FAILURE MAP
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FA-58261 / Double-entry ledger accounting / Open access

Receivables subledger tie-out: credit balances in total · case 01

Customer overpayments create a phantom reconciling difference.

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

ROOT CAUSE

Only debit customer balances are summed into the subledger total.

THE FAILURE

Only debit customer balances are summed into the subledger total.

Unsuccessful approach: Summing absolute values adds overpayments instead of netting them.

Case contract

x = {'control': [[day, amount]], 'sub': {customer: [[day, amount]]}, 'as_of': day}. Only rows dated on or before as_of count. The subledger total nets every customer balance, including credit (negative) balances. Return {'control', 'subledger', 'difference': control - subledger, 'credit_balances': customers with negative balance sorted by name, 'open_customers': count of nonzero balances}.

Why this case matters

Ledger software must keep debits equal to credits and apply normal-balance, period and cutoff rules exactly; small sign or boundary slips silently misstate financial statements.

1 / The failure

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

N = 1
observations = []
def solve(x):
    cut = x['as_of']
    control = sum(a for d, a in x['control'] if d <= cut)
    per = {}
    for cust, rows in x['sub'].items():
        per[cust] = sum(a for d, a in rows if d <= cut)
    sub_total = sum(v for v in per.values() if v > 0)
    credit = sorted(c for c, v in per.items() if v < 0)
    return {'control': control, 'subledger': sub_total, 'difference': control - sub_total, 'credit_balances': credit, 'open_customers': sum(1 for v in per.values() if v != 0)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: credit balances in total', {'control': [[9, 250], [10, 100], [11, 400]], 'sub': {'dyna': [[1, 400], [11, 400]], 'acme': [[1, -300], [10, 250], [1, -80]], 'bolt': [[1, -80]]}, 'as_of': 10}, {'control': 350, 'subledger': 190, 'difference': 160, 'credit_balances': ['acme', 'bolt'], 'open_customers': 3}], ['control 1', {'control': [[5, 100], [19, -80], [21, -80]], 'sub': {'bolt': [[5, -80], [1, 250], [5, -80]], 'acme': [[21, 100]], 'dyna': [[20, 400], [1, 250], [20, 100]], 'crux': [[20, 400], [5, 100]]}, 'as_of': 20}, {'control': 20, 'subledger': 1340, 'difference': -1320, 'credit_balances': [], 'open_customers': 3}], ['control 2', {'control': [[21, 400], [5, 250], [19, 250], [20, 400], [19, -80]], 'sub': {'bolt': [[5, 250]]}, 'as_of': 20}, {'control': 820, 'subledger': 250, 'difference': 570, 'credit_balances': [], 'open_customers': 1}], ['control 3', {'control': [[9, 100], [10, 100], [9, 400], [10, 100], [1, 250], [9, 250]], 'sub': {'dyna': [[1, 400], [11, 400], [1, 400]]}, 'as_of': 10}, {'control': 1200, 'subledger': 800, 'difference': 400, 'credit_balances': [], 'open_customers': 1}], ['control 4', {'control': [[10, 400], [10, 100], [9, 250], [11, 250], [1, 400]], 'sub': {'bolt': [[11, 400], [10, 400], [5, 100]]}, 'as_of': 10}, {'control': 1150, 'subledger': 500, 'difference': 650, 'credit_balances': [], 'open_customers': 1}], ['control 5', {'control': [[5, 400], [1, 250], [9, -80], [5, -80], [5, 250]], 'sub': {'acme': [[5, 