FAILURE MAP
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FA-58066 / Double-entry ledger accounting / Open access

Account running balance report: line ordering key · case 01

Back-dated entries appear at the end of the ledger with wrong running balances.

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

ROOT CAUSE

Lines are ordered by sequence number only, ignoring the posting date.

THE FAILURE

Lines are ordered by sequence number only, ignoring the posting date.

Unsuccessful approach: Sorting by day alone leaves same-day lines in arrival order rather than sequence order.

Case contract

x = {'normal': 'D'|'C', 'opening': balance before all lines, 'lines': [[seq, day, side, amount]], 'from': day, 'to': day}. Balances are signed positive on the normal side. The report opening is the opening plus every line dated before 'from'. Lines dated from..to inclusive are listed in (day, seq) order with the running balance after each; closing is the last running balance (the report opening if none). Return {'opening', 'rows': [[seq, day, running]], 'closing'}.

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):
    sign = {'D': 1, 'C': -1} if x['normal'] == 'D' else {'D': -1, 'C': 1}
    lines = sorted(x['lines'], key=lambda l: l[0])
    opening = x['opening'] + sum(sign[s] * a for q, d, s, a in lines if d < x['from'])
    bal = opening
    rows = []
    for seq, date, side, amt in lines:
        if x['from'] <= date <= x['to']:
            bal += sign[side] * amt
            rows.append([seq, date, bal])
    return {'opening': opening, 'rows': rows, 'closing': bal}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: line ordering key', {'normal': 'C', 'opening': 250, 'lines': [[6, 5, 'D', 300], [4, 5, 'D', 300], [1, 8, 'D', 300], [5, 8, 'C', 10], [2, 8, 'D', 125], [3, 8, 'C', 10]], 'from': 1, 'to': 8}, {'opening': 250, 'rows': [[4, 5, -50], [6, 5, -350], [1, 8, -650], [2, 8, -775], [3, 8, -765], [5, 8, -755]], 'closing': -755}], ['control 1', {'normal': 'C', 'opening': 0, 'lines': [[3, 5, 'C', 50], [6, 1, 'C', 10], [5, 10, 'C', 50], [4, 12, 'D', 300], [8, 5, 'D', 125], [2, 5, 'C', 125], [7, 12, 'D', 125], [1, 12, 'C', 50]], 'from': 6, 'to': 6}, {'opening': 60, 'rows': [], 'closing': 60}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[1, 8, 'D', 125], [8, 1, 'D', 125], [2, 10, 'D', 125], [7, 10, 'D', 50], [6, 5, 'C', 300], [3, 12, 'D', 300], [5, 12, 'C', 125], [4, 1, 'C', 125]], 'from': 6, 'to': 8}, {'opening': 700, 'rows': [[1, 8, 825]], 'closing': 825}], ['control 3', {'normal': 'D', 'opening': 250, 'lines': [[4, 5, 'D', 300], [3, 8, 'C', 125], [2, 5, 'C', 10], [1, 8, 'D', 50]], 'from': 6, 'to': 8}, {'opening': 540, 'rows': [[1, 8, 590], [3, 8, 465]], 'closing': 465}], ['control 4', {'normal': 'C', 'opening': 0, 'lines': [[5, 12, 'C', 