FAILURE MAP
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FA-60306 / Inventory cost layering / Open access

Periodic weighted average with vendor returns: COGS rounding leak · case 01

Ending inventory plus COGS no longer equals goods available by a cent.

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

ROOT CAUSE

COGS is rounded independently from sold units instead of being derived as pool minus ending value.

THE FAILURE

COGS is rounded independently from sold units instead of being derived as pool minus ending value.

Unsuccessful approach: Truncating the independently computed COGS changes which cent is lost but still breaks the identity.

Case contract

Input {begin:[qty,value], purchases:[[qty,value]], vendor_returns:[[purchase_index,qty]], ending_qty}. Each vendor return removes qty units and floor(value*qty/purchase_qty) value of that purchase. The pool is beginning plus purchases less returns; ending value = round-half-up(ending_qty*pool value/pool units); COGS = pool value - ending value. ending_qty outside [0, pool units] returns {"error"}. Return {units, pool, ending_value, cogs}.

Why this case matters

Inventory valuation and cost-of-goods decisions depend on this rule.

1 / The failure

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

N = 1
observations = []
def solve(x):
    units = x['begin'][0] + sum(q for q, v in x['purchases'])
    pool = x['begin'][1] + sum(v for q, v in x['purchases'])
    for i, rq in x['vendor_returns']:
        pq, pv = x['purchases'][i]
        pool -= pv * rq // pq
        units -= rq
    e = x['ending_qty']
    if e < 0 or e > units:
        return {'error': 'invalid count'}
    ending = (2 * e * pool + units) // (2 * units) if units else 0
    return {'units': units, 'pool': pool, 'ending_value': ending, 'cogs': (2 * (units - e) * pool + units) // (2 * units) if units else pool}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1501]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4451, 'ending_value': 1526, 'cogs': 2925}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 781]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1261, 'ending_value': 378, 'cogs': 883}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 3]], 'ending_qty': 5}, {'units': 7, 'pool': 544, 'ending_value': 389, 'cogs': 155}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 7}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1410]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1824, 'ending_value': 1026, 'cogs': 798}], ['pricey begin', {'begin': [5, 2501], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3001, 'ending_value': 1200, 'cogs': 1801}], ['half cent both ways', {'begin': [1, 1], 'purchases': [[1, 2]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 3, 'ending_value': 2, 'cogs': 1}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1502]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4452, 'ending_value': 1526, 'cogs': 2926}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 782]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1262, 'ending_value': 379, 'cogs': 883}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 2]], 'ending_qty': 5}, {'units': 8, 'pool': 655, 'ending_value': 409, 'cogs': 246}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 6}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1411]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1824, 'ending_value': 1026, 'cogs': 798}], ['pricey begin', {'begin': [5, 2502], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3002, 'ending_value': 1201, 'cogs': 1801}], ['half cent both ways', {'begin': [1, 2], 'purchases': [[1, 3]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 5, 'ending_value': 3, 'cogs': 2}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1503]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4453, 'ending_value': 1527, 'cogs': 2926}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 783]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1263, 'ending_value': 379, 'cogs': 884}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 3]], 'ending_qty': 5}, {'units': 7, 'pool': 544, 'ending_value': 389, 'cogs': 155}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 7}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1412]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1825, 'ending_value': 1027, 'cogs': 798}], ['pricey begin', {'begin': [5, 2503], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3003, 'ending_value': 1201, 'cogs': 1802}], ['half cent both ways', {'begin': [1, 3], 'purchases': [[1, 4]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 7, 'ending_value': 4, 'cogs': 3}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1504]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4454, 'ending_value': 1527, 'cogs': 2927}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 784]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1264, 'ending_value': 379, 'cogs': 885}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 2]], 'ending_qty': 5}, {'units': 8, 'pool': 655, 'ending_value': 409, 'cogs': 246}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 6}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1413]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1826, 'ending_value': 1027, 'cogs': 799}], ['pricey begin', {'begin': [5, 2504], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3004, 'ending_value': 1202, 'cogs': 1802}], ['half cent both ways', {'begin': [1, 4], 'purchases': [[1, 5]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 9, 'ending_value': 5, 'cogs': 4}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1505]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4455, 'ending_value': 1527, 'cogs': 2928}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 785]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1265, 'ending_value': 380, 'cogs': 885}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 3]], 'ending_qty': 5}, {'units': 7, 'pool': 544, 'ending_value': 389, 'cogs': 155}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 7}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1414]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1826, 'ending_value': 1027, 'cogs': 799}], ['pricey begin', {'begin': [5, 2505], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3005, 'ending_value': 1202, 'cogs': 1803}], ['half cent both ways', {'begin': [1, 5], 'purchases': [[1, 6]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 11, 'ending_value': 6, 'cogs': 5}]]]
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
basic{'cogs': 2925, 'ending_value': 1526, 'pool': 4451, 'units': 35}{'cogs': 2925, 'ending_value': 1526, 'pool': 4451, 'units': 35}Passed
no returns{'cogs': 883, 'ending_value': 378, 'pool': 1261, 'units': 10}{'cogs': 883, 'ending_value': 378, 'pool': 1261, 'units': 10}Passed
return second{'cogs': 155, 'ending_value': 389, 'pool': 544, 'units': 7}{'cogs': 155, 'ending_value': 389, 'pool': 544, 'units': 7}Passed
too many counted{'error': 'invalid count'}{'error': 'invalid count'}Passed
empty count{'cogs': 590, 'ending_value': 0, 'pool': 590, 'units': 5}{'cogs': 590, 'ending_value': 0, 'pool': 590, 'units': 5}Passed
odd costs{'cogs': 798, 'ending_value': 1026, 'pool': 1824, 'units': 16}{'cogs': 798, 'ending_value': 1026, 'pool': 1824, 'units': 16}Passed
pricey begin{'cogs': 1801, 'ending_value': 1200, 'pool': 3001, 'units': 10}{'cogs': 1801, 'ending_value': 1200, 'pool': 3001, 'units': 10}Passed
half cent both ways{'cogs': 2, 'ending_value': 2, 'pool': 3, 'units': 2}{'cogs': 1, 'ending_value': 2, 'pool': 3, 'units': 2}Failed