250], [11, 100]], 'crux': [[5, 400]], 'dyna': [[5, 250]]}, 'as_of': 10}, {'control': 740, 'subledger': 900, 'difference': -160, 'credit_balances': [], 'open_customers': 3}], ['control 6', {'control': [[11, 250], [1, -80], [11, 400], [1, -80]], 'sub': {'acme': [[1, 250], [1, -80], [11, 250]], 'bolt': [[11, 100]], 'dyna': [[11, -80]]}, 'as_of': 10}, {'control': -160, 'subledger': 170, 'difference': -330, 'credit_balances': [], 'open_customers': 1}]], [['regression: credit balances in total', {'control': [[31, 400], [30, 250]], 'sub': {'bolt': [[1, 400], [1, 400], [5, -300]], 'acme': [[32, 250]], 'crux': [[5, -300], [31, 400], [5, -300]]}, 'as_of': 31}, {'control': 650, 'subledger': 300, 'difference': 350, 'credit_balances': ['crux'], 'open_customers': 2}], ['control 1', {'control': [[1, 400], [11, 250]], 'sub': {'dyna': [[1, 250]], 'crux': [[1, 250], [1, 250], [1, 100]], 'acme': [[10, 250], [1, 250], [11, 250]], 'bolt': [[11, 250], [5, 400]]}, 'as_of': 10}, {'control': 400, 'subledger': 1750, 'difference': -1350, 'credit_balances': [], 'open_customers': 4}], ['control 2', {'control': [[20, 250], [19, 100], [5, 400]], 'sub': {'bolt': [[20, 250]], 'acme': [[1, -300], [1, 100], [1, 250]]}, 'as_of': 20}, {'control': 750, 'subledger': 300, 'difference': 450, 'credit_balances': [], 'open_customers': 2}], ['control 3', {'control': [[5, 400], [20, -80], [19, 250]], 'sub': {'acme': [[21, 250]], 'bolt': [[20, 250], [1, -80], [1, -80]], 'dyna': [[21, -80], [20, 100]], 'crux': [[5, 400], [21, 400], [20, -300]]}, 'as_of': 20}, {'control': 570, 'subledger': 290, 'difference': 280, 'credit_balances': [], 'open_customers': 3}], ['control 4', {'control': [[10, 250], [9, -80], [1, 250], [1, 100]], 'sub': {'dyna': [[1, 400], [10, 400]], 'acme': [[10, 250], [5, 400], [11, -300]], 'crux': [[11, 250], [1, 400], [5, -300]], 'bolt': [[5, 250]]}, 'as_of': 10}, {'control': 520, 'subledger': 1800, 'difference': -1280, 'credit_balances': [], 'open_customers': 4}], ['control 5', {'control': [[5, -80], [19, 400], [1, -80]], 'sub': {'crux': [[21, -300], [21, 400]], 'bolt': [[1, 250], [21, 250]], 'dyna': [[21, -300], [20, 250], [5, 250]]}, 'as_of': 20}, {'control': 240, 'subledger': 750, 'difference': -510, 'credit_balances': [], 'open_customers': 2}], ['control 6', {'control': [[10, 100], [5, 250], [5, 400], [11, -80], [1, 400], [9, 400]], 'sub': {'dyna': [[5, 250]]}, 'as_of': 10}, {'control': 1550, 'subledger': 250, 'difference': 1300, 'credit_balances': [], 'open_customers': 1}]], [['regression: credit balances in total', {'control': [[9, 250], [11, 100], [11, -80], [11, 250]], 'sub': {'dyna': [[1, 250], [11, 400], [10, -80]], 'acme': [[11, -300], [1, 400], [1, 400]], 'bolt': [[1, -300]]}, 'as_of': 10}, {'control': 250, 'subledger': 670, 'difference': -420, 'credit_balances': ['bolt'], 'open_customers': 3}], ['control 1', {'control': [[1, -80], [1, 100], [32, 400], [31, 250]], 'sub': {'bolt': [[1, 250]]}, 'as_of': 31}, {'control': 270, 'subledger': 250, 'difference': 20, 'credit_balances': [], 'open_customers': 1}], ['control 2', {'control': [[5, 400], [1, 250], [5, -80], [5, 250], [11, -80], [1, 400]], 'sub': {'dyna': [[11, 100]], 'acme': [[5, 400], [1, 100]], 'crux': [[5, 400], [5, -300]]}, 'as_of': 10}, {'control': 1220, 