FAILURE MAP
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FA-60771 / Loyalty points ledgers / Open access

Points plus cash split: tenths-of-cent scaling · case 01

Only a tenth of the allowed points are applied.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The room in cents is divided by the point value in tenths without scaling by 10.

VERIFIED REPAIR

Multiply the room by 10 before dividing by cpp10.

Unsuccessful approach: Scaling by 100 applies ten times too many points.

Case contract

Input {price, balance, cpp10 (point value in tenths of a cent), min_cash}. Points may cover at most price - min_cash (never negative): max points = floor((price - min_cash)*10/cpp10), limited by balance. Credit = floor(points*cpp10/10); cash = price - credit. Return {points, cash}.

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):
    room = x['price'] - x['min_cash']
    maxp = max(0, room // x['cpp10'])
    pts = min(x['balance'], maxp)
    credit = pts * x['cpp10'] // 10
    return {'points': pts, 'cash': x['price'] - credit}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 501}, {'points': 7915, 'cash': 502}], ['balance limits', {'price': 10000, 'balance': 3001, 'cpp10': 10, 'min_cash': 100}, {'points': 3001, 'cash': 6999}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 2}, {'points': 7138, 'cash': 3}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 401}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 990}, {'points': 4, 'cash': 990}], ['odd credit', {'price': 2503, 'balance': 1238, 'cpp10': 13, 'min_cash': 3}, {'points': 1238, 'cash': 894}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 502}, {'points': 7915, 'cash': 502}], ['balance limits', {'price': 10000, 'balance': 3002, 'cpp10': 10, 'min_cash': 100}, {'points': 3002, 'cash': 6998}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 3}, {'points': 7137, 'cash': 4}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 402}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 980}, {'points': 8, 'cash': 980}], ['odd credit', {'price': 2503, 'balance': 1239, 'cpp10': 13, 'min_cash': 3}, {'points': 1239, 'cash': 893}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 503}, {'points': 7914, 'cash': 504}], ['balance limits', {'price': 10000, 'balance': 3003, 'cpp10': 10, 'min_cash': 100}, {'points': 3003, 'cash': 6997}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 4}, {'points': 7135, 'cash': 5}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 403}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 970}, {'points': 12, 'cash': 970}], ['odd credit', {'price': 2503, 'balance': 1240, 'cpp10': 13, 'min_cash': 3}, {'points': 1240, 'cash': 891}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 504}, {'points': 7913, 'cash': 505}], ['balance limits', {'price': 10000, 'balance': 3004, 'cpp10': 10, 'min_cash': 100}, {'points': 3004, 'cash': 6996}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 5}, {'points': 7134, 'cash': 6}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 404}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 960}, {'points': 16, 'cash': 960}], ['odd credit', {'price': 2503, 'balance': 1241, 'cpp10': 13, 'min_cash': 3}, {'points': 1241, 'cash': 890}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 505}, {'points': 7912, 'cash': 506}], ['balance limits', {'price': 10000, 'balance': 3005, 'cpp10': 10, 'min_cash': 100}, {'points': 3005, 'cash': 6995}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 6}, {'points': 7132, 'cash': 7}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 405}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 950}, {'points': 20, 'cash': 950}], ['odd credit', {'price': 2503, 'balance': 1242, 'cpp10': 13, 'min_cash': 3}, {'points': 1242, 'cash': 889}]]]
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
points cover most{'cash': 9051, 'points': 791}{'cash': 502, 'points': 7915}Failed
balance limits{'cash': 9010, 'points': 990}{'cash': 6999, 'points': 3001}Failed
fractional value{'cash': 4500, 'points': 713}{'cash': 3, 'points': 7138}Failed
price below minimum cash{'cash': 300, 'points': 0}{'cash': 300, 'points': 0}Passed
exact minimum{'cash': 1000, 'points': 0}{'cash': 990, 'points': 4}Failed
odd credit{'cash': 2254, 'points': 192}{'cash': 894, 'points': 1238}Failed

