Wraps the four slices closing the heating-systems corpus from
Σ|ΔSAP_c| 1.24 → 0 (25/25 cascade-OK variants SAP/cost/CO2/PE
EXACT, except solid fuel 2 summer-immersion-blend artifact).
Highest-leverage next slice: close solid fuel 2 (the only remaining
open variant in the cascade-OK tier) via the S0380.154 blend code
path — likely a parallel Elmhurst-mirror gate for the summer-
immersion CO2/PE factors.
Other open fronts: 16 blocked-tier mapper extensions; pcdb 1 sub-
tolerance -0.011 SAP; cohort-2 golden residuals tightening per
[[feedback-golden-residuals-near-zero]].
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
