FA-68570 / Toll and parking fee computation / Member archive

Express lane dynamic price: price decreases are not rate limited · case 05

Express lane dynamic price returns a wrong result when price decreases are not rate limited.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input {density, prev_price, bands: [[density upto, price]] ascending, max_step, min_price, max_price, occupancy, hov_free_min, hov2_pct}. The target is the first band whose upto is >= density, else max_price. The posted price moves from prev_price toward the target by at most max_step either way, then is clamped to [min_price, max_price]. Vehicles with occupancy >= hov_free_min pay 0; occupancy 2 (when not free) pays hov2_pct percent floored to 5 cents. Return [posted, charged].

Why this case matters

Fee engines bill customers in integer cents; a wrong boundary, rounding stage or cap scope silently over- or under-charges.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
fee oracle 5	`[450, 225]`	`[650, 325]`	Failed

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