{"abstract":"A rider who kept the driver 61 seconds past grace pays for one minute instead of two.","category":"Ride-hailing fare and surge pricing","checks":7,"contract":"Wait time starts at driver arrival, or at the scheduled pickup time if the ride was scheduled and the driver arrived early. The first grace seconds are free; beyond that each started minute is billed at per_min cents, up to cap_min billed minutes. Return the wait fee in cents.","contract_signature":"ev, policy","evaluation_group":"w2-ride-hailing-fare-surge-pickup-wait-billing","failed_approach":"Rounding to the nearest minute still drops short partial minutes.","family":"w2-ride-hailing-fare-surge-pickup-wait-billing-started-minute-billing","id":"FA-85426","implementations":{"attempt":{"sha256":"de64f9a6f1c7f08b5304f387d0810a52439a28646af200037c5eec779ebdee2d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(ev, policy):\n    start = ev['arrive'] if ev['scheduled'] is None else max(ev['arrive'], ev['scheduled'])\n    wait = ev['board'] - start\n    if wait <= policy['grace']:\n        return 0\n    minutes = round((wait - policy['grace']) / 60)\n    return min(minutes, policy['cap_min']) * policy['per_min']\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   80),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10421, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 25),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10401, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   200),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10120, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 0),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 11020, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10060, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}], 0)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10241, 'scheduled': 10120}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 25),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10421, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 40}], 40),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10121, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 35),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10420, 'scheduled': 10300}, {'cap_min': 10, 'grace': 120, 'per_min': 40}], 0),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 11178, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10060, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 0),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10600, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   320)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   80),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 70),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10121, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 25}], 25),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 11020, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 10300, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 0),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   400),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': 9940}, {'cap_min': 5, 'grace': 120, 'per_min': 35}],\n   175)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10421, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 40}], 40),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10181, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 40}], 80),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10642, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   360),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10300, 'scheduled': 10300}, {'cap_min': 10, 'grace': 120, 'per_min': 25}], 0),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 10872, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 175),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10060, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 0),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10120, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 35}], 0)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 70),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10181, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 70),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10121, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 35}], 35),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': 9940}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 175),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 11162, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10180, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 25),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 11200, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 35}],\n   175)]]\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":"9c6b5940f65cffa0ae6e6db8c493fdbef4d0831750d8efebe7e937596a5fd0cc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(ev, policy):\n    start = ev['arrive'] if ev['scheduled'] is None else max(ev['arrive'], ev['scheduled'])\n    wait = ev['board'] - start\n    if wait <= policy['grace']:\n        return 0\n    minutes = (wait - policy['grace']) // 60\n    return min(minutes, policy['cap_min']) * policy['per_min']\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   80),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10421, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 25),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10401, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   200),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10120, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 0),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 11020, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10060, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}], 0)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10241, 'scheduled': 10120}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 25),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10421, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 40}], 40),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10121, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 35),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10420, 'scheduled': 10300}, {'cap_min': 10, 'grace': 120, 'per_min': 40}], 0),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 11178, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10060, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 0),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10600, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   320)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   80),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 70),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10121, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 25}], 25),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 11020, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 10300, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 0),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   400),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': 9940}, {'cap_min': 5, 'grace': 120, 'per_min': 35}],\n   175)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10421, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 40}], 40),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10181, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 40}], 80),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10642, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 40}],\n   360),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10300, 'scheduled': 10300}, {'cap_min': 10, 'grace': 120, 'per_min': 25}], 0),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 10872, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 175),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10060, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 0),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 10120, 'scheduled': None}, {'cap_min': 10, 'grace': 120, 'per_min': 35}], 0)],\n [('regression: started minute billing',\n   [{'arrive': 10000, 'board': 10301, 'scheduled': 10120}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 70),\n  ('partial repair probe: started minute billing',\n   [{'arrive': 10000, 'board': 10181, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 70),\n  ('second regression',\n   [{'arrive': 10000, 'board': 10121, 'scheduled': 9940}, {'cap_min': 10, 'grace': 120, 'per_min': 35}], 35),\n  ('normal control 1',\n   [{'arrive': 10000, 'board': 10900, 'scheduled': 9940}, {'cap_min': 5, 'grace': 120, 'per_min': 35}], 175),\n  ('normal control 2',\n   [{'arrive': 10000, 'board': 11162, 'scheduled': 10120}, {'cap_min': 10, 'grace': 120, 'per_min': 25}],\n   250),\n  ('normal control 3',\n   [{'arrive': 10000, 'board': 10180, 'scheduled': None}, {'cap_min': 5, 'grace': 120, 'per_min': 25}], 25),\n  ('normal control 4',\n   [{'arrive': 10000, 'board': 11200, 'scheduled': 10300}, {'cap_min': 5, 'grace': 120, 'per_min': 35}],\n   175)]]\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":"A deterministic toy pricing contract stipulated for this example; it does not reproduce the pricing of any real ride-hailing operator or regulator. 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-ride-hailing-fare-surge-pickup-wait-billing-started-minute-billing","generated_at":"2026-09-29T14:50:40.272105+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Ride-hailing prices are computed per trip at scale; ordering, unit and boundary slips become systematic over- or under-charging.","root_cause":"Billable seconds are floor-divided into minutes.","sha256":"2620b773c85a0255f84965ba148b487d1df5353b1e5cce01ad02be05d53abefa","title":"Partial wait minutes not billed · 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":41.588,"exit_code":1,"observations":[{"actual":40,"check":"regression: started minute billing","expected":80,"passed":false},{"actual":0,"check":"partial repair probe: started minute billing","expected":25,"passed":false},{"actual":200,"check":"second regression","expected":200,"passed":true},{"actual":0,"check":"normal control 1","expected":0,"passed":true},{"actual":250,"check":"normal control 2","expected":250,"passed":true},{"actual":250,"check":"normal control 3","expected":250,"passed":true},{"actual":0,"check":"normal control 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: started minute billing\", \"actual\": 40, \"expected\": 80, \"passed\": false}, {\"check\": \"partial repair probe: started minute billing\", \"actual\": 0, \"expected\": 25, \"passed\": false}, {\"check\": \"second regression\", \"actual\": 200, \"expected\": 200, \"passed\": true}, {\"check\": \"normal control 1\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"normal control 2\", \"actual\": 250, \"expected\": 250, \"passed\": true}, {\"check\": \"normal control 3\", \"actual\": 250, \"expected\": 250, \"passed\": true}, {\"check\": \"normal control 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.721,"exit_code":1,"observations":[{"actual":40,"check":"regression: started minute billing","expected":80,"passed":false},{"actual":0,"check":"partial repair probe: started minute billing","expected":25,"passed":false},{"actual":160,"check":"second regression","expected":200,"passed":false},{"actual":0,"check":"normal control 1","expected":0,"passed":true},{"actual":250,"check":"normal control 2","expected":250,"passed":true},{"actual":250,"check":"normal control 3","expected":250,"passed":true},{"actual":0,"check":"normal control 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: started minute billing\", \"actual\": 40, \"expected\": 80, \"passed\": false}, {\"check\": \"partial repair probe: started minute billing\", \"actual\": 0, \"expected\": 25, \"passed\": false}, {\"check\": \"second regression\", \"actual\": 160, \"expected\": 200, \"passed\": false}, {\"check\": \"normal control 1\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"normal control 2\", \"actual\": 250, \"expected\": 250, \"passed\": true}, {\"check\": \"normal control 3\", \"actual\": 250, \"expected\": 250, \"passed\": true}, {\"check\": \"normal control 4\", \"actual\": 0, \"expected\": 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."}}