{"abstract":"Escrow accounts with plenty of funds are told they have a shortage.","category":"Loan amortization schedules","checks":7,"contract":"x = {'disbursements': annual amounts, 'low_point': projected lowest balance, 'cushion_months', 'refund_threshold'}. total = sum; base = round_half_up(total/12); cushion = round_half_up(total*cushion_months/12); diff = low_point - cushion; shortage = max(0, -diff) is collected over 12 months rounded up; surplus = max(0, diff) is refunded when >= refund_threshold, otherwise floor(surplus/12) is credited monthly. Return {'base', 'cushion', 'shortage', 'refund', 'monthly'}.","evaluation_group":"w2-loan-amortization-schedules-escrow-analysis","failed_approach":"Comparing against one month base ignores the configured cushion.","family":"w2-loan-amortization-schedules-escrow-analysis-low-point-comparison","id":"FA-58696","implementations":{"attempt":{"sha256":"c2c63740a4cefca527667e7abf538052508cf5daa91503050a026d22d51c67ef","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def rnd(n, d):\n        q, r = divmod(n, d)\n        return q + (1 if 2 * r >= d else 0)\n    total = sum(x['disbursements'])\n    base = rnd(total, 12)\n    cushion = rnd(total * x['cushion_months'], 12)\n    diff = x['low_point'] - base\n    shortage = max(0, -diff)\n    surplus = max(0, diff)\n    refund = surplus if surplus >= x['refund_threshold'] else 0\n    monthly = base + (shortage + 11) // 12 - (0 if refund else surplus // 12)\n    return {'base': base, 'cushion': cushion, 'shortage': shortage, 'refund': refund, 'monthly': monthly}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression: low point comparison', {'disbursements': [120000, 36000, 99999], 'low_point': -5000, 'cushion_months': 2, 'refund_threshold': 20000}, {'base': 21333, 'cushion': 42667, 'shortage': 47667, 'refund': 0, 'monthly': 25306}], ['control 1', {'disbursements': [36000, 7, 36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 6001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 6001}], ['control 2', {'disbursements': [7, 36000, 250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 23834, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 23834}], ['control 3', {'disbursements': [120000, 7, 7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 10001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10001}], ['control 4', {'disbursements': [120000, 120000], 'low_point': 40000, 'cushion_months': 2, 'refund_threshold': 0}, {'base': 20000, 'cushion': 40000, 'shortage': 0, 'refund': 0, 'monthly': 20000}], ['control 5', {'disbursements': [120000, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 28333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 28333}], ['control 6', {'disbursements': [120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10000}]], [['regression: low point comparison', {'disbursements': [120000, 36000], 'low_point': 80000, 'cushion_months': 1, 'refund_threshold': 0}, {'base': 13000, 'cushion': 13000, 'shortage': 0, 'refund': 67000, 'monthly': 13000}], ['regression: low point comparison, partial-repair probe', {'disbursements': [36000], 'low_point': 10000, 'cushion_months': 2, 'refund_threshold': 5000}, {'base': 3000, 'cushion': 6000, 'shortage': 0, 'refund': 0, 'monthly': 2667}], ['control 1', {'disbursements': [7, 36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 3001}], ['control 2', {'disbursements': [120000, 120000], 'low_point': 40000, 'cushion_months': 2, 'refund_threshold': 5000}, {'base': 20000, 'cushion': 40000, 'shortage': 0, 'refund': 0, 'monthly': 20000}], ['control 3', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 4', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 5', {'disbursements': [7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 1, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 1}]], [['regression: low point comparison', {'disbursements': [250000, 120000], 'low_point': 80000, 'cushion_months': 1, 'refund_threshold': 20000}, {'base': 30833, 'cushion': 30833, 'shortage': 0, 'refund': 49167, 'monthly': 30833}], ['regression: low point comparison, partial-repair probe', {'disbursements': [36000], 'low_point': 0, 'cushion_months': 5, 'refund_threshold': 5000}, {'base': 3000, 'cushion': 15000, 'shortage': 15000, 'refund': 0, 'monthly': 4250}], ['control 1', {'disbursements': [36000, 99999, 250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 32167, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 32167}], ['control 2', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 20000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 3', {'disbursements': [120000, 7, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 18334, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 18334}], ['control 4', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 5000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 5', {'disbursements': [250000, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 39167, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 39167}]], [['regression: low point comparison', {'disbursements': [36000], 