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FA-41211 / Heap invariants / Open access

Paged heap exact-multiple tail pages are full rather than empty · case 01

The bounded paged heap layout certificate reports an incorrect tail occupancy.

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

ROOT CAUSE

Paged heap exact-multiple tail pages are full rather than empty.

THE FAILURE

Paged heap exact-multiple tail pages are full rather than empty.

Unsuccessful approach: The local patch uses b and still violates the stated relation.

Case contract

A binary heap is stored in fixed-size pages of B slots using zero-based global indices. For n logical members and selected live index i report its page/offset, parent address or None, child addresses, allocated page count, last-page live occupancy, and pages touched by reading i and its existing children. B>=1 and 0<=i<n.

Why this case matters

This isolates an internal heap representation or priority-structure invariant using deterministic finite records.

1 / The failure

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

N = 1
observations = []
def solve(d):
    n=d['size']; b=d['page_size']; i=d['index']; children=[j for j in (2*i+1,2*i+2) if j<n]
    def address(j): return [j//b,j%b]
    return {'address': address(i),
    'parent': None if i==0 else address((i-1)//2),
    'children': [address(j) for j in children],
    'pages': (n+b-1)//b,
    'tail_occupancy': n%b,
    'touched': sorted({j//b for j in [i]+children})}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 11, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'tail_occupancy': 2, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 12, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'tail_occupancy': 3, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 13, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 5, 'tail_occupancy': 1, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 14, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 5, 'tail_occupancy': 2, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 15, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 5, 'tail_occupancy': 3, 'touched': [1, 3]})]][N-1]
check('regression certificate 1', solve(cases[0][0]), cases[0][1])
check('regression certificate 2', solve(cases[1][0]), cases[1][1])
check('regression certificate 3', solve(cases[2][0]), cases[2][1])
check('regression certificate 4', solve(cases[3][0]), cases[3][1])
check('regression certificate 5', solve(cases[4][0]), cases[4][1])
check('regression certificate 6', solve(cases[5][0]), cases[5][1])
check('variant-dependent certificate', solve(cases[6][0]), cases[6][1])
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 certificate 1{'address': [0, 0], 'children': [], 'pages': 1, 'parent': None, 'tail_occupancy': 1, 'touched': [0]}{'address': [0, 0], 'children': [], 'pages': 1, 'parent': None, 'tail_occupancy': 1, 'touched': [0]}Passed
regression certificate 2{'address': [0, 3], 'children': [[1, 3]], 'pages': 2, 'parent': [0, 1], 'tail_occupancy': 0, 'touched': [0, 1]}{'address': [0, 3], 'children': [[1, 3]], 'pages': 2, 'parent': [0, 1], 'tail_occupancy': 4, 'touched': [0, 1]}Failed
regression certificate 3{'address': [0, 2], 'children': [[1, 1], [1, 2]], 'pages': 3, 'parent': [0, 0], 'tail_occupancy': 1, 'touched': [0, 1]}{'address': [0, 2], 'children': [[1, 1], [1, 2]], 'pages': 3, 'parent': [0, 0], 'tail_occupancy': 1, 'touched': [0, 1]}Passed
regression certificate 4{'address': [2, 0], 'children': [[4, 1], [4, 2]], 'pages': 5, 'parent': [0, 2], 'tail_occupancy': 0, 'touched': [2, 4]}{'address': [2, 0], 'children': [[4, 1], [4, 2]], 'pages': 5, 'parent': [0, 2], 'tail_occupancy': 3, 'touched': [2, 4]}Failed
regression certificate 5{'address': [1, 3], 'children': [[3, 3]], 'pages': 4, 'parent': [0, 3], 'tail_occupancy': 0, 'touched': [1, 3]}{'address': [1, 3], 'children': [[3, 3]], 'pages': 4, 'parent': [0, 3], 'tail_occupancy': 4, 'touched': [1, 3]}Failed
regression certificate 6{'address': [1, 1], 'children': [[3, 0]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 1, 'touched': [1, 3]}{'address': [1, 1], 'children': [[3, 0]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 1, 'touched': [1, 3]}Passed
variant-dependent certificate{'address': [1, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 2, 'touched': [1, 3]}{'address': [1, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 2, 'touched': [1, 3]}Passed

