FA-66471 / Airline fare rule evaluation / Open access

Forfeit fares issue residual credit · case 01

Non-refundable downgrades produce a travel credit.

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ROOT CAUSE

The residual check compares against a sentinel that never occurs, so FORFEIT behaves like CREDIT.

THE FAILURE

The residual check compares against a sentinel that never occurs, so FORFEIT behaves like CREDIT.

Unsuccessful approach: A truthiness test still accepts the non-empty FORFEIT string.

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.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    paid, new = x['paid'], x['new_fare']
    if x['hours_since_ticket'] <= x['waiver_h']:
        fee = 0.0
    elif x['fee_rule'] == 'FLAT':
        fee = x['fee']
    else:
        fee = max(x['fee'], x['fee_pct'] * paid / 100)
    collect = max(0.0, new - paid) + fee
    credit = max(0.0, paid - new) if x['residual'] != 'NONE' else 0.0
    return [round(collect, 2), round(credit, 2)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1101.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [291.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 51}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 421.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 310.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 0.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 945.21, 'new_fare': 746.1, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 397}, [141.78, 0.0]], ['sampled case 2', {'paid': 616.49, 'new_fare': 852.38, 'fee': 150.0, 'fee_pct': 10, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 48}, [385.89, 0.0]], ['sampled case 3', {'paid': 832.44, 'new_fare': 589.1, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 24}, [0.0, 0.0]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1102.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [292.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 52}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 422.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 320.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 10.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 187.06, 'new_fare': 196.65, 'fee': 150.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [9.59, 0.0]], ['sampled case 2', {'paid': 1518.15, 'new_fare': 1549.03, 'fee': 150.0, 'fee_pct': 20, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [30.88, 0.0]], ['sampled case 3', {'paid': 1212.02, 'new_fare': 1432.47, 'fee': 100.0, 'fee_pct': 5, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 49}, [320.45, 0.0]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1103.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [293.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 53}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 423.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 330.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 20.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 1440.92, 'new_fare': 1296.99, 'fee': 75.0, 'fee_pct': 20, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'waiver_h': 48, 'hours_since_ticket': 24}, [0.0, 143.93]], ['sampled case 2', {'paid': 1622.18, 'new_fare': 873.9, 'fee': 150.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 48}, [243.33, 0.0]], ['sampled case 3', {'paid': 1642.66, 'new_fare': 1568.49, 'fee': 75.0, 'fee_pct': 20, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 48}, [0.0, 0.0]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1104.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [294.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 54}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 424.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 340.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 30.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 1227.57, 'new_fare': 1031.14, 'fee': 75.0, 'fee_pct': 20, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 48}, [245.51, 0.0]], ['sampled case 2', {'paid': 762.01, 'new_fare': 1039.32, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [277.31, 0.0]], ['sampled case 3', {'paid': 1675.54, 'new_fare': 1027.22, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [0.0, 648.32]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1105.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [295.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 55}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 425.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 350.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 40.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 938.24, 'new_fare': 955.89, 'fee': 100.0, 'fee_pct': 15, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'waiver_h': 48, 'hours_since_ticket': 57.2}, [117.65, 0.0]], ['sampled case 2', {'paid': 1989.4, 'new_fare': 2128.3, 'fee': 150.0, 'fee_pct': 10, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 12.8}, [138.9, 0.0]], ['sampled case 3', {'paid': 1315.4, 'new_fare': 1527.5, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 24}, [212.1, 0.0]]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
upgrade HIGHER rule	`[291.0, 0.0]`	`[291.0, 0.0]`	Passed
downgrade with credit	`[75.0, 150.0]`	`[75.0, 150.0]`	Passed
downgrade forfeit	`[75.0, 179.0]`	`[75.0, 0.0]`	Failed
exactly 24h after ticketing	`[20.0, 0.0]`	`[20.0, 0.0]`	Passed
cheap fare minimum fee	`[75.0, 0.0]`	`[75.0, 0.0]`	Passed
pct fee exceeds flat	`[150.0, 300.0]`	`[150.0, 300.0]`	Passed
fee larger than residual	`[75.0, 40.0]`	`[75.0, 40.0]`	Passed
sampled case 1	`[141.78, 199.11]`	`[141.78, 0.0]`	Failed
sampled case 2	`[385.89, 0.0]`	`[385.89, 0.0]`	Passed
sampled case 3	`[0.0, 243.34]`	`[0.0, 0.0]`	Failed

