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FA-86171 / Game economy crafting balance / Open access

Inventory stack insertion: Top-up ignores existing count · case 01

Partial stacks overflow past max_stack.

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

ROOT CAUSE

The top-up amount ignores how many items the stack already holds.

VERIFIED REPAIR

Restore `min(left, max_stack - s[1])` at the top-up amount step.

Unsuccessful approach: Filling to max regardless of the remaining quantity creates items.

Case contract

slots = list of None or [name, count]; names are case sensitive. First top up partial stacks (count < max_stack) of the same item in slot order, then fill empty slots in order with new stacks of at most max_stack. Reserved placeholders [name, 0] count as partial stacks. Legacy stacks above max_stack are left untouched. Returns {slots, leftover}.

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(slots, item, qty, max_stack):
    slots = [s if s is None else list(s) for s in slots]
    left = qty
    for s in slots:
        if left == 0:
            break
        if s is not None and s[0] == item and s[1] < max_stack:
            add = min(left, max_stack)
            s[1] += add
            left -= add
    for i in range(len(slots)):
        if left == 0:
            break
        if slots[i] is None:
            add = min(left, max_stack)
            slots[i] = [item, add]
            left -= add
    return {'slots': slots, 'leftover': left}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[None, ['Arrow', 1], ['arrow', 1], ['Potion', 20], ['arrow', 19]], 'arrow', 20, 20],
   {'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]], 'leftover': 0}),
  ('fault site top-up amount #2',
   [[None, ['arrow', 5], None, None], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]], 'leftover': 10}),
  ('partial repair boundary #1',
   [[None, ['Potion', 0], ['Potion', 20], ['arrow', 1]], 'arrow', 1, 10],
   {'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 5], ['Arrow', 1]], 'Arrow', 1, 20],
   {'slots': [['arrow', 5], ['Arrow', 2]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[None, ['arrow', 5], None, None], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]], 'leftover': 10}),
  ('fault site top-up amount #2',
   [[None, ['arrow', 1], ['Arrow', 19], ['arrow', 10], None], 'arrow', 20, 5],
   {'slots': [['arrow', 5], ['arrow', 5], ['Arrow', 19], ['arrow', 10], ['arrow', 5]], 'leftover': 6}),
  ('partial repair boundary #1',
   [[['arrow', 5], ['Arrow', 1]], 'Arrow', 1, 20],
   {'slots': [['arrow', 5], ['Arrow', 2]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['Arrow', 25], ['Arrow', 25], ['Potion', 1]], 'Potion', 7, 20],
   {'slots': [['Arrow', 25], ['Arrow', 25], ['Potion', 8]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['Potion', 17], ['arrow', 1], ['Arrow', 0], ['arrow', 19]], 'arrow', 45, 20],
   {'slots': [['Potion', 17], ['arrow', 20], ['Arrow', 0], ['arrow', 20]], 'leftover': 25}),
  ('fault site top-up amount #2',
   [[['Arrow', 5]], 'Arrow', 20, 20],
   {'slots': [['Arrow', 20]], 'leftover': 5}),
  ('partial repair boundary #1',
   [[['arrow', 1], None, ['Potion', 5]], 'arrow', 7, 20],
   {'slots': [['arrow', 8], None, ['Potion', 5]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 20], ['Arrow', 0], ['Potion', 19]], 'Arrow', 7, 10],