SHA-256 / e5205e33e304fd9a99da5dedf427283cbdf3e7ef2ef85ec37cc300c08004e9e0

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    room = x['price'] - x['min_cash']
    maxp = max(0, room * 100 // x['cpp10'])
    pts = min(x['balance'], maxp)
    credit = pts * x['cpp10'] // 10
    return {'points': pts, 'cash': x['price'] - credit}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 501}, {'points': 7915, 'cash': 502}], ['balance limits', {'price': 10000, 'balance': 3001, 'cpp10': 10, 'min_cash': 100}, {'points': 3001, 'cash': 6999}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 2}, {'points': 7138, 'cash': 3}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 401}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 990}, {'points': 4, 'cash': 990}], ['odd credit', {'price': 2503, 'balance': 1238, 'cpp10': 13, 'min_cash': 3}, {'points': 1238, 'cash': 894}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 502}, {'points': 7915, 'cash': 502}], ['balance limits', {'price': 10000, 'balance': 3002, 'cpp10': 10, 'min_cash': 100}, {'points': 3002, 'cash': 6998}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 3}, {'points': 7137, 'cash': 4}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 402}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 980}, {'points': 8, 'cash': 980}], ['odd credit', {'price': 2503, 'balance': 1239, 'cpp10': 13, 'min_cash': 3}, {'points': 1239, 'cash': 893}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 503}, {'points': 7914, 'cash': 504}], ['balance limits', {'price': 10000, 'balance': 3003, 'cpp10': 10, 'min_cash': 100}, {'points': 3003, 'cash': 6997}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 4}, {'points': 7135, 'cash': 5}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 403}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 970}, {'points': 12, 'cash': 970}], ['odd credit', {'price': 2503, 'balance': 1240, 'cpp10': 13, 'min_cash': 3}, {'points': 1240, 'cash': 891}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 504}, {'points': 7913, 'cash': 505}], ['balance limits', {'price': 10000, 'balance': 3004, 'cpp10': 10, 'min_cash': 100}, {'points': 3004, 'cash': 6996}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 5}, {'points': 7134, 'cash': 6}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 404}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 960}, {'points': 16, 'cash': 960}], ['odd credit', {'price': 2503, 'balance': 1241, 'cpp10': 13, 'min_cash': 3}, {'points': 1241, 'cash': 890}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 505}, {'points': 7912, 'cash': 506}], ['balance limits', {'price': 10000, 'balance': 3005, 'cpp10': 10, 'min_cash': 100}, {'points': 3005, 'cash': 6995}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 6}, {'points': 7132, 'cash': 7}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 405}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 950}, {'points': 20, 'cash': 950}], ['odd credit', {'price': 2503, 'balance': 1242, 'cpp10': 13, 'min_cash': 3}, {'points': 1242, 'cash': 889}]]]
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
points cover most{'cash': -50000, 'points': 50000}{'cash': 502, 'points': 7915}Failed
balance limits{'cash': 6999, 'points': 3001}{'cash': 6999, 'points': 3001}Passed
fractional value{'cash': -44970, 'points': 71385}{'cash': 3, 'points': 7138}Failed
price below minimum cash{'cash': 300, 'points': 0}{'cash': 300, 'points': 0}Passed
exact minimum{'cash': 900, 'points': 40}{'cash': 990, 'points': 4}Failed
odd credit{'cash': 894, 'points': 1238}{'cash': 894, 'points': 1238}Passed

