{"abstract":"The queue reservation operation is admitted even though a message is delivered after its expiration deadline.","category":"Queues","checks":9,"contract":"Return a Boolean admission decision for reserve a queued message for delivery. The record r must satisfy all of: r['visible_now'][0] >= r['visible_now'][1]; r['not_expired'][0] < r['not_expired'][1]; r['no_live_reservation'][0] is None or r['no_live_reservation'][1] >= r['no_live_reservation'][0]; r['consumer_credit'][0] < r['consumer_credit'][1]; r['group_head'][0] == min(r['group_head'][1]). Extra tracing fields are ignored; validation does not mutate the record.","contract_signature":"r","evaluation_group":"xd-queue-reservation","failed_approach":"Adding the not expired check repairs the reported defect, but replacing the adjacent no live reservation check loses that independent invariant.","family":"xd-queue-reservation-not_expired","id":"FA-756","implementations":{"attempt":{"sha256":"d4c6193a29f2c6b92304693ac7f8dc112db5e97546c999c4db29ce99efed41b9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['visible_now'][0] >= r['visible_now'][1]) and (r['not_expired'][0] < r['not_expired'][1]) and (r['consumer_credit'][0] < r['consumer_credit'][1]) and (r['group_head'][0] == min(r['group_head'][1]))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'visible_now': [10, 10], 'not_expired': [9, 10], 'no_live_reservation': [8, 8], 'consumer_credit': [2, 3], 'group_head': [3, [3, 4]]}\ncheck('valid operation', solve(r), True)\ncheck('A scheduled message is delivered before its visibility instant', solve(dict(r, **{'visible_now': [9, 10]})), False)\ncheck('A message is delivered after its expiration deadline', solve(dict(r, **{'not_expired': [10, 10]})), False)\ncheck('A second worker reserves a currently leased message', solve(dict(r, **{'no_live_reservation': [9, 8]})), False)\ncheck('The broker exceeds consumer in-flight credit', solve(dict(r, **{'consumer_credit': [3, 3]})), False)\ncheck('A FIFO message overtakes an earlier group member', solve(dict(r, **{'group_head': [4, [3, 4]]})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'visible_now': [9, 10], 'not_expired': [10, 10], 'no_live_reservation': [9, 8], 'consumer_credit': [3, 3], 'group_head': [4, [3, 4]]}\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":"a6d0a29d42da4f9ccf8c52aba76f627c5276f0aaa5486a62ba8d68276f5e62bb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['visible_now'][0] >= r['visible_now'][1]) and (r['no_live_reservation'][0] is None or r['no_live_reservation'][1] >= r['no_live_reservation'][0]) and (r['consumer_credit'][0] < r['consumer_credit'][1]) and (r['group_head'][0] == min(r['group_head'][1]))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'visible_now': [10, 10], 'not_expired': [9, 10], 'no_live_reservation': [8, 8], 'consumer_credit': [2, 3], 'group_head': [3, [3, 4]]}\ncheck('valid operation', solve(r), True)\ncheck('A scheduled message is delivered before its visibility instant', solve(dict(r, **{'visible_now': [9, 10]})), False)\ncheck('A message is delivered after its expiration deadline', solve(dict(r, **{'not_expired': [10, 10]})), False)\ncheck('A second worker reserves a currently leased message', solve(dict(r, **{'no_live_reservation': [9, 8]})), False)\ncheck('The broker exceeds consumer in-flight credit', solve(dict(r, **{'consumer_credit': [3, 3]})), False)\ncheck('A FIFO message overtakes an earlier group member', solve(dict(r, **{'group_head': [4, [3, 4]]})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'visible_now': [9, 10], 'not_expired': [10, 10], 'no_live_reservation': [9, 8], 'consumer_credit': [3, 3], 'group_head': [4, [3, 4]]}\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-queue-reservation-not_expired","generated_at":"2026-09-29T14:36:55.999365+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic local contract for queues. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.","root_cause":"The admission path omits the not expired invariant while validating the other operation preconditions.","sha256":"abbd5c75b865fe495983c593f02fb634c5ad93d8a42d1fc8dcd3885cc0e5d79a","title":"Reserve a queued message for delivery: A message is delivered after its expiration deadline · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":33.234,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A scheduled message is delivered before its visibility instant","expected":false,"passed":true},{"actual":false,"check":"A message is delivered after its expiration deadline","expected":false,"passed":true},{"actual":true,"check":"A second worker reserves a currently leased message","expected":false,"passed":false},{"actual":false,"check":"The broker exceeds consumer in-flight credit","expected":false,"passed":true},{"actual":false,"check":"A FIFO message overtakes an earlier group member","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\": \"A scheduled message is delivered before its visibility instant\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A message is delivered after its expiration deadline\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A second worker reserves a currently leased message\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"The broker exceeds consumer in-flight credit\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A FIFO message overtakes an earlier group member\", \"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":30.014,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A scheduled message is delivered before its visibility instant","expected":false,"passed":true},{"actual":true,"check":"A message is delivered after its expiration deadline","expected":false,"passed":false},{"actual":false,"check":"A second worker reserves a currently leased message","expected":false,"passed":true},{"actual":false,"check":"The broker exceeds consumer in-flight credit","expected":false,"passed":true},{"actual":false,"check":"A FIFO message overtakes an earlier group member","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\": \"A scheduled message is delivered before its visibility instant\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A message is delivered after its expiration deadline\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"A second worker reserves a currently leased message\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The broker exceeds consumer in-flight credit\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A FIFO message overtakes an earlier group member\", \"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"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}