125], [3, 5, 'C', 10], [4, 1, 'D', 50], [8, 5, 'C', 125], [1, 10, 'C', 10], [6, 1, 'C', 10], [7, 8, 'C', 125], [2, 3, 'C', 10]], 'from': 6, 'to': 6}, {'opening': 105, 'rows': [], 'closing': 105}], ['control 5', {'normal': 'D', 'opening': 1000, 'lines': [[4, 5, 'C', 300], [2, 1, 'C', 300], [1, 3, 'C', 50], [3, 12, 'C', 125], [5, 5, 'D', 50]], 'from': 3, 'to': 10}, {'opening': 700, 'rows': [[1, 3, 650], [4, 5, 350], [5, 5, 400]], 'closing': 400}], ['control 6', {'normal': 'D', 'opening': 250, 'lines': [[1, 8, 'D', 50], [2, 3, 'D', 125], [3, 10, 'C', 125]], 'from': 1, 'to': 1}, {'opening': 250, 'rows': [], 'closing': 250}]], [['regression: line ordering key', {'normal': 'C', 'opening': 250, 'lines': [[4, 8, 'C', 50], [1, 10, 'C', 50], [2, 12, 'D', 125], [6, 10, 'D', 125], [5, 5, 'D', 10], [3, 12, 'D', 50]], 'from': 3, 'to': 8}, {'opening': 250, 'rows': [[5, 5, 240], [4, 8, 290]], 'closing': 290}], ['regression: line ordering key, partial-repair probe', {'normal': 'C', 'opening': 250, 'lines': [[2, 8, 'C', 125], [3, 3, 'D', 300], [1, 8, 'D', 50]], 'from': 1, 'to': 8}, {'opening': 250, 'rows': [[3, 3, -50], [1, 8, -100], [2, 8, 25]], 'closing': 25}], ['control 1', {'normal': 'D', 'opening': 1000, 'lines': [[2, 5, 'C', 300], [3, 3, 'D', 125], [4, 8, 'C', 50], [1, 5, 'C', 125], [5, 3, 'C', 300]], 'from': 5, 'to': 10}, {'opening': 825, 'rows': [[1, 5, 700], [2, 5, 400], [4, 8, 350]], 'closing': 350}], ['control 2', {'normal': 'D', 'opening': 0, 'lines': [[3, 5, 'D', 125], [5, 3, 'D', 50], [2, 1, 'C', 125], [4, 8, 'D', 125], [1, 5, 'C', 10]], 'from': 5, 'to': 7}, {'opening': -75, 'rows': [[1, 5, -85], [3, 5, 40]], 'closing': 40}], ['control 3', {'normal': 'D', 'opening': 0, 'lines': [[6, 3, 'C', 50], [7, 1, 'C', 50], [1, 3, 'C', 300], [5, 12, 'D', 50], [4, 5, 'C', 300], [3, 12, 'D', 10], [2, 1, 'D', 50]], 'from': 5, 'to': 10}, {'opening': -350, 'rows': [[4, 5, -650]], 'closing': -650}], ['control 4', {'normal': 'C', 'opening': 250, 'lines': [[1, 8, 'D', 300], [2, 3, 'D', 10], [3, 3, 'D', 10], [4, 12, 'C', 300], [5, 12, 'D', 10]], 'from': 1, 'to': 1}, {'opening': 250, 'rows': [], 'closing': 250}], ['control 5', {'normal': 'D', 'opening': 250, 'lines': [[6, 8, 'C', 300], [4, 1, 'C', 50], [1, 8, 'D', 300], [5, 1, 'D', 50], [2, 3, 'D', 300], [3, 5, 'C', 125]], 'from': 5, 'to': 7}, {'opening': 550, 'rows': [[3, 5, 425]], 'closing': 425}]], [['regression: line ordering key', {'normal': 'C', 'opening': 0, 'lines': [[3, 1, 'D', 10], [2, 5, 'D', 125], [1, 1, 'D', 10], [5, 5, 'D', 300], [4, 3, 'C', 125]], 'from': 3, 'to': 8}, {'opening': -20, 'rows': [[4, 3, 105], [2, 5, -20], [5, 5, -320]], 'closing': -320}], ['regression: line ordering key, partial-repair probe', {'normal': 'C', 'opening': 1000, 'lines': [[4, 10, 'D', 125], [2, 1, 'D', 50], [3, 12, 'D', 10], [5, 3, 'C', 125], [6, 