{"abstract":"Late joiners are billed for only a fraction of the usage they consumed.","category":"Subscription proration billing","checks":8,"contract":"Input {flat, period_days, from, cancel|None, unit, events: [[day, qty]]}. Active window is [from, end) with end = min(cancel, period_days) or period_days. The flat fee is prorated by active days half-up; usage is not prorated: every event inside the window is billed qty*unit. Return [flat_charge, usage_charge].","evaluation_group":"w2-subscription-proration-metered-with-flat-fee","failed_approach":"The attempt stops prorating but also stops windowing usage to the active period.","family":"w2-subscription-proration-metered-with-flat-fee-usage-not-prorated","id":"FA-59656","implementations":{"attempt":{"sha256":"dc3aceb19bd3a4e36b0df914ce8bd9e19246c240b97c829c44b94cd78782d5bc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    end = x['period_days'] if x['cancel'] is None else min(x['cancel'], x['period_days'])\n    active = max(0, end - x['from'])\n    flat = (x['flat'] * active * 2 + x['period_days']) // (2 * x['period_days'])\n    usage = sum(q for d, q in x['events']) * x['unit']\n    return [flat, usage]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'flat': 2900, 'period_days': 30, 'from': 15, 'cancel': None, 'unit': 5, 'events': [[26, 260], [12, 213]]}, [1450, 1300]), ('regression', {'flat': 12170, 'period_days': 30, 'from': 3, 'cancel': None, 'unit': 12, 'events': [[23, 155], [28, 348], [21, 236]]}, [10953, 8868]), ('partial-repair probe', {'flat': 2900, 'period_days': 31, 'from': 23, 'cancel': None, 'unit': 12, 'events': [[13, 491]]}, [748, 0]), ('partial-repair probe', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('normal control', {'flat': 8044, 'period_days': 31, 'from': 14, 'cancel': None, 'unit': 5, 'events': []}, [4411, 0]), ('normal control', {'flat': 2900, 'period_days': 31, 'from': 0, 'cancel': None, 'unit': 5, 'events': [[10, 43], [0, 320]]}, [2900, 1815]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 10, 'cancel': None, 'unit': 5, 'events': []}, [1933, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 26, 'cancel': 17, 'unit': 1, 'events': []}, [0, 0])], [('regression', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('regression', {'flat': 12170, 'period_days': 30, 'from': 3, 'cancel': None, 'unit': 12, 'events': [[23, 155], [28, 348], [21, 236]]}, [10953, 8868]), ('partial-repair probe', {'flat': 6972, 'period_days': 31, 'from': 29, 'cancel': 18, 'unit': 12, 'events': [[29, 170]]}, [0, 0]), ('partial-repair probe', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 7, 'cancel': 17, 'unit': 12, 'events': []}, [967, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 29, 'cancel': 2, 'unit': 5, 'events': []}, [0, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 11, 'cancel': None, 'unit': 1, 'events': []}, [6270, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 9, 'cancel': None, 'unit': 1, 'events': []}, [7026, 0])], [('regression', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('regression', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 2, 'cancel': 7, 'unit': 12, 'events': [[8, 9], [1, 189]]}, [1597, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 7, 'cancel': 9, 'unit': 12, 'events': []}, [639, 0]), ('normal control', {'flat': 11296, 'period_days': 30, 'from': 23, 'cancel': None, 'unit': 1, 'events': []}, [2636, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 25, 'cancel': 29, 'unit': 12, 'events': []}, [1320, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 9, 'cancel': None, 'unit': 5, 'events': []}, [7026, 0])], [('regression', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('regression', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 