Designs the heating Recommendation Generator via /grill-with-docs. Load-bearing
decisions: HW + controls + fuel + meter fold into each competing whole-system
bundle (the legacy heating-vs-HW split double-counted); each bundle is a fixed,
real, contractor-installable end-state (ASHP via PCDB index, HHR storage via
sap_main_heating_code=409), Product stays cost-only; eligibility encodes only
physical/planning installability since the Optimiser owns the economics (the
legacy ASHP built-form / 120 m² rule is dropped — research found no
authoritative basis); the Simulation Overlay is the deepest surface yet,
spanning main_heating_details[0] + sap_heating + top-level EpcPropertyData +
sap_energy_source. Build order HHRSH -> ASHP -> boiler (deferred).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