8, 'D', 10], [1, 8, 'D', 50]], 'from': 1, 'to': 8}, {'opening': 1000, 'rows': [[2, 1, 950], [5, 3, 1075], [1, 8, 1025], [6, 8, 1015]], 'closing': 1015}], ['control 1', {'normal': 'C', 'opening': 250, 'lines': [[2, 12, 'C', 50], [1, 8, 'C', 125], [3, 5, 'D', 125]], 'from': 5, 'to': 7}, {'opening': 250, 'rows': [[3, 5, 125]], 'closing': 125}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[2, 8, 'C', 125], [1, 8, 'D', 50], [3, 5, 'D', 125]], 'from': 3, 'to': 5}, {'opening': 1000, 'rows': [[3, 5, 1125]], 'closing': 1125}], ['control 3', {'normal': 'D', 'opening': 250, 'lines': [[6, 8, 'D', 10], [3, 1, 'D', 300], [1, 8, 'D', 50], [2, 10, 'C', 10], [5, 5, 'C', 10], [4, 5, 'D', 125]], 'from': 1, 'to': 3}, {'opening': 250, 'rows': [[3, 1, 550]], 'closing': 550}], ['control 4', {'normal': 'D', 'opening': 1000, 'lines': [[2, 8, 'C', 10], [1, 12, 'C', 10], [3, 5, 'C', 50]], 'from': 6, 'to': 8}, {'opening': 950, 'rows': [[2, 8, 940]], 'closing': 940}], ['control 5', {'normal': 'C', 'opening': 0, 'lines': [[1, 8, 'D', 125], [3, 10, 'C', 300], [2, 3, 'C', 300]], 'from': 3, 'to': 5}, {'opening': 0, 'rows': [[2, 3, 300]], 'closing': 300}]], [['regression: line ordering key', {'normal': 'D', 'opening': 250, 'lines': [[2, 5, 'D', 300], [3, 5, 'C', 50], [6, 8, 'D', 10], [7, 3, 'D', 300], [5, 5, 'C', 50], [4, 3, 'C', 10], [1, 5, 'D', 300]], 'from': 3, 'to': 5}, {'opening': 250, 'rows': [[4, 3, 240], [7, 3, 540], [1, 5, 840], [2, 5, 1140], [3, 5, 1090], [5, 5, 1040]], 'closing': 1040}], ['control 1', {'normal': 'C', 'opening': 250, 'lines': [[2, 3, 'D', 10], [3, 5, 'D', 50], [4, 8, 'D', 10], [1, 5, 'D', 300]], 'from': 6, 'to': 6}, {'opening': -110, 'rows': [], 'closing': -110}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[7, 8, 'C', 125], [5, 12, 'C', 10], [6, 5, 'D', 10], [4, 10, 'D', 10], [3, 8, 'C', 10], [2, 8, 'D', 50], [1, 5, 'D', 10]], 'from': 3, 'to': 5}, {'opening': 1000, 'rows': [[1, 5, 1010], [6, 5, 1020]], 'closing': 1020}], ['control 3', {'normal': 'C', 'opening': 1000, 'lines': [[5, 5, 'C', 300], [3, 1, 'D', 10], [2, 10, 'D', 10], [4, 5, 'C', 300], [1, 5, 'C', 10]], 'from': 1, 'to': 3}, {'opening': 1000, 'rows': [[3, 1, 990]], 'closing': 990}], ['control 4', {'normal': 'C', 'opening': 0, 'lines': [[1, 5, 'D', 300], [4, 8, 'C', 300], [3, 12, 'C', 50], [2, 10, 'C', 125]], 'from': 1, 'to': 6}, {'opening': 0, 'rows': [[1, 5, -300]], 'closing': -300}], ['control 5', {'normal': 'C', 'opening': 1000, 'lines': [[2, 12, 'C', 50], [1, 3, 'C', 125], [3, 1, 'D', 10], [4, 5, 'D', 50]], 'from': 6, 'to': 11}, {'opening': 1065, 'rows': [], 'closing': 1065}], ['control 6', {'normal': 'D', 'opening': 1000, 'lines': [[2, 10, 'C', 300], [1, 10, 'C', 10], [6, 12, 'C', 50], [5, 5, 'D', 300], [3, 3, 'C', 50], [4, 12, 'D', 50]], 'from': 5, 'to': 5}, {'opening': 950, 'rows': [[5, 