2, 'cancel': 7, 'unit': 12, 'events': [[8, 9], [1, 189]]}, [1597, 0]), ('partial-repair probe', {'flat': 11245, 'period_days': 30, 'from': 4, 'cancel': None, 'unit': 5, 'events': [[15, 26], [32, 318], [2, 320], [5, 358]]}, [9746, 1920]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 29, 'cancel': 16, 'unit': 12, 'events': []}, [0, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 26, 'cancel': None, 'unit': 12, 'events': []}, [387, 0]), ('normal control', {'flat': 8533, 'period_days': 30, 'from': 5, 'cancel': 4, 'unit': 12, 'events': []}, [0, 0]), ('normal control', {'flat': 3099, 'period_days': 30, 'from': 5, 'cancel': None, 'unit': 1, 'events': []}, [2583, 0])], [('regression', {'flat': 11245, 'period_days': 30, 'from': 4, 'cancel': None, 'unit': 5, 'events': [[15, 26], [32, 318], [2, 320], [5, 358]]}, [9746, 1920]), ('regression', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('partial-repair probe', {'flat': 6064, 'period_days': 30, 'from': 12, 'cancel': 13, 'unit': 12, 'events': [[26, 133], [7, 193]]}, [202, 0]), ('partial-repair probe', {'flat': 2900, 'period_days': 30, 'from': 26, 'cancel': None, 'unit': 5, 'events': [[15, 372], [6, 377], [28, 0]]}, [387, 0]), ('normal control', {'flat': 19748, 'period_days': 30, 'from': 10, 'cancel': None, 'unit': 5, 'events': []}, [13165, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 28, 'cancel': None, 'unit': 12, 'events': []}, [958, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 22, 'cancel': None, 'unit': 5, 'events': []}, [773, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 8, 'cancel': None, 'unit': 1, 'events': []}, [2127, 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":"e8363874f15b5a677e4679feb50cce3b874cf14c15ef36243d5466d79764a3dd","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    end = x['period_days'] if x['cancel'] is None else min(x['cancel'], x['period_days'])\n    active = max(0, end - x['from'])\n    flat = (x['flat'] * active * 2 + x['period_days']) // (2 * x['period_days'])\n    usage = sum(q for d, q in x['events'] if x['from'] <= d < end) * x['unit'] * active // x['period_days']\n    return [flat, usage]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'flat': 2900, 'period_days': 30, 'from': 15, 'cancel': None, 'unit': 5, 'events': [[26, 260], [12, 213]]}, [1450, 1300]), ('regression', {'flat': 12170, 'period_days': 30, 'from': 3, 'cancel': None, 'unit': 12, 'events': [[23, 155], [28, 348], [21, 236]]}, [10953, 8868]), ('partial-repair probe', {'flat': 2900, 'period_days': 31, 'from': 23, 'cancel': None, 'unit': 12, 'events': [[13, 491]]}, [748, 0]), ('partial-repair probe', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('normal control', {'flat': 8044, 'period_days': 31, 'from': 14, 'cancel': None, 'unit': 5, 'events': []}, [4411, 0]), ('normal control', {'flat': 2900, 'period_days': 31, 'from': 0, 'cancel': None, 'unit': 5, 'events': [[10, 43], [0, 320]]}, [2900, 1815]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 10, 'cancel': None, 'unit': 5, 'events': []}, [1933, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 26, 'cancel': 17, 'unit': 1, 'events': []}, [0, 0])], [('regression', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('regression', {'flat': 12170, 'period_days': 30, 'from': 3, 'cancel': None, 'unit': 12, 'events': [[23, 155], [28, 348], [21, 236]]}, [10953, 8868]), ('partial-repair probe', {'flat': 6972, 'period_days': 31, 'from': 29, 'cancel': 18, 'unit': 12, 'events': [[29, 170]]}, [0, 0]), ('partial-repair probe', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 7, 'cancel': 17, 'unit': 12, 'events': []}, [967, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 29, 'cancel': 2, 'unit': 5, 