'subledger': 600, 'difference': 620, 'credit_balances': [], 'open_customers': 2}], ['control 3', {'control': [[9, 250], [1, 400], [11, 100]], 'sub': {'crux': [[5, -80], [1, 250], [1, 250]]}, 'as_of': 10}, {'control': 650, 'subledger': 420, 'difference': 230, 'credit_balances': [], 'open_customers': 1}], ['control 4', {'control': [[5, 250], [30, 400], [30, -80], [1, -80], [5, 250]], 'sub': {'bolt': [[5, 250]], 'acme': [[1, 250]], 'dyna': [[31, 400]]}, 'as_of': 31}, {'control': 740, 'subledger': 900, 'difference': -160, 'credit_balances': [], 'open_customers': 3}], ['control 5', {'control': [[19, 100], [21, 250], [20, -80], [20, -80], [19, 400], [21, 100]], 'sub': {'dyna': [[21, 100]], 'acme': [[21, 100], [21, 400], [20, 250]], 'crux': [[20, -80], [21, -80], [5, 250]]}, 'as_of': 20}, {'control': 340, 'subledger': 420, 'difference': -80, 'credit_balances': [], 'open_customers': 2}], ['control 6', {'control': [[31, -80], [32, 400], [31, -80], [5, -80], [31, 250]], 'sub': {'dyna': [[1, 400], [1, 250]], 'acme': [[32, -80], [31, 100]]}, 'as_of': 31}, {'control': 10, 'subledger': 750, 'difference': -740, 'credit_balances': [], 'open_customers': 2}]], [['regression: credit balances in total', {'control': [[31, -80], [5, 100], [31, 100]], 'sub': {'crux': [[32, 250]], 'dyna': [[32, 250]], 'acme': [[1, -300], [32, 250]]}, 'as_of': 31}, {'control': 120, 'subledger': -300, 'difference': 420, 'credit_balances': ['acme'], 'open_customers': 1}], ['control 1', {'control': [[20, -80], [21, 100]], 'sub': {'dyna': [[1, -80], [20, 250]], 'bolt': [[1, -300], [20, 400], [21, -300]]}, 'as_of': 20}, {'control': -80, 'subledger': 270, 'difference': -350, 'credit_balances': [], 'open_customers': 2}], ['control 2', {'control': [[1, -80], [20, -80], [19, -80], [19, -80], [21, 400]], 'sub': {'acme': [[21, 250]]}, 'as_of': 20}, {'control': -320, 'subledger': 0, 'difference': -320, 'credit_balances': [], 'open_customers': 0}], ['control 3', {'control': [[5, 250], [5, 400], [1, -80], [31, 100], [30, 100]], 'sub': {'dyna': [[32, -300]], 'crux': [[5, 250], [1, 250]], 'acme': [[31, 400]]}, 'as_of': 31}, {'control': 770, 'subledger': 900, 'difference': -130, 'credit_balances': [], 'open_customers': 2}], ['control 4', {'control': [[31, 250], [1, -80], [5, 100], [31, 250], [5, 100]], 'sub': {'crux': [[32, -300], [1, 250]]}, 'as_of': 31}, {'control': 620, 'subledger': 250, 'difference': 370, 'credit_balances': [], 'open_customers': 1}], ['control 5', {'control': [[31, 250], [5, -80], [1, 400], [32, 400], [1, 400]], 'sub': {'crux': [[5, 250], [1, 400]]}, 'as_of': 31}, {'control': 970, 'subledger': 650, 'difference': 320, 'credit_balances': [], 'open_customers': 1}], ['control 6', {'control': [[1, 100], [11, 100], [1, 100], [9, 400], [9, 100], [9, 100]], 'sub': {'dyna': [[1, 100], [5, 100]]}, 'as_of': 10}, {'control': 800, 'subledger': 200, 'difference': 600, 'credit_balances': [], 'open_customers': 1}]], [['regression: credit balances in total', {'control': [[5, 100], [5, 250], [19, -80], [21, 250], [21, 250]], 'sub': {'crux': [[20, -80], [20, -80]], 'acme': [[21, 100]]}, 'as_of': 20}, {'control': 270, 'subledger': -160, 'difference': 430, 'credit_balances': ['crux'], 'open_customers': 1}], ['control 1', {'control': [[1, -80], [5, 100], [20, 