5, 1250]], 'closing': 1250}]], [['regression: line ordering key', {'normal': 'C', 'opening': 250, 'lines': [[3, 8, 'C', 10], [2, 5, 'C', 10], [1, 8, 'C', 300]], 'from': 1, 'to': 8}, {'opening': 250, 'rows': [[2, 5, 260], [1, 8, 560], [3, 8, 570]], 'closing': 570}], ['control 1', {'normal': 'C', 'opening': 250, 'lines': [[3, 5, 'C', 300], [5, 5, 'C', 50], [4, 5, 'C', 300], [2, 10, 'D', 300], [1, 12, 'D', 300]], 'from': 5, 'to': 5}, {'opening': 250, 'rows': [[3, 5, 550], [4, 5, 850], [5, 5, 900]], 'closing': 900}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[3, 5, 'D', 10], [7, 5, 'C', 10], [5, 8, 'D', 50], [4, 3, 'C', 300], [6, 10, 'C', 300], [8, 10, 'D', 125], [1, 1, 'C', 10], [2, 5, 'C', 125]], 'from': 1, 'to': 1}, {'opening': 1000, 'rows': [[1, 1, 990]], 'closing': 990}], ['control 3', {'normal': 'D', 'opening': 1000, 'lines': [[3, 3, 'D', 125], [6, 5, 'C', 125], [2, 8, 'C', 125], [1, 10, 'C', 125], [5, 12, 'C', 125], [7, 5, 'C', 300], [4, 5, 'D', 300]], 'from': 6, 'to': 8}, {'opening': 1000, 'rows': [[2, 8, 875]], 'closing': 875}], ['control 4', {'normal': 'C', 'opening': 0, 'lines': [[3, 8, 'C', 300], [1, 1, 'C', 10], [2, 12, 'C', 125]], 'from': 3, 'to': 3}, {'opening': 10, 'rows': [], 'closing': 10}], ['control 5', {'normal': 'D', 'opening': 1000, 'lines': [[4, 5, 'D', 300], [5, 12, 'D', 125], [3, 12, 'D', 125], [1, 1, 'D', 300], [2, 8, 'C', 10]], 'from': 3, 'to': 5}, {'opening': 1300, 'rows': [[4, 5, 1600]], 'closing': 1600}], ['control 6', {'normal': 'C', 'opening': 1000, 'lines': [[2, 8, 'C', 300], [3, 5, 'D', 300], [4, 8, 'C', 50], [5, 1, 'C', 300], [1, 5, 'C', 10]], 'from': 6, 'to': 11}, {'opening': 1010, 'rows': [[2, 8, 1310], [4, 8, 1360]], 'closing': 1360}]]]
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: line ordering key{'closing': -755, 'opening': 250, 'rows': [[1, 8, -50], [2, 8, -175], [3, 8, -165], [4, 5, -465], [5, 8, -455], [6, 5, -755]]}{'closing': -755, 'opening': 250, 'rows': [[4, 5, -50], [6, 5, -350], [1, 8, -650], [2, 8, -775], [3, 8, -765], [5, 8, -755]]}Failed
control 1{'closing': 60, 'opening': 60, 'rows': []}{'closing': 60, 'opening': 60, 'rows': []}Passed
control 2{'closing': 825, 'opening': 700, 'rows': [[1, 8, 825]]}{'closing': 825, 'opening': 700, 'rows': [[1, 8, 825]]}Passed
control 3{'closing': 465, 'opening': 540, 'rows': [[1, 8, 590], [3, 8, 465]]}{'closing': 465, 'opening': 540, 'rows': [[1, 8, 590], [3, 8, 465]]}Passed
control 4{'closing': 105, 'opening': 105, 'rows': []}{'closing': 105, 'opening': 105, 'rows': []}Passed
control 5{'closing': 400, 'opening': 700, 'rows': [[1, 3, 650], [4, 5, 350], [5, 5, 400]]}{'closing': 400, 'opening': 700, 'rows': [[1, 3, 650], [4, 5, 350], [5, 5, 400]]}Passed
control 6{'closing': 250, 'opening': 250, 'rows': []}{'closing': 250, 'opening': 250, 'rows': []}Passed

