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FA-85791 / Ride-hailing fare and surge pricing / Open access

Surge cap applied to non-members · case 01

Non-members pay 2.0x during a 2.5x surge.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The member surge cap is applied unconditionally.

THE FAILURE

The member surge cap is applied unconditionally.

Unsuccessful approach: Also capping extreme surges for everyone still gives non-members the benefit.

Case contract

Membership is active if the flag is set and today is on or before the expiry day. Active members have surge capped at 2.0x (20 tenths) and, when the (capped) surge is at most 1.5x, get 10% off the surged fare (floored); fees are never discounted. Return the amount due in cents.

Why this case matters

Ride-hailing prices are computed per trip at scale; ordering, unit and boundary slips become systematic over- or under-charging.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(fare, member, now):
    active = member['active'] and now <= member['expires']
    surge = fare['surge']
    surge = min(surge, 20)
    surged = (fare['core'] * surge * 2 + 10) // 20
    disc = 0
    if active and surge <= 15:
        disc = surged // 10
    return surged - disc + fare['fees']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: member-only surge cap',
   [{'core': 2555, 'fees': 250, 'surge': 25}, {'active': False, 'expires': 100}, 100], 6638),
  ('partial repair probe: member-only surge cap',
   [{'core': 999, 'fees': 245, 'surge': 30}, {'active': False, 'expires': 100}, 101], 3242),
  ('second regression', [{'core': 1234, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101],
   3901),
  ('normal control 1', [{'core': 999, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 100],
   2197),
  ('normal control 2', [{'core': 999, 'fees': 199, 'surge': 12}, {'active': True, 'expires': 100}, 100],
   1279),
  ('normal control 3', [{'core': 1234, 'fees': 0, 'surge': 30}, {'active': True, 'expires': 100}, 100], 2468),
  ('normal control 4', [{'core': 1000, 'fees': 0, 'surge': 17}, {'active': True, 'expires': 100}, 101],
   1700)],
 [('regression: member-only surge cap',
   [{'core': 1234, 'fees': 245, 'surge': 30}, {'active': True, 'expires': 100}, 101], 3947),
  ('partial repair probe: member-only surge cap',
   [{'core': 1234, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101], 3901),
  ('second regression', [{'core': 1000, 'fees': 245, 'surge': 25}, {'active': False, 'expires': 100}, 99],
   2745),
  ('normal control 1', [{'core': 999, 'fees': 0, 'surge': 17}, {'active': True, 'expires': 100}, 99], 1698),
  ('normal control 2', [{'core': 1234, 'fees': 0, 'surge': 10}, {'active': True, 'expires': 100}, 99], 1111),
  ('normal control 3', [{'core': 1234, 'fees': 0, 'surge': 30}, {'active': True, 'expires': 100}, 100], 2468),
  ('normal control 4', [{'core': 999, 'fees': 199, 'surge': 17}, {'active': True, 'expires': 100}, 100],
