{"abstract":"The bank absorbs up to half a cent per withdrawal.","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":"Flooring the charge absorbs almost a full cent per withdrawal.","family":"w2-currency_rounding_and_fx_conversion-atm-foreign-note-dispense-charge-rounding","id":"FA-62291","implementations":{"attempt":{"sha256":"8188e48800d1f33cefd1a87d994c98646876c6cb3aa56fb1d41b5ae0025c1cff","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_FLOOR)\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_FLOOR)) + 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 charge-rounding 1', (1000, '0.92', 5, 0), [5, 544]),\n  ('regression charge-rounding 2', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('partial repair guard 1', (20000, '151.37', 1000, 500), [30000, 20319]),\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  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801])],\n [('regression charge-rounding 1', (97345, '30.034', 10, 0), [29230, 97324]),\n  ('regression charge-rounding 2', (128997, '1606.6071', 1000, 250), [2072000, 129218]),\n  ('partial repair guard 1', (10870, '0.92', 10, 300), [100, 11170]),\n  ('partial repair guard 2', (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  ('control: euro fives', (1000, '0.92', 5, 0), [5, 544]),\n  ('control: below note', (500, '0.92', 5, 250), 'ERR:below-min-note')],\n [('regression charge-rounding 1', (100634, '12628.590', 10000, 250), [12700000, 100816]),\n  ('regression charge-rounding 2', (51281, '1711.2188', 1000, 250), [877000, 51501]),\n  ('partial repair guard 1', (7777, '0.7893', 10, 199), [60, 7801]),\n  ('partial repair guard 2', (20395, '717.2790', 20, 199), [146280, 20593]),\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 charge-rounding 1', (48730, '311.732', 10000, 250), [150000, 48369]),\n  ('regression charge-rounding 2', (197227, '597.2986', 5, 199), [1178030, 197426]),\n  ('partial repair guard 1', (130189, '821.097', 5, 0), [1068975, 130189]),\n  ('partial repair guard 2', (85223, '170817.58', 5, 500), [145575865, 85723]),\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 charge-rounding 1', (79885, '2964.227', 50, 199), [2367950, 80084]),\n  ('regression charge-rounding 2', (10316, '108100.20', 1000, 250), [11151000, 10566]),\n  ('partial repair guard 1', (97345, '30.034', 10, 0), [29230, 97324]),\n  ('partial repair guard 2', (127362, '68153.76', 10, 500), [86801990, 127862]),\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":"88e350178f058b91062eedf5e7800e10edd65e012e6e3636deacd3ea54f85286","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_FLOOR)\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_HALF_EVEN)) + 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 charge-rounding 1', (1000, '0.92', 5, 0), [5, 544]),\n  ('regression charge-rounding 2', (100000, '1352.5', 10000, 0), [1350000, 99816]),\n  ('partial repair guard 1', (20000, '151.37', 1000, 500), [30000, 20319]),\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  ('control: sterling tens', (7777, '0.7893', 10, 199), [60, 7801])],\n [('regression charge-rounding 1', (97345, '30.034', 10, 0), [29230, 97324]),\n  ('regression charge-rounding 2', (128997, '1606.6071', 1000, 250), [2072000, 129218]),\n  ('partial repair guard 1', (10870, '0.92', 10, 300), [100, 11170]),\n  ('partial repair guard 2', (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  ('control: euro fives', (1000, '0.92', 5, 0), [5, 544]),\n  ('control: below note', (500, '0.92', 5, 250), 'ERR:below-min-note')],\n [('regression charge-rounding 1', (100634, '12628.590', 10000, 250), [12700000, 100816]),\n  ('regression charge-rounding 2', (51281, '1711.2188', 1000, 250), [877000, 51501]),\n  ('partial repair guard 1', (7777, '0.7893', 10, 199), [60, 7801]),\n  ('partial repair guard 2', (20395, '717.2790', 20, 199), [146280, 