Check a spread you already have

A spreadsheet produced by a model — a chat session, another tool — usually carries a validation sheet of its own. That sheet is not a check. It is written in the same pass as the figures, by the thing being graded, and “Matches face” is a phrase it predicts rather than a subtraction anybody performed.

This recomputes every relationship the workbook implies, in Python, against the figures in the file. Nothing is read, nothing is guessed and no model is called — so it costs nothing, takes seconds, and does not touch your allowance.