{"abstract":"The ATM dispenses more foreign currency than the customer requested.","category":"Currency rounding and FX conversion","checks":6,"contract":"solve(home_minor, rate, note, fee_minor): a request of home_minor home cents at rate foreign major units per home major unit is dispensed as the largest multiple of the smallest note not exceeding the converted amount (floor). If nothing can be dispensed return 'ERR:below-min-note'. The customer is charged the dispensed foreign amount converted back at the same rate, rounded UP to a home cent, plus fee_minor. Return [foreign_dispensed, charged_minor].","contract_signature":"home_minor, rate, note, fee_minor","evaluation_group":"w2-currency_rounding_and_fx_conversion-atm-foreign-note-dispense","failed_approach":"Rounding half-down still dispenses an extra note when the fraction exceeds one half.","family":"w2-currency_rounding_and_fx_conversion-atm-foreign-note-dispense-note-rounding","id":"FA-62281","implementations":{"attempt":{"sha256":"16b2a1fcacf03ca512538fe976ed854013c4a6a7bdebe1d35bef5ea5119df1b4","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom decimal import Decimal, ROUND_HALF_EVEN, ROUND_HALF_UP, ROUND_FLOOR, ROUND_CEILING, ROUND_DOWN, ROUND_UP, ROUND_HALF_DOWN\nN = 1\nobservations = []\ndef solve(home_minor, rate, note, fee_minor):\n    r = Decimal(rate)\n    home = Decimal(home_minor) / 100\n    units = (home * r / note).to_integral_value(rounding=ROUND_HALF_DOWN)\n    foreign = int(units) * note\n    if foreign == 0: return 'ERR:below-min-note'\n    charged = int((Decimal(foreign) / r * 100).to_integral_value(rounding=ROUND_CEILING)) + fee_minor\n    return [foreign, charged]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression note-rounding 1', (1000, '0.92', 5, 0), [5, 544]),\n  ('regression note-rounding 2', (500, '0.92', 5, 250), 'ERR:below-min-note'),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319]),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170]),\n  ('control: big notes', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801])],\n [('regression note-rounding 1', (130189, '821.097', 5, 0), [1068975, 130189]),\n  ('regression note-rounding 2', (97345, '30.034', 10, 0), [29230, 97324]),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170]),\n  ('control: big notes', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319])],\n [('regression note-rounding 1', (190855, '53583.55', 5, 500), [102266880, 191355]),\n  ('regression note-rounding 2', (42899, '157086.46', 10000, 500), [67380000, 43394]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319]),\n  ('control: euro fives', (1000, '0.92', 5, 0), [5, 544]),\n  ('control: below note', (500, '0.92', 5, 250), 'ERR:below-min-note'),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170])],\n [('regression note-rounding 1', (86470, '264.5122', 10000, 500), [220000, 83672]),\n  ('regression note-rounding 2', (2489, '60494.94', 10, 0), [1505710, 2489]),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170]),\n  ('control: big notes', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319])],\n [('regression note-rounding 1', (16458, '4444.030', 20, 0), [731380, 16458]),\n  ('regression note-rounding 2', (100634, '12628.590', 10000, 250), [12700000, 100816]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319]),\n  ('control: euro fives', (1000, '0.92', 5, 0), [5, 544]),\n  ('control: below note', (500, '0.92', 5, 250), 'ERR:below-min-note'),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170])]]\nfor label, args, expected in cases[N - 1]:\n    check(label, solve(*args), 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":"d27d67ca7b90497034b659bea75702531e4532d0eaecb970b7e2522ea6ce1ac7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom decimal import Decimal, ROUND_HALF_EVEN, ROUND_HALF_UP, ROUND_FLOOR, ROUND_CEILING, ROUND_DOWN, ROUND_UP, ROUND_HALF_DOWN\nN = 1\nobservations = []\ndef solve(home_minor, rate, note, fee_minor):\n    r = Decimal(rate)\n    home = Decimal(home_minor) / 100\n    units = (home * r / note).to_integral_value(rounding=ROUND_HALF_EVEN)\n    foreign = int(units) * note\n    if foreign == 0: return 'ERR:below-min-note'\n    charged = int((Decimal(foreign) / r * 100).to_integral_value(rounding=ROUND_CEILING)) + fee_minor\n    return [foreign, charged]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression note-rounding 1', (1000, '0.92', 5, 0), [5, 544]),\n  ('regression note-rounding 2', (500, '0.92', 5, 250), 'ERR:below-min-note'),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319]),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170]),\n  ('control: big notes', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801])],\n [('regression note-rounding 1', (130189, '821.097', 5, 0), [1068975, 130189]),\n  ('regression note-rounding 2', (97345, '30.034', 10, 0), [29230, 