{"abstract":"Customers who cancel get part of the one-time setup fee back.","category":"Subscription proration billing","checks":8,"contract":"Input {price, setup, period_days, used_days, min_days, mode immediate|period_end}. Unused = max(0, period_days - used_days). period_end: no refund, access continues for the unused days. immediate: charged days = max(used_days, min_days); refund = price*max(0, period_days - charged)/period_days floored (never over-refund); the setup fee is never refunded; access ends. Return [refund, access_days].","contract_signature":"x","evaluation_group":"w2-subscription-proration-cancellation-refund","failed_approach":"The attempt excludes the fee from the base but then deducts it from the refund as a penalty.","family":"w2-subscription-proration-cancellation-refund-setup-fee-exclusion","id":"FA-59471","implementations":{"attempt":{"sha256":"60837400229a282aed1ad1b54b8015150c14fa282f0c6af0896dd5e246ebfdfc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    unused = max(0, x['period_days'] - x['used_days'])\n    if x['mode'] == 'period_end':\n        return [0, unused]\n    charged_days = max(x['used_days'], x['min_days'])\n    refundable_days = max(0, x['period_days'] - charged_days)\n    refund = max(0, x['price'] * refundable_days // x['period_days'] - x['setup'])\n    return [refund, 0]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'price': 4900, 'setup': 2500, 'period_days': 90, 'used_days': 1, 'min_days': 7, 'mode': 'immediate'}, [4518, 0]), ('regression', {'price': 999, 'setup': 2500, 'period_days': 30, 'used_days': 18, 'min_days': 14, 'mode': 'immediate'}, [399, 0]), ('partial-repair probe', {'price': 999, 'setup': 2500, 'period_days': 31, 'used_days': 16, 'min_days': 0, 'mode': 'immediate'}, [483, 0]), ('partial-repair probe', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('normal control', {'price': 4900, 'setup': 9483, 'period_days': 31, 'used_days': 13, 'min_days': 0, 'mode': 'period_end'}, [0, 18]), ('normal control', {'price': 32440, 'setup': 0, 'period_days': 90, 'used_days': 25, 'min_days': 14, 'mode': 'period_end'}, [0, 65]), ('normal control', {'price': 28584, 'setup': 2500, 'period_days': 90, 'used_days': 93, 'min_days': 14, 'mode': 'immediate'}, [0, 0]), ('normal control', {'price': 4970, 'setup': 0, 'period_days': 90, 'used_days': 0, 'min_days': 7, 'mode': 'immediate'}, [4583, 0])], [('regression', {'price': 999, 'setup': 2500, 'period_days': 30, 'used_days': 18, 'min_days': 14, 'mode': 'immediate'}, [399, 0]), ('regression', {'price': 999, 'setup': 2500, 'period_days': 31, 'used_days': 16, 'min_days': 0, 'mode': 'immediate'}, [483, 0]), ('partial-repair probe', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('partial-repair probe', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('normal control', {'price': 119900, 'setup': 0, 'period_days': 30, 'used_days': 22, 'min_days': 14, 'mode': 'immediate'}, [31973, 0]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 90, 'used_days': 66, 'min_days': 0, 'mode': 'period_end'}, [0, 24]), ('normal control', {'price': 86963, 'setup': 0, 'period_days': 90, 'used_days': 71, 'min_days': 14, 'mode': 'immediate'}, [18358, 0]), ('normal control', {'price': 999, 'setup': 0, 'period_days': 365, 'used_days': 45, 'min_days': 30, 'mode': 'period_end'}, [0, 320])], [('regression', {'price': 999, 'setup': 2500, 'period_days': 31, 'used_days': 16, 'min_days': 0, 'mode': 'immediate'}, [483, 0]), ('regression', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('partial-repair probe', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('partial-repair probe', {'price': 4900, 'setup': 2500, 'period_days': 365, 'used_days': 232, 'min_days': 0, 'mode': 'immediate'}, [1785, 0]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 31, 'used_days': 10, 'min_days': 30, 'mode': 'period_end'}, [0, 21]), ('normal control', {'price': 999, 'setup': 0, 'period_days': 30, 