400], [19, 250], [1, 250]], 'sub': {'crux': [[20, 250], [20, -80], [20, 250]]}, 'as_of': 20}, {'control': 920, 'subledger': 420, 'difference': 500, 'credit_balances': [], 'open_customers': 1}], ['control 2', {'control': [[9, -80], [11, 400]], 'sub': {'bolt': [[5, 100], [5, 250]], 'acme': [[11, 100], [11, -80], [10, 250]]}, 'as_of': 10}, {'control': -80, 'subledger': 600, 'difference': -680, 'credit_balances': [], 'open_customers': 2}], ['control 3', {'control': [[1, 100], [1, 250], [5, 250], [1, 100], [1, 400], [5, -80]], 'sub': {'bolt': [[10, -80], [10, 400]], 'crux': [[1, 250], [10, 250]]}, 'as_of': 10}, {'control': 1020, 'subledger': 820, 'difference': 200, 'credit_balances': [], 'open_customers': 2}], ['control 4', {'control': [[32, 250], [1, 100], [32, 100], [31, 100], [1, -80]], 'sub': {'dyna': [[5, 100]], 'acme': [[5, 400], [5, -80]], 'crux': [[32, -80]], 'bolt': [[32, -80]]}, 'as_of': 31}, {'control': 120, 'subledger': 420, 'difference': -300, 'credit_balances': [], 'open_customers': 2}], ['control 5', {'control': [[5, 400], [11, 100]], 'sub': {'bolt': [[5, 400], [1, -80]], 'acme': [[5, 400], [1, 100], [5, -300]], 'dyna': [[1, 100]]}, 'as_of': 10}, {'control': 400, 'subledger': 620, 'difference': -220, 'credit_balances': [], 'open_customers': 3}], ['control 6', {'control': [[31, 400], [32, 400]], 'sub': {'acme': [[1, -80], [31, 400]]}, 'as_of': 31}, {'control': 400, 'subledger': 320, 'difference': 80, 'credit_balances': [], 'open_customers': 1}]]]
for label, args, expected in fixtures[N-1]:
    try:
        actual = solve(args)
    except Exception as exc:
        actual = 'raised ' + type(exc).__name__
    check(label, actual, 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
regression: credit balances in total{'control': 350, 'credit_balances': ['acme', 'bolt'], 'difference': -50, 'open_customers': 3, 'subledger': 400}{'control': 350, 'credit_balances': ['acme', 'bolt'], 'difference': 160, 'open_customers': 3, 'subledger': 190}Failed
control 1{'control': 20, 'credit_balances': [], 'difference': -1320, 'open_customers': 3, 'subledger': 1340}{'control': 20, 'credit_balances': [], 'difference': -1320, 'open_customers': 3, 'subledger': 1340}Passed
control 2{'control': 820, 'credit_balances': [], 'difference': 570, 'open_customers': 1, 'subledger': 250}{'control': 820, 'credit_balances': [], 'difference': 570, 'open_customers': 1, 'subledger': 250}Passed
control 3{'control': 1200, 'credit_balances': [], 'difference': 400, 'open_customers': 1, 'subledger': 800}{'control': 1200, 'credit_balances': [], 'difference': 400, 'open_customers': 1, 'subledger': 800}Passed
control 4{'control': 1150, 'credit_balances': [], 'difference': 650, 'open_customers': 1, 'subledger': 500}{'control': 1150, 'credit_balances': [], 'difference': 650, 'open_customers': 1, 'subledger': 500}Passed
control 5{'control': 740, 'credit_balances': [], 'difference': -160, 'open_customers': 3, 'subledger': 900}{'control': 740, 'credit_balances': [], 'difference': -160, 'open_customers': 3, 'subledger': 900}Passed
control 6{'control': -160, 'credit_balances': [], 'difference': -330, 'open_customers': 1, 'subledger': 170}{'control': -160, 'credit_balances': [], 'difference': -330, 'open_customers': 1, 'subledger': 170}Passed