'low_point': -5000, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3000, 'cushion': 0, 'shortage': 5000, 'refund': 0, 'monthly': 3417}], ['control 1', {'disbursements': [120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 18333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 18333}], ['control 2', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 3', {'disbursements': [36000, 7, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 13001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 13001}], ['control 4', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 5000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 5', {'disbursements': [120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 6', {'disbursements': [99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 8333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 8333}]], [['regression: low point comparison', {'disbursements': [120000], 'low_point': 150000, 'cushion_months': 5, 'refund_threshold': 20000}, {'base': 10000, 'cushion': 50000, 'shortage': 0, 'refund': 100000, 'monthly': 10000}], ['control 1', {'disbursements': [7, 7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 1, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 1}], ['control 2', {'disbursements': [7, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10001}], ['control 3', {'disbursements': [250000, 250000, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 51667, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 51667}], ['control 4', {'disbursements': [99999, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 26667, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 26667}], ['control 5', {'disbursements': [36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 3000}], ['control 6', {'disbursements': [36000, 120000, 36000], 'low_point': 80000, 'cushion_months': 5, 'refund_threshold': 20000}, {'base': 16000, 'cushion': 80000, 'shortage': 0, 'refund': 0, 'monthly': 16000}]]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'raised ' + type(exc).__name__\n    check(label, actual, expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"4a0ae55c3ded96ec9bad9f016206526a4559f24433abb43e9d789f8c4786f886","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def rnd(n, d):\n        q, r = divmod(n, d)\n        return q + (1 if 2 * r >= d else 0)\n    total = sum(x['disbursements'])\n    base = rnd(total, 12)\n    cushion = rnd(total * x['cushion_months'], 12)\n    diff = cushion - x['low_point']\n    shortage = max(0, -diff)\n    surplus = max(0, diff)\n    refund = surplus if surplus >= x['refund_threshold'] else 0\n    monthly = base + (shortage + 11) // 12 - (0 if refund else surplus // 12)\n    return {'base': base, 'cushion': cushion, 'shortage': shortage, 'refund': refund, 'monthly': monthly}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression: low point comparison', {'disbursements': [120000, 36000, 99999], 'low_point': -5000, 'cushion_months': 2, 'refund_threshold': 20000}, {'base': 21333, 'cushion': 42667, 'shortage': 47667, 'refund': 0, 'monthly': 25306}], ['control 1', {'disbursements': [36000, 7, 36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 6001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 6001}], ['control 2', {'disbursements': [7, 36000, 250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 23834, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 23834}], ['control 3', {'disbursements': [120000, 7, 7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 10001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10001}], ['control 4', {'disbursements': [120000, 120000], 'low_point': 40000, 'cushion_months': 2, 'refund_threshold': 0}, {'base': 20000, 'cushion': 40000, 'shortage': 0, 'refund': 0, 'monthly': 20000}], ['control 5', {'disbursements': [120000, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 28333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 28333}], ['control 6', {'disbursements': [120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10000}]], [['regression: low point comparison', {'disbursements': [120000, 36000], 'low_point': 80000, 'cushion_months': 1, 'refund_threshold': 0}, {'base': 13000, 'cushion': 13000, 'shortage': 0, 'refund': 67000, 'monthly': 13000}], ['regression: low point comparison, partial-repair probe', {'disbursements': [36000], 'low_point': 10000, 'cushion_months': 2, 'refund_threshold': 5000}, {'base': 3000, 'cushion': 6000, 'shortage': 0, 'refund': 0, 'monthly': 2667}], ['control 1', {'disbursements': [7, 36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 3001}], ['control 2', {'disbursements': [120000, 120000], 'low_point': 40000, 'cushion_months': 2, 'refund_threshold': 5000}, {'base': 20000, 'cushion': 40000, 'shortage': 0, 'refund': 0, 'monthly': 20000}], ['control 3', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 4', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 5', {'disbursements': [7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 1, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 1}]], [['regression: low point comparison', {'disbursements': [250000, 