The error series of the engine

One dated row per run. Each run builds figures from the SEC data, plants wrong ones beside the true ones, and counts what the engine did with them, plus a fixed list of real company restatements. These are counts from machine-built tests; a person reading real notes is a separate measurement, and the counts stay counts. Any later change to a past row makes the check below fail, and a timestamp from an outside authority dates the file.