FAILURE MAP
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FA-60516 / Loyalty points ledgers / Open access

Member-to-member point transfers: fee payer · case 01

The recipient receives fewer points than were sent while the sender pays only the principal.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The fee is deducted from the credited amount instead of charged to the sender.

THE FAILURE

The fee is deducted from the credited amount instead of charged to the sender.

Unsuccessful approach: Charging the fee to both parties double collects it.

Case contract

Input {members:{id:balance}, transfers:[[from,to,pts]], fee_bp, min_transfer, annual_cap, sent_ytd}. Self transfers or unknown members are "invalid"; pts below the minimum are "below minimum"; sent_ytd + pts above annual_cap is "cap" (fees do not count toward the cap). The fee is ceil(pts*fee_bp/10000) points charged to the sender, who must hold pts + fee ("insufficient" otherwise). The recipient receives pts. Return {results (fee or reason), balances:[[id,bal]] sorted}.

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 = dict(x['members'])
    sent = dict(x['sent_ytd'])
    out = []
    for f, t, p in x['transfers']:
        if f == t or f not in bal or t not in bal:
            out.append('invalid')
            continue
        if p < x['min_transfer']:
            out.append('below minimum')
            continue
        if sent.get(f, 0) + p > x['annual_cap']:
            out.append('cap')
            continue
        fee = (p * x['fee_bp'] + 9999) // 10000
        if bal[f] < p + fee:
            out.append('insufficient')
            continue
        bal[f] -= p
        bal[t] += p - fee
        sent[f] = sent.get(f, 0) + p
        out.append(fee)
    return {'results': out, 'balances': [[k, bal[k]] for k in sorted(bal)]}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2000]], 'sent_ytd': {}}, {'results': [50], 'balances': [['a', 2950], ['b', 2100]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1001]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1013], ['b', 1001]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14999}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5001]], 'sent_ytd': {'a': 14999}}, {'results': [126], 'balances': [['a', 84873], ['b', 5001]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1004], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48962], ['b', 1011]]}], ['fees do not use cap', {'fee_bp': 501, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [501, 501], 'balances': [['a', 68998], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2001]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2948], ['b', 2101]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1002]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1012], ['b', 1002]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14998}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5002]], 'sent_ytd': {'a': 14998}}, {'results': [126], 'balances': [['a', 84872], ['b', 5002]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1007], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48959], ['b', 1014]]}], ['fees do not use cap', {'fee_bp': 502, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [502, 502], 'balances': [['a', 68996], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2002]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2947], ['b', 2102]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1003]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1011], ['b', 1003]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14997}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5003]], 'sent_ytd': {'a': 14997}}, {'results': [126], 'balances': [['a', 84871], ['b', 5003]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1010], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48956], ['b', 1017]]}], ['fees do not use cap', {'fee_bp': 503, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [503, 503], 'balances': [['a', 68994], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2003]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2946], ['b', 2103]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1004]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1010], ['b', 1004]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14996}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5004]], 'sent_ytd': {'a': 14996}}, {'results': [126], 'balances': [['a', 84870], ['b', 5004]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1013], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48953], ['b', 1020]]}], ['fees do not use cap', {'fee_bp': 504, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [504, 504], 'balances': [['a', 68992], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2004]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2945], ['b', 2104]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1005]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1009], ['b', 1005]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14995}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5005]], 'sent_ytd': {'a': 14995}}, {'results': [126], 'balances': [['a', 84869], ['b', 5005]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1016], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48950], ['b', 1023]]}], ['fees do not use cap', {'fee_bp': 505, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [505, 505], 'balances': [['a', 68990], ['c', 20000]]}]]]
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 transfer{'balances': [['a', 3000], ['b', 2050]], 'results': [50]}{'balances': [['a', 2950], ['b', 2100]], 'results': [50]}Failed
fee needs balance{'balances': [['a', 1039], ['b', 975]], 'results': ['insufficient', 26]}{'balances': [['a', 1013], ['b', 1001]], 'results': ['insufficient', 26]}Failed
cap edge{'balances': [['a', 85000], ['b', 4875]], 'results': [125]}{'balances': [['a', 84875], ['b', 5000]], 'results': [125]}Failed
cap exact{'balances': [['a', 84999], ['b', 4875]], 'results': [126]}{'balances': [['a', 84873], ['b', 5001]], 'results': [126]}Failed
invalid parties{'balances': [['a', 5000], ['b', 0]], 'results': ['invalid', 'invalid', 'below minimum']}{'balances': [['a', 5000], ['b', 0]], 'results': ['invalid', 'invalid', 'below minimum']}Passed
fee rounding{'balances': [['a', 48996], ['b', 977]], 'results': [34, 'insufficient']}{'balances': [['a', 48962], ['b', 1011]], 'results': [34, 'insufficient']}Failed
fees do not use cap{'balances': [['a', 70000], ['c', 18998]], 'results': [501, 501]}{'balances': [['a', 68998], ['c', 20000]], 'results': [501, 501]}Failed

