FAILURE MAP
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FA-60411 / Loyalty points ledgers / Open access

Points redemption at checkout: minimum balance boundary · case 01

A member with exactly the 500-point minimum cannot redeem.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The minimum-balance test rejects balances equal to the minimum.

VERIFIED REPAIR

Reject only balances below 500 points.

Unsuccessful approach: Checking the requested points instead of the balance lets small balances through.

Case contract

Input {balance, order_cents, request_pts, max_pct, cpp (cents per point)}. Balance below 500 returns {"error":"below minimum"}. Points are used in blocks of 100: used = min(request floored to a block, balance floored to a block, cap) where cap = floor(order*max_pct/100 / cpp) floored to a block. Cash due = order - used*cpp. Return {points_used, cash_due}.

Why this case matters

Member point balances, statements and the program liability depend on this ledger rule.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    bal = x['balance']
    order = x['order_cents']
    if bal <= 500:
        return {'error': 'below minimum'}
    blk = 100
    cap_cents = order * x['max_pct'] // 100
    cap = cap_cents // x['cpp'] // blk * blk
    use = min(x['request_pts'] // blk * blk, bal // blk * blk, cap)
    return {'points_used': use, 'cash_due': order - use * x['cpp']}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['normal', {'balance': 2750, 'order_cents': 4001, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2201}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5001, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1291, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 51, 'cpp': 2}, {'points_used': 1200, 'cash_due': 2600}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1285, 'max_pct': 90, 'cpp': 1}, {'points_used': 1200, 'cash_due': 8800}], ['small balance big request', {'balance': 451, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4002, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2202}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5002, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 2}, {'points_used': 500, 'cash_due': 8999}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1292, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 52, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1295, 'max_pct': 90, 'cpp': 1}, {'points_used': 1200, 'cash_due': 8800}], ['small balance big request', {'balance': 452, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4003, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2203}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5003, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1293, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 53, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1305, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 453, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4004, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2204}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5004, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 2}, {'points_used': 500, 'cash_due': 8999}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1294, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 54, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1315, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 454, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4005, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2205}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5005, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1295, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 55, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1325, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 455, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]]]
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 fixtureActualExpectedOutcome
normal{'cash_due': 2201, 'points_used': 1800}{'cash_due': 2201, 'points_used': 1800}Passed
cap binds{'cash_due': 1800, 'points_used': 1200}{'cash_due': 1800, 'points_used': 1200}Passed
minimum balance edge{'error': 'below minimum'}{'cash_due': 8499, 'points_used': 500}Failed
below minimum{'error': 'below minimum'}{'error': 'below minimum'}Passed
balance binds{'cash_due': 48800, 'points_used': 1200}{'cash_due': 48800, 'points_used': 1200}Passed
two cents per point{'cash_due': 2600, 'points_used': 1200}{'cash_due': 2600, 'points_used': 1200}Passed
odd request{'cash_due': 8800, 'points_used': 1200}{'cash_due': 8800, 'points_used': 1200}Passed
small balance big request{'error': 'below minimum'}{'error': 'below minimum'}Passed

SHA-256 / fb701156358696738ff8941c5da50dcc42cf5d944067fb6f523dece8bbbeaaa9

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    bal = x['balance']
    order = x['order_cents']
    if x['request_pts'] < 500:
        return {'error': 'below minimum'}
    blk = 100
    cap_cents = order * x['max_pct'] // 100
    cap = cap_cents // x['cpp'] // blk * blk
    use = min(x['request_pts'] // blk * blk, bal // blk * blk, cap)
    return {'points_used': use, 'cash_due': order - use * x['cpp']}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['normal', {'balance': 2750, 'order_cents': 4001, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2201}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5001, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1291, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 51, 'cpp': 2}, {'points_used': 1200, 'cash_due': 2600}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1285, 'max_pct': 90, 'cpp': 1}, {'points_used': 1200, 'cash_due': 8800}], ['small balance big request', {'balance': 451, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4002, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2202}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5002, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 2}, {'points_used': 500, 'cash_due': 8999}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1292, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 52, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1295, 'max_pct': 90, 'cpp': 1}, {'points_used': 1200, 'cash_due': 8800}], ['small balance big request', {'balance': 452, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4003, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2203}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5003, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1293, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 53, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1305, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 453, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4004, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2204}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5004, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 2}, {'points_used': 500, 'cash_due': 8999}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1294, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 54, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1315, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 454, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4005, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2205}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5005, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1295, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 55, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1325, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 455, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]]]
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 fixtureActualExpectedOutcome
normal{'cash_due': 2201, 'points_used': 1800}{'cash_due': 2201, 'points_used': 1800}Passed
cap binds{'cash_due': 1800, 'points_used': 1200}{'cash_due': 1800, 'points_used': 1200}Passed
minimum balance edge{'cash_due': 8499, 'points_used': 500}{'cash_due': 8499, 'points_used': 500}Passed
below minimum{'error': 'below minimum'}{'error': 'below minimum'}Passed
balance binds{'cash_due': 48800, 'points_used': 1200}{'cash_due': 48800, 'points_used': 1200}Passed
two cents per point{'cash_due': 2600, 'points_used': 1200}{'cash_due': 2600, 'points_used': 1200}Passed
odd request{'cash_due': 8800, 'points_used': 1200}{'cash_due': 8800, 'points_used': 1200}Passed
small balance big request{'cash_due': 8600, 'points_used': 400}{'error': 'below minimum'}Failed