120000], 'low_point': 80000, 'cushion_months': 1, 'refund_threshold': 20000}, {'base': 30833, 'cushion': 30833, 'shortage': 0, 'refund': 49167, 'monthly': 30833}], ['regression: low point comparison, partial-repair probe', {'disbursements': [36000], 'low_point': 0, 'cushion_months': 5, 'refund_threshold': 5000}, {'base': 3000, 'cushion': 15000, 'shortage': 15000, 'refund': 0, 'monthly': 4250}], ['control 1', {'disbursements': [36000, 99999, 250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 32167, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 32167}], ['control 2', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 20000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 3', {'disbursements': [120000, 7, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 18334, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 18334}], ['control 4', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 5000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 5', {'disbursements': [250000, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 39167, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 39167}]], [['regression: low point comparison', {'disbursements': [36000], 'low_point': -5000, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3000, 'cushion': 0, 'shortage': 5000, 'refund': 0, 'monthly': 3417}], ['control 1', {'disbursements': [120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 18333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 18333}], ['control 2', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 3', {'disbursements': [36000, 7, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 13001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 13001}], ['control 4', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 5000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 5', {'disbursements': [120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 6', {'disbursements': [99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 8333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 8333}]], [['regression: low point comparison', {'disbursements': [120000], 'low_point': 150000, 'cushion_months': 5, 'refund_threshold': 20000}, {'base': 10000, 'cushion': 50000, 'shortage': 0, 'refund': 100000, 'monthly': 10000}], ['control 1', {'disbursements': [7, 7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 1, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 1}], ['control 2', {'disbursements': [7, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10001}], ['control 3', {'disbursements': [250000, 250000, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 51667, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 51667}], ['control 4', {'disbursements': [99999, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 26667, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 26667}], ['control 5', {'disbursements': [36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 3000}], ['control 6', {'disbursements': [36000, 120000, 36000], 'low_point': 80000, 'cushion_months': 5, 'refund_threshold': 20000}, {'base': 16000, 'cushion': 80000, 'shortage': 0, 'refund': 0, 'monthly': 16000}]]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'raised ' + type(exc).__name__\n    check(label, actual, expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"cf8a476dd11a82e9cf0d1b11a849cdc9534f25a3c99e1627d51cff54913ebd79","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def rnd(n, d):\n        q, r = divmod(n, d)\n        return q + (1 if 2 * r >= d else 0)\n    total = sum(x['disbursements'])\n    base = rnd(total, 12)\n    cushion = rnd(total * x['cushion_months'], 12)\n    diff = x['low_point'] - cushion\n    shortage = max(0, -diff)\n    surplus = max(0, diff)\n    refund = surplus if surplus >= x['refund_threshold'] else 0\n    monthly = base + (shortage + 11) // 12 - (0 if refund else surplus // 12)\n    return {'base': base, 'cushion': cushion, 'shortage': shortage, 'refund': refund, 'monthly': monthly}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression: low point comparison', {'disbursements': [120000, 36000, 99999], 'low_point': -5000, 'cushion_months': 2, 'refund_threshold': 20000}, {'base': 21333, 'cushion': 42667, 'shortage': 47667, 'refund': 0, 'monthly': 25306}], ['control 1', {'disbursements': [36000, 7, 36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 6001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 6001}], ['control 2', {'disbursements': [7, 36000, 250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 23834, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 23834}], ['control 3', {'disbursements': [120000, 7, 7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 10001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10001}], ['control 4', {'disbursements': [120000, 120000], 'low_point': 40000, 'cushion_months': 2, 'refund_threshold': 0}, {'base': 20000, 'cushion': 40000, 'shortage': 0, 'refund': 0, 'monthly': 20000}], ['control 5', {'disbursements': [120000, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 28333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 