'used_days': 19, 'min_days': 0, 'mode': 'immediate'}, [366, 0]), ('normal control', {'price': 119900, 'setup': 0, 'period_days': 365, 'used_days': 32, 'min_days': 0, 'mode': 'immediate'}, [109388, 0]), ('normal control', {'price': 93530, 'setup': 0, 'period_days': 30, 'used_days': 29, 'min_days': 14, 'mode': 'immediate'}, [3117, 0])], [('regression', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('regression', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('partial-repair probe', {'price': 119900, 'setup': 3409, 'period_days': 31, 'used_days': 27, 'min_days': 7, 'mode': 'immediate'}, [15470, 0]), ('partial-repair probe', {'price': 119900, 'setup': 2500, 'period_days': 30, 'used_days': 6, 'min_days': 14, 'mode': 'immediate'}, [63946, 0]), ('normal control', {'price': 119900, 'setup': 2500, 'period_days': 31, 'used_days': 17, 'min_days': 14, 'mode': 'period_end'}, [0, 14]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 90, 'used_days': 53, 'min_days': 30, 'mode': 'immediate'}, [2014, 0]), ('normal control', {'price': 119900, 'setup': 0, 'period_days': 90, 'used_days': 22, 'min_days': 7, 'mode': 'period_end'}, [0, 68]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 90, 'used_days': 55, 'min_days': 14, 'mode': 'period_end'}, [0, 35])], [('regression', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('regression', {'price': 4900, 'setup': 2500, 'period_days': 365, 'used_days': 232, 'min_days': 0, 'mode': 'immediate'}, [1785, 0]), ('partial-repair probe', {'price': 4900, 'setup': 7, 'period_days': 90, 'used_days': 46, 'min_days': 0, 'mode': 'immediate'}, [2395, 0]), ('partial-repair probe', {'price': 24966, 'setup': 5091, 'period_days': 31, 'used_days': 26, 'min_days': 0, 'mode': 'immediate'}, [4026, 0]), ('normal control', {'price': 999, 'setup': 0, 'period_days': 90, 'used_days': 3, 'min_days': 14, 'mode': 'period_end'}, [0, 87]), ('normal control', {'price': 119900, 'setup': 5059, 'period_days': 90, 'used_days': 7, 'min_days': 0, 'mode': 'period_end'}, [0, 83]), ('normal control', {'price': 119900, 'setup': 2500, 'period_days': 365, 'used_days': 323, 'min_days': 7, 'mode': 'period_end'}, [0, 42]), ('normal control', {'price': 67850, 'setup': 0, 'period_days': 31, 'used_days': 10, 'min_days': 30, 'mode': 'immediate'}, [2188, 0])]]\nfor i, (label, args, expected) in enumerate(fixtures[N-1]):\n    check(\"%s %d\" % (label, i), 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":"c1515fa6259cef49dc7bc6f450bd526ad1936f1bfe5ffbefbb07f8e9357d4cd9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    unused = max(0, x['period_days'] - x['used_days'])\n    if x['mode'] == 'period_end':\n        return [0, unused]\n    charged_days = max(x['used_days'], x['min_days'])\n    refundable_days = max(0, x['period_days'] - charged_days)\n    refund = (x['price'] + x['setup']) * refundable_days // x['period_days']\n    return [refund, 0]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'price': 4900, 'setup': 2500, 'period_days': 90, 'used_days': 1, 'min_days': 7, 'mode': 'immediate'}, [4518, 0]), ('regression', {'price': 999, 'setup': 2500, 'period_days': 30, 'used_days': 18, 'min_days': 14, 'mode': 'immediate'}, [399, 0]), ('partial-repair probe', {'price': 999, 'setup': 2500, 'period_days': 31, 'used_days': 16, 'min_days': 0, 'mode': 'immediate'}, [483, 0]), ('partial-repair probe', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('normal control', {'price': 4900, 'setup': 9483, 'period_days': 31, 'used_days': 13, 'min_days': 0, 'mode': 'period_end'}, [0, 18]), ('normal control', {'price': 32440, 'setup': 0, 'period_days': 90, 'used_days': 25, 'min_days': 14, 'mode': 'period_end'}, [0, 65]), ('normal control', {'price': 28584, 'setup': 2500, 'period_days': 90, 'used_days': 93, 'min_days': 14, 'mode': 'immediate'}, [0, 0]), ('normal control', {'price': 4970, 'setup': 0, 'period_days': 90, 'used_days': 0, 'min_days': 7, 'mode': 'immediate'}, [4583, 