A financial app must prove its money math, not sample it. tests/
moneyProperties.test.js fuzzes utils/money.mts: toCents always integer;
dollars→cents→dollars == roundMoney (no drift); sumMoney is cent-exact;
integer cents round-trip; classic float-drift cases exact; invalid inputs
never yield a bogus number. 6 properties, all hold.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
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