FA-66477 / Airline fare rule evaluation / Member archive

Downgrade fare difference reduces the amount collected · case 02

Downgrades report a collection below the fee, sometimes negative.

Member previewVariant 2 · 3 implementations · 10 checks per implementation

Case contract

Input {'paid','new_fare','fee','fee_pct','fee_rule' FLAT|HIGHER,'residual' CREDIT|FORFEIT,'waiver_h','hours_since_ticket'}. Fee waived when hours_since_ticket <= waiver_h; FLAT fee = fee; HIGHER = max(fee, fee_pct% of the original paid fare). Collect = max(0, new-paid) + fee; residual credit = max(0, paid-new) only when residual is CREDIT (the fee is never netted against credit). Return [collect, credit] rounded 2.

Why this case matters

Voluntary change pricing combines a fare difference, a penalty with a higher-of rule, a free-change window and residual value handling.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
downgrade with credit	`[-75.0, 150.0]`	`[75.0, 150.0]`	Failed

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