SHA-256 / f5ea7efe3d893d560e119535a234e16912bcbc6e228b92be354e59ac010fddd2

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    paid, new = x['paid'], x['new_fare']
    if x['hours_since_ticket'] <= x['waiver_h']:
        fee = 0.0
    elif x['fee_rule'] == 'FLAT':
        fee = x['fee']
    else:
        fee = max(x['fee'], x['fee_pct'] * paid / 100)
    collect = max(0.0, new - paid) + fee
    credit = max(0.0, paid - new) if x['residual'] else 0.0
    return [round(collect, 2), round(credit, 2)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1101.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [291.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 51}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 421.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 310.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 0.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 945.21, 'new_fare': 746.1, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 397}, [141.78, 0.0]], ['sampled case 2', {'paid': 616.49, 'new_fare': 852.38, 'fee': 150.0, 'fee_pct': 10, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 48}, [385.89, 0.0]], ['sampled case 3', {'paid': 832.44, 'new_fare': 589.1, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 24}, [0.0, 0.0]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1102.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [292.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 52}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 422.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 320.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 10.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 187.06, 'new_fare': 196.65, 'fee': 150.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [9.59, 0.0]], ['sampled case 2', {'paid': 1518.15, 'new_fare': 1549.03, 'fee': 150.0, 'fee_pct': 20, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [30.88, 0.0]], ['sampled case 3', {'paid': 1212.02, 'new_fare': 1432.47, 'fee': 100.0, 'fee_pct': 5, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 49}, [320.45, 0.0]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1103.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [293.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 53}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 423.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 330.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 20.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 1440.92, 'new_fare': 1296.99, 'fee': 75.0, 'fee_pct': 20, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'waiver_h': 48, 'hours_since_ticket': 24}, [0.0, 143.93]], ['sampled case 2', {'paid': 1622.18, 'new_fare': 873.9, 'fee': 150.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 48}, [243.33, 0.0]], ['sampled case 3', {'paid': 1642.66, 'new_fare': 1568.49, 'fee': 75.0, 'fee_pct': 20, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 48}, [0.0, 0.0]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1104.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [294.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 54}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 424.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 340.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 30.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 1227.57, 'new_fare': 1031.14, 'fee': 75.0, 'fee_pct': 20, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 48}, [245.51, 0.0]], ['sampled case 2', {'paid': 762.01, 'new_fare': 1039.32, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [277.31, 0.0]], ['sampled case 3', {'paid': 1675.54, 'new_fare': 1027.22, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'waiver_h': 24, 'hours_since_ticket': 24}, [0.0, 648.32]]], [['upgrade HIGHER rule', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 900.0, 'new_fare': 1105.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 100}, [295.0, 0.0]], ['downgrade with credit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 450.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 55}, [75.0, 150.0]], ['downgrade forfeit', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 600.0, 'new_fare': 425.0, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'hours_since_ticket': 72}, [75.0, 0.0]], ['exactly 24h after ticketing', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 520.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 24}, [20.0, 0.0]], ['cheap fare minimum fee', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 350.0, 'new_fare': 310.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 30}, [75.0, 40.0]], ['pct fee exceeds flat', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 1500.0, 'new_fare': 1200.0, 'fee_rule': 'HIGHER', 'residual': 'CREDIT', 'hours_since_ticket': 200}, [150.0, 300.0]], ['fee larger than residual', {'waiver_h': 24, 'fee': 75.0, 'fee_pct': 10, 'paid': 500.0, 'new_fare': 460.0, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'hours_since_ticket': 48}, [75.0, 40.0]], ['sampled case 1', {'paid': 938.24, 'new_fare': 955.89, 'fee': 100.0, 'fee_pct': 15, 'fee_rule': 'FLAT', 'residual': 'CREDIT', 'waiver_h': 48, 'hours_since_ticket': 57.2}, [117.65, 0.0]], ['sampled case 2', {'paid': 1989.4, 'new_fare': 2128.3, 'fee': 150.0, 'fee_pct': 10, 'fee_rule': 'HIGHER', 'residual': 'FORFEIT', 'waiver_h': 24, 'hours_since_ticket': 12.8}, [138.9, 0.0]], ['sampled case 3', {'paid': 1315.4, 'new_fare': 1527.5, 'fee': 50.0, 'fee_pct': 15, 'fee_rule': 'FLAT', 'residual': 'FORFEIT', 'waiver_h': 48, 'hours_since_ticket': 24}, [212.1, 0.0]]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
upgrade HIGHER rule	`[291.0, 0.0]`	`[291.0, 0.0]`	Passed
downgrade with credit	`[75.0, 150.0]`	`[75.0, 150.0]`	Passed
downgrade forfeit	`[75.0, 179.0]`	`[75.0, 0.0]`	Failed
exactly 24h after ticketing	`[20.0, 0.0]`	`[20.0, 0.0]`	Passed
cheap fare minimum fee	`[75.0, 0.0]`	`[75.0, 0.0]`	Passed
pct fee exceeds flat	`[150.0, 300.0]`	`[150.0, 300.0]`	Passed
fee larger than residual	`[75.0, 40.0]`	`[75.0, 40.0]`	Passed
sampled case 1	`[141.78, 199.11]`	`[141.78, 0.0]`	Failed
sampled case 2	`[385.89, 0.0]`	`[385.89, 0.0]`	Passed
sampled case 3	`[0.0, 243.34]`	`[0.0, 0.0]`	Failed

SHA-256 / af928608194051a56f3656f73065371bb0890c4c3856c01f80102ec17c3bdd3e

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 10 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

A stipulated toy fare-rule contract with invented constants; it is not an ATPCO or carrier tariff implementation and makes no claim of industry-standard conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:47:44.136510+00:00.

Case digest / f6b66040de56661c2b2babcc7cd87a1eff57d00968c6f0924bd031543e61ca03