   {'slots': [['arrow', 20], ['Arrow', 7], ['Potion', 19]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['arrow', 25], None, ['Potion', 5], None, ['arrow', 20]], 'Potion', 7, 10],
   {'slots': [['arrow', 25], ['Potion', 2], ['Potion', 10], None, ['arrow', 20]], 'leftover': 0}),
  ('fault site top-up amount #2',
   [[None, None, ['Arrow', 11], ['Potion', 10], ['Arrow', 25], None], 'Potion', 20, 20],
   {'slots': [['Potion', 10], None, ['Arrow', 11], ['Potion', 20], ['Arrow', 25], None], 'leftover': 0}),
  ('partial repair boundary #1',
   [[['arrow', 5], ['Potion', 5], ['Potion', 1], ['Potion', 1], ['Arrow', 3]], 'arrow', 1, 20],
   {'slots': [['arrow', 6], ['Potion', 5], ['Potion', 1], ['Potion', 1], ['Arrow', 3]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 20], ['Arrow', 16], ['arrow', 20], None, None, ['Potion', 0]], 'Potion', 1, 20],
   {'slots': [['arrow', 20], ['Arrow', 16], ['arrow', 20], None, None, ['Potion', 1]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[None, ['Arrow', 16], ['arrow', 20], None, ['Arrow', 25], None], 'Potion', 20, 10],
   {'slots': [['Potion', 10], ['Arrow', 16], ['arrow', 20], ['Potion', 10], ['Arrow', 25], None],
    'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['Potion', 0], ['Arrow', 0], ['Arrow', 1]], 'Arrow', 45, 10],
   {'slots': [['Potion', 0], ['Arrow', 10], ['Arrow', 10]], 'leftover': 26}),
  ('fault site top-up amount #2',
   [[None, ['Potion', 11], ['arrow', 5], ['Potion', 19], None, ['Arrow', 0]], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['Potion', 11], ['arrow', 10], ['Potion', 19], ['arrow', 10], ['Arrow', 0]],
    'leftover': 20}),
  ('partial repair boundary #1',
   [[['Arrow', 5], None, ['Arrow', 20], ['arrow', 0], ['Potion', 0]], 'arrow', 7, 20],
   {'slots': [['Arrow', 5], None, ['Arrow', 20], ['arrow', 7], ['Potion', 0]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[None, None, ['arrow', 14], ['Arrow', 0], None, None], 'Arrow', 1, 5],
   {'slots': [None, None, ['arrow', 14], ['Arrow', 1], None, None], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1', [[['Potion', 0]], 'Arrow', 45, 5], {'slots': [['Potion', 0]], 'leftover': 45})]]
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
two partial stacks #1{'leftover': 0, 'slots': [['Arrow', 22], ['Arrow', 15], None]}{'leftover': 0, 'slots': [['Arrow', 20], ['Arrow', 17], None]}Failed
fault site top-up amount #1{'leftover': 0, 'slots': [None, ['Arrow', 1], ['arrow', 21], ['Potion', 20], ['arrow', 19]]}{'leftover': 0, 'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]]}Failed
fault site top-up amount #2{'leftover': 5, 'slots': [['arrow', 10], ['arrow', 15], ['arrow', 10], ['arrow', 10]]}{'leftover': 10, 'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]]}Failed
partial repair boundary #1{'leftover': 0, 'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]]}{'leftover': 0, 'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]]}Passed
partial repair boundary #2{'leftover': 0, 'slots': [['arrow', 5], ['Arrow', 2]]}{'leftover': 0, 'slots': [['arrow', 5], ['Arrow', 2]]}Passed
legacy overfull stack #1{'leftover': 0, 'slots': [['Arrow', 25], ['Arrow', 3]]}{'leftover': 0, 'slots': [['Arrow', 25], ['Arrow', 3]]}Passed
case distinct item #1{'leftover': 2, 'slots': [['arrow', 3]]}{'leftover': 2, 'slots': [['arrow', 3]]}Passed
control #1{'leftover': 0, 'slots': [['Arrow', 6], None, ['arrow', 5]]}{'leftover': 0, 'slots': [['Arrow', 6], None, ['arrow', 5]]}Passed