SHA-256 / bd36527df5f885fdbf02b75d7e95dfd1fc544af4f3a0e71f13b874b60a1be10e

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    bal = dict(x['members'])
    sent = dict(x['sent_ytd'])
    out = []
    for f, t, p in x['transfers']:
        if f == t or f not in bal or t not in bal:
            out.append('invalid')
            continue
        if p < x['min_transfer']:
            out.append('below minimum')
            continue
        if sent.get(f, 0) + p > x['annual_cap']:
            out.append('cap')
            continue
        fee = (p * x['fee_bp'] + 9999) // 10000
        if bal[f] < p + fee:
            out.append('insufficient')
            continue
        bal[f] -= p + fee
        bal[t] += p - fee
        sent[f] = sent.get(f, 0) + p
        out.append(fee)
    return {'results': out, 'balances': [[k, bal[k]] for k in sorted(bal)]}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2000]], 'sent_ytd': {}}, {'results': [50], 'balances': [['a', 2950], ['b', 2100]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1001]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1013], ['b', 1001]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14999}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5001]], 'sent_ytd': {'a': 14999}}, {'results': [126], 'balances': [['a', 84873], ['b', 5001]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1004], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48962], ['b', 1011]]}], ['fees do not use cap', {'fee_bp': 501, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [501, 501], 'balances': [['a', 68998], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2001]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2948], ['b', 2101]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1002]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1012], ['b', 1002]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14998}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5002]], 'sent_ytd': {'a': 14998}}, {'results': [126], 'balances': [['a', 84872], ['b', 5002]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1007], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48959], ['b', 1014]]}], ['fees do not use cap', {'fee_bp': 502, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [502, 502], 'balances': [['a', 68996], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2002]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2947], ['b', 2102]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1003]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1011], ['b', 1003]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14997}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5003]], 'sent_ytd': {'a': 14997}}, {'results': [126], 'balances': [['a', 84871], ['b', 5003]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1010], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48956], ['b', 1017]]}], ['fees do not use cap', {'fee_bp': 503, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [503, 503], 'balances': [['a', 68994], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2003]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2946], ['b', 2103]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1004]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1010], ['b', 1004]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14996}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5004]], 'sent_ytd': {'a': 14996}}, {'results': [126], 'balances': [['a', 84870], ['b', 5004]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1013], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48953], ['b', 1020]]}], ['fees do not use cap', {'fee_bp': 504, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [504, 504], 'balances': [['a', 68992], ['c', 20000]]}]], [['normal transfer', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 100}, 'transfers': [['a', 'b', 2004]], 'sent_ytd': {}}, {'results': [51], 'balances': [['a', 2945], ['b', 2104]]}], ['fee needs balance', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 2040, 'b': 0}, 'transfers': [['a', 'b', 2000], ['a', 'b', 1005]], 'sent_ytd': {}}, {'results': ['insufficient', 26], 'balances': [['a', 1009], ['b', 1005]]}], ['cap edge', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5000]], 'sent_ytd': {'a': 14995}}, {'results': [125], 'balances': [['a', 84875], ['b', 5000]]}], ['cap exact', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'b': 0}, 'transfers': [['a', 'b', 5005]], 'sent_ytd': {'a': 14995}}, {'results': [126], 'balances': [['a', 84869], ['b', 5005]]}], ['invalid parties', {'fee_bp': 250, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 5000, 'b': 0}, 'transfers': [['a', 'a', 1000], ['a', 'z', 1000], ['a', 'b', 999]], 'sent_ytd': {}}, {'results': ['invalid', 'invalid', 'below minimum'], 'balances': [['a', 5000], ['b', 0]]}], ['fee rounding', {'fee_bp': 333, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 50000, 'b': 7}, 'transfers': [['a', 'b', 1016], ['b', 'a', 1000]], 'sent_ytd': {}}, {'results': [34, 'insufficient'], 'balances': [['a', 48950], ['b', 1023]]}], ['fees do not use cap', {'fee_bp': 505, 'min_transfer': 1000, 'annual_cap': 20000, 'members': {'a': 90000, 'c': 0}, 'transfers': [['a', 'c', 10000], ['a', 'c', 10000]], 'sent_ytd': {'a': 0}}, {'results': [505, 505], 'balances': [['a', 68990], ['c', 20000]]}]]]
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 transfer{'balances': [['a', 2950], ['b', 2050]], 'results': [50]}{'balances': [['a', 2950], ['b', 2100]], 'results': [50]}Failed
fee needs balance{'balances': [['a', 1013], ['b', 975]], 'results': ['insufficient', 26]}{'balances': [['a', 1013], ['b', 1001]], 'results': ['insufficient', 26]}Failed
cap edge{'balances': [['a', 84875], ['b', 4875]], 'results': [125]}{'balances': [['a', 84875], ['b', 5000]], 'results': [125]}Failed
cap exact{'balances': [['a', 84873], ['b', 4875]], 'results': [126]}{'balances': [['a', 84873], ['b', 5001]], 'results': [126]}Failed
invalid parties{'balances': [['a', 5000], ['b', 0]], 'results': ['invalid', 'invalid', 'below minimum']}{'balances': [['a', 5000], ['b', 0]], 'results': ['invalid', 'invalid', 'below minimum']}Passed
fee rounding{'balances': [['a', 48962], ['b', 977]], 'results': [34, 'insufficient']}{'balances': [['a', 48962], ['b', 1011]], 'results': [34, 'insufficient']}Failed
fees do not use cap{'balances': [['a', 68998], ['c', 18998]], 'results': [501, 501]}{'balances': [['a', 68998], ['c', 20000]], 'results': [501, 501]}Failed

SHA-256 / 7d3f957b6fa9f1ee43e1e72f04f9be86bade1c98fdc77fefee48d59958cbaf50

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This mechanism has 7 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.

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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 2026-09-29T14:46:46.425202+00:00.

Case digest / e87507023c97ecf8caf4b55b5d1d3f1907f20d89c34d2a1898fde37da5d027ee