SHA-256 / 5c6b3b4d54aa4d981030d30db484514b6395e8f75047272c8a9c087a51cad4c2

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    cut = x['as_of']
    control = sum(a for d, a in x['control'] if d <= cut)
    per = {}
    for cust, rows in x['sub'].items():
        per[cust] = sum(a for d, a in rows if d <= cut)
    sub_total = sum(abs(v) for v in per.values())
    credit = sorted(c for c, v in per.items() if v < 0)
    return {'control': control, 'subledger': sub_total, 'difference': control - sub_total, 'credit_balances': credit, 'open_customers': sum(1 for v in per.values() if v != 0)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: credit balances in total', {'control': [[9, 250], [10, 100], [11, 400]], 'sub': {'dyna': [[1, 400], [11, 400]], 'acme': [[1, -300], [10, 250], [1, -80]], 'bolt': [[1, -80]]}, 'as_of': 10}, {'control': 350, 'subledger': 190, 'difference': 160, 'credit_balances': ['acme', 'bolt'], 'open_customers': 3}], ['control 1', {'control': [[5, 100], [19, -80], [21, -80]], 'sub': {'bolt': [[5, -80], [1, 250], [5, -80]], 'acme': [[21, 100]], 'dyna': [[20, 400], [1, 250], [20, 100]], 'crux': [[20, 400], [5, 100]]}, 'as_of': 20}, {'control': 20, 'subledger': 1340, 'difference': -1320, 'credit_balances': [], 'open_customers': 3}], ['control 2', {'control': [[21, 400], [5, 250], [19, 250], [20, 400], [19, -80]], 'sub': {'bolt': [[5, 250]]}, 'as_of': 20}, {'control': 820, 'subledger': 250, 'difference': 570, 'credit_balances': [], 'open_customers': 1}], ['control 3', {'control': [[9, 100], [10, 100], [9, 400], [10, 100], [1, 250], [9, 250]], 'sub': {'dyna': [[1, 400], [11, 400], [1, 400]]}, 'as_of': 10}, {'control': 1200, 'subledger': 800, 'difference': 400, 'credit_balances': [], 'open_customers': 1}], ['control 4', {'control': [[10, 400], [10, 100], [9, 250], [11, 250], [1, 400]], 'sub': {'bolt': [[11, 400], [10, 400], [5, 100]]}, 'as_of': 10}, {'control': 1150, 'subledger': 500, 'difference': 650, 'credit_balances': [], 'open_customers': 1}], ['control 5', {'control': [[5, 400], [1, 250], [9, -80], [5, -80], [5, 250]], 'sub': {'acme': [[5, 250], [11, 100]], 'crux': [[5, 400]], 'dyna': [[5, 250]]}, 'as_of': 10}, {'control': 740, 'subledger': 900, 'difference': -160, 'credit_balances': [], 'open_customers': 3}], ['control 6', {'control': [[11, 250], [1, -80], [11, 400], [1, -80]], 'sub': {'acme': [[1, 250], [1, -80], [11, 250]], 'bolt': [[11, 100]], 'dyna': [[11, -80]]}, 'as_of': 10}, {'control': -160, 'subledger': 170, 'difference': -330, 'credit_balances': [], 'open_customers': 1}]], [['regression: credit balances in total', {'control': [[31, 400], [30, 250]], 'sub': {'bolt': [[1, 400], [1, 400], [5, -300]], 'acme': [[32, 250]], 'crux': [[5, -300], [31, 400], [5, -300]]}, 'as_of': 31}, {'control': 650, 'subledger': 300, 'difference': 350, 'credit_balances': ['crux'], 'open_customers': 2}], ['control 1', {'control': [[1, 400], [11, 250]], 'sub': {'dyna': [[1, 250]], 'crux': [[1, 250], [1, 250], [1, 100]], 'acme': [[10, 250], [1, 250], [11, 250]], 'bolt': [[11, 250], [5, 400]]}, 'as_of': 10}, {'control': 400, 'subledger': 1750, 'difference': -1350, 