Two committed artifacts that nothing checked against each other, which is the same shape as the report drift #240 guarded. unit-stats.json is collected from the two report.json files and neither regenerates the other, so a refreshed report left every weight on a force card describing a machine that may no longer be in the fight. The script has had a --check since it was written and nothing ran it; prek does now. It is hermetic and takes 46ms, unlike boards.json or megamek-text.ts, which need MegaMek and so cannot be gated this way. daily.json's per-unit battle values and its side totals come from different parts of the same report, and nothing compared them. Summing one against the other is also what says `mms index`'s positional join still lines up: the report lists a faction in MegaMek's order, and if that stopped matching the file's order the units would keep their names and swap their values - no total would move, every row would be wrong. Two of Bug Company's Stingers differ by 124 BV on skills alone. Both checked by mutation: a hand-edited weight fails the hook, a hand-edited per-unit value fails the test.