FA-1516 / Concurrency / Open access

Release a coordination lease: Retried release decrements live-lease accounting twice · case 01

The lease release operation is admitted even though retried release decrements live-lease accounting twice.

Verified by executionVariant 1 · 9 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The admission path omits the release not seen invariant while validating the other operation preconditions.

VERIFIED REPAIR

Require r['release_not_seen'] is False together with every other stated precondition before accepting the operation.

Unsuccessful approach: Adding the release not seen check repairs the reported defect, but replacing the adjacent successor protected check loses that independent invariant.

Case contract

Return a Boolean admission decision for release a coordination lease. The record r must satisfy all of: r['owner_match'][0] == r['owner_match'][1]; r['acquisition_match'][0] == r['acquisition_match'][1]; r['resource_match'][0] == r['resource_match'][1]; r['release_not_seen'] is False; r['successor_protected'][0] <= r['successor_protected'][1]. Extra tracing fields are ignored; validation does not mutate the record.

Why this case matters

A deterministic local contract for concurrency. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(r):
    return (r['owner_match'][0] == r['owner_match'][1]) and (r['acquisition_match'][0] == r['acquisition_match'][1]) and (r['resource_match'][0] == r['resource_match'][1]) and (r['successor_protected'][0] <= r['successor_protected'][1])
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
r = {'owner_match': ['a', 'a'], 'acquisition_match': [4, 4], 'resource_match': ['r1', 'r1'], 'release_not_seen': False, 'successor_protected': [4, 4]}
check('valid operation', solve(r), True)
check('One owner releases another owner lease', solve(dict(r, **{'owner_match': ['b', 'a']})), False)
check('A delayed release deletes a later acquisition by the same owner', solve(dict(r, **{'acquisition_match': [3, 4]})), False)
check('A release applies to a different leased resource', solve(dict(r, **{'resource_match': ['r2', 'r1']})), False)
check('Retried release decrements live-lease accounting twice', solve(dict(r, **{'release_not_seen': True})), False)
check('Release removes successor state after ownership transfer', solve(dict(r, **{'successor_protected': [5, 4]})), False)
check('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)
check('repeat validation is pure', solve(r), True)
invalid = {'owner_match': ['b', 'a'], 'acquisition_match': [3, 4], 'resource_match': ['r2', 'r1'], 'release_not_seen': True, 'successor_protected': [5, 4]}
keys = list(invalid)
pair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}
check('two independent violations in variant', solve(dict(r, **pair)), False)
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 fixture	Actual	Expected	Outcome
valid operation	`True`	`True`	Passed
One owner releases another owner lease	`False`	`False`	Passed
A delayed release deletes a later acquisition by the same owner	`False`	`False`	Passed
A release applies to a different leased resource	`False`	`False`	Passed
Retried release decrements live-lease accounting twice	`True`	`False`	Failed
Release removes successor state after ownership transfer	`False`	`False`	Passed
unrelated tracing metadata	`True`	`True`	Passed
repeat validation is pure	`True`	`True`	Passed
two independent violations in variant	`False`	`False`	Passed

SHA-256 / 6a7f40af8707226121fa65516fff7faa762a076393cc77076577d6f6990db5b0

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(r):
    return (r['owner_match'][0] == r['owner_match'][1]) and (r['acquisition_match'][0] == r['acquisition_match'][1]) and (r['resource_match'][0] == r['resource_match'][1]) and (r['release_not_seen'] is False)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
r = {'owner_match': ['a', 'a'], 'acquisition_match': [4, 4], 'resource_match': ['r1', 'r1'], 'release_not_seen': False, 'successor_protected': [4, 4]}
check('valid operation', solve(r), True)
check('One owner releases another owner lease', solve(dict(r, **{'owner_match': ['b', 'a']})), False)
check('A delayed release deletes a later acquisition by the same owner', solve(dict(r, **{'acquisition_match': [3, 4]})), False)
check('A release applies to a different leased resource', solve(dict(r, **{'resource_match': ['r2', 'r1']})), False)
check('Retried release decrements live-lease accounting twice', solve(dict(r, **{'release_not_seen': True})), False)
check('Release removes successor state after ownership transfer', solve(dict(r, **{'successor_protected': [5, 4]})), False)
check('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)
check('repeat validation is pure', solve(r), True)
invalid = {'owner_match': ['b', 'a'], 'acquisition_match': [3, 4], 'resource_match': ['r2', 'r1'], 'release_not_seen': True, 'successor_protected': [5, 4]}
keys = list(invalid)
pair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}
check('two independent violations in variant', solve(dict(r, **pair)), False)
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 fixture	Actual	Expected	Outcome
valid operation	`True`	`True`	Passed
One owner releases another owner lease	`False`	`False`	Passed
A delayed release deletes a later acquisition by the same owner	`False`	`False`	Passed
A release applies to a different leased resource	`False`	`False`	Passed
Retried release decrements live-lease accounting twice	`False`	`False`	Passed
Release removes successor state after ownership transfer	`True`	`False`	Failed
unrelated tracing metadata	`True`	`True`	Passed
repeat validation is pure	`True`	`True`	Passed
two independent violations in variant	`False`	`False`	Passed

SHA-256 / c9a88c27c0ce17e91a212d701aa8378599e1531ca14b83c1870b2f837887546a

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(r):
    return (r['owner_match'][0] == r['owner_match'][1]) and (r['acquisition_match'][0] == r['acquisition_match'][1]) and (r['resource_match'][0] == r['resource_match'][1]) and (r['release_not_seen'] is False) and (r['successor_protected'][0] <= r['successor_protected'][1])
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
r = {'owner_match': ['a', 'a'], 'acquisition_match': [4, 4], 'resource_match': ['r1', 'r1'], 'release_not_seen': False, 'successor_protected': [4, 4]}
check('valid operation', solve(r), True)
check('One owner releases another owner lease', solve(dict(r, **{'owner_match': ['b', 'a']})), False)
check('A delayed release deletes a later acquisition by the same owner', solve(dict(r, **{'acquisition_match': [3, 4]})), False)
check('A release applies to a different leased resource', solve(dict(r, **{'resource_match': ['r2', 'r1']})), False)
check('Retried release decrements live-lease accounting twice', solve(dict(r, **{'release_not_seen': True})), False)
check('Release removes successor state after ownership transfer', solve(dict(r, **{'successor_protected': [5, 4]})), False)
check('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)
check('repeat validation is pure', solve(r), True)
invalid = {'owner_match': ['b', 'a'], 'acquisition_match': [3, 4], 'resource_match': ['r2', 'r1'], 'release_not_seen': True, 'successor_protected': [5, 4]}
keys = list(invalid)
pair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}
check('two independent violations in variant', solve(dict(r, **pair)), False)
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 fixture	Actual	Expected	Outcome
valid operation	`True`	`True`	Passed
One owner releases another owner lease	`False`	`False`	Passed
A delayed release deletes a later acquisition by the same owner	`False`	`False`	Passed
A release applies to a different leased resource	`False`	`False`	Passed
Retried release decrements live-lease accounting twice	`False`	`False`	Passed
Release removes successor state after ownership transfer	`False`	`False`	Passed
unrelated tracing metadata	`True`	`True`	Passed
repeat validation is pure	`True`	`True`	Passed
two independent violations in variant	`False`	`False`	Passed

SHA-256 / 80efec07898498973c6efedd2d507e38c96f681f84efc4d1fe9073e4362c5442

Verification & scope

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 2026-09-29T14:37:02.976544+00:00.

Case digest / 099e5d1c057d1b16209caf2dc580b3f821d00ba28e688fa037eac3438db2db25