'credit_balances': [], 'open_customers': 4}], ['control 2', {'control': [[20, 250], [19, 100], [5, 400]], 'sub': {'bolt': [[20, 250]], 'acme': [[1, -300], [1, 100], [1, 250]]}, 'as_of': 20}, {'control': 750, 'subledger': 300, 'difference': 450, 'credit_balances': [], 'open_customers': 2}], ['control 3', {'control': [[5, 400], [20, -80], [19, 250]], 'sub': {'acme': [[21, 250]], 'bolt': [[20, 250], [1, -80], [1, -80]], 'dyna': [[21, -80], [20, 100]], 'crux': [[5, 400], [21, 400], [20, -300]]}, 'as_of': 20}, {'control': 570, 'subledger': 290, 'difference': 280, 'credit_balances': [], 'open_customers': 3}], ['control 4', {'control': [[10, 250], [9, -80], [1, 250], [1, 100]], 'sub': {'dyna': [[1, 400], [10, 400]], 'acme': [[10, 250], [5, 400], [11, -300]], 'crux': [[11, 250], [1, 400], [5, -300]], 'bolt': [[5, 250]]}, 'as_of': 10}, {'control': 520, 'subledger': 1800, 'difference': -1280, 'credit_balances': [], 'open_customers': 4}], ['control 5', {'control': [[5, -80], [19, 400], [1, -80]], 'sub': {'crux': [[21, -300], [21, 400]], 'bolt': [[1, 250], [21, 250]], 'dyna': [[21, -300], [20, 250], [5, 250]]}, 'as_of': 20}, {'control': 240, 'subledger': 750, 'difference': -510, 'credit_balances': [], 'open_customers': 2}], ['control 6', {'control': [[10, 100], [5, 250], [5, 400], [11, -80], [1, 400], [9, 400]], 'sub': {'dyna': [[5, 250]]}, 'as_of': 10}, {'control': 1550, 'subledger': 250, 'difference': 1300, 'credit_balances': [], 'open_customers': 1}]], [['regression: credit balances in total', {'control': [[9, 250], [11, 100], [11, -80], [11, 250]], 'sub': {'dyna': [[1, 250], [11, 400], [10, -80]], 'acme': [[11, -300], [1, 400], [1, 400]], 'bolt': [[1, -300]]}, 'as_of': 10}, {'control': 250, 'subledger': 670, 'difference': -420, 'credit_balances': ['bolt'], 'open_customers': 3}], ['control 1', {'control': [[1, -80], [1, 100], [32, 400], [31, 250]], 'sub': {'bolt': [[1, 250]]}, 'as_of': 31}, {'control': 270, 'subledger': 250, 'difference': 20, 'credit_balances': [], 'open_customers': 1}], ['control 2', {'control': [[5, 400], [1, 250], [5, -80], [5, 250], [11, -80], [1, 400]], 'sub': {'dyna': [[11, 100]], 'acme': [[5, 400], [1, 100]], 'crux': [[5, 400], [5, -300]]}, 'as_of': 10}, {'control': 1220, 'subledger': 600, 'difference': 620, 'credit_balances': [], 'open_customers': 2}], ['control 3', {'control': [[9, 250], [1, 400], [11, 100]], 'sub': {'crux': [[5, -80], [1, 250], [1, 250]]}, 'as_of': 10}, {'control': 650, 'subledger': 420, 'difference': 230, 'credit_balances': [], 'open_customers': 1}], ['control 4', {'control': [[5, 250], [30, 400], [30, -80], [1, -80], [5, 250]], 'sub': {'bolt': [[5, 250]], 'acme': [[1, 250]], 'dyna': [[31, 400]]}, 'as_of': 31}, {'control': 740, 'subledger': 900, 'difference': -160, 'credit_balances': [], 'open_customers': 3}], ['control 5', {'control': [[19, 100], [21, 250], [20, -80], [20, -80], [19, 400], [21, 100]], 'sub': {'dyna': [[21, 100]], 'acme': [[21, 100], [21, 400], [20, 250]], 'crux': [[20, -80], [21, -80], [5, 250]]}, 'as_of': 20}, {'control': 340, 'subledger': 420, 'difference': -80, 'credit_balances': [], 'open_customers': 2}], ['control 