0])], [('regression', {'price': 999, 'setup': 2500, 'period_days': 30, 'used_days': 18, 'min_days': 14, 'mode': 'immediate'}, [399, 0]), ('regression', {'price': 999, 'setup': 2500, 'period_days': 31, 'used_days': 16, 'min_days': 0, 'mode': 'immediate'}, [483, 0]), ('partial-repair probe', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('partial-repair probe', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('normal control', {'price': 119900, 'setup': 0, 'period_days': 30, 'used_days': 22, 'min_days': 14, 'mode': 'immediate'}, [31973, 0]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 90, 'used_days': 66, 'min_days': 0, 'mode': 'period_end'}, [0, 24]), ('normal control', {'price': 86963, 'setup': 0, 'period_days': 90, 'used_days': 71, 'min_days': 14, 'mode': 'immediate'}, [18358, 0]), ('normal control', {'price': 999, 'setup': 0, 'period_days': 365, 'used_days': 45, 'min_days': 30, 'mode': 'period_end'}, [0, 320])], [('regression', {'price': 999, 'setup': 2500, 'period_days': 31, 'used_days': 16, 'min_days': 0, 'mode': 'immediate'}, [483, 0]), ('regression', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('partial-repair probe', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('partial-repair probe', {'price': 4900, 'setup': 2500, 'period_days': 365, 'used_days': 232, 'min_days': 0, 'mode': 'immediate'}, [1785, 0]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 31, 'used_days': 10, 'min_days': 30, 'mode': 'period_end'}, [0, 21]), ('normal control', {'price': 999, 'setup': 0, 'period_days': 30, 'used_days': 19, 'min_days': 0, 'mode': 'immediate'}, [366, 0]), ('normal control', {'price': 119900, 'setup': 0, 'period_days': 365, 'used_days': 32, 'min_days': 0, 'mode': 'immediate'}, [109388, 0]), ('normal control', {'price': 93530, 'setup': 0, 'period_days': 30, 'used_days': 29, 'min_days': 14, 'mode': 'immediate'}, [3117, 0])], [('regression', {'price': 4900, 'setup': 1208, 'period_days': 365, 'used_days': 78, 'min_days': 14, 'mode': 'immediate'}, [3852, 0]), ('regression', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('partial-repair probe', {'price': 119900, 'setup': 3409, 'period_days': 31, 'used_days': 27, 'min_days': 7, 'mode': 'immediate'}, [15470, 0]), ('partial-repair probe', {'price': 119900, 'setup': 2500, 'period_days': 30, 'used_days': 6, 'min_days': 14, 'mode': 'immediate'}, [63946, 0]), ('normal control', {'price': 119900, 'setup': 2500, 'period_days': 31, 'used_days': 17, 'min_days': 14, 'mode': 'period_end'}, [0, 14]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 90, 'used_days': 53, 'min_days': 30, 'mode': 'immediate'}, [2014, 0]), ('normal control', {'price': 119900, 'setup': 0, 'period_days': 90, 'used_days': 22, 'min_days': 7, 'mode': 'period_end'}, [0, 68]), ('normal control', {'price': 4900, 'setup': 0, 'period_days': 90, 'used_days': 55, 'min_days': 14, 'mode': 'period_end'}, [0, 35])], [('regression', {'price': 119900, 'setup': 1279, 'period_days': 30, 'used_days': 14, 'min_days': 7, 'mode': 'immediate'}, [63946, 0]), ('regression', {'price': 4900, 'setup': 2500, 'period_days': 365, 'used_days': 232, 'min_days': 0, 'mode': 'immediate'}, [1785, 0]), ('partial-repair probe', {'price': 4900, 'setup': 7, 'period_days': 90, 'used_days': 46, 'min_days': 0, 'mode': 'immediate'}, [2395, 0]), ('partial-repair probe', {'price': 24966, 'setup': 5091, 'period_days': 31, 'used_days': 26, 'min_days': 0, 'mode': 'immediate'}, [4026, 0]), ('normal control', {'price': 999, 'setup': 0, 'period_days': 90, 'used_days': 3, 'min_days': 14, 'mode': 'period_end'}, [0, 87]), ('normal control', {'price': 119900, 'setup': 5059, 'period_days': 90, 'used_days': 7, 'min_days': 0, 'mode': 'period_end'}, [0, 83]), ('normal control', {'price': 119900, 'setup': 2500, 'period_days': 365, 'used_days': 323, 'min_days': 7, 'mode': 'period_end'}, [0, 42]), ('normal control', {'price': 67850, 'setup': 0, 'period_days': 31, 'used_days': 10, 'min_days': 30, 'mode': 'immediate'}, [2188, 0])]]\nfor i, (label, args, expected) in enumerate(fixtures[N-1]):\n    check(\"%s %d\" % (label, i), 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 teaching model of a stipulated billing rule. It makes no claim to reproduce any billing provider's exact behaviour and is not billing software. 