FA-62253 / Currency rounding and FX conversion / Member archive

Old minor digits are dropped before applying the redenomination factor · case 03

Legacy amounts with fractional old units lose value when redenominated.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

solve(amount_minor, date, cutover, factor, old_exp, new_exp): amounts dated on or after the cutover (ISO date strings) are already in the new currency and returned unchanged as [amount_minor, 'native']. Earlier amounts are old-currency minor units: new = amount_minor / factor * 10**(new_exp - old_exp), rounded half away from zero, returned as [new, 'converted']. factor is old units per new unit.

Why this case matters

Currency amounts must be rounded at the right stage and in the right unit, or ledgers, quotes and settlements drift by minor units.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression old-minor-digits 1	`[123456700000, "converted"]`	`[123457, "converted"]`	Failed

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