6', {'control': [[31, -80], [32, 400], [31, -80], [5, -80], [31, 250]], 'sub': {'dyna': [[1, 400], [1, 250]], 'acme': [[32, -80], [31, 100]]}, 'as_of': 31}, {'control': 10, 'subledger': 750, 'difference': -740, 'credit_balances': [], 'open_customers': 2}]], [['regression: credit balances in total', {'control': [[31, -80], [5, 100], [31, 100]], 'sub': {'crux': [[32, 250]], 'dyna': [[32, 250]], 'acme': [[1, -300], [32, 250]]}, 'as_of': 31}, {'control': 120, 'subledger': -300, 'difference': 420, 'credit_balances': ['acme'], 'open_customers': 1}], ['control 1', {'control': [[20, -80], [21, 100]], 'sub': {'dyna': [[1, -80], [20, 250]], 'bolt': [[1, -300], [20, 400], [21, -300]]}, 'as_of': 20}, {'control': -80, 'subledger': 270, 'difference': -350, 'credit_balances': [], 'open_customers': 2}], ['control 2', {'control': [[1, -80], [20, -80], [19, -80], [19, -80], [21, 400]], 'sub': {'acme': [[21, 250]]}, 'as_of': 20}, {'control': -320, 'subledger': 0, 'difference': -320, 'credit_balances': [], 'open_customers': 0}], ['control 3', {'control': [[5, 250], [5, 400], [1, -80], [31, 100], [30, 100]], 'sub': {'dyna': [[32, -300]], 'crux': [[5, 250], [1, 250]], 'acme': [[31, 400]]}, 'as_of': 31}, {'control': 770, 'subledger': 900, 'difference': -130, 'credit_balances': [], 'open_customers': 2}], ['control 4', {'control': [[31, 250], [1, -80], [5, 100], [31, 250], [5, 100]], 'sub': {'crux': [[32, -300], [1, 250]]}, 'as_of': 31}, {'control': 620, 'subledger': 250, 'difference': 370, 'credit_balances': [], 'open_customers': 1}], ['control 5', {'control': [[31, 250], [5, -80], [1, 400], [32, 400], [1, 400]], 'sub': {'crux': [[5, 250], [1, 400]]}, 'as_of': 31}, {'control': 970, 'subledger': 650, 'difference': 320, 'credit_balances': [], 'open_customers': 1}], ['control 6', {'control': [[1, 100], [11, 100], [1, 100], [9, 400], [9, 100], [9, 100]], 'sub': {'dyna': [[1, 100], [5, 100]]}, 'as_of': 10}, {'control': 800, 'subledger': 200, 'difference': 600, 'credit_balances': [], 'open_customers': 1}]], [['regression: credit balances in total', {'control': [[5, 100], [5, 250], [19, -80], [21, 250], [21, 250]], 'sub': {'crux': [[20, -80], [20, -80]], 'acme': [[21, 100]]}, 'as_of': 20}, {'control': 270, 'subledger': -160, 'difference': 430, 'credit_balances': ['crux'], 'open_customers': 1}], ['control 1', {'control': [[1, -80], [5, 100], [20, 400], [19, 250], [1, 250]], 'sub': {'crux': [[20, 250], [20, -80], [20, 250]]}, 'as_of': 20}, {'control': 920, 'subledger': 420, 'difference': 500, 'credit_balances': [], 'open_customers': 1}], ['control 2', {'control': [[9, -80], [11, 400]], 'sub': {'bolt': [[5, 100], [5, 250]], 'acme': [[11, 100], [11, -80], [10, 250]]}, 'as_of': 10}, {'control': -80, 'subledger': 600, 'difference': -680, 'credit_balances': [], 'open_customers': 2}], ['control 3', {'control': [[1, 100], [1, 250], [5, 250], [1, 100], [1, 400], [5, -80]], 'sub': {'bolt': [[10, -80], [10, 400]], 'crux': [[1, 250], [10, 250]]}, 'as_of': 10}, {'control': 1020, 'subledger': 820, 'difference': 200, 'credit_balances': [], 'open_customers': 2}], ['control 4', {'control': [[32, 250], [1, 100], [32, 