SHA-256 / 14946f55e5852e01d86e4de858c018a6bc031e4c92c66e028a5edad544491b21

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    units = x['begin'][0] + sum(q for q, v in x['purchases'])
    pool = x['begin'][1] + sum(v for q, v in x['purchases'])
    for i, rq in x['vendor_returns']:
        pq, pv = x['purchases'][i]
        pool -= pv * rq // pq
        units -= rq
    e = x['ending_qty']
    if e < 0 or e > units:
        return {'error': 'invalid count'}
    ending = (2 * e * pool + units) // (2 * units) if units else 0
    return {'units': units, 'pool': pool, 'ending_value': ending, 'cogs': (units - e) * pool // units if units else pool}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1501]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4451, 'ending_value': 1526, 'cogs': 2925}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 781]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1261, 'ending_value': 378, 'cogs': 883}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 3]], 'ending_qty': 5}, {'units': 7, 'pool': 544, 'ending_value': 389, 'cogs': 155}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 7}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1410]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1824, 'ending_value': 1026, 'cogs': 798}], ['pricey begin', {'begin': [5, 2501], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3001, 'ending_value': 1200, 'cogs': 1801}], ['half cent both ways', {'begin': [1, 1], 'purchases': [[1, 2]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 3, 'ending_value': 2, 'cogs': 1}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1502]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4452, 'ending_value': 1526, 'cogs': 2926}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 782]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1262, 'ending_value': 379, 'cogs': 883}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 2]], 'ending_qty': 5}, {'units': 8, 'pool': 655, 'ending_value': 409, 'cogs': 246}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 6}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1411]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1824, 'ending_value': 1026, 'cogs': 798}], ['pricey begin', {'begin': [5, 2502], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3002, 'ending_value': 1201, 'cogs': 1801}], ['half cent both ways', {'begin': [1, 2], 'purchases': [[1, 3]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 5, 'ending_value': 3, 'cogs': 2}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1503]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4453, 'ending_value': 1527, 'cogs': 2926}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 783]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1263, 'ending_value': 379, 'cogs': 884}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 3]], 'ending_qty': 5}, {'units': 7, 'pool': 544, 'ending_value': 389, 'cogs': 155}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 7}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1412]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1825, 'ending_value': 1027, 'cogs': 798}], ['pricey begin', {'begin': [5, 2503], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3003, 'ending_value': 1201, 'cogs': 1802}], ['half cent both ways', {'begin': [1, 3], 'purchases': [[1, 4]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 7, 'ending_value': 4, 'cogs': 3}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1504]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4454, 'ending_value': 1527, 'cogs': 2927}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 