Complete procedures with a way back.

Build a production catalog assistant that imports merchant-approved structured product data, generates reproducible embeddings, combines semantic retrieval with exact price and category filters, treats stale inventory as unknown, keeps recommendation language inside explicit boundaries, and turns account or order help into a local handoff draft that a merchant operator must approve before a separate dispatcher writes to support.

Pin PostgreSQL 18 and pgvector 0.8.5, enforce tenant RLS, store one validated vector dimension, ingest idempotently, measure HNSW and IVFFlat against exact recall, and prove maintenance, PITR, restore and rollback.

Govern source revisions, preserve ACLs through parsing and chunking, pin embeddings, combine lexical and semantic retrieval, validate claim-level citations, evaluate abstention, and release immutable indexes with safe rollback.