SHA-256 / 2ba347c1fe3e45aeebbb16efd664b702a66e754dd1947cfc942fcffd20e0a8d6

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    sign = {'D': 1, 'C': -1} if x['normal'] == 'D' else {'D': -1, 'C': 1}
    lines = sorted(x['lines'], key=lambda l: l[1])
    opening = x['opening'] + sum(sign[s] * a for q, d, s, a in lines if d < x['from'])
    bal = opening
    rows = []
    for seq, date, side, amt in lines:
        if x['from'] <= date <= x['to']:
            bal += sign[side] * amt
            rows.append([seq, date, bal])
    return {'opening': opening, 'rows': rows, 'closing': bal}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: line ordering key', {'normal': 'C', 'opening': 250, 'lines': [[6, 5, 'D', 300], [4, 5, 'D', 300], [1, 8, 'D', 300], [5, 8, 'C', 10], [2, 8, 'D', 125], [3, 8, 'C', 10]], 'from': 1, 'to': 8}, {'opening': 250, 'rows': [[4, 5, -50], [6, 5, -350], [1, 8, -650], [2, 8, -775], [3, 8, -765], [5, 8, -755]], 'closing': -755}], ['control 1', {'normal': 'C', 'opening': 0, 'lines': [[3, 5, 'C', 50], [6, 1, 'C', 10], [5, 10, 'C', 50], [4, 12, 'D', 300], [8, 5, 'D', 125], [2, 5, 'C', 125], [7, 12, 'D', 125], [1, 12, 'C', 50]], 'from': 6, 'to': 6}, {'opening': 60, 'rows': [], 'closing': 60}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[1, 8, 'D', 125], [8, 1, 'D', 125], [2, 10, 'D', 125], [7, 10, 'D', 50], [6, 5, 'C', 300], [3, 12, 'D', 300], [5, 12, 'C', 125], [4, 1, 'C', 125]], 'from': 6, 'to': 8}, {'opening': 700, 'rows': [[1, 8, 825]], 'closing': 825}], ['control 3', {'normal': 'D', 'opening': 250, 'lines': [[4, 5, 'D', 300], [3, 8, 'C', 125], [2, 5, 'C', 10], [1, 8, 'D', 50]], 'from': 6, 'to': 8}, {'opening': 540, 'rows': [[1, 8, 590], [3, 8, 465]], 'closing': 465}], ['control 4', {'normal': 'C', 'opening': 0, 'lines': [[5, 12, 'C', 125], [3, 5, 'C', 10], [4, 1, 'D', 50], [8, 5, 'C', 125], [1, 10, 'C', 10], [6, 1, 'C', 10], [7, 8, 'C', 125], [2, 3, 'C', 10]], 'from': 6, 'to': 6}, {'opening': 105, 'rows': [], 'closing': 105}], ['control 5', {'normal': 'D', 'opening': 1000, 'lines': [[4, 5, 'C', 300], [2, 1, 'C', 300], [1, 3, 'C', 50], [3, 12, 'C', 125], [5, 5, 'D', 50]], 'from': 3, 'to': 10}, {'opening': 700, 'rows': [[1, 3, 650], [4, 5, 350], [5, 5, 400]], 'closing': 400}], ['control 6', {'normal': 'D', 'opening': 250, 'lines': [[1, 8, 'D', 50], [2, 3, 'D', 125], [3, 10, 'C', 125]], 'from': 1, 'to': 1}, {'opening': 250, 'rows': [], 'closing': 250}]], [['regression: line ordering key', {'normal': 'C', 'opening': 250, 'lines': [[4, 8, 'C', 50], [1, 10, 'C', 50], [2, 12, 'D', 125], [6, 10, 'D', 125], [5, 5, 'D', 10], [3, 12, 'D', 50]], 'from': 3, 'to': 8}, {'opening': 250, 'rows': [[5, 