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FA-85981 / Game economy crafting balance / Open access

Auction house fees: Cheap stacks list for free · case 01

Low-value items pay no deposit and flood the auction house.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The one-copper minimum per block is missing.

THE FAILURE

The one-copper minimum per block is missing.

Unsuccessful approach: Applying the minimum before the percentage still floors cheap stacks to zero.

Case contract

Deposit = per_block * (hours//12) where per_block = max(1, floor(stack_value*15/100)). Sold: net = price - cut with cut = 5% of price rounded half up (deposit refunded). Expired: net = -deposit. Cancelled: net = -deposit - floor(bid*5/100) (bid defaults to 0). Returns {deposit, net} in copper.

Why this case matters

Game economies leak or destroy currency when one crafting or pricing rule is off by one boundary, rounding stage or state update; the defect is observable in exact integer outcomes.

1 / The failure

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

N = 1
observations = []
def solve(listing, outcome):
    blocks = listing['hours'] // 12
    per_block = listing['stack_value'] * 15 // 100
    deposit = per_block * blocks
    status = outcome['status']
    if status == 'sold':
        cut = (listing['price'] * 5 + 50) // 100
        net = listing['price'] - cut
    elif status == 'cancelled':
        net = -deposit - outcome.get('bid', 0) * 5 // 100
    else:
        net = -deposit
    return {'deposit': deposit, 'net': net}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 10, 'hours': 48, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #2',
   [{'price': 50, 'hours': 24, 'stack_value': 6}, {'status': 'expired'}],
   {'deposit': 2, 'net': -2}),
  ('regression per-block minimum #3',
   [{'price': 11, 'hours': 12, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 1, 'net': -1}),
  ('regression per-block minimum #4',
   [{'price': 10, 'hours': 12, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 1, 'net': -5}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 11, 'hours': 24, 'stack_value': 13}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 2, 'net': -2})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 50, 'hours': 24, 'stack_value': 6}, {'status': 'expired'}],
   {'deposit': 2, 'net': -2}),
  ('regression per-block minimum #2',
   [{'price': 11, 'hours': 12, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 1, 'net': -1}),
  ('regression per-block minimum #3',
   [{'price': 10, 'hours': 12, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 1, 'net': -5}),
  ('regression per-block minimum #4',
   [{'price': 912, 'hours': 24, 'stack_value': 0}, {'status': 'cancelled'}],
   {'deposit': 2, 'net': -2}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 11, 'hours': 24, 'stack_value': 13}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 2, 'net': -2})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 10, 'hours': 12, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 1, 'net': -5}),
  ('regression per-block minimum #2',
   [{'price': 912, 'hours': 24, 'stack_value': 0}, {'status': 'cancelled'}],
   {'deposit': 2, 'net': -2}),
  ('regression per-block minimum #3',
   [{'price': 190, 'hours': 48, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 4, 'net': -8}),
  ('regression per-block minimum #4',
   [{'price': 30, 'hours': 12, 'stack_value': 6}, {'status': 'sold'}],
   {'deposit': 1, 'net': 28}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 11, 'hours': 24, 'stack_value': 13}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 2, 'net': -2})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 190, 'hours': 48, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 4, 'net': -8}),
  ('regression per-block minimum #2',
   [{'price': 30, 'hours': 12, 'stack_value': 6}, {'status': 'sold'}],
   {'deposit': 1, 'net': 28}),
  ('regression per-block minimum #3',
   [{'price': 30, 'hours': 48, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #4',
   [{'price': 190, 'hours': 12, 'stack_value': 0}, {'status': 'sold'}],
   {'deposit': 1, 'net': 180}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 1, 'hours': 12, 'stack_value': 4743}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 711, 'net': -711})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 30, 'hours': 48, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #2',
   [{'price': 190, 'hours': 12, 'stack_value': 0}, {'status': 'sold'}],
   {'deposit': 1, 'net': 180}),
  ('regression per-block minimum #3',
   [{'price': 66296, 'hours': 48, 'stack_value': 1}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #4',
   [{'price': 30, 'hours': 12, 'stack_value': 1}, {'status': 'expired'}],
   {'deposit': 1, 'net': -1}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 190, 'hours': 24, 'stack_value': 13}, {'status': 'expired'}],
   {'deposit': 2, 'net': -2})]]
for label, args, expected in cases[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
long cheap listing #1{'deposit': 0, 'net': 0}{'deposit': 4, 'net': -4}Failed
regression per-block minimum #1{'deposit': 0, 'net': 0}{'deposit': 4, 'net': -4}Failed
regression per-block minimum #2{'deposit': 0, 'net': 0}{'deposit': 2, 'net': -2}Failed
regression per-block minimum #3{'deposit': 0, 'net': 0}{'deposit': 1, 'net': -1}Failed
regression per-block minimum #4{'deposit': 0, 'net': -4}{'deposit': 1, 'net': -5}Failed
half-up cut boundary #1{'deposit': 15, 'net': 9}{'deposit': 15, 'net': 9}Passed
cancel with bid #1{'deposit': 12, 'net': -31}{'deposit': 12, 'net': -31}Passed
control #1{'deposit': 2, 'net': -2}{'deposit': 2, 'net': -2}Passed