28333}], ['control 6', {'disbursements': [120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10000}]], [['regression: low point comparison', {'disbursements': [120000, 36000], 'low_point': 80000, 'cushion_months': 1, 'refund_threshold': 0}, {'base': 13000, 'cushion': 13000, 'shortage': 0, 'refund': 67000, 'monthly': 13000}], ['regression: low point comparison, partial-repair probe', {'disbursements': [36000], 'low_point': 10000, 'cushion_months': 2, 'refund_threshold': 5000}, {'base': 3000, 'cushion': 6000, 'shortage': 0, 'refund': 0, 'monthly': 2667}], ['control 1', {'disbursements': [7, 36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 3001}], ['control 2', {'disbursements': [120000, 120000], 'low_point': 40000, 'cushion_months': 2, 'refund_threshold': 5000}, {'base': 20000, 'cushion': 40000, 'shortage': 0, 'refund': 0, 'monthly': 20000}], ['control 3', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 4', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 5', {'disbursements': [7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 1, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 1}]], [['regression: low point comparison', {'disbursements': [250000, 120000], 'low_point': 80000, 'cushion_months': 1, 'refund_threshold': 20000}, {'base': 30833, 'cushion': 30833, 'shortage': 0, 'refund': 49167, 'monthly': 30833}], ['regression: low point comparison, partial-repair probe', {'disbursements': [36000], 'low_point': 0, 'cushion_months': 5, 'refund_threshold': 5000}, {'base': 3000, 'cushion': 15000, 'shortage': 15000, 'refund': 0, 'monthly': 4250}], ['control 1', {'disbursements': [36000, 99999, 250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 32167, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 32167}], ['control 2', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 20000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 3', {'disbursements': [120000, 7, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 18334, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 18334}], ['control 4', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 5000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 5', {'disbursements': [250000, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 39167, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 39167}]], [['regression: low point comparison', {'disbursements': [36000], 'low_point': -5000, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3000, 'cushion': 0, 'shortage': 5000, 'refund': 0, 'monthly': 3417}], ['control 1', {'disbursements': [120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 5000}, {'base': 18333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 18333}], ['control 2', {'disbursements': [250000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 20833, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 20833}], ['control 3', {'disbursements': [36000, 7, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 13001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 13001}], ['control 4', {'disbursements': [120000], 'low_point': 10000, 'cushion_months': 1, 'refund_threshold': 5000}, {'base': 10000, 'cushion': 10000, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 5', {'disbursements': [120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10000}], ['control 6', {'disbursements': [99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 20000}, {'base': 8333, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 8333}]], [['regression: low point comparison', {'disbursements': [120000], 'low_point': 150000, 'cushion_months': 5, 'refund_threshold': 20000}, {'base': 10000, 'cushion': 50000, 'shortage': 0, 'refund': 100000, 'monthly': 10000}], ['control 1', {'disbursements': [7, 7], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 1, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 1}], ['control 2', {'disbursements': [7, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 10001, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 10001}], ['control 3', {'disbursements': [250000, 250000, 120000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 51667, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 51667}], ['control 4', {'disbursements': [99999, 120000, 99999], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 26667, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 26667}], ['control 5', {'disbursements': [36000], 'low_point': 0, 'cushion_months': 0, 'refund_threshold': 0}, {'base': 3000, 'cushion': 0, 'shortage': 0, 'refund': 0, 'monthly': 3000}], ['control 6', {'disbursements': [36000, 120000, 36000], 'low_point': 80000, 'cushion_months': 5, 'refund_threshold': 20000}, {'base': 16000, 'cushion': 80000, 'shortage': 0, 'refund': 0, 'monthly': 16000}]]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'raised ' + type(exc).