{"abstract":"Riders with a metered fare above booked pay no reservation fee.","category":"Ride-hailing fare and surge pricing","checks":7,"contract":"Scheduled rides guarantee the booked price: the rider pays the lower of booked and metered fare plus the reservation fee. If the driver never shows, nothing is charged and the reservation fee is refunded. Return charge cents and whether the fee is refunded.","evaluation_group":"w2-ride-hailing-fare-surge-scheduled-ride-guarantee","failed_approach":"Adding the fee to the booked side only drops it when the meter is lower.","family":"w2-ride-hailing-fare-surge-scheduled-ride-guarantee-reservation-fee-placement","id":"FA-85821","implementations":{"attempt":{"sha256":"5115b7d995bd7f145eebb8679da8de692588738d874c96d87d4ca825721ed1a0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(booked_price, metered, driver_no_show, reservation_fee):\n    if driver_no_show:\n        return {'charge': 0, 'refund_fee': True}\n    return {'charge': min(booked_price + reservation_fee, metered), 'refund_fee': False}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: reservation fee placement', [3200, 3200, False, 300], {'charge': 3500, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [4100, 4100, False, 300],\n   {'charge': 4400, 'refund_fee': False}),\n  ('second regression', [3200, 3199, False, 200], {'charge': 3399, 'refund_fee': False}),\n  ('normal control 1', [2500, 1800, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [4100, 3400, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3201, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2501, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [3200, 3200, False, 200], {'charge': 3400, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [2500, 2500, False, 300],\n   {'charge': 2800, 'refund_fee': False}),\n  ('second regression', [2500, 2500, False, 200], {'charge': 2700, 'refund_fee': False}),\n  ('normal control 1', [2500, 2501, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [3200, 4100, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 4100, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2500, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [3200, 3199, False, 200], {'charge': 3399, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [2500, 1800, False, 200],\n   {'charge': 2000, 'refund_fee': False}),\n  ('second regression', [2500, 2499, False, 300], {'charge': 2799, 'refund_fee': False}),\n  ('normal control 1', [3200, 3200, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [3200, 3201, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 2500, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2500, True, 200], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [4100, 4101, False, 300], {'charge': 4400, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [3200, 3199, False, 200],\n   {'charge': 3399, 'refund_fee': False}),\n  ('second regression', [4100, 4101, False, 200], {'charge': 4300, 'refund_fee': False}),\n  ('normal control 1', [2500, 2501, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [2500, 2501, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3200, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [3200, 3199, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [4100, 4099, False, 200], {'charge': 4299, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [4100, 3400, False, 300],\n   {'charge': 3700, 'refund_fee': False}),\n  ('second regression', [4100, 4101, False, 300], {'charge': 4400, 'refund_fee': False}),\n  ('normal control 1', [2500, 2500, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [4100, 4099, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3201, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [3200, 3199, True, 200], {'charge': 0, 'refund_fee': True})]]\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":"d127af91b72e80a9ab539adf860f95b8b53a551da6d9b32be455622971e98489","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(booked_price, metered, driver_no_show, reservation_fee):\n    if driver_no_show:\n        return {'charge': 0, 'refund_fee': True}\n    return {'charge': min(booked_price, metered + reservation_fee), 'refund_fee': False}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: reservation fee placement', [3200, 3200, False, 300], {'charge': 3500, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [4100, 4100, False, 300],\n   {'charge': 4400, 'refund_fee': False}),\n  ('second regression', [3200, 3199, False, 200], {'charge': 3399, 'refund_fee': False}),\n  ('normal control 1', [2500, 1800, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [4100, 3400, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3201, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2501, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [3200, 3200, False, 200], {'charge': 3400, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [2500, 2500, False, 300],\n   {'charge': 2800, 'refund_fee': False}),\n  ('second regression', [2500, 2500, False, 200], {'charge': 2700, 'refund_fee': False}),\n  ('normal control 1', [2500, 2501, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [3200, 4100, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 