5, 240], [4, 8, 290]], 'closing': 290}], ['regression: line ordering key, partial-repair probe', {'normal': 'C', 'opening': 250, 'lines': [[2, 8, 'C', 125], [3, 3, 'D', 300], [1, 8, 'D', 50]], 'from': 1, 'to': 8}, {'opening': 250, 'rows': [[3, 3, -50], [1, 8, -100], [2, 8, 25]], 'closing': 25}], ['control 1', {'normal': 'D', 'opening': 1000, 'lines': [[2, 5, 'C', 300], [3, 3, 'D', 125], [4, 8, 'C', 50], [1, 5, 'C', 125], [5, 3, 'C', 300]], 'from': 5, 'to': 10}, {'opening': 825, 'rows': [[1, 5, 700], [2, 5, 400], [4, 8, 350]], 'closing': 350}], ['control 2', {'normal': 'D', 'opening': 0, 'lines': [[3, 5, 'D', 125], [5, 3, 'D', 50], [2, 1, 'C', 125], [4, 8, 'D', 125], [1, 5, 'C', 10]], 'from': 5, 'to': 7}, {'opening': -75, 'rows': [[1, 5, -85], [3, 5, 40]], 'closing': 40}], ['control 3', {'normal': 'D', 'opening': 0, 'lines': [[6, 3, 'C', 50], [7, 1, 'C', 50], [1, 3, 'C', 300], [5, 12, 'D', 50], [4, 5, 'C', 300], [3, 12, 'D', 10], [2, 1, 'D', 50]], 'from': 5, 'to': 10}, {'opening': -350, 'rows': [[4, 5, -650]], 'closing': -650}], ['control 4', {'normal': 'C', 'opening': 250, 'lines': [[1, 8, 'D', 300], [2, 3, 'D', 10], [3, 3, 'D', 10], [4, 12, 'C', 300], [5, 12, 'D', 10]], 'from': 1, 'to': 1}, {'opening': 250, 'rows': [], 'closing': 250}], ['control 5', {'normal': 'D', 'opening': 250, 'lines': [[6, 8, 'C', 300], [4, 1, 'C', 50], [1, 8, 'D', 300], [5, 1, 'D', 50], [2, 3, 'D', 300], [3, 5, 'C', 125]], 'from': 5, 'to': 7}, {'opening': 550, 'rows': [[3, 5, 425]], 'closing': 425}]], [['regression: line ordering key', {'normal': 'C', 'opening': 0, 'lines': [[3, 1, 'D', 10], [2, 5, 'D', 125], [1, 1, 'D', 10], [5, 5, 'D', 300], [4, 3, 'C', 125]], 'from': 3, 'to': 8}, {'opening': -20, 'rows': [[4, 3, 105], [2, 5, -20], [5, 5, -320]], 'closing': -320}], ['regression: line ordering key, partial-repair probe', {'normal': 'C', 'opening': 1000, 'lines': [[4, 10, 'D', 125], [2, 1, 'D', 50], [3, 12, 'D', 10], [5, 3, 'C', 125], [6, 8, 'D', 10], [1, 8, 'D', 50]], 'from': 1, 'to': 8}, {'opening': 1000, 'rows': [[2, 1, 950], [5, 3, 1075], [1, 8, 1025], [6, 8, 1015]], 'closing': 1015}], ['control 1', {'normal': 'C', 'opening': 250, 'lines': [[2, 12, 'C', 50], [1, 8, 'C', 125], [3, 5, 'D', 125]], 'from': 5, 'to': 7}, {'opening': 250, 'rows': [[3, 5, 125]], 'closing': 125}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[2, 8, 'C', 125], [1, 8, 'D', 50], [3, 5, 'D', 125]], 'from': 3, 'to': 5}, {'opening': 1000, 'rows': [[3, 5, 1125]], 'closing': 1125}], ['control 3', {'normal': 'D', 'opening': 250, 'lines': [[6, 8, 'D', 10], [3, 1, 'D', 300], [1, 8, 'D', 50], [2, 10, 'C', 10], [5, 5, 'C', 10], [4, 5, 'D', 125]], 'from': 1, 'to': 