Thirty days is enough to recover a week's worth of over-billing — if someone reads the invoice in time. The audit produces the per-carrier split (UPS ≈30 days, FedEx ≈21 days) and flags the lines that close inside the week.
Paste or upload the shipment records you handed over and the carrier's invoice lines. The audit runs in this page — the same deterministic engine the agent tools call.
The examples are synthetic worked cases (the same fixtures the build gate asserts against). Your own files are audited in the browser: no upload, no LLM, no third-party call.