Banks write the same amount many ways: $1,234.56, (59.99) for money out, or 59.99- with the sign trailing. A reader should not care.
ai-bookkeeper now has a generated test that rewrites the decimal amounts of every CSV fixture in those four spellings and requires identical rows (date, cents, description).
One fixture failed: a header-less Australian-style file with trailing-minus amounts. The shape check for header-less layouts did not accept 45.20- as an amount, so the file fell through to a generic guesser that read 04/03/2026 as 3 April instead of 4 March. No error, only wrong dates.
The fix is one character in a regular expression. The test now guards it. Fixtures are our own made-up rows; no real bank download was tried.