Procurement expertise tells operators what to buy and what price to negotiate. Nobody verifies that the negotiated price is what got billed, that delivered quantity matches the invoice, that credits were applied, or that contract terms held. That verification gap is where restaurants silently lose 2–5% of COGS. M04 runs the same Sentry loop that powers M01 and M02 — ingest, certify, trust-score, watch, CAAR, recover — against every vendor invoice.
Conservative estimate: a 10-location chain loses $1,200–$4,000/month per location in supply chain variance — $144K–$480K a year. Every finding ships as a certified, SHA-256 sealed CAAR the vendor can't dispute.