'events': []}, [0, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 11, 'cancel': None, 'unit': 1, 'events': []}, [6270, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 9, 'cancel': None, 'unit': 1, 'events': []}, [7026, 0])], [('regression', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('regression', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 2, 'cancel': 7, 'unit': 12, 'events': [[8, 9], [1, 189]]}, [1597, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 7, 'cancel': 9, 'unit': 12, 'events': []}, [639, 0]), ('normal control', {'flat': 11296, 'period_days': 30, 'from': 23, 'cancel': None, 'unit': 1, 'events': []}, [2636, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 25, 'cancel': 29, 'unit': 12, 'events': []}, [1320, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 9, 'cancel': None, 'unit': 5, 'events': []}, [7026, 0])], [('regression', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('regression', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 2, 'cancel': 7, 'unit': 12, 'events': [[8, 9], [1, 189]]}, [1597, 0]), ('partial-repair probe', {'flat': 11245, 'period_days': 30, 'from': 4, 'cancel': None, 'unit': 5, 'events': [[15, 26], [32, 318], [2, 320], [5, 358]]}, [9746, 1920]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 29, 'cancel': 16, 'unit': 12, 'events': []}, [0, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 26, 'cancel': None, 'unit': 12, 'events': []}, [387, 0]), ('normal control', {'flat': 8533, 'period_days': 30, 'from': 5, 'cancel': 4, 'unit': 12, 'events': []}, [0, 0]), ('normal control', {'flat': 3099, 'period_days': 30, 'from': 5, 'cancel': None, 'unit': 1, 'events': []}, [2583, 0])], [('regression', {'flat': 11245, 'period_days': 30, 'from': 4, 'cancel': None, 'unit': 5, 'events': [[15, 26], [32, 318], [2, 320], [5, 358]]}, [9746, 1920]), ('regression', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('partial-repair probe', {'flat': 6064, 'period_days': 30, 'from': 12, 'cancel': 13, 'unit': 12, 'events': [[26, 133], [7, 193]]}, [202, 0]), ('partial-repair probe', {'flat': 2900, 'period_days': 30, 'from': 26, 'cancel': None, 'unit': 5, 'events': [[15, 372], [6, 377], [28, 0]]}, [387, 0]), ('normal control', {'flat': 19748, 'period_days': 30, 'from': 10, 'cancel': None, 'unit': 5, 'events': []}, [13165, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 28, 'cancel': None, 'unit': 12, 'events': []}, [958, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 22, 'cancel': None, 'unit': 5, 'events': []}, [773, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 8, 'cancel': None, 'unit': 1, 'events': []}, [2127, 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"},"fixed":{"sha256":"34c76cbe67801816d2448513fcdde39ff5e53a771fc3822d3d06c626f4ff84ec","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    end = x['period_days'] if x['cancel'] is None else min(x['cancel'], x['period_days'])\n    active = max(0, end - x['from'])\n    flat = (x['flat'] * active * 2 + x['period_days']) // (2 * x['period_days'])\n    usage = sum(q for d, q in x['events'] if x['from'] <= d < end) * x['unit']\n    return [flat, usage]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'flat': 2900, 'period_days': 30, 'from': 15, 'cancel': None, 'unit': 5, 'events': [[26, 260], [12, 213]]}, [1450, 1300]), ('regression', {'flat': 12170, 'period_days': 30, 'from': 3, 'cancel': None, 'unit': 12, 'events': [[23, 155], [28, 348], [21, 236]]}, [10953, 8868]), ('partial-repair probe', {'flat': 2900, 'period_days': 31, 'from': 23, 'cancel': None, 'unit': 12, 'events': [[13, 491]]}, [748, 0]), ('partial-repair probe', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('normal control', {'flat': 8044, 'period_days': 31, 'from': 14, 'cancel': None, 'unit': 