100], [31, 100], [1, -80]], 'sub': {'dyna': [[5, 100]], 'acme': [[5, 400], [5, -80]], 'crux': [[32, -80]], 'bolt': [[32, -80]]}, 'as_of': 31}, {'control': 120, 'subledger': 420, 'difference': -300, 'credit_balances': [], 'open_customers': 2}], ['control 5', {'control': [[5, 400], [11, 100]], 'sub': {'bolt': [[5, 400], [1, -80]], 'acme': [[5, 400], [1, 100], [5, -300]], 'dyna': [[1, 100]]}, 'as_of': 10}, {'control': 400, 'subledger': 620, 'difference': -220, 'credit_balances': [], 'open_customers': 3}], ['control 6', {'control': [[31, 400], [32, 400]], 'sub': {'acme': [[1, -80], [31, 400]]}, 'as_of': 31}, {'control': 400, 'subledger': 320, 'difference': 80, 'credit_balances': [], 'open_customers': 1}]]]
for label, args, expected in fixtures[N-1]:
    try:
        actual = solve(args)
    except Exception as exc:
        actual = 'raised ' + type(exc).__name__
    check(label, actual, 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
regression: credit balances in total{'control': 350, 'credit_balances': ['acme', 'bolt'], 'difference': -260, 'open_customers': 3, 'subledger': 610}{'control': 350, 'credit_balances': ['acme', 'bolt'], 'difference': 160, 'open_customers': 3, 'subledger': 190}Failed
control 1{'control': 20, 'credit_balances': [], 'difference': -1320, 'open_customers': 3, 'subledger': 1340}{'control': 20, 'credit_balances': [], 'difference': -1320, 'open_customers': 3, 'subledger': 1340}Passed
control 2{'control': 820, 'credit_balances': [], 'difference': 570, 'open_customers': 1, 'subledger': 250}{'control': 820, 'credit_balances': [], 'difference': 570, 'open_customers': 1, 'subledger': 250}Passed
control 3{'control': 1200, 'credit_balances': [], 'difference': 400, 'open_customers': 1, 'subledger': 800}{'control': 1200, 'credit_balances': [], 'difference': 400, 'open_customers': 1, 'subledger': 800}Passed
control 4{'control': 1150, 'credit_balances': [], 'difference': 650, 'open_customers': 1, 'subledger': 500}{'control': 1150, 'credit_balances': [], 'difference': 650, 'open_customers': 1, 'subledger': 500}Passed
control 5{'control': 740, 'credit_balances': [], 'difference': -160, 'open_customers': 3, 'subledger': 900}{'control': 740, 'credit_balances': [], 'difference': -160, 'open_customers': 3, 'subledger': 900}Passed
control 6{'control': -160, 'credit_balances': [], 'difference': -330, 'open_customers': 1, 'subledger': 170}{'control': -160, 'credit_balances': [], 'difference': -330, 'open_customers': 1, 'subledger': 170}Passed

SHA-256 / 5ba2f42ecefd3cff505fd01c6e6bc800ce8f29878ba93ffeb30a37ee4deec822

HELD IN THE MEMBER ARCHIVE

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

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.

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 deterministic bounded teaching model with stipulated toy bookkeeping rules stated in the contract; amounts are integer cents; it makes no claim of conformance to any accounting standard or product. 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 2026-09-29T14:46:24.955041+00:00.

Case digest / ea8e30e655ff31b9206b23689e933293041cd632fe092d2262d2ce22ae670e1a