SHA-256 / 6939d87e2705e765091fb892bfa0e6b9abcb25b7265962739770259e507fc7e0

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(listing, outcome):
    blocks = listing['hours'] // 12
    per_block = max(1, listing['stack_value']) * 15 // 100
    deposit = per_block * blocks
    status = outcome['status']
    if status == 'sold':
        cut = (listing['price'] * 5 + 50) // 100
        net = listing['price'] - cut
    elif status == 'cancelled':
        net = -deposit - outcome.get('bid', 0) * 5 // 100
    else:
        net = -deposit
    return {'deposit': deposit, 'net': net}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 10, 'hours': 48, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #2',
   [{'price': 50, 'hours': 24, 'stack_value': 6}, {'status': 'expired'}],
   {'deposit': 2, 'net': -2}),
  ('regression per-block minimum #3',
   [{'price': 11, 'hours': 12, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 1, 'net': -1}),
  ('regression per-block minimum #4',
   [{'price': 10, 'hours': 12, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 1, 'net': -5}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 11, 'hours': 24, 'stack_value': 13}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 2, 'net': -2})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 50, 'hours': 24, 'stack_value': 6}, {'status': 'expired'}],
   {'deposit': 2, 'net': -2}),
  ('regression per-block minimum #2',
   [{'price': 11, 'hours': 12, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 1, 'net': -1}),
  ('regression per-block minimum #3',
   [{'price': 10, 'hours': 12, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 1, 'net': -5}),
  ('regression per-block minimum #4',
   [{'price': 912, 'hours': 24, 'stack_value': 0}, {'status': 'cancelled'}],
   {'deposit': 2, 'net': -2}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 11, 'hours': 24, 'stack_value': 13}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 2, 'net': -2})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 10, 'hours': 12, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 1, 'net': -5}),
  ('regression per-block minimum #2',
   [{'price': 912, 'hours': 24, 'stack_value': 0}, {'status': 'cancelled'}],
   {'deposit': 2, 'net': -2}),
  ('regression per-block minimum #3',
   [{'price': 190, 'hours': 48, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 4, 'net': -8}),
  ('regression per-block minimum #4',
   [{'price': 30, 'hours': 12, 'stack_value': 6}, {'status': 'sold'}],
   {'deposit': 1, 'net': 28}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 11, 'hours': 24, 'stack_value': 13}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 2, 'net': -2})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 190, 'hours': 48, 'stack_value': 0}, {'status': 'cancelled', 'bid': 99}],
   {'deposit': 4, 'net': -8}),
  ('regression per-block minimum #2',
   [{'price': 30, 'hours': 12, 'stack_value': 6}, {'status': 'sold'}],
   {'deposit': 1, 'net': 28}),
  ('regression per-block minimum #3',
   [{'price': 30, 'hours': 48, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #4',
   [{'price': 190, 'hours': 12, 'stack_value': 0}, {'status': 'sold'}],
   {'deposit': 1, 'net': 180}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 1, 'hours': 12, 'stack_value': 4743}, {'status': 'cancelled', 'bid': 0}],
   {'deposit': 711, 'net': -711})],
 [('long cheap listing #1',
   [{'price': 10, 'hours': 48, 'stack_value': 3}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #1',
   [{'price': 30, 'hours': 48, 'stack_value': 0}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #2',
   [{'price': 190, 'hours': 12, 'stack_value': 0}, {'status': 'sold'}],
   {'deposit': 1, 'net': 180}),
  ('regression per-block minimum #3',
   [{'price': 66296, 'hours': 48, 'stack_value': 1}, {'status': 'expired'}],
   {'deposit': 4, 'net': -4}),
  ('regression per-block minimum #4',
   [{'price': 30, 'hours': 12, 'stack_value': 1}, {'status': 'expired'}],
   {'deposit': 1, 'net': -1}),
  ('half-up cut boundary #1',
   [{'price': 10, 'hours': 12, 'stack_value': 100}, {'status': 'sold'}],
   {'deposit': 15, 'net': 9}),
  ('cancel with bid #1',
   [{'price': 500, 'hours': 24, 'stack_value': 40}, {'status': 'cancelled', 'bid': 390}],
   {'deposit': 12, 'net': -31}),
  ('control #1',
   [{'price': 190, 'hours': 24, 'stack_value': 13}, {'status': 'expired'}],
   {'deposit': 2, 'net': -2})]]
for label, args, expected in cases[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
long cheap listing #1{'deposit': 0, 'net': 0}{'deposit': 4, 'net': -4}Failed
regression per-block minimum #1{'deposit': 0, 'net': 0}{'deposit': 4, 'net': -4}Failed
regression per-block minimum #2{'deposit': 0, 'net': 0}{'deposit': 2, 'net': -2}Failed
regression per-block minimum #3{'deposit': 0, 'net': 0}{'deposit': 1, 'net': -1}Failed
regression per-block minimum #4{'deposit': 0, 'net': -4}{'deposit': 1, 'net': -5}Failed
half-up cut boundary #1{'deposit': 15, 'net': 9}{'deposit': 15, 'net': 9}Passed
cancel with bid #1{'deposit': 12, 'net': -31}{'deposit': 12, 'net': -31}Passed
control #1{'deposit': 2, 'net': -2}{'deposit': 2, 'net': -2}Passed

SHA-256 / 0b413b4bb3b31a26e4b49d9054d65e61bb6bcaac7333139a63c5ec4377cfdd37

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 8 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.

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Verification & scope

Deterministic toy contract stipulated for this model; integer or exact arithmetic only, not a reproduction of any specific game engine. 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 2026-09-29T14:50:45.449046+00:00.

Case digest / eed6f91d236748f77cfe9210e4610defe81e942d94f6c44df03a90759c66fe21