{"abstract":"The ETA of calls behind the car ignores stops made on the way back.","category":"Elevator dispatch scheduling","checks":8,"contract":"A moving car at floor with direction and car stops estimates its arrival at a hall call (target, call direction). Work in the car direction (mirror floors for down). If the target is strictly ahead and the call is in the car direction, the car goes straight there, stopping at stops strictly between. Otherwise it runs to the farthest of its stops ahead and the target, reverses and returns to the target, stopping at every stop ahead plus stops strictly between target and floor behind. A stop at the target floor is not extra. ETA = floors travelled * per_floor_s + stops * stop_s.","contract_signature":"x","evaluation_group":"w2-elevator_dispatch_scheduling-hall-call-eta","failed_approach":"Counting stops up to the reversal floor double-counts the stops ahead.","family":"w2-elevator_dispatch_scheduling-hall-call-eta-return-leg-stops","id":"FA-67546","implementations":{"attempt":{"sha256":"0dbd5ddf60238af922b9f03ebf549ac69e5a4d6e47d1ddb6ddfb4050310368c8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    sg = 1 if x['dir'] == 'up' else -1\n    f = x['floor'] * sg\n    t = x['target'] * sg\n    stops = [s * sg for s in x['stops'] if s * sg != t]\n    same = x['call_dir'] == x['dir']\n    if t > f and same:\n        path = t - f\n        n = len([s for s in stops if f < s < t])\n    else:\n        ahead = [s for s in stops if s > f]\n        far = max(ahead + [t, f])\n        path = (far - f) + (far - t)\n        n = len(ahead) + len([s for s in stops if t < s <= far])\n    return path * x['per_floor_s'] + n * x['stop_s']\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 9', {'floor': 15, 'dir': 'up', 'target': 9, 'call_dir': 'down', 'stops': [13, 11, 12], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 1', {'floor': 6, 'dir': 'down', 'target': 12, 'call_dir': 'down', 'stops': [3, 4], 'per_floor_s': 2, 'stop_s': 12}, 48), ('sampled regression 4', {'floor': 1, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [3, 10, 5], 'per_floor_s': 2, 'stop_s': 12}, 62), ('control 7', {'floor': 7, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [1, 13, 9, 2], 'per_floor_s': 3, 'stop_s': 12}, 24)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('sampled regression 59', {'floor': 15, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [14, 13], 'per_floor_s': 3, 'stop_s': 10}, 59), ('control 3', {'floor': 13, 'dir': 'up', 'target': 9, 'call_dir': 'up', 'stops': [2, 15, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 32), ('boundary: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('control 12', {'floor': 12, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 8, 7, 15], 'per_floor_s': 3, 'stop_s': 10}, 3), ('control 15', {'floor': 15, 'dir': 'up', 'target': 11, 'call_dir': 'down', 'stops': [3], 'per_floor_s': 3, 'stop_s': 12}, 12), ('sampled regression 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 9', {'floor': 15, 'dir': 'up', 'target': 9, 'call_dir': 'down', 'stops': [13, 11, 12], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('boundary: stop at the target floor', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'up', 'stops': [8, 5], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 23', {'floor': 4, 'dir': 'up', 'target': 13, 'call_dir': 'up', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 18), ('control 26', {'floor': 14, 'dir': 'up', 'target': 15, 'call_dir': 'down', 'stops': [1, 14], 'per_floor_s': 2, 'stop_s': 8}, 2), ('control 29', {'floor': 8, 'dir': 'down', 'target': 6, 'call_dir': 'down', 'stops': [14, 15, 3], 'per_floor_s': 3, 'stop_s': 10}, 6)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 59', {'floor': 15, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [14, 13], 'per_floor_s': 3, 'stop_s': 10}, 59), ('control 52', {'floor': 6, 'dir': 'down', 'target': 13, 'call_dir': 'down', 'stops': [1, 2, 0, 15], 'per_floor_s': 2, 'stop_s': 12}, 74), ('boundary: stops beyond the target', {'floor': 2, 'dir': 'up', 'target': 6, 'call_dir': 'up', 'stops': [4, 10], 'per_floor_s': 2, 'stop_s': 10}, 18), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 34', {'floor': 7, 'dir': 'down', 'target': 7, 'call_dir': 'up', 'stops': [10, 7], 'per_floor_s': 2, 'stop_s': 8}, 0), ('sampled regression 37', {'floor': 14, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [7, 4, 13, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('control 