RAG systems: the answer is only as good as what you retrieved

Why MegaMart Assist cited a superseded return policy 212 times, and the pipeline that prevents it: structure-aware parsing and chunking, contextual retrieval, metadata and dedup, CDC into idempotent upserts with deletes, a DLQ and a freshness SLO, effective-dated versions, blue/green re-embedding, query rewriting, hybrid retrieval then a cross-encoder reranker, context within a token budget, verified citations, permission-aware retrieval, failure modes, and when RAG is the wrong tool.