Classifarr

Service decomposition and layered migration patterns for Classifarr. USE FOR: extracting adapters over legacy tables, building façade service boundaries, adding new DB tables alongside existing ones (dual-write / shadow-read), writing deterministic backfill scripts, normalizing key formats, hardening PolicyEngine contracts, building phase-gated migrations. DO NOT USE FOR: full PolicyEngine rewrites, schema cutovers without a compatibility phase, removing legacy tables before shadow parity is proven.