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 9', {'floor': 15, 'dir': 'up', 'target': 9, 'call_dir': 'down', 'stops': [13, 11, 12], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 63', {'floor': 5, 'dir': 'down', 'target': 13, 'call_dir': 'down', 'stops': [4, 11, 7, 9], 'per_floor_s': 2, 'stop_s': 8}, 52), ('boundary: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('control 45', {'floor': 2, 'dir': 'down', 'target': 0, 'call_dir': 'down', 'stops': [3, 12, 7, 11], 'per_floor_s': 2, 'stop_s': 8}, 4), ('control 48', {'floor': 8, 'dir': 'down', 'target': 2, 'call_dir': 'up', 'stops': [8, 7, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 42), ('control 51', {'floor': 11, 'dir': 'up', 'target': 4, 'call_dir': 'down', 'stops': [], 'per_floor_s': 3, 'stop_s': 12}, 21)]]\nfor label, args, expected in fixtures[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":"eb1104d4de170222fa70a85efe1e1edbd09ec99c80bb93bacf23546d06ba39ed","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    sg = 1 if x['dir'] == 'up' else -1\n    f = x['floor'] * sg\n    t = x['target'] * sg\n    stops = [s * sg for s in x['stops'] if s * sg != t]\n    same = x['call_dir'] == x['dir']\n    if t > f and same:\n        path = t - f\n        n = len([s for s in stops if f < s < t])\n    else:\n        ahead = [s for s in stops if s > f]\n        far = max(ahead + [t, f])\n        path = (far - f) + (far - t)\n        n = len(ahead)\n    return path * x['per_floor_s'] + n * x['stop_s']\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 9', {'floor': 15, 'dir': 'up', 'target': 9, 'call_dir': 'down', 'stops': [13, 11, 12], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 1', {'floor': 6, 'dir': 'down', 'target': 12, 'call_dir': 'down', 'stops': [3, 4], 'per_floor_s': 2, 'stop_s': 12}, 48), ('sampled regression 4', {'floor': 1, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [3, 10, 5], 'per_floor_s': 2, 'stop_s': 12}, 62), ('control 7', {'floor': 7, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [1, 13, 9, 2], 'per_floor_s': 3, 'stop_s': 12}, 24)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('sampled regression 59', {'floor': 15, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [14, 13], 'per_floor_s': 3, 'stop_s': 10}, 59), ('control 3', {'floor': 13, 'dir': 'up', 'target': 9, 'call_dir': 'up', 'stops': [2, 15, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 32), ('boundary: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('control 12', {'floor': 12, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 8, 7, 15], 'per_floor_s': 3, 'stop_s': 10}, 3), ('control 15', {'floor': 15, 'dir': 'up', 'target': 11, 'call_dir': 'down', 'stops': [3], 'per_floor_s': 3, 'stop_s': 12}, 12), ('sampled regression 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 9', {'floor': 15, 'dir': 'up', 'target': 9, 'call_dir': 'down', 'stops': [13, 11, 12], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('boundary: stop at the target floor', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'up', 'stops': [8, 5], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 23', {'floor': 4, 'dir': 'up', 'target': 13, 'call_dir': 'up', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 18), ('control 26', {'floor': 14, 'dir': 'up', 'target': 15, 'call_dir': 'down', 'stops': [1, 14], 'per_floor_s': 2, 'stop_s': 8}, 2), ('control 29', {'floor': 8, 'dir': 'down', 'target': 6, 'call_dir': 'down', 'stops': [14, 15, 3], 'per_floor_s': 3, 'stop_s': 10}, 6)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 59', {'floor': 15, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [14, 13], 'per_floor_s': 3, 'stop_s': 10}, 59), ('control 52', {'floor': 6, 'dir': 'down', 'target': 13, 'call_dir': 'down', 'stops': [1, 2, 0, 15], 'per_floor_s': 2, 'stop_s': 12}, 74), ('boundary: stops beyond the target', {'floor': 2, 'dir': 'up', 'target': 6, 'call_dir': 'up', 'stops': [4, 10], 'per_floor_s': 2, 'stop_s': 10}, 18), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 34', {'floor': 7, 'dir': 'down', 'target': 7, 'call_dir': 'up', 'stops': [10, 7], 'per_floor_s': 2, 'stop_s': 8}, 0), ('sampled regression 37', {'floor': 14, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [7, 4, 13, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('control 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 9', {'floor': 15, 'dir': 'up', 'target': 9, 'call_dir': 'down', 'stops': [13, 11, 12], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 