__name__\n    check(label, actual, expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"A deterministic bounded teaching model with stipulated toy lending rules stated in the contract; money is integer cents and rates are basis points; it makes no claim of conformance to any regulation, servicing 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-loan-amortization-schedules-escrow-analysis-low-point-comparison","generated_at":"2026-09-29T14:46:29.149793+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Amortization engines drive borrower statements, payoff quotes and investor remittances; a misplaced rounding step, boundary or ordering rule compounds across hundreds of periods.","repair":"Compare the projected low point against the cushion.","root_cause":"The difference is taken as cushion minus low point.","sha256":"10ca1496154fa1f1d7b1edd9b76c94023347234dcac6acdb90015ec7892fedf0","title":"Annual escrow analysis: low point comparison · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":41.853,"exit_code":1,"observations":[{"actual":{"base":21333,"cushion":42667,"monthly":23528,"refund":0,"shortage":26333},"check":"regression: low point comparison","expected":{"base":21333,"cushion":42667,"monthly":25306,"refund":0,"shortage":47667},"passed":false},{"actual":{"base":6001,"cushion":0,"monthly":6502,"refund":0,"shortage":6001},"check":"control 1","expected":{"base":6001,"cushion":0,"monthly":6001,"refund":0,"shortage":0},"passed":false},{"actual":{"base":23834,"cushion":0,"monthly":25821,"refund":0,"shortage":23834},"check":"control 2","expected":{"base":23834,"cushion":0,"monthly":23834,"refund":0,"shortage":0},"passed":false},{"actual":{"base":10001,"cushion":0,"monthly":10835,"refund":0,"shortage":10001},"check":"control 3","expected":{"base":10001,"cushion":0,"monthly":10001,"refund":0,"shortage":0},"passed":false},{"actual":{"base":20000,"cushion":40000,"monthly":20000,"refund":20000,"shortage":0},"check":"control 4","expected":{"base":20000,"cushion":40000,"monthly":20000,"refund":0,"shortage":0},"passed":false},{"actual":{"base":28333,"cushion":0,"monthly":30695,"refund":0,"shortage":28333},"check":"control 5","expected":{"base":28333,"cushion":0,"monthly":28333,"refund":0,"shortage":0},"passed":false},{"actual":{"base":10000,"cushion":0,"monthly":10834,"refund":0,"shortage":10000},"check":"control 6","expected":{"base":10000,"cushion":0,"monthly":10000,"refund":0,"shortage":0},"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: low point comparison\", \"actual\": {\"base\": 21333, \"cushion\": 42667, \"shortage\": 26333, \"refund\": 0, \"monthly\": 23528}, \"expected\": {\"base\": 21333, \"cushion\": 42667, \"shortage\": 47667, \"refund\": 0, \"monthly\": 25306}, \"passed\": false}, {\"check\": \"control 1\", \"actual\": {\"base\": 6001, \"cushion\": 0, \"shortage\": 6001, \"refund\": 0, \"monthly\": 6502}, \"expected\": {\"base\": 6001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 6001}, \"passed\": false}, {\"check\": \"control 2\", \"actual\": {\"base\": 23834, \"cushion\": 0, \"shortage\": 23834, \"refund\": 0, \"monthly\": 25821}, \"expected\": {\"base\": 23834, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 23834}, \"passed\": false}, {\"check\": \"control 3\", \"actual\": {\"base\": 10001, \"cushion\": 0, \"shortage\": 10001, \"refund\": 0, \"monthly\": 10835}, \"expected\": {\"base\": 10001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10001}, \"passed\": false}, {\"check\": \"control 4\", \"actual\": {\"base\": 20000, \"cushion\": 40000, \"shortage\": 0, \"refund\": 20000, \"monthly\": 20000}, \"expected\": {\"base\": 20000, \"cushion\": 40000, \"shortage\": 0, \"refund\": 0, \"monthly\": 20000}, \"passed\": false}, {\"check\": \"control 5\", \"actual\": {\"base\": 28333, \"cushion\": 0, \"shortage\": 28333, \"refund\": 0, \"monthly\": 30695}, \"expected\": {\"base\": 28333, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 28333}, \"passed\": false}, {\"check\": \"control 6\", \"actual\": {\"base\": 10000, \"cushion\": 0, \"shortage\": 10000, \"refund\": 0, \"monthly\": 10834}, \"expected\": {\"base\": 10000, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10000}, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.592,"exit_code":1,"observations":[{"actual":{"base":21333,"cushion":42667,"monthly":21333,"refund":47667,"shortage":0},"check":"regression: low point comparison","expected":{"base":21333,"cushion":42667,"monthly":25306,"refund":0,"shortage":47667},"passed":false},{"actual":{"base":6001,"cushion":0,"monthly":6001,"refund":0,"shortage":0},"check":"control 1","expected":{"base":6001,"cushion":0,"monthly":6001,"refund":0,"shortage":0},"passed":true},{"actual":{"base":23834,"cushion":0,"monthly":23834,"refund":0,"shortage":0},"check":"control 2","expected":{"base":23834,"cushion":0,"monthly":23834,"refund":0,"shortage":0},"passed":true},{"actual":{"base":10001,"cushion":0,"monthly":10001,"refund":0,"shortage":0},"check":"control 3","expected":{"base":10001,"cushion":0,"monthly":10001,"refund":0,"shortage":0},"passed":true},{"actual":{"base":20000,"cushion":40000,"monthly":20000,"refund":0,"shortage":0},"check":"control 4","expected":{"base":20000,"cushion":40000,"monthly":20000,"refund":0,"shortage":0},"passed":true},{"actual":{"base":28333,"cushion":0,"monthly":28333,"refund":0,"shortage":0},"check":"control 