97324]),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170]),\n  ('control: big notes', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319])],\n [('regression note-rounding 1', (190855, '53583.55', 5, 500), [102266880, 191355]),\n  ('regression note-rounding 2', (42899, '157086.46', 10000, 500), [67380000, 43394]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319]),\n  ('control: euro fives', (1000, '0.92', 5, 0), [5, 544]),\n  ('control: below note', (500, '0.92', 5, 250), 'ERR:below-min-note'),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170])],\n [('regression note-rounding 1', (86470, '264.5122', 10000, 500), [220000, 83672]),\n  ('regression note-rounding 2', (2489, '60494.94', 10, 0), [1505710, 2489]),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170]),\n  ('control: big notes', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319])],\n [('regression note-rounding 1', (16458, '4444.030', 20, 0), [731380, 16458]),\n  ('regression note-rounding 2', (100634, '12628.590', 10000, 250), [12700000, 100816]),\n  ('control: yen notes', (20000, '151.37', 1000, 500), [30000, 20319]),\n  ('control: euro fives', (1000, '0.92', 5, 0), [5, 544]),\n  ('control: below note', (500, '0.92', 5, 250), 'ERR:below-min-note'),\n  ('control: exact multiple', (10870, '0.92', 10, 300), [100, 11170])]]\nfor label, args, expected in cases[N - 1]:\n    check(label, solve(*args), 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 a stipulated toy contract; it makes no claim of conformance to any real regulation, standard, or institution's rules. 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-currency_rounding_and_fx_conversion-atm-foreign-note-dispense-note-rounding","generated_at":"2026-09-29T14:47:03.148611+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Currency amounts must be rounded at the right stage and in the right unit, or ledgers, quotes and settlements drift by minor units.","root_cause":"Note units are rounded half-even instead of floored.","sha256":"6ca53899b23ca6019b5676ff3ad44ba62da471c7449ace28b78483f2b9217dbc","title":"The dispensed amount is rounded to the nearest note · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":42.026,"exit_code":1,"observations":[{"actual":[10,1087],"check":"regression note-rounding 1","expected":[5,544],"passed":false},{"actual":[5,794],"check":"regression note-rounding 2","expected":"ERR:below-min-note","passed":false},{"actual":[30000,20319],"check":"control: yen notes","expected":[30000,20319],"passed":true},{"actual":[100,11170],"check":"control: exact multiple","expected":[100,11170],"passed":true},{"actual":[1350000,99816],"check":"control: big notes","expected":[1350000,99816],"passed":true},{"actual":[60,7801],"check":"control: sterling tens","expected":[60,7801],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression note-rounding 1\", \"actual\": [10, 1087], \"expected\": [5, 544], \"passed\": false}, {\"check\": \"regression note-rounding 2\", \"actual\": [5, 794], \"expected\": \"ERR:below-min-note\", \"passed\": false}, {\"check\": \"control: yen notes\", \"actual\": [30000, 20319], \"expected\": [30000, 20319], \"passed\": true}, {\"check\": \"control: exact multiple\", \"actual\": [100, 11170], \"expected\": [100, 11170], \"passed\": true}, {\"check\": \"control: big notes\", \"actual\": [1350000, 99816], \"expected\": [1350000, 99816], \"passed\": true}, {\"check\": \"control: sterling tens\", \"actual\": [60, 7801], \"expected\": [60, 7801], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.524,"exit_code":1,"observations":[{"actual":[10,1087],"check":"regression note-rounding 1","expected":[5,544],"passed":false},{"actual":[5,794],"check":"regression note-rounding 2","expected":"ERR:below-min-note","passed":false},{"actual":[30000,20319],"check":"control: yen notes","expected":[30000,20319],"passed":true},{"actual":[100,11170],"check":"control: exact multiple","expected":[100,11170],"passed":true},{"actual":[1350000,99816],"check":"control: big notes","expected":[1350000,99816],"passed":true},{"actual":[60,7801],"check":"control: sterling tens","expected":[60,7801],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression note-rounding 1\", \"actual\": [10, 1087], \"expected\": [5, 544], \"passed\": false}, {\"check\": \"regression note-rounding 2\", \"actual\": [5, 794], \"expected\": \"ERR:below-min-note\", \"passed\": false}, {\"check\": \"control: yen notes\", \"actual\": [30000, 20319], \"expected\": [30000, 20319], \"passed\": true}, {\"check\": \"control: exact multiple\", \"actual\": [100, 11170], \"expected\": [100, 11170], \"passed\": true}, {\"check\": \"control: big notes\", \"actual\": [1350000, 99816], \"expected\": [1350000, 99816], \"passed\": true}, {\"check\": \"control: sterling tens\", \"actual\": [60, 7801], \"expected\": [60, 7801], \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}