{"abstract":"The wal retention operation is admitted even though the only recoverable copy is deleted before archival.","category":"Replication","checks":9,"contract":"Return a Boolean admission decision for delete a write-ahead log segment. The record r must satisfy all of: r['slowest_replica'][0] < min(r['slowest_replica'][1]); r['backup_pin'][0] not in r['backup_pin'][1]; r['archive_confirmed'] is True; r['segment_sealed'] is True; r['recovery_floor'][0] < r['recovery_floor'][1]. Extra tracing fields are ignored; validation does not mutate the record.","evaluation_group":"xd-wal-retention","failed_approach":"Adding the archive confirmed check repairs the reported defect, but replacing the adjacent segment sealed check loses that independent invariant.","family":"xd-wal-retention-archive_confirmed","id":"FA-686","implementations":{"attempt":{"sha256":"354752881f257bc8ae3114d2c6275f8c948835f2ab71bf72a7b728fbb59bc79a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['slowest_replica'][0] < min(r['slowest_replica'][1])) and (r['backup_pin'][0] not in r['backup_pin'][1]) and (r['archive_confirmed'] is True) and (r['recovery_floor'][0] < r['recovery_floor'][1])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'slowest_replica': [9, [10, 12]], 'backup_pin': [9, [10, 11]], 'archive_confirmed': True, 'segment_sealed': True, 'recovery_floor': [7, 8]}\ncheck('valid operation', solve(r), True)\ncheck('Deletion removes the next segment needed by a lagging replica', solve(dict(r, **{'slowest_replica': [10, [10, 12]]})), False)\ncheck('A backup still needs the selected log segment', solve(dict(r, **{'backup_pin': [10, [10, 11]]})), False)\ncheck('The only recoverable copy is deleted before archival', solve(dict(r, **{'archive_confirmed': False})), False)\ncheck('Garbage collection deletes a segment still accepting writes', solve(dict(r, **{'segment_sealed': False})), False)\ncheck('Deletion crosses the crash recovery replay floor', solve(dict(r, **{'recovery_floor': [8, 8]})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'slowest_replica': [10, [10, 12]], 'backup_pin': [10, [10, 11]], 'archive_confirmed': False, 'segment_sealed': False, 'recovery_floor': [8, 8]}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"85b93e047ab6878c96db6bf6b2584c80cbacd871e39fbe1c9d585bdbf0ad5629","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['slowest_replica'][0] < min(r['slowest_replica'][1])) and (r['backup_pin'][0] not in r['backup_pin'][1]) and (r['segment_sealed'] is True) and (r['recovery_floor'][0] < r['recovery_floor'][1])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'slowest_replica': [9, [10, 12]], 'backup_pin': [9, [10, 11]], 'archive_confirmed': True, 'segment_sealed': True, 'recovery_floor': [7, 8]}\ncheck('valid operation', solve(r), True)\ncheck('Deletion removes the next segment needed by a lagging replica', solve(dict(r, **{'slowest_replica': [10, [10, 12]]})), False)\ncheck('A backup still needs the selected log segment', solve(dict(r, **{'backup_pin': [10, [10, 11]]})), False)\ncheck('The only recoverable copy is deleted before archival', solve(dict(r, **{'archive_confirmed': False})), False)\ncheck('Garbage collection deletes a segment still accepting writes', solve(dict(r, **{'segment_sealed': False})), False)\ncheck('Deletion crosses the crash recovery replay floor', solve(dict(r, **{'recovery_floor': [8, 8]})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'slowest_replica': [10, [10, 12]], 'backup_pin': [10, [10, 11]], 'archive_confirmed': False, 'segment_sealed': False, 'recovery_floor': [8, 8]}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"6409c47c634524496e8ce5493b9f7e6ad33bed4115ca9dc79df7814cd574c6dc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['slowest_replica'][0] < min(r['slowest_replica'][1])) and (r['backup_pin'][0] not in r['backup_pin'][1]) and (r['archive_confirmed'] is True) and (r['segment_sealed'] is True) and (r['recovery_floor'][0] < r['recovery_floor'][1])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'slowest_replica': [9, [10, 12]], 'backup_pin': [9, [10, 11]], 'archive_confirmed': True, 'segment_sealed': True, 'recovery_floor': [7, 8]}\ncheck('valid operation', solve(r), True)\ncheck('Deletion removes the next segment needed by a lagging replica', solve(dict(r, **{'slowest_replica': [10, [10, 12]]})), False)\ncheck('A backup still needs the selected log segment', solve(dict(r, **{'backup_pin': [10, [10, 11]]})), False)\ncheck('The only recoverable copy is deleted before archival', solve(dict(r, **{'archive_confirmed': False})), False)\ncheck('Garbage collection deletes a segment still accepting writes', solve(dict(r, **{'segment_sealed': False})), False)\ncheck('Deletion crosses the crash recovery replay floor', solve(dict(r, **{'recovery_floor': [8, 8]})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'slowest_replica': [10, [10, 12]], 'backup_pin': [10, [10, 11]], 'archive_confirmed': False, 'segment_sealed': False, 'recovery_floor': [8, 8]}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":" 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"xd-wal-retention-archive_confirmed","generated_at":"2026-09-29T14:36:55.012461+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic local contract for replication. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.","repair":"Require r['archive_confirmed'] is True together with every other stated precondition before accepting the operation.","root_cause":"The admission path omits the archive confirmed invariant while validating the other operation preconditions.","sha256":"bde85ebf18271665cd4efa680e096e3151430b924c34edc10a5cb88b8245f74b","title":"Delete a write-ahead log segment: The only recoverable copy is deleted before archival · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":112.062,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"Deletion removes the next segment needed by a lagging replica","expected":false,"passed":true},{"actual":false,"check":"A backup still needs the selected log segment","expected":false,"passed":true},{"actual":false,"check":"The only recoverable copy is deleted before archival","expected":false,"passed":true},{"actual":true,"check":"Garbage collection deletes a segment still accepting writes","expected":false,"passed":false},{"actual":false,"check":"Deletion crosses the crash recovery replay floor","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"Deletion removes the next segment needed by a lagging replica\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A backup still needs the selected log segment\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The only recoverable copy is deleted before archival\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Garbage collection deletes a segment still accepting writes\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"Deletion crosses the crash recovery replay floor\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":35.35,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"Deletion removes the next segment needed by a lagging replica","expected":false,"passed":true},{"actual":false,"check":"A backup still needs the selected log segment","expected":false,"passed":true},{"actual":true,"check":"The only recoverable copy is deleted before archival","expected":false,"passed":false},{"actual":false,"check":"Garbage collection deletes a segment still accepting writes","expected":false,"passed":true},{"actual":false,"check":"Deletion crosses the crash recovery replay floor","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"Deletion removes the next segment needed by a lagging replica\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A backup still needs the selected log segment\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The only recoverable copy is deleted before archival\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"Garbage collection deletes a segment still accepting writes\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Deletion crosses the crash recovery replay floor\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":37.658,"exit_code":0,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"Deletion removes the next segment needed by a lagging replica","expected":false,"passed":true},{"actual":false,"check":"A backup still needs the selected log segment","expected":false,"passed":true},{"actual":false,"check":"The only recoverable copy is deleted before archival","expected":false,"passed":true},{"actual":false,"check":"Garbage collection deletes a segment still accepting writes","expected":false,"passed":true},{"actual":false,"check":"Deletion crosses the crash recovery replay floor","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"Deletion removes the next segment needed by a lagging replica\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A backup still needs the selected log segment\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The only recoverable copy is deleted before archival\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Garbage collection deletes a segment still accepting writes\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Deletion crosses the crash recovery replay floor\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}