SHA-256 / 1c64e7d66b4a1378ad45050571fb487dd29065e8bccf969eaadb0fcf62dc74e9

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(slots, item, qty, max_stack):
    slots = [s if s is None else list(s) for s in slots]
    left = qty
    for s in slots:
        if left == 0:
            break
        if s is not None and s[0] == item and s[1] < max_stack:
            add = max_stack - s[1]
            s[1] += add
            left -= add
    for i in range(len(slots)):
        if left == 0:
            break
        if slots[i] is None:
            add = min(left, max_stack)
            slots[i] = [item, add]
            left -= add
    return {'slots': slots, 'leftover': left}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[None, ['Arrow', 1], ['arrow', 1], ['Potion', 20], ['arrow', 19]], 'arrow', 20, 20],
   {'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]], 'leftover': 0}),
  ('fault site top-up amount #2',
   [[None, ['arrow', 5], None, None], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]], 'leftover': 10}),
  ('partial repair boundary #1',
   [[None, ['Potion', 0], ['Potion', 20], ['arrow', 1]], 'arrow', 1, 10],
   {'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 5], ['Arrow', 1]], 'Arrow', 1, 20],
   {'slots': [['arrow', 5], ['Arrow', 2]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[None, ['arrow', 5], None, None], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]], 'leftover': 10}),
  ('fault site top-up amount #2',
   [[None, ['arrow', 1], ['Arrow', 19], ['arrow', 10], None], 'arrow', 20, 5],
   {'slots': [['arrow', 5], ['arrow', 5], ['Arrow', 19], ['arrow', 10], ['arrow', 5]], 'leftover': 6}),
  ('partial repair boundary #1',
   [[['arrow', 5], ['Arrow', 1]], 'Arrow', 1, 20],
   {'slots': [['arrow', 5], ['Arrow', 2]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['Arrow', 25], ['Arrow', 25], ['Potion', 1]], 'Potion', 7, 20],
   {'slots': [['Arrow', 25], ['Arrow', 25], ['Potion', 8]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['Potion', 17], ['arrow', 1], ['Arrow', 0], ['arrow', 19]], 'arrow', 45, 20],
   {'slots': [['Potion', 17], ['arrow', 20], ['Arrow', 0], ['arrow', 20]], 'leftover': 25}),
  ('fault site top-up amount #2',
   [[['Arrow', 5]], 'Arrow', 20, 20],
   {'slots': [['Arrow', 20]], 'leftover': 5}),
  ('partial repair boundary #1',
   [[['arrow', 1], None, ['Potion', 5]], 'arrow', 7, 20],
   {'slots': [['arrow', 8], None, ['Potion', 5]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 20], ['Arrow', 0], ['Potion', 19]], 'Arrow', 7, 10],
   {'slots': [['arrow', 20], ['Arrow', 7], ['Potion', 19]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['arrow', 25], None, ['Potion', 5], None, ['arrow', 20]], 'Potion', 7, 10],
   {'slots': [['arrow', 25], ['Potion', 2], ['Potion', 10], None, ['arrow', 20]], 'leftover': 0}),
  ('fault site top-up amount #2',
   [[None, None, ['Arrow', 11], ['Potion', 10], ['Arrow', 25], None], 'Potion', 20, 20],
   {'slots': [['Potion', 10], None, ['Arrow', 11], ['Potion', 20], ['Arrow', 25], None], 'leftover': 0}),
  ('partial repair boundary #1',
   [[['arrow', 5], ['Potion', 5], ['Potion', 1], ['Potion', 1], ['Arrow', 3]], 'arrow', 1, 20],
   {'slots': [['arrow', 6], ['Potion', 5], ['Potion', 1], ['Potion', 1], ['Arrow', 3]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 20], ['Arrow', 16], ['arrow', 20], None, None, ['Potion', 0]], 'Potion', 1, 20],
   {'slots': [['arrow', 20], ['Arrow', 16], ['arrow', 20], None, None, ['Potion', 1]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[None, ['Arrow', 16], ['arrow', 20], None, ['Arrow', 25], None], 'Potion', 20, 10],
   {'slots': [['Potion', 10], ['Arrow', 16], ['arrow', 20], ['Potion', 10], ['Arrow', 25], None],
    'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['Potion', 0], ['Arrow', 0], ['Arrow', 1]], 'Arrow', 45, 10],
   {'slots': [['Potion', 0], ['Arrow', 10], ['Arrow', 10]], 'leftover': 26}),
  ('fault site top-up amount #2',
   [[None, ['Potion', 11], ['arrow', 5], ['Potion', 19], None, ['Arrow', 0]], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['Potion', 11], ['arrow', 10], ['Potion', 19], ['arrow', 10], ['Arrow', 0]],
    'leftover': 20}),
  ('partial repair boundary #1',
   [[['Arrow', 5], None, ['Arrow', 20], ['arrow', 0], ['Potion', 0]], 'arrow', 7, 20],
   {'slots': [['Arrow', 5], None, ['Arrow', 20], ['arrow', 7], ['Potion', 0]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[None, None, ['arrow', 14], ['Arrow', 0], None, None], 'Arrow', 1, 5],
   {'slots': [None, None, ['arrow', 14], ['Arrow', 1], None, None], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1', [[['Potion', 0]], 'Arrow', 45, 5], {'slots': [['Potion', 0]], 'leftover': 45})]]
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
two partial stacks #1{'leftover': 0, 'slots': [['Arrow', 20], ['Arrow', 20], ['Arrow', -3]]}{'leftover': 0, 'slots': [['Arrow', 20], ['Arrow', 17], None]}Failed
fault site top-up amount #1{'leftover': 0, 'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]]}{'leftover': 0, 'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]]}Passed
fault site top-up amount #2{'leftover': 10, 'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]]}{'leftover': 10, 'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]]}Passed
partial repair boundary #1{'leftover': 0, 'slots': [['arrow', -8], ['Potion', 0], ['Potion', 20], ['arrow', 10]]}{'leftover': 0, 'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]]}Failed
partial repair boundary #2{'leftover': -18, 'slots': [['arrow', 5], ['Arrow', 20]]}{'leftover': 0, 'slots': [['arrow', 5], ['Arrow', 2]]}Failed
legacy overfull stack #1{'leftover': 0, 'slots': [['Arrow', 25], ['Arrow', 3]]}{'leftover': 0, 'slots': [['Arrow', 25], ['Arrow', 3]]}Passed
case distinct item #1{'leftover': 2, 'slots': [['arrow', 3]]}{'leftover': 2, 'slots': [['arrow', 3]]}Passed
control #1{'leftover': 0, 'slots': [['Arrow', 6], None, ['arrow', 5]]}{'leftover': 0, 'slots': [['Arrow', 6], None, ['arrow', 5]]}Passed

