PO Price-Variance Audit — From Raw Extract to Three Director Actions

📥 Download the practice file: data/case-file.txt — one contract price schedule (two suppliers) and six months of purchase orders, 40 lines. Paste it into your AI tool to follow along — the worked runs below were captured on ChatGPT, Claude, Copilot, and Gemini.

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Summit Packaging, corrugated carton 18×14×12: $62.50. Lakeshore Industrial, same carton: $2.65. You have bought from both suppliers for a year and you cannot say which one is cheaper. Not "it's close" — you genuinely cannot tell, because $62.50 is per case of 25 and $2.65 is per each, and the only place that says so is a contract footnote you signed and have not opened since.

That footnote is the whole lesson. Your 40-line PO extract covers about $179,574 of spend across two suppliers and six months. It has every number. What it does not have is the handful of contract rules that decide what those numbers mean — a unit convention, a freight term, a discount threshold, an escalation clause. Miss any one and the variance report is confidently wrong. The skill is three moves: feed the AI those rules explicitly, cross-validate every transaction against the contract clauses, and compress the audit into three actions a director can authorize. The same three moves work on any PO extract, any AI platform.

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