784]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1264, 'ending_value': 379, 'cogs': 885}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 2]], 'ending_qty': 5}, {'units': 8, 'pool': 655, 'ending_value': 409, 'cogs': 246}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 6}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1413]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1826, 'ending_value': 1027, 'cogs': 799}], ['pricey begin', {'begin': [5, 2504], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3004, 'ending_value': 1202, 'cogs': 1802}], ['half cent both ways', {'begin': [1, 4], 'purchases': [[1, 5]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 9, 'ending_value': 5, 'cogs': 4}]], [['basic', {'begin': [10, 1000], 'purchases': [[20, 2600], [10, 1505]], 'vendor_returns': [[0, 5]], 'ending_qty': 12}, {'units': 35, 'pool': 4455, 'ending_value': 1527, 'cogs': 2928}], ['no returns', {'begin': [4, 480], 'purchases': [[6, 785]], 'vendor_returns': [], 'ending_qty': 3}, {'units': 10, 'pool': 1265, 'ending_value': 380, 'cogs': 885}], ['return second', {'begin': [0, 0], 'purchases': [[3, 100], [7, 777]], 'vendor_returns': [[1, 3]], 'ending_qty': 5}, {'units': 7, 'pool': 544, 'ending_value': 389, 'cogs': 155}], ['too many counted', {'begin': [2, 200], 'purchases': [[5, 600]], 'vendor_returns': [[0, 2]], 'ending_qty': 7}, {'error': 'invalid count'}], ['empty count', {'begin': [3, 330], 'purchases': [[3, 390]], 'vendor_returns': [[0, 1]], 'ending_qty': 0}, {'units': 5, 'pool': 590, 'ending_value': 0, 'cogs': 590}], ['odd costs', {'begin': [7, 701], 'purchases': [[3, 337], [11, 1414]], 'vendor_returns': [[1, 4], [0, 1]], 'ending_qty': 9}, {'units': 16, 'pool': 1826, 'ending_value': 1027, 'cogs': 799}], ['pricey begin', {'begin': [5, 2505], 'purchases': [[5, 500]], 'vendor_returns': [], 'ending_qty': 4}, {'units': 10, 'pool': 3005, 'ending_value': 1202, 'cogs': 1803}], ['half cent both ways', {'begin': [1, 5], 'purchases': [[1, 6]], 'vendor_returns': [], 'ending_qty': 1}, {'units': 2, 'pool': 11, 'ending_value': 6, 'cogs': 5}]]]
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
basic{'cogs': 2924, 'ending_value': 1526, 'pool': 4451, 'units': 35}{'cogs': 2925, 'ending_value': 1526, 'pool': 4451, 'units': 35}Failed
no returns{'cogs': 882, 'ending_value': 378, 'pool': 1261, 'units': 10}{'cogs': 883, 'ending_value': 378, 'pool': 1261, 'units': 10}Failed
return second{'cogs': 155, 'ending_value': 389, 'pool': 544, 'units': 7}{'cogs': 155, 'ending_value': 389, 'pool': 544, 'units': 7}Passed
too many counted{'error': 'invalid count'}{'error': 'invalid count'}Passed
empty count{'cogs': 590, 'ending_value': 0, 'pool': 590, 'units': 5}{'cogs': 590, 'ending_value': 0, 'pool': 590, 'units': 5}Passed
odd costs{'cogs': 798, 'ending_value': 1026, 'pool': 1824, 'units': 16}{'cogs': 798, 'ending_value': 1026, 'pool': 1824, 'units': 16}Passed
pricey begin{'cogs': 1800, 'ending_value': 1200, 'pool': 3001, 'units': 10}{'cogs': 1801, 'ending_value': 1200, 'pool': 3001, 'units': 10}Failed
half cent both ways{'cogs': 1, 'ending_value': 2, 'pool': 3, 'units': 2}{'cogs': 1, 'ending_value': 2, 'pool': 3, 'units': 2}Passed

SHA-256 / e2d8e238d27de4f9e964bb2feba3a863bc6e50900d40317ddfec045997e81c52

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This mechanism has 8 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 teaching model with explicit toy rules; not an accounting-standard implementation. 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 2026-09-29T14:46:44.374136+00:00.

Case digest / 6fdb6c050a8325d87ddf9912494d59728716eb399faf2c0f058561d2f475e298