SHA-256 / f8f3aba15a13785218f8a20a1a50ed2aa9d11c8361fa082ee6c6dff1946e67b1

3 / The verified repair

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

N = 1
observations = []
def solve(x):
    room = x['price'] - x['min_cash']
    maxp = max(0, room * 10 // x['cpp10'])
    pts = min(x['balance'], maxp)
    credit = pts * x['cpp10'] // 10
    return {'points': pts, 'cash': x['price'] - credit}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 501}, {'points': 7915, 'cash': 502}], ['balance limits', {'price': 10000, 'balance': 3001, 'cpp10': 10, 'min_cash': 100}, {'points': 3001, 'cash': 6999}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 2}, {'points': 7138, 'cash': 3}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 401}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 990}, {'points': 4, 'cash': 990}], ['odd credit', {'price': 2503, 'balance': 1238, 'cpp10': 13, 'min_cash': 3}, {'points': 1238, 'cash': 894}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 502}, {'points': 7915, 'cash': 502}], ['balance limits', {'price': 10000, 'balance': 3002, 'cpp10': 10, 'min_cash': 100}, {'points': 3002, 'cash': 6998}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 3}, {'points': 7137, 'cash': 4}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 402}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 980}, {'points': 8, 'cash': 980}], ['odd credit', {'price': 2503, 'balance': 1239, 'cpp10': 13, 'min_cash': 3}, {'points': 1239, 'cash': 893}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 503}, {'points': 7914, 'cash': 504}], ['balance limits', {'price': 10000, 'balance': 3003, 'cpp10': 10, 'min_cash': 100}, {'points': 3003, 'cash': 6997}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 4}, {'points': 7135, 'cash': 5}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 403}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 970}, {'points': 12, 'cash': 970}], ['odd credit', {'price': 2503, 'balance': 1240, 'cpp10': 13, 'min_cash': 3}, {'points': 1240, 'cash': 891}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 504}, {'points': 7913, 'cash': 505}], ['balance limits', {'price': 10000, 'balance': 3004, 'cpp10': 10, 'min_cash': 100}, {'points': 3004, 'cash': 6996}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 5}, {'points': 7134, 'cash': 6}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 404}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 960}, {'points': 16, 'cash': 960}], ['odd credit', {'price': 2503, 'balance': 1241, 'cpp10': 13, 'min_cash': 3}, {'points': 1241, 'cash': 890}]], [['points cover most', {'price': 10000, 'balance': 50000, 'cpp10': 12, 'min_cash': 505}, {'points': 7912, 'cash': 506}], ['balance limits', {'price': 10000, 'balance': 3005, 'cpp10': 10, 'min_cash': 100}, {'points': 3005, 'cash': 6995}], ['fractional value', {'price': 4999, 'balance': 99999, 'cpp10': 7, 'min_cash': 6}, {'points': 7132, 'cash': 7}], ['price below minimum cash', {'price': 300, 'balance': 1000, 'cpp10': 10, 'min_cash': 405}, {'points': 0, 'cash': 300}], ['exact minimum', {'price': 1000, 'balance': 100000, 'cpp10': 25, 'min_cash': 950}, {'points': 20, 'cash': 950}], ['odd credit', {'price': 2503, 'balance': 1242, 'cpp10': 13, 'min_cash': 3}, {'points': 1242, 'cash': 889}]]]
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
points cover most{'cash': 502, 'points': 7915}{'cash': 502, 'points': 7915}Passed
balance limits{'cash': 6999, 'points': 3001}{'cash': 6999, 'points': 3001}Passed
fractional value{'cash': 3, 'points': 7138}{'cash': 3, 'points': 7138}Passed
price below minimum cash{'cash': 300, 'points': 0}{'cash': 300, 'points': 0}Passed
exact minimum{'cash': 990, 'points': 4}{'cash': 990, 'points': 4}Passed
odd credit{'cash': 894, 'points': 1238}{'cash': 894, 'points': 1238}Passed

SHA-256 / 6a3a096f75629960c941299f5b1f3aa96e6ad7e702b531f61a3cf1fcd888a4e7

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 2026-09-29T14:46:48.677743+00:00.

Case digest / 8e514e1c07e829b9c09d14b3b6846adced3d5819cf9d9acf5ea57161f337d522