3}, {'opening': 250, 'rows': [[3, 1, 550]], 'closing': 550}], ['control 4', {'normal': 'D', 'opening': 1000, 'lines': [[2, 8, 'C', 10], [1, 12, 'C', 10], [3, 5, 'C', 50]], 'from': 6, 'to': 8}, {'opening': 950, 'rows': [[2, 8, 940]], 'closing': 940}], ['control 5', {'normal': 'C', 'opening': 0, 'lines': [[1, 8, 'D', 125], [3, 10, 'C', 300], [2, 3, 'C', 300]], 'from': 3, 'to': 5}, {'opening': 0, 'rows': [[2, 3, 300]], 'closing': 300}]], [['regression: line ordering key', {'normal': 'D', 'opening': 250, 'lines': [[2, 5, 'D', 300], [3, 5, 'C', 50], [6, 8, 'D', 10], [7, 3, 'D', 300], [5, 5, 'C', 50], [4, 3, 'C', 10], [1, 5, 'D', 300]], 'from': 3, 'to': 5}, {'opening': 250, 'rows': [[4, 3, 240], [7, 3, 540], [1, 5, 840], [2, 5, 1140], [3, 5, 1090], [5, 5, 1040]], 'closing': 1040}], ['control 1', {'normal': 'C', 'opening': 250, 'lines': [[2, 3, 'D', 10], [3, 5, 'D', 50], [4, 8, 'D', 10], [1, 5, 'D', 300]], 'from': 6, 'to': 6}, {'opening': -110, 'rows': [], 'closing': -110}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[7, 8, 'C', 125], [5, 12, 'C', 10], [6, 5, 'D', 10], [4, 10, 'D', 10], [3, 8, 'C', 10], [2, 8, 'D', 50], [1, 5, 'D', 10]], 'from': 3, 'to': 5}, {'opening': 1000, 'rows': [[1, 5, 1010], [6, 5, 1020]], 'closing': 1020}], ['control 3', {'normal': 'C', 'opening': 1000, 'lines': [[5, 5, 'C', 300], [3, 1, 'D', 10], [2, 10, 'D', 10], [4, 5, 'C', 300], [1, 5, 'C', 10]], 'from': 1, 'to': 3}, {'opening': 1000, 'rows': [[3, 1, 990]], 'closing': 990}], ['control 4', {'normal': 'C', 'opening': 0, 'lines': [[1, 5, 'D', 300], [4, 8, 'C', 300], [3, 12, 'C', 50], [2, 10, 'C', 125]], 'from': 1, 'to': 6}, {'opening': 0, 'rows': [[1, 5, -300]], 'closing': -300}], ['control 5', {'normal': 'C', 'opening': 1000, 'lines': [[2, 12, 'C', 50], [1, 3, 'C', 125], [3, 1, 'D', 10], [4, 5, 'D', 50]], 'from': 6, 'to': 11}, {'opening': 1065, 'rows': [], 'closing': 1065}], ['control 6', {'normal': 'D', 'opening': 1000, 'lines': [[2, 10, 'C', 300], [1, 10, 'C', 10], [6, 12, 'C', 50], [5, 5, 'D', 300], [3, 3, 'C', 50], [4, 12, 'D', 50]], 'from': 5, 'to': 5}, {'opening': 950, 'rows': [[5, 5, 1250]], 'closing': 1250}]], [['regression: line ordering key', {'normal': 'C', 'opening': 250, 'lines': [[3, 8, 'C', 10], [2, 5, 'C', 10], [1, 8, 'C', 300]], 'from': 1, 'to': 8}, {'opening': 250, 'rows': [[2, 5, 260], [1, 8, 560], [3, 8, 570]], 'closing': 570}], ['control 1', {'normal': 'C', 'opening': 250, 'lines': [[3, 5, 'C', 300], [5, 5, 'C', 50], [4, 5, 'C', 300], [2, 10, 'D', 300], [1, 12, 'D', 300]], 'from': 5, 'to': 5}, {'opening': 250, 'rows': [[3, 5, 550], [4, 5, 850], [5, 5, 900]], 'closing': 900}], ['control 2', {'normal': 'D', 'opening': 