SHA-256 / c320952eb28d0d8c8c5276b30e83876336e04ddb922662d66d186ed7f07fca8a

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(slots, item, qty, max_stack):
    slots = [s if s is None else list(s) for s in slots]
    left = qty
    for s in slots:
        if left == 0:
            break
        if s is not None and s[0] == item and s[1] < max_stack:
            add = min(left, max_stack - s[1])
            s[1] += add
            left -= add
    for i in range(len(slots)):
        if left == 0:
            break
        if slots[i] is None:
            add = min(left, max_stack)
            slots[i] = [item, add]
            left -= add
    return {'slots': slots, 'leftover': left}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[None, ['Arrow', 1], ['arrow', 1], ['Potion', 20], ['arrow', 19]], 'arrow', 20, 20],
   {'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]], 'leftover': 0}),
  ('fault site top-up amount #2',
   [[None, ['arrow', 5], None, None], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]], 'leftover': 10}),
  ('partial repair boundary #1',
   [[None, ['Potion', 0], ['Potion', 20], ['arrow', 1]], 'arrow', 1, 10],
   {'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 5], ['Arrow', 1]], 'Arrow', 1, 20],
   {'slots': [['arrow', 5], ['Arrow', 2]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[None, ['arrow', 5], None, None], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]], 'leftover': 10}),
  ('fault site top-up amount #2',
   [[None, ['arrow', 1], ['Arrow', 19], ['arrow', 10], None], 'arrow', 20, 5],
   {'slots': [['arrow', 5], ['arrow', 5], ['Arrow', 19], ['arrow', 10], ['arrow', 5]], 'leftover': 6}),
  ('partial repair boundary #1',
   [[['arrow', 5], ['Arrow', 1]], 'Arrow', 1, 20],
   {'slots': [['arrow', 5], ['Arrow', 2]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['Arrow', 25], ['Arrow', 25], ['Potion', 1]], 'Potion', 7, 20],
   {'slots': [['Arrow', 25], ['Arrow', 25], ['Potion', 8]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['Potion', 17], ['arrow', 1], ['Arrow', 0], ['arrow', 19]], 'arrow', 45, 20],
   {'slots': [['Potion', 17], ['arrow', 20], ['Arrow', 0], ['arrow', 20]], 'leftover': 25}),
  ('fault site top-up amount #2',
   [[['Arrow', 5]], 'Arrow', 20, 20],
   {'slots': [['Arrow', 20]], 'leftover': 5}),
  ('partial repair boundary #1',
   [[['arrow', 1], None, ['Potion', 5]], 'arrow', 7, 20],
   {'slots': [['arrow', 8], None, ['Potion', 5]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 20], ['Arrow', 0], ['Potion', 19]], 'Arrow', 7, 10],
   {'slots': [['arrow', 20], ['Arrow', 7], ['Potion', 19]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[['Arrow', 6], None, ['arrow', 5]], 'Potion', 0, 20],
   {'slots': [['Arrow', 6], None, ['arrow', 5]], 'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['arrow', 25], None, ['Potion', 5], None, ['arrow', 20]], 'Potion', 7, 10],
   {'slots': [['arrow', 25], ['Potion', 2], ['Potion', 10], None, ['arrow', 20]], 'leftover': 0}),
  ('fault site top-up amount #2',
   [[None, None, ['Arrow', 11], ['Potion', 10], ['Arrow', 25], None], 'Potion', 20, 20],
   {'slots': [['Potion', 10], None, ['Arrow', 11], ['Potion', 20], ['Arrow', 25], None], 'leftover': 0}),
  ('partial repair boundary #1',
   [[['arrow', 5], ['Potion', 5], ['Potion', 1], ['Potion', 1], ['Arrow', 3]], 'arrow', 1, 20],
