🔧 Why output-stage PII masking is the wrong protective surface for data exfiltration in RAG

"The output filter runs after the LLM has already seen the confidential data. By then, three classes of leak can no longer be stopped. The right surface is retrieval. Walking through a real implementation."

TL;DR
Most RAG-with-RBAC stacks I see in production put the access-control gate at the output stage: an LLM-response post-filter that masks...