1000, 'lines': [[3, 5, 'D', 10], [7, 5, 'C', 10], [5, 8, 'D', 50], [4, 3, 'C', 300], [6, 10, 'C', 300], [8, 10, 'D', 125], [1, 1, 'C', 10], [2, 5, 'C', 125]], 'from': 1, 'to': 1}, {'opening': 1000, 'rows': [[1, 1, 990]], 'closing': 990}], ['control 3', {'normal': 'D', 'opening': 1000, 'lines': [[3, 3, 'D', 125], [6, 5, 'C', 125], [2, 8, 'C', 125], [1, 10, 'C', 125], [5, 12, 'C', 125], [7, 5, 'C', 300], [4, 5, 'D', 300]], 'from': 6, 'to': 8}, {'opening': 1000, 'rows': [[2, 8, 875]], 'closing': 875}], ['control 4', {'normal': 'C', 'opening': 0, 'lines': [[3, 8, 'C', 300], [1, 1, 'C', 10], [2, 12, 'C', 125]], 'from': 3, 'to': 3}, {'opening': 10, 'rows': [], 'closing': 10}], ['control 5', {'normal': 'D', 'opening': 1000, 'lines': [[4, 5, 'D', 300], [5, 12, 'D', 125], [3, 12, 'D', 125], [1, 1, 'D', 300], [2, 8, 'C', 10]], 'from': 3, 'to': 5}, {'opening': 1300, 'rows': [[4, 5, 1600]], 'closing': 1600}], ['control 6', {'normal': 'C', 'opening': 1000, 'lines': [[2, 8, 'C', 300], [3, 5, 'D', 300], [4, 8, 'C', 50], [5, 1, 'C', 300], [1, 5, 'C', 10]], 'from': 6, 'to': 11}, {'opening': 1010, 'rows': [[2, 8, 1310], [4, 8, 1360]], 'closing': 1360}]]]
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: line ordering key{'closing': -755, 'opening': 250, 'rows': [[6, 5, -50], [4, 5, -350], [1, 8, -650], [5, 8, -640], [2, 8, -765], [3, 8, -755]]}{'closing': -755, 'opening': 250, 'rows': [[4, 5, -50], [6, 5, -350], [1, 8, -650], [2, 8, -775], [3, 8, -765], [5, 8, -755]]}Failed
control 1{'closing': 60, 'opening': 60, 'rows': []}{'closing': 60, 'opening': 60, 'rows': []}Passed
control 2{'closing': 825, 'opening': 700, 'rows': [[1, 8, 825]]}{'closing': 825, 'opening': 700, 'rows': [[1, 8, 825]]}Passed
control 3{'closing': 465, 'opening': 540, 'rows': [[3, 8, 415], [1, 8, 465]]}{'closing': 465, 'opening': 540, 'rows': [[1, 8, 590], [3, 8, 465]]}Failed
control 4{'closing': 105, 'opening': 105, 'rows': []}{'closing': 105, 'opening': 105, 'rows': []}Passed
control 5{'closing': 400, 'opening': 700, 'rows': [[1, 3, 650], [4, 5, 350], [5, 5, 400]]}{'closing': 400, 'opening': 700, 'rows': [[1, 3, 650], [4, 5, 350], [5, 5, 400]]}Passed
control 6{'closing': 250, 'opening': 250, 'rows': []}{'closing': 250, 'opening': 250, 'rows': []}Passed

SHA-256 / d685313e4e2d8212030f483022fbe7dfaf9bc04b2bb4056753465467a6d68b24

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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.

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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 2026-09-29T14:46:23.174094+00:00.

Case digest / 90a1b028c18ee9f5ac391b8ca4f75ded3078e9b6e03e91e1bc50f3696d160854