63', {'floor': 5, 'dir': 'down', 'target': 13, 'call_dir': 'down', 'stops': [4, 11, 7, 9], 'per_floor_s': 2, 'stop_s': 8}, 52), ('boundary: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('control 45', {'floor': 2, 'dir': 'down', 'target': 0, 'call_dir': 'down', 'stops': [3, 12, 7, 11], 'per_floor_s': 2, 'stop_s': 8}, 4), ('control 48', {'floor': 8, 'dir': 'down', 'target': 2, 'call_dir': 'up', 'stops': [8, 7, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 42), ('control 51', {'floor': 11, 'dir': 'up', 'target': 4, 'call_dir': 'down', 'stops': [], 'per_floor_s': 3, 'stop_s': 12}, 21)]]\nfor label, args, expected in fixtures[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":"Stipulated toy lift-control contract for a bounded teaching model; it makes no claim of conformance to any lift code or vendor dispatcher and omits real safety cases. 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-elevator_dispatch_scheduling-hall-call-eta-return-leg-stops","generated_at":"2026-09-29T14:47:53.911038+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Lift group controllers make these decisions many times per minute; a wrong answer strands passengers, wastes trips or overrides a safety rule.","root_cause":"Stops between the target and the car on the return leg are not counted.","sha256":"d2f52a0ffcd87f6c44bbd279f9967f5ff3875942cb2870dfe935a1fb15762c55","title":"Hall call ETA with intermediate stops: return leg stops · 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":44.742,"exit_code":1,"observations":[{"actual":52,"check":"regression: stops behind served on return","expected":42,"passed":false},{"actual":40,"check":"boundary: call behind a down car","expected":30,"passed":false},{"actual":42,"check":"sampled regression 9","expected":42,"passed":true},{"actual":54,"check":"boundary: call ahead but opposite direction","expected":44,"passed":false},{"actual":22,"check":"boundary: down car mirrored","expected":22,"passed":true},{"actual":72,"check":"control 1","expected":48,"passed":false},{"actual":62,"check":"sampled regression 4","expected":62,"passed":true},{"actual":24,"check":"control 7","expected":24,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: stops behind served on return\", \"actual\": 52, \"expected\": 42, \"passed\": false}, {\"check\": \"boundary: call behind a down car\", \"actual\": 40, \"expected\": 30, \"passed\": false}, {\"check\": \"sampled regression 9\", \"actual\": 42, \"expected\": 42, \"passed\": true}, {\"check\": \"boundary: call ahead but opposite direction\", \"actual\": 54, \"expected\": 44, \"passed\": false}, {\"check\": \"boundary: down car mirrored\", \"actual\": 22, \"expected\": 22, \"passed\": true}, {\"check\": \"control 1\", \"actual\": 72, \"expected\": 48, \"passed\": false}, {\"check\": \"sampled regression 4\", \"actual\": 62, \"expected\": 62, \"passed\": true}, {\"check\": \"control 7\", \"actual\": 24, \"expected\": 24, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.95,"exit_code":1,"observations":[{"actual":32,"check":"regression: stops behind served on return","expected":42,"passed":false},{"actual":30,"check":"boundary: call behind a down car","expected":30,"passed":true},{"actual":12,"check":"sampled regression 9","expected":42,"passed":false},{"actual":44,"check":"boundary: call ahead but opposite direction","expected":44,"passed":true},{"actual":22,"check":"boundary: down car mirrored","expected":22,"passed":true},{"actual":48,"check":"control 1","expected":48,"passed":true},{"actual":26,"check":"sampled regression 4","expected":62,"passed":false},{"actual":24,"check":"control 7","expected":24,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: stops behind served on return\", \"actual\": 32, \"expected\": 42, \"passed\": false}, {\"check\": \"boundary: call behind a down car\", \"actual\": 30, \"expected\": 30, \"passed\": true}, {\"check\": \"sampled regression 9\", \"actual\": 12, \"expected\": 42, \"passed\": false}, {\"check\": \"boundary: call ahead but opposite direction\", \"actual\": 44, \"expected\": 44, \"passed\": true}, {\"check\": \"boundary: down car mirrored\", \"actual\": 22, \"expected\": 22, \"passed\": true}, {\"check\": \"control 1\", \"actual\": 48, \"expected\": 48, \"passed\": true}, {\"check\": \"sampled regression 4\", \"actual\": 26, \"expected\": 62, \"passed\": false}, {\"check\": \"control 7\", \"actual\": 24, \"expected\": 24, \"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."}}