4100, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2500, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [3200, 3199, False, 200], {'charge': 3399, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [2500, 1800, False, 200],\n   {'charge': 2000, 'refund_fee': False}),\n  ('second regression', [2500, 2499, False, 300], {'charge': 2799, 'refund_fee': False}),\n  ('normal control 1', [3200, 3200, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [3200, 3201, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 2500, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2500, True, 200], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [4100, 4101, False, 300], {'charge': 4400, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [3200, 3199, False, 200],\n   {'charge': 3399, 'refund_fee': False}),\n  ('second regression', [4100, 4101, False, 200], {'charge': 4300, 'refund_fee': False}),\n  ('normal control 1', [2500, 2501, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [2500, 2501, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3200, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [3200, 3199, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [4100, 4099, False, 200], {'charge': 4299, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [4100, 3400, False, 300],\n   {'charge': 3700, 'refund_fee': False}),\n  ('second regression', [4100, 4101, False, 300], {'charge': 4400, 'refund_fee': False}),\n  ('normal control 1', [2500, 2500, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [4100, 4099, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3201, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [3200, 3199, True, 200], {'charge': 0, 'refund_fee': True})]]\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"},"fixed":{"sha256":"2e56bf6cfcff0facf2546b2ec66113d4258c53845799caf80ce53b44d6df0301","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(booked_price, metered, driver_no_show, reservation_fee):\n    if driver_no_show:\n        return {'charge': 0, 'refund_fee': True}\n    return {'charge': min(booked_price, metered) + reservation_fee, 'refund_fee': False}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: reservation fee placement', [3200, 3200, False, 300], {'charge': 3500, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [4100, 4100, False, 300],\n   {'charge': 4400, 'refund_fee': False}),\n  ('second regression', [3200, 3199, False, 200], {'charge': 3399, 'refund_fee': False}),\n  ('normal control 1', [2500, 1800, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [4100, 3400, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3201, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2501, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [3200, 3200, False, 200], {'charge': 3400, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [2500, 2500, False, 300],\n   {'charge': 2800, 'refund_fee': False}),\n  ('second regression', [2500, 2500, False, 200], {'charge': 2700, 'refund_fee': False}),\n  ('normal control 1', [2500, 2501, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [3200, 4100, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 4100, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2500, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [3200, 3199, False, 200], {'charge': 3399, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [2500, 1800, False, 200],\n   {'charge': 2000, 'refund_fee': False}),\n  ('second regression', [2500, 2499, False, 300], {'charge': 2799, 'refund_fee': False}),\n  ('normal control 1', [3200, 3200, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [3200, 3201, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 2500, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [2500, 2500, True, 200], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [4100, 4101, False, 300], {'charge': 4400, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [3200, 3199, False, 200],\n   {'charge': 3399, 'refund_fee': False}),\n  ('second regression', [4100, 4101, False, 200], {'charge': 4300, 'refund_fee': False}),\n  ('normal control 1', [2500, 2501, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [2500, 2501, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3200, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [3200, 3199, True, 300], {'charge': 0, 'refund_fee': True})],\n [('regression: reservation fee placement', [4100, 4099, False, 200], {'charge': 4299, 'refund_fee': False}),\n  ('partial repair probe: reservation fee placement', [4100, 3400, False, 300],\n   {'charge': 3700, 'refund_fee': False}),\n  ('second regression', [4100, 4101, False, 300], {'charge': 4400, 'refund_fee': False}),\n  ('normal control 1', [2500, 2500, True, 200], {'charge': 0, 'refund_fee': True}),\n  ('normal control 2', [4100, 4099, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 3', [3200, 3201, True, 300], {'charge': 0, 'refund_fee': True}),\n  ('normal control 4', [3200, 3199, True, 200], {'charge': 0, 'refund_fee': True})]]\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-scheduled-ride-guarantee-reservation-fee-placement","generated_at":"2026-09-29T14:50:43.842334+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.","repair":"Add the reservation fee after taking the lower