5, 'events': []}, [4411, 0]), ('normal control', {'flat': 2900, 'period_days': 31, 'from': 0, 'cancel': None, 'unit': 5, 'events': [[10, 43], [0, 320]]}, [2900, 1815]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 10, 'cancel': None, 'unit': 5, 'events': []}, [1933, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 26, 'cancel': 17, 'unit': 1, 'events': []}, [0, 0])], [('regression', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('regression', {'flat': 12170, 'period_days': 30, 'from': 3, 'cancel': None, 'unit': 12, 'events': [[23, 155], [28, 348], [21, 236]]}, [10953, 8868]), ('partial-repair probe', {'flat': 6972, 'period_days': 31, 'from': 29, 'cancel': 18, 'unit': 12, 'events': [[29, 170]]}, [0, 0]), ('partial-repair probe', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 7, 'cancel': 17, 'unit': 12, 'events': []}, [967, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 29, 'cancel': 2, 'unit': 5, 'events': []}, [0, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 11, 'cancel': None, 'unit': 1, 'events': []}, [6270, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 9, 'cancel': None, 'unit': 1, 'events': []}, [7026, 0])], [('regression', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('regression', {'flat': 7431, 'period_days': 31, 'from': 30, 'cancel': None, 'unit': 12, 'events': [[6, 380], [30, 5], [32, 257], [4, 247]]}, [240, 60]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 2, 'cancel': 7, 'unit': 12, 'events': [[8, 9], [1, 189]]}, [1597, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 7, 'cancel': 9, 'unit': 12, 'events': []}, [639, 0]), ('normal control', {'flat': 11296, 'period_days': 30, 'from': 23, 'cancel': None, 'unit': 1, 'events': []}, [2636, 0]), ('normal control', {'flat': 9900, 'period_days': 30, 'from': 25, 'cancel': 29, 'unit': 12, 'events': []}, [1320, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 9, 'cancel': None, 'unit': 5, 'events': []}, [7026, 0])], [('regression', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('regression', {'flat': 2900, 'period_days': 31, 'from': 7, 'cancel': None, 'unit': 5, 'events': [[19, 421], [6, 32], [33, 481]]}, [2245, 2105]), ('partial-repair probe', {'flat': 9900, 'period_days': 31, 'from': 2, 'cancel': 7, 'unit': 12, 'events': [[8, 9], [1, 189]]}, [1597, 0]), ('partial-repair probe', {'flat': 11245, 'period_days': 30, 'from': 4, 'cancel': None, 'unit': 5, 'events': [[15, 26], [32, 318], [2, 320], [5, 358]]}, [9746, 1920]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 29, 'cancel': 16, 'unit': 12, 'events': []}, [0, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 26, 'cancel': None, 'unit': 12, 'events': []}, [387, 0]), ('normal control', {'flat': 8533, 'period_days': 30, 'from': 5, 'cancel': 4, 'unit': 12, 'events': []}, [0, 0]), ('normal control', {'flat': 3099, 'period_days': 30, 'from': 5, 'cancel': None, 'unit': 1, 'events': []}, [2583, 0])], [('regression', {'flat': 11245, 'period_days': 30, 'from': 4, 'cancel': None, 'unit': 5, 'events': [[15, 26], [32, 318], [2, 320], [5, 358]]}, [9746, 1920]), ('regression', {'flat': 9900, 'period_days': 31, 'from': 22, 'cancel': None, 'unit': 12, 'events': [[18, 186], [30, 275], [20, 173], [26, 168]]}, [2874, 5316]), ('partial-repair probe', {'flat': 6064, 'period_days': 30, 'from': 12, 'cancel': 13, 'unit': 12, 'events': [[26, 133], [7, 193]]}, [202, 0]), ('partial-repair probe', {'flat': 2900, 'period_days': 30, 'from': 26, 'cancel': None, 'unit': 5, 'events': [[15, 372], [6, 377], [28, 0]]}, [387, 0]), ('normal control', {'flat': 19748, 'period_days': 30, 'from': 10, 'cancel': None, 'unit': 5, 'events': []}, [13165, 0]), ('normal control', {'flat': 9900, 'period_days': 31, 'from': 28, 'cancel': None, 'unit': 