   {'slots': [['arrow', 6], ['Potion', 5], ['Potion', 1], ['Potion', 1], ['Arrow', 3]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[['arrow', 20], ['Arrow', 16], ['arrow', 20], None, None, ['Potion', 0]], 'Potion', 1, 20],
   {'slots': [['arrow', 20], ['Arrow', 16], ['arrow', 20], None, None, ['Potion', 1]], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1',
   [[None, ['Arrow', 16], ['arrow', 20], None, ['Arrow', 25], None], 'Potion', 20, 10],
   {'slots': [['Potion', 10], ['Arrow', 16], ['arrow', 20], ['Potion', 10], ['Arrow', 25], None],
    'leftover': 0})],
 [('two partial stacks #1',
   [[['Arrow', 18], ['Arrow', 15], None], 'Arrow', 4, 20],
   {'slots': [['Arrow', 20], ['Arrow', 17], None], 'leftover': 0}),
  ('fault site top-up amount #1',
   [[['Potion', 0], ['Arrow', 0], ['Arrow', 1]], 'Arrow', 45, 10],
   {'slots': [['Potion', 0], ['Arrow', 10], ['Arrow', 10]], 'leftover': 26}),
  ('fault site top-up amount #2',
   [[None, ['Potion', 11], ['arrow', 5], ['Potion', 19], None, ['Arrow', 0]], 'arrow', 45, 10],
   {'slots': [['arrow', 10], ['Potion', 11], ['arrow', 10], ['Potion', 19], ['arrow', 10], ['Arrow', 0]],
    'leftover': 20}),
  ('partial repair boundary #1',
   [[['Arrow', 5], None, ['Arrow', 20], ['arrow', 0], ['Potion', 0]], 'arrow', 7, 20],
   {'slots': [['Arrow', 5], None, ['Arrow', 20], ['arrow', 7], ['Potion', 0]], 'leftover': 0}),
  ('partial repair boundary #2',
   [[None, None, ['arrow', 14], ['Arrow', 0], None, None], 'Arrow', 1, 5],
   {'slots': [None, None, ['arrow', 14], ['Arrow', 1], None, None], 'leftover': 0}),
  ('legacy overfull stack #1',
   [[['Arrow', 25], None], 'Arrow', 3, 20],
   {'slots': [['Arrow', 25], ['Arrow', 3]], 'leftover': 0}),
  ('case distinct item #1', [[['arrow', 3]], 'Arrow', 2, 20], {'slots': [['arrow', 3]], 'leftover': 2}),
  ('control #1', [[['Potion', 0]], 'Arrow', 45, 5], {'slots': [['Potion', 0]], 'leftover': 45})]]
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
two partial stacks #1{'leftover': 0, 'slots': [['Arrow', 20], ['Arrow', 17], None]}{'leftover': 0, 'slots': [['Arrow', 20], ['Arrow', 17], None]}Passed
fault site top-up amount #1{'leftover': 0, 'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]]}{'leftover': 0, 'slots': [None, ['Arrow', 1], ['arrow', 20], ['Potion', 20], ['arrow', 20]]}Passed
fault site top-up amount #2{'leftover': 10, 'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]]}{'leftover': 10, 'slots': [['arrow', 10], ['arrow', 10], ['arrow', 10], ['arrow', 10]]}Passed
partial repair boundary #1{'leftover': 0, 'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]]}{'leftover': 0, 'slots': [None, ['Potion', 0], ['Potion', 20], ['arrow', 2]]}Passed
partial repair boundary #2{'leftover': 0, 'slots': [['arrow', 5], ['Arrow', 2]]}{'leftover': 0, 'slots': [['arrow', 5], ['Arrow', 2]]}Passed
legacy overfull stack #1{'leftover': 0, 'slots': [['Arrow', 25], ['Arrow', 3]]}{'leftover': 0, 'slots': [['Arrow', 25], ['Arrow', 3]]}Passed
case distinct item #1{'leftover': 2, 'slots': [['arrow', 3]]}{'leftover': 2, 'slots': [['arrow', 3]]}Passed
control #1{'leftover': 0, 'slots': [['Arrow', 6], None, ['arrow', 5]]}{'leftover': 0, 'slots': [['Arrow', 6], None, ['arrow', 5]]}Passed

SHA-256 / 7342b71235e00bae9aec787f2b06311054aa6f5901bede49878b3225542c0659

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 2026-09-29T14:50:47.033569+00:00.

Case digest / dd7b16af3f6153548f9928b032c17b5c85a4e72e506f1466213fdd0d0b564d3a