20593]),\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 charge-rounding 1', (48730, '311.732', 10000, 250), [150000, 48369]),\n  ('regression charge-rounding 2', (197227, '597.2986', 5, 199), [1178030, 197426]),\n  ('partial repair guard 1', (130189, '821.097', 5, 0), [1068975, 130189]),\n  ('partial repair guard 2', (85223, '170817.58', 5, 500), [145575865, 85723]),\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 charge-rounding 1', (79885, '2964.227', 50, 199), [2367950, 80084]),\n  ('regression charge-rounding 2', (10316, '108100.20', 1000, 250), [11151000, 10566]),\n  ('partial repair guard 1', (97345, '30.034', 10, 0), [29230, 97324]),\n  ('partial repair guard 2', (127362, '68153.76', 10, 500), [86801990, 127862]),\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-charge-rounding","generated_at":"2026-09-29T14:47:03.304258+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":"The back-converted charge is rounded half-even.","sha256":"40b44be6eb167a0de3617d3364e84bc1e65fff25ccb96fdc1a9ce2849280cb1d","title":"The home-currency charge is rounded to nearest instead of up · 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":42.699,"exit_code":1,"observations":[{"actual":[5,543],"check":"regression charge-rounding 1","expected":[5,544],"passed":false},{"actual":[1350000,99815],"check":"regression charge-rounding 2","expected":[1350000,99816],"passed":false},{"actual":[30000,20318],"check":"partial repair guard 1","expected":[30000,20319],"passed":false},{"actual":"ERR:below-min-note","check":"control: below note","expected":"ERR:below-min-note","passed":true},{"actual":[100,11169],"check":"control: exact multiple","expected":[100,11170],"passed":false},{"actual":[60,7800],"check":"control: sterling tens","expected":[60,7801],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression charge-rounding 1\", \"actual\": [5, 543], \"expected\": [5, 544], \"passed\": false}, {\"check\": \"regression charge-rounding 2\", \"actual\": [1350000, 99815], \"expected\": [1350000, 99816], \"passed\": false}, {\"check\": \"partial repair guard 1\", \"actual\": [30000, 20318], \"expected\": [30000, 20319], \"passed\": false}, {\"check\": \"control: below note\", \"actual\": \"ERR:below-min-note\", \"expected\": \"ERR:below-min-note\", \"passed\": true}, {\"check\": \"control: exact multiple\", \"actual\": [100, 11169], \"expected\": [100, 11170], \"passed\": false}, {\"check\": \"control: sterling tens\", \"actual\": [60, 7800], \"expected\": [60, 7801], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.114,"exit_code":1,"observations":[{"actual":[5,543],"check":"regression charge-rounding 1","expected":[5,544],"passed":false},{"actual":[1350000,99815],"check":"regression charge-rounding 2","expected":[1350000,99816],"passed":false},{"actual":[30000,20319],"check":"partial repair guard 1","expected":[30000,20319],"passed":true},{"actual":"ERR:below-min-note","check":"control: below note","expected":"ERR:below-min-note","passed":true},{"actual":[100,11170],"check":"control: exact multiple","expected":[100,11170],"passed":true},{"actual":[60,7801],"check":"control: sterling tens","expected":[60,7801],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression charge-rounding 1\", \"actual\": [5, 543], \"expected\": [5, 544], \"passed\": false}, {\"check\": \"regression charge-rounding 2\", \"actual\": [1350000, 99815], \"expected\": [1350000, 99816], \"passed\": false}, {\"check\": \"partial repair guard 1\", \"actual\": [30000, 20319], \"expected\": [30000, 20319], \"passed\": true}, {\"check\": \"control: below note\", \"actual\": \"ERR:below-min-note\", \"expected\": \"ERR:below-min-note\", \"passed\": true}, {\"check\": \"control: exact multiple\", \"actual\": [100, 11170], \"expected\": [100, 11170], \"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."}}