   1897)],
 [('regression: member-only surge cap',
   [{'core': 1000, 'fees': 199, 'surge': 25}, {'active': True, 'expires': 100}, 101], 2699),
  ('partial repair probe: member-only surge cap',
   [{'core': 1000, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101], 3199),
  ('second regression', [{'core': 999, 'fees': 250, 'surge': 25}, {'active': False, 'expires': 100}, 100],
   2748),
  ('normal control 1', [{'core': 1000, 'fees': 250, 'surge': 10}, {'active': False, 'expires': 100}, 100],
   1250),
  ('normal control 2', [{'core': 1000, 'fees': 250, 'surge': 20}, {'active': True, 'expires': 100}, 101],
   2250),
  ('normal control 3', [{'core': 1234, 'fees': 0, 'surge': 30}, {'active': True, 'expires': 100}, 100], 2468),
  ('normal control 4', [{'core': 999, 'fees': 245, 'surge': 17}, {'active': True, 'expires': 100}, 99],
   1943)],
 [('regression: member-only surge cap',
   [{'core': 1000, 'fees': 250, 'surge': 30}, {'active': False, 'expires': 100}, 99], 3250),
  ('partial repair probe: member-only surge cap',
   [{'core': 999, 'fees': 199, 'surge': 30}, {'active': False, 'expires': 100}, 99], 3196),
  ('second regression', [{'core': 1000, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101],
   3199),
  ('normal control 1', [{'core': 999, 'fees': 245, 'surge': 25}, {'active': True, 'expires': 100}, 100],
   2243),
  ('normal control 2', [{'core': 1234, 'fees': 245, 'surge': 17}, {'active': True, 'expires': 100}, 101],
   2343),
  ('normal control 3', [{'core': 1000, 'fees': 0, 'surge': 10}, {'active': True, 'expires': 100}, 100], 900),
  ('normal control 4', [{'core': 1000, 'fees': 199, 'surge': 15}, {'active': True, 'expires': 100}, 100],
   1549)],
 [('regression: member-only surge cap',
   [{'core': 1234, 'fees': 245, 'surge': 25}, {'active': False, 'expires': 100}, 100], 3330),
  ('partial repair probe: member-only surge cap',
   [{'core': 1234, 'fees': 199, 'surge': 30}, {'active': False, 'expires': 100}, 100], 3901),
  ('second regression', [{'core': 2555, 'fees': 0, 'surge': 25}, {'active': False, 'expires': 100}, 100],
   6388),
  ('normal control 1', [{'core': 1234, 'fees': 250, 'surge': 17}, {'active': True, 'expires': 100}, 100],
   2348),
  ('normal control 2', [{'core': 999, 'fees': 199, 'surge': 17}, {'active': True, 'expires': 100}, 100],
   1897),
  ('normal control 3', [{'core': 1234, 'fees': 250, 'surge': 12}, {'active': True, 'expires': 100}, 100],
   1583),
  ('normal control 4', [{'core': 2555, 'fees': 245, 'surge': 15}, {'active': True, 'expires': 100}, 101],
   4078)]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: member-only surge cap53606638Failed
partial repair probe: member-only surge cap22433242Failed
second regression26673901Failed
normal control 121972197Passed
normal control 212791279Passed
normal control 324682468Passed
normal control 417001700Passed