5","expected":{"base":28333,"cushion":0,"monthly":28333,"refund":0,"shortage":0},"passed":true},{"actual":{"base":10000,"cushion":0,"monthly":10000,"refund":0,"shortage":0},"check":"control 6","expected":{"base":10000,"cushion":0,"monthly":10000,"refund":0,"shortage":0},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: low point comparison\", \"actual\": {\"base\": 21333, \"cushion\": 42667, \"shortage\": 0, \"refund\": 47667, \"monthly\": 21333}, \"expected\": {\"base\": 21333, \"cushion\": 42667, \"shortage\": 47667, \"refund\": 0, \"monthly\": 25306}, \"passed\": false}, {\"check\": \"control 1\", \"actual\": {\"base\": 6001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 6001}, \"expected\": {\"base\": 6001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 6001}, \"passed\": true}, {\"check\": \"control 2\", \"actual\": {\"base\": 23834, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 23834}, \"expected\": {\"base\": 23834, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 23834}, \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"base\": 10001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10001}, \"expected\": {\"base\": 10001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10001}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"base\": 20000, \"cushion\": 40000, \"shortage\": 0, \"refund\": 0, \"monthly\": 20000}, \"expected\": {\"base\": 20000, \"cushion\": 40000, \"shortage\": 0, \"refund\": 0, \"monthly\": 20000}, \"passed\": true}, {\"check\": \"control 5\", \"actual\": {\"base\": 28333, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 28333}, \"expected\": {\"base\": 28333, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 28333}, \"passed\": true}, {\"check\": \"control 6\", \"actual\": {\"base\": 10000, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10000}, \"expected\": {\"base\": 10000, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10000}, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":41.945,"exit_code":0,"observations":[{"actual":{"base":21333,"cushion":42667,"monthly":25306,"refund":0,"shortage":47667},"check":"regression: low point comparison","expected":{"base":21333,"cushion":42667,"monthly":25306,"refund":0,"shortage":47667},"passed":true},{"actual":{"base":6001,"cushion":0,"monthly":6001,"refund":0,"shortage":0},"check":"control 1","expected":{"base":6001,"cushion":0,"monthly":6001,"refund":0,"shortage":0},"passed":true},{"actual":{"base":23834,"cushion":0,"monthly":23834,"refund":0,"shortage":0},"check":"control 2","expected":{"base":23834,"cushion":0,"monthly":23834,"refund":0,"shortage":0},"passed":true},{"actual":{"base":10001,"cushion":0,"monthly":10001,"refund":0,"shortage":0},"check":"control 3","expected":{"base":10001,"cushion":0,"monthly":10001,"refund":0,"shortage":0},"passed":true},{"actual":{"base":20000,"cushion":40000,"monthly":20000,"refund":0,"shortage":0},"check":"control 4","expected":{"base":20000,"cushion":40000,"monthly":20000,"refund":0,"shortage":0},"passed":true},{"actual":{"base":28333,"cushion":0,"monthly":28333,"refund":0,"shortage":0},"check":"control 5","expected":{"base":28333,"cushion":0,"monthly":28333,"refund":0,"shortage":0},"passed":true},{"actual":{"base":10000,"cushion":0,"monthly":10000,"refund":0,"shortage":0},"check":"control 6","expected":{"base":10000,"cushion":0,"monthly":10000,"refund":0,"shortage":0},"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: low point comparison\", \"actual\": {\"base\": 21333, \"cushion\": 42667, \"shortage\": 47667, \"refund\": 0, \"monthly\": 25306}, \"expected\": {\"base\": 21333, \"cushion\": 42667, \"shortage\": 47667, \"refund\": 0, \"monthly\": 25306}, \"passed\": true}, {\"check\": \"control 1\", \"actual\": {\"base\": 6001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 6001}, \"expected\": {\"base\": 6001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 6001}, \"passed\": true}, {\"check\": \"control 2\", \"actual\": {\"base\": 23834, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 23834}, \"expected\": {\"base\": 23834, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 23834}, \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"base\": 10001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10001}, \"expected\": {\"base\": 10001, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10001}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"base\": 20000, \"cushion\": 40000, \"shortage\": 0, \"refund\": 0, \"monthly\": 20000}, \"expected\": {\"base\": 20000, \"cushion\": 40000, \"shortage\": 0, \"refund\": 0, \"monthly\": 20000}, \"passed\": true}, {\"check\": \"control 5\", \"actual\": {\"base\": 28333, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 28333}, \"expected\": {\"base\": 28333, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 28333}, \"passed\": true}, {\"check\": \"control 6\", \"actual\": {\"base\": 10000, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10000}, \"expected\": {\"base\": 10000, \"cushion\": 0, \"shortage\": 0, \"refund\": 0, \"monthly\": 10000}, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}