fare.","root_cause":"The fee is inside the min, so the guarantee swallows it.","sha256":"0bacd484f3401191ff2c1e9b0b18cec6d1aedb42110dcdb755f2829b6ffd9820","title":"Reservation fee absorbed by the guarantee · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":40.912,"exit_code":1,"observations":[{"actual":{"charge":3200,"refund_fee":false},"check":"regression: reservation fee placement","expected":{"charge":3500,"refund_fee":false},"passed":false},{"actual":{"charge":4100,"refund_fee":false},"check":"partial repair probe: reservation fee placement","expected":{"charge":4400,"refund_fee":false},"passed":false},{"actual":{"charge":3199,"refund_fee":false},"check":"second regression","expected":{"charge":3399,"refund_fee":false},"passed":false},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 1","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 2","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 3","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 4","expected":{"charge":0,"refund_fee":true},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: reservation fee placement\", \"actual\": {\"charge\": 3200, \"refund_fee\": false}, \"expected\": {\"charge\": 3500, \"refund_fee\": false}, \"passed\": false}, {\"check\": \"partial repair probe: reservation fee placement\", \"actual\": {\"charge\": 4100, \"refund_fee\": false}, \"expected\": {\"charge\": 4400, \"refund_fee\": false}, \"passed\": false}, {\"check\": \"second regression\", \"actual\": {\"charge\": 3199, \"refund_fee\": false}, \"expected\": {\"charge\": 3399, \"refund_fee\": false}, \"passed\": false}, {\"check\": \"normal control 1\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 2\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 3\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 4\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.045,"exit_code":1,"observations":[{"actual":{"charge":3200,"refund_fee":false},"check":"regression: reservation fee placement","expected":{"charge":3500,"refund_fee":false},"passed":false},{"actual":{"charge":4100,"refund_fee":false},"check":"partial repair probe: reservation fee placement","expected":{"charge":4400,"refund_fee":false},"passed":false},{"actual":{"charge":3200,"refund_fee":false},"check":"second regression","expected":{"charge":3399,"refund_fee":false},"passed":false},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 1","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 2","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 3","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 4","expected":{"charge":0,"refund_fee":true},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: reservation fee placement\", \"actual\": {\"charge\": 3200, \"refund_fee\": false}, \"expected\": {\"charge\": 3500, \"refund_fee\": false}, \"passed\": false}, {\"check\": \"partial repair probe: reservation fee placement\", \"actual\": {\"charge\": 4100, \"refund_fee\": false}, \"expected\": {\"charge\": 4400, \"refund_fee\": false}, \"passed\": false}, {\"check\": \"second regression\", \"actual\": {\"charge\": 3200, \"refund_fee\": false}, \"expected\": {\"charge\": 3399, \"refund_fee\": false}, \"passed\": false}, {\"check\": \"normal control 1\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 2\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 3\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 4\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.185,"exit_code":0,"observations":[{"actual":{"charge":3500,"refund_fee":false},"check":"regression: reservation fee placement","expected":{"charge":3500,"refund_fee":false},"passed":true},{"actual":{"charge":4400,"refund_fee":false},"check":"partial repair probe: reservation fee placement","expected":{"charge":4400,"refund_fee":false},"passed":true},{"actual":{"charge":3399,"refund_fee":false},"check":"second regression","expected":{"charge":3399,"refund_fee":false},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 1","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 2","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 3","expected":{"charge":0,"refund_fee":true},"passed":true},{"actual":{"charge":0,"refund_fee":true},"check":"normal control 4","expected":{"charge":0,"refund_fee":true},"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: reservation fee placement\", \"actual\": {\"charge\": 3500, \"refund_fee\": false}, \"expected\": {\"charge\": 3500, \"refund_fee\": false}, \"passed\": true}, {\"check\": \"partial repair probe: reservation fee placement\", \"actual\": {\"charge\": 4400, \"refund_fee\": false}, \"expected\": {\"charge\": 4400, \"refund_fee\": false}, \"passed\": true}, {\"check\": \"second regression\", \"actual\": {\"charge\": 3399, \"refund_fee\": false}, \"expected\": {\"charge\": 3399, \"refund_fee\": false}, \"passed\": true}, {\"check\": \"normal control 1\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 2\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 3\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}, {\"check\": \"normal control 4\", \"actual\": {\"charge\": 0, \"refund_fee\": true}, \"expected\": {\"charge\": 0, \"refund_fee\": true}, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}