SHA-256 / 89ea0f70a15e2c1f3552da1dea9a7c8fe171ef582b71609345ef4678a92fc02b

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(fare, member, now):
    active = member['active'] and now <= member['expires']
    surge = fare['surge']
    if active or fare['surge'] > 25:
        surge = min(surge, 20)
    surged = (fare['core'] * surge * 2 + 10) // 20
    disc = 0
    if active and surge <= 15:
        disc = surged // 10
    return surged - disc + fare['fees']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: member-only surge cap',
   [{'core': 2555, 'fees': 250, 'surge': 25}, {'active': False, 'expires': 100}, 100], 6638),
  ('partial repair probe: member-only surge cap',
   [{'core': 999, 'fees': 245, 'surge': 30}, {'active': False, 'expires': 100}, 101], 3242),
  ('second regression', [{'core': 1234, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101],
   3901),
  ('normal control 1', [{'core': 999, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 100],
   2197),
  ('normal control 2', [{'core': 999, 'fees': 199, 'surge': 12}, {'active': True, 'expires': 100}, 100],
   1279),
  ('normal control 3', [{'core': 1234, 'fees': 0, 'surge': 30}, {'active': True, 'expires': 100}, 100], 2468),
  ('normal control 4', [{'core': 1000, 'fees': 0, 'surge': 17}, {'active': True, 'expires': 100}, 101],
   1700)],
 [('regression: member-only surge cap',
   [{'core': 1234, 'fees': 245, 'surge': 30}, {'active': True, 'expires': 100}, 101], 3947),
  ('partial repair probe: member-only surge cap',
   [{'core': 1234, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101], 3901),
  ('second regression', [{'core': 1000, 'fees': 245, 'surge': 25}, {'active': False, 'expires': 100}, 99],
   2745),
  ('normal control 1', [{'core': 999, 'fees': 0, 'surge': 17}, {'active': True, 'expires': 100}, 99], 1698),
  ('normal control 2', [{'core': 1234, 'fees': 0, 'surge': 10}, {'active': True, 'expires': 100}, 99], 1111),
  ('normal control 3', [{'core': 1234, 'fees': 0, 'surge': 30}, {'active': True, 'expires': 100}, 100], 2468),
  ('normal control 4', [{'core': 999, 'fees': 199, 'surge': 17}, {'active': True, 'expires': 100}, 100],
   1897)],
 [('regression: member-only surge cap',
   [{'core': 1000, 'fees': 199, 'surge': 25}, {'active': True, 'expires': 100}, 101], 2699),
  ('partial repair probe: member-only surge cap',
   [{'core': 1000, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101], 3199),
  ('second regression', [{'core': 999, 'fees': 250, 'surge': 25}, {'active': False, 'expires': 100}, 100],
   2748),
  ('normal control 1', [{'core': 1000, 'fees': 250, 'surge': 10}, {'active': False, 'expires': 100}, 100],
   1250),
  ('normal control 2', [{'core': 1000, 'fees': 250, 'surge': 20}, {'active': True, 'expires': 100}, 101],
   2250),
  ('normal control 3', [{'core': 1234, 'fees': 0, 'surge': 30}, {'active': True, 'expires': 100}, 100], 2468),
  ('normal control 4', [{'core': 999, 'fees': 245, 'surge': 17}, {'active': True, 'expires': 100}, 99],
   1943)],
 [('regression: member-only surge cap',
   [{'core': 1000, 'fees': 250, 'surge': 30}, {'active': False, 'expires': 100}, 99], 3250),
  ('partial repair probe: member-only surge cap',
   [{'core': 999, 'fees': 199, 'surge': 30}, {'active': False, 'expires': 100}, 99], 3196),
  ('second regression', [{'core': 1000, 'fees': 199, 'surge': 30}, {'active': True, 'expires': 100}, 101],
   3199),
  ('normal control 1', [{'core': 999, 'fees': 245, 'surge': 25}, {'active': True, 'expires': 100}, 100],
   2243),
  ('normal control 2', [{'core': 1234, 'fees': 245, 'surge': 17}, {'active': True, 'expires': 100}, 101],
   2343),
  ('normal control 3', [{'core': 1000, 'fees': 0, 'surge': 10}, {'active': True, 'expires': 100}, 100], 900),
  ('normal control 4', [{'core': 1000, 'fees': 199, 'surge': 15}, {'active': True, 'expires': 100}, 100],
   1549)],
 [('regression: member-only surge cap',
   [{'core': 1234, 'fees': 245, 'surge': 25}, {'active': False, 'expires': 100}, 100], 3330),
  ('partial repair probe: member-only surge cap',
   [{'core': 1234, 'fees': 199, 'surge': 30}, {'active': False, 'expires': 100}, 100], 3901),
  ('second regression', [{'core': 2555, 'fees': 0, 'surge': 25}, {'active': False, 'expires': 100}, 100],
   6388),
  ('normal control 1', [{'core': 1234, 'fees': 250, 'surge': 17}, {'active': True, 'expires': 100}, 100],
   2348),
  ('normal control 2', [{'core': 999, 'fees': 199, 'surge': 17}, {'active': True, 'expires': 100}, 100],
   1897),
  ('normal control 3', [{'core': 1234, 'fees': 250, 'surge': 12}, {'active': True, 'expires': 100}, 100],
   1583),
  ('normal control 4', [{'core': 2555, 'fees': 245, 'surge': 15}, {'active': True, 'expires': 100}, 101],
   4078)]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: member-only surge cap66386638Passed
partial repair probe: member-only surge cap22433242Failed
second regression26673901Failed
normal control 121972197Passed
normal control 212791279Passed
normal control 324682468Passed
normal control 417001700Passed

SHA-256 / 6a80d44a70cb5599f142d17f66e0940ea4008965bfee382878b8329ad3b005e1

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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Verification & scope

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.

Observations recorded using Python 3.12.14 at 2026-09-29T14:50:43.644514+00:00.

Case digest / 74756da44f097f441cdb9f2b5ef5dce8583698fc8ed868d866eee5455d57e9a4