An audit that finds an overcharge after the window has closed changes nothing. The clock is computed per line from the invoice date, so recovery effort goes to the lines that can still be claimed — and the expired ones are counted honestly instead of inflating the number.
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.