FA-62064 / Currency rounding and FX conversion / Member archive

The fee is converted and rounded separately from the gross amount · case 04

The payout differs by a minor unit from converting the net amount once.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

solve(amount, rate, src_exp, dst_exp, fee_bps, min_fee): amount and min_fee are source minor units, fee_bps a non-negative integer. fee = max(min_fee, ceil(amount*fee_bps/10000)) in source minor units, deducted before conversion. A fee greater than or equal to the amount returns 'ERR:amount-below-fee'; a non-positive amount or negative bps returns 'ERR:input'. The net amount is converted exactly (net * rate * 10**(dst_exp - src_exp)) and rounded half-even. Return [fee, converted].

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 fee-conversion-order 1	`[1000, 130]`	`[1000, 129]`	Failed

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