12, 'events': []}, [958, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 22, 'cancel': None, 'unit': 5, 'events': []}, [773, 0]), ('normal control', {'flat': 2900, 'period_days': 30, 'from': 8, 'cancel': None, 'unit': 1, 'events': []}, [2127, 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-metered-with-flat-fee-usage-not-prorated","generated_at":"2026-09-29T14:46:38.318171+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Only the recurring fee is prorated; metered usage is billed exactly for the active window.","repair":"Restore the contract rule at the usage not prorated step: use `usage = sum(q for d, q in x['events'] if x['from'] <= d < end) * x['unit']`.","root_cause":"Metered usage is prorated like the flat fee.","sha256":"c618869b4e6fc440be5fff84f9530ebe40e134167bfb6100a12b21e0fb95fcd2","title":"Flat fee proration with metered usage: usage not prorated · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":41.476,"exit_code":1,"observations":[{"actual":[1450,2365],"check":"regression 0","expected":[1450,1300],"passed":false},{"actual":[10953,8868],"check":"regression 1","expected":[10953,8868],"passed":true},{"actual":[748,5892],"check":"partial-repair probe 2","expected":[748,0],"passed":false},{"actual":[240,10668],"check":"partial-repair probe 3","expected":[240,60],"passed":false},{"actual":[4411,0],"check":"normal control 4","expected":[4411,0],"passed":true},{"actual":[2900,1815],"check":"normal control 5","expected":[2900,1815],"passed":true},{"actual":[1933,0],"check":"normal control 6","expected":[1933,0],"passed":true},{"actual":[0,0],"check":"normal control 7","expected":[0,0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression 0\", \"actual\": [1450, 2365], \"expected\": [1450, 1300], \"passed\": false}, {\"check\": \"regression 1\", \"actual\": [10953, 8868], \"expected\": [10953, 8868], \"passed\": true}, {\"check\": \"partial-repair probe 2\", \"actual\": [748, 5892], \"expected\": [748, 0], \"passed\": false}, {\"check\": \"partial-repair probe 3\", \"actual\": [240, 10668], \"expected\": [240, 60], \"passed\": false}, {\"check\": \"normal control 4\", \"actual\": [4411, 0], \"expected\": [4411, 0], \"passed\": true}, {\"check\": \"normal control 5\", \"actual\": [2900, 1815], \"expected\": [2900, 1815], \"passed\": true}, {\"check\": \"normal control 6\", \"actual\": [1933, 0], \"expected\": [1933, 0], \"passed\": true}, {\"check\": \"normal control 7\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.471,"exit_code":1,"observations":[{"actual":[1450,650],"check":"regression 0","expected":[1450,1300],"passed":false},{"actual":[10953,7981],"check":"regression 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\"passed\": false}, {\"check\": \"normal control 4\", \"actual\": [4411, 0], \"expected\": [4411, 0], \"passed\": true}, {\"check\": \"normal control 5\", \"actual\": [2900, 1815], \"expected\": [2900, 1815], \"passed\": true}, {\"check\": \"normal control 6\", \"actual\": [1933, 0], \"expected\": [1933, 0], \"passed\": true}, {\"check\": \"normal control 7\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":39.834,"exit_code":0,"observations":[{"actual":[1450,1300],"check":"regression 0","expected":[1450,1300],"passed":true},{"actual":[10953,8868],"check":"regression 1","expected":[10953,8868],"passed":true},{"actual":[748,0],"check":"partial-repair probe 2","expected":[748,0],"passed":true},{"actual":[240,60],"check":"partial-repair probe 3","expected":[240,60],"passed":true},{"actual":[4411,0],"check":"normal control 4","expected":[4411,0],"passed":true},{"actual":[2900,1815],"check":"normal control 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\"normal control 7\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}