

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

domain/modelling/optimisation/optimiser.py

@@ -272,7 +272,7 @@ def optimise_package_fabric_first(
         None if budget is None else budget - _package_cost(fabric_package.selected)
     )
     top_up: OptimisedPackage = optimise_package(
-        groups=remaining_groups,
+        groups=_rescored_groups(remaining_groups, post_fabric_scorer, baseline_epc),
         scorer=post_fabric_scorer,
         baseline_epc=baseline_epc,
         budget=leftover_budget,
@@ -293,6 +293,31 @@ def _is_fabric_group(group: list[ScoredOption]) -> bool:
     )
 
 
+def _rescored_groups(
+    groups: list[list[ScoredOption]],
+    scorer: Scorer,
+    baseline_epc: EpcPropertyData,
+) -> list[list[ScoredOption]]:
+    """The groups with every Option's role-1 warm-start signal re-scored
+    through ``scorer`` — for phase 2, its independent gain on the post-fabric
+    dwelling rather than the raw baseline, so options whose worth changes once
+    the envelope is treated (a boiler on an insulated home) are re-ranked."""
+    start_sap: float = scorer.score(baseline_epc, []).sap_continuous
+    return [
+        [
+            ScoredOption(
+                option=scored.option,
+                sap_gain=scorer.score(
+                    baseline_epc, [scored.option.overlay]
+                ).sap_continuous
+                - start_sap,
+            )
+            for scored in group
+        ]
+        for group in groups
+    ]
+
+
 class _PrefixedScorer:
     """A Scorer view of the dwelling with a committed package already applied:
     every score call sees the ``prefix`` overlays before the candidate's own.