FA-84533 / Betting odds conversion / Member archive

Commission charged per winning bet instead of per market · case 03

A hedged market pays commission on the winning leg despite a small net profit.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

Betting exchange settlement. bets rows are [market, side, stake_cents, price, won] where won says whether the bet won. Back: win profit floor(stake * (price - 1)), loss -stake. Lay: win +stake, loss -ceil(stake * (price - 1)) (the liability). Commission is charged per market on the market net profit only when that net is positive, at rate_pct percent rounded half up to a cent. Return [total net after commission, total commission] in cents.

Why this case matters

Exchanges charge commission on net market winnings, not per winning bet.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
boundary hedged market nets out	`[400, 100]`	`[475, 25]`	Failed

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