SHA-256 / 7aca55faecb23354e4e89855771b8585447baf55d688a271cf6e091dd0b6ecac

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    bal = x['balance']
    order = x['order_cents']
    if bal < 500:
        return {'error': 'below minimum'}
    blk = 100
    cap_cents = order * x['max_pct'] // 100
    cap = cap_cents // x['cpp'] // blk * blk
    use = min(x['request_pts'] // blk * blk, bal // blk * blk, cap)
    return {'points_used': use, 'cash_due': order - use * x['cpp']}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['normal', {'balance': 2750, 'order_cents': 4001, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2201}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5001, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1291, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 51, 'cpp': 2}, {'points_used': 1200, 'cash_due': 2600}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1285, 'max_pct': 90, 'cpp': 1}, {'points_used': 1200, 'cash_due': 8800}], ['small balance big request', {'balance': 451, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4002, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2202}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5002, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 2}, {'points_used': 500, 'cash_due': 8999}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1292, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 52, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1295, 'max_pct': 90, 'cpp': 1}, {'points_used': 1200, 'cash_due': 8800}], ['small balance big request', {'balance': 452, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4003, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2203}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5003, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1293, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 53, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1305, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 453, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4004, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2204}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5004, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 2}, {'points_used': 500, 'cash_due': 8999}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1294, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 54, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1315, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 454, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]], [['normal', {'balance': 2750, 'order_cents': 4005, 'request_pts': 1850, 'max_pct': 50, 'cpp': 1}, {'points_used': 1800, 'cash_due': 2205}], ['cap binds', {'balance': 9000, 'order_cents': 3000, 'request_pts': 5005, 'max_pct': 40, 'cpp': 1}, {'points_used': 1200, 'cash_due': 1800}], ['minimum balance edge', {'balance': 500, 'order_cents': 9999, 'request_pts': 500, 'max_pct': 100, 'cpp': 3}, {'points_used': 500, 'cash_due': 8499}], ['below minimum', {'balance': 499, 'order_cents': 9999, 'request_pts': 400, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}], ['balance binds', {'balance': 1295, 'order_cents': 50000, 'request_pts': 3000, 'max_pct': 60, 'cpp': 1}, {'points_used': 1200, 'cash_due': 48800}], ['two cents per point', {'balance': 5000, 'order_cents': 5000, 'request_pts': 4000, 'max_pct': 55, 'cpp': 2}, {'points_used': 1300, 'cash_due': 2400}], ['odd request', {'balance': 3000, 'order_cents': 10000, 'request_pts': 1325, 'max_pct': 90, 'cpp': 1}, {'points_used': 1300, 'cash_due': 8700}], ['small balance big request', {'balance': 455, 'order_cents': 9000, 'request_pts': 600, 'max_pct': 100, 'cpp': 1}, {'error': 'below minimum'}]]]
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 fixtureActualExpectedOutcome
normal{'cash_due': 2201, 'points_used': 1800}{'cash_due': 2201, 'points_used': 1800}Passed
cap binds{'cash_due': 1800, 'points_used': 1200}{'cash_due': 1800, 'points_used': 1200}Passed
minimum balance edge{'cash_due': 8499, 'points_used': 500}{'cash_due': 8499, 'points_used': 500}Passed
below minimum{'error': 'below minimum'}{'error': 'below minimum'}Passed
balance binds{'cash_due': 48800, 'points_used': 1200}{'cash_due': 48800, 'points_used': 1200}Passed
two cents per point{'cash_due': 2600, 'points_used': 1200}{'cash_due': 2600, 'points_used': 1200}Passed
odd request{'cash_due': 8800, 'points_used': 1200}{'cash_due': 8800, 'points_used': 1200}Passed
small balance big request{'error': 'below minimum'}{'error': 'below minimum'}Passed

SHA-256 / d1143619211eda229af8eb9c724af7bb86a96061694de4d2607d44c24f357b9e

Verification & scope

Stipulated bounded loyalty-program model with explicit toy rules; not any real program terms. 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 2026-09-29T14:46:45.362973+00:00.

Case digest / a29efeeacbee5c0da970cbf091c80614b0d8218e71bb67f6212370761064d2cc