SHA-256 / 502ffde041455715009a406cb54c0400f88572a17e6df7c57facdcbc8a77782b

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(d):
    n=d['size']; b=d['page_size']; i=d['index']; children=[j for j in (2*i+1,2*i+2) if j<n]
    def address(j): return [j//b,j%b]
    return {'address': address(i),
    'parent': None if i==0 else address((i-1)//2),
    'children': [address(j) for j in children],
    'pages': (n+b-1)//b,
    'tail_occupancy': b,
    'touched': sorted({j//b for j in [i]+children})}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 11, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'tail_occupancy': 2, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 12, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'tail_occupancy': 3, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 13, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 5, 'tail_occupancy': 1, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 14, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 5, 'tail_occupancy': 2, 'touched': [1, 3]})], [({'size': 1, 'page_size': 4, 'index': 0}, {'address': [0, 0], 'parent': None, 'children': [], 'pages': 1, 'tail_occupancy': 1, 'touched': [0]}), ({'size': 8, 'page_size': 4, 'index': 3}, {'address': [0, 3], 'parent': [0, 1], 'children': [[1, 3]], 'pages': 2, 'tail_occupancy': 4, 'touched': [0, 1]}), ({'size': 9, 'page_size': 4, 'index': 2}, {'address': [0, 2], 'parent': [0, 0], 'children': [[1, 1], [1, 2]], 'pages': 3, 'tail_occupancy': 1, 'touched': [0, 1]}), ({'size': 15, 'page_size': 3, 'index': 6}, {'address': [2, 0], 'parent': [0, 2], 'children': [[4, 1], [4, 2]], 'pages': 5, 'tail_occupancy': 3, 'touched': [2, 4]}), ({'size': 16, 'page_size': 4, 'index': 7}, {'address': [1, 3], 'parent': [0, 3], 'children': [[3, 3]], 'pages': 4, 'tail_occupancy': 4, 'touched': [1, 3]}), ({'size': 10, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0]], 'pages': 4, 'tail_occupancy': 1, 'touched': [1, 3]}), ({'size': 15, 'page_size': 3, 'index': 4}, {'address': [1, 1], 'parent': [0, 1], 'children': [[3, 0], [3, 1]], 'pages': 5, 'tail_occupancy': 3, 'touched': [1, 3]})]][N-1]
check('regression certificate 1', solve(cases[0][0]), cases[0][1])
check('regression certificate 2', solve(cases[1][0]), cases[1][1])
check('regression certificate 3', solve(cases[2][0]), cases[2][1])
check('regression certificate 4', solve(cases[3][0]), cases[3][1])
check('regression certificate 5', solve(cases[4][0]), cases[4][1])
check('regression certificate 6', solve(cases[5][0]), cases[5][1])
check('variant-dependent certificate', solve(cases[6][0]), cases[6][1])
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 certificate 1{'address': [0, 0], 'children': [], 'pages': 1, 'parent': None, 'tail_occupancy': 4, 'touched': [0]}{'address': [0, 0], 'children': [], 'pages': 1, 'parent': None, 'tail_occupancy': 1, 'touched': [0]}Failed
regression certificate 2{'address': [0, 3], 'children': [[1, 3]], 'pages': 2, 'parent': [0, 1], 'tail_occupancy': 4, 'touched': [0, 1]}{'address': [0, 3], 'children': [[1, 3]], 'pages': 2, 'parent': [0, 1], 'tail_occupancy': 4, 'touched': [0, 1]}Passed
regression certificate 3{'address': [0, 2], 'children': [[1, 1], [1, 2]], 'pages': 3, 'parent': [0, 0], 'tail_occupancy': 4, 'touched': [0, 1]}{'address': [0, 2], 'children': [[1, 1], [1, 2]], 'pages': 3, 'parent': [0, 0], 'tail_occupancy': 1, 'touched': [0, 1]}Failed
regression certificate 4{'address': [2, 0], 'children': [[4, 1], [4, 2]], 'pages': 5, 'parent': [0, 2], 'tail_occupancy': 3, 'touched': [2, 4]}{'address': [2, 0], 'children': [[4, 1], [4, 2]], 'pages': 5, 'parent': [0, 2], 'tail_occupancy': 3, 'touched': [2, 4]}Passed
regression certificate 5{'address': [1, 3], 'children': [[3, 3]], 'pages': 4, 'parent': [0, 3], 'tail_occupancy': 4, 'touched': [1, 3]}{'address': [1, 3], 'children': [[3, 3]], 'pages': 4, 'parent': [0, 3], 'tail_occupancy': 4, 'touched': [1, 3]}Passed
regression certificate 6{'address': [1, 1], 'children': [[3, 0]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 3, 'touched': [1, 3]}{'address': [1, 1], 'children': [[3, 0]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 1, 'touched': [1, 3]}Failed
variant-dependent certificate{'address': [1, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 3, 'touched': [1, 3]}{'address': [1, 1], 'children': [[3, 0], [3, 1]], 'pages': 4, 'parent': [0, 1], 'tail_occupancy': 2, 'touched': [1, 3]}Failed

SHA-256 / c4ee2fed30db13bb9db6a2e5cd5f322511a9c5e2adda3b5b85ffce9e6d16f5ab

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.

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Verification & scope

A stipulated offline diagnostic model; it does not implement a production allocator, concurrency protocol, or complete heap library. 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 2026-09-29T14:43:38.699345+00:00.

Case digest / 56e0f6c7ea47db57beb2c3dc9323a8d42a85d1b576883e3482196ef7f65812d1