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-subscription-proration-cancellation-refund-setup-fee-exclusion","generated_at":"2026-09-29T14:46:36.571664+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Refund math must respect minimum-charge terms and exclude non-refundable fees.","root_cause":"The setup fee is included in the prorated refund base.","sha256":"9ec5eb64311d1af9e37b8bec7e9b22a822a84442929493f31a0d58dd884b68f6","title":"Cancellation refund for unused days: setup fee exclusion · 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":40.986,"exit_code":1,"observations":[{"actual":[2018,0],"check":"regression 0","expected":[4518,0],"passed":false},{"actual":[0,0],"check":"regression 1","expected":[399,0],"passed":false},{"actual":[0,0],"check":"partial-repair probe 2","expected":[483,0],"passed":false},{"actual":[2644,0],"check":"partial-repair probe 3","expected":[3852,0],"passed":false},{"actual":[0,18],"check":"normal control 4","expected":[0,18],"passed":true},{"actual":[0,65],"check":"normal control 5","expected":[0,65],"passed":true},{"actual":[0,0],"check":"normal control 6","expected":[0,0],"passed":true},{"actual":[4583,0],"check":"normal control 7","expected":[4583,0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression 0\", \"actual\": [2018, 0], \"expected\": [4518, 0], \"passed\": false}, {\"check\": \"regression 1\", \"actual\": [0, 0], \"expected\": [399, 0], \"passed\": false}, {\"check\": \"partial-repair probe 2\", \"actual\": [0, 0], \"expected\": [483, 0], \"passed\": false}, {\"check\": \"partial-repair probe 3\", \"actual\": [2644, 0], \"expected\": [3852, 0], \"passed\": false}, {\"check\": \"normal control 4\", \"actual\": [0, 18], \"expected\": [0, 18], \"passed\": true}, {\"check\": \"normal control 5\", \"actual\": [0, 65], \"expected\": [0, 65], \"passed\": true}, {\"check\": \"normal control 6\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}, {\"check\": \"normal control 7\", \"actual\": [4583, 0], \"expected\": [4583, 0], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.29,"exit_code":1,"observations":[{"actual":[6824,0],"check":"regression 0","expected":[4518,0],"passed":false},{"actual":[1399,0],"check":"regression 1","expected":[399,0],"passed":false},{"actual":[1693,0],"check":"partial-repair probe 2","expected":[483,0],"passed":false},{"actual":[4802,0],"check":"partial-repair probe 3","expected":[3852,0],"passed":false},{"actual":[0,18],"check":"normal control 4","expected":[0,18],"passed":true},{"actual":[0,65],"check":"normal control 5","expected":[0,65],"passed":true},{"actual":[0,0],"check":"normal control 6","expected":[0,0],"passed":true},{"actual":[4583,0],"check":"normal control 7","expected":[4583,0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression 0\", \"actual\": [6824, 0], \"expected\": [4518, 0], \"passed\": false}, {\"check\": \"regression 1\", \"actual\": [1399, 0], \"expected\": [399, 0], \"passed\": false}, {\"check\": \"partial-repair probe 2\", \"actual\": [1693, 0], \"expected\": [483, 0], \"passed\": false}, {\"check\": \"partial-repair probe 3\", \"actual\": [4802, 0], \"expected\": [3852, 0], \"passed\": false}, {\"check\": \"normal control 4\", \"actual\": [0, 18], \"expected\": [0, 18], \"passed\": true}, {\"check\": \"normal control 5\", \"actual\": [0, 65], \"expected\": [0, 65], \"passed\": true}, {\"check\": \"normal control 6\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}, {\"check\": \"normal control 7\", \"actual\": [4583, 0], \"expected\": [4583, 0], \"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."}}