{"abstract":"Identity snapshot violates retry transition semantics","category":"HTTP retries","checks":8,"contract":"open(file identity,size,mtime,offset) snapshots file metadata and starting byte. inspect(current identity,size,mtime) records current metadata. read(count) advances bounded cursor only while valid. retry compares all snapshot metadata before rewinding; any mismatch permanently invalidates this body. close invalidates. New open resets validity. Return read byte counts and retry dispositions.","contract_signature":"events","evaluation_group":"s3-http_retries-file-replay-integrity","failed_approach":"The attempted repair changes the faulty site to snapshot=(e[1],e[2],0); current=snapshot but still violates a regression oracle.","family":"s3-http_retries-file-replay-integrity-identity-snapshot","id":"FA-30056","implementations":{"attempt":{"sha256":"c526739d8c1800fd4283b64d2df5b081f4eae6d3ee7821b040aa8f15e77e357d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    snapshot=None; current=None; origin=0; cursor=0; valid=False; out=[]\n    for e in events:\n        if e[0]=='open':\n            snapshot=(e[1],e[2],0); current=snapshot\n            origin=e[4]; cursor=origin\n            valid=True\n        elif e[0]=='inspect': current=tuple(e[1:4])\n        elif e[0]=='close': valid=False\n        elif e[0]=='read':\n            if not valid: out.append('invalid'); continue\n            amount=min(e[1],max(0,snapshot[1]-cursor))\n            cursor+=amount\n            out.append(amount)\n        elif e[0]=='retry':\n            if not valid: out.append('invalid'); continue\n            if current!=snapshot:\n                valid=False; out.append('changed'); continue\n            cursor=origin\n            out.append('rewound')\n    return [out,cursor]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [[],0])\ncheck('1', solve([('open','a',N+5,1,2),('read',2),('read',N+9),('read',1),('retry',),('read',1)]), [[2,N+1,0,'rewound',1],3])\ncheck('2', solve([('open','a',5,1,0),('inspect','b',5,1),('retry',),('read',1)]), [['changed','invalid'],0])\ncheck('3', solve([('open','a',5,1,0),('inspect','a',6,1),('retry',),('retry',)]), [['changed','invalid'],0])\ncheck('4', solve([('open','a',5,1,0),('inspect','a',5,2),('retry',),('inspect','a',5,1),('retry',)]), [['changed','invalid'],0])\ncheck('5', solve([('open','a',0,1,0),('read',1),('retry',),('close',),('read',1),('retry',)]), [[0,'rewound','invalid','invalid'],0])\ncheck('6', solve([('open','a',N+3,1,1),('close',),('open','b',2,2,1),('read',1)]), [[1],2])\ncheck('7', solve([('open','a',N+3,1,1),('inspect','a',N+3,1),('retry',),('close',),('read',1),('retry',)]), [['rewound','invalid','invalid'],1])\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":"b1c60aad7cfc180ed30f3c7d6c44e46920cf986ca4bcb8e6b0acbe13d2e4deff","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    snapshot=None; current=None; origin=0; cursor=0; valid=False; out=[]\n    for e in events:\n        if e[0]=='open':\n            snapshot=(None,e[2],e[3]); current=snapshot\n            origin=e[4]; cursor=origin\n            valid=True\n        elif e[0]=='inspect': current=tuple(e[1:4])\n        elif e[0]=='close': valid=False\n        elif e[0]=='read':\n            if not valid: out.append('invalid'); continue\n            amount=min(e[1],max(0,snapshot[1]-cursor))\n            cursor+=amount\n            out.append(amount)\n        elif e[0]=='retry':\n            if not valid: out.append('invalid'); continue\n            if current!=snapshot:\n                valid=False; out.append('changed'); continue\n            cursor=origin\n            out.append('rewound')\n    return [out,cursor]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [[],0])\ncheck('1', solve([('open','a',N+5,1,2),('read',2),('read',N+9),('read',1),('retry',),('read',1)]), [[2,N+1,0,'rewound',1],3])\ncheck('2', solve([('open','a',5,1,0),('inspect','b',5,1),('retry',),('read',1)]), [['changed','invalid'],0])\ncheck('3', solve([('open','a',5,1,0),('inspect','a',6,1),('retry',),('retry',)]), [['changed','invalid'],0])\ncheck('4', solve([('open','a',5,1,0),('inspect','a',5,2),('retry',),('inspect','a',5,1),('retry',)]), [['changed','invalid'],0])\ncheck('5', solve([('open','a',0,1,0),('read',1),('retry',),('close',),('read',1),('retry',)]), [[0,'rewound','invalid','invalid'],0])\ncheck('6', solve([('open','a',N+3,1,1),('close',),('open','b',2,2,1),('read',1)]), [[1],2])\ncheck('7', solve([('open','a',N+3,1,1),('inspect','a',N+3,1),('retry',),('close',),('read',1),('retry',)]), [['rewound','invalid','invalid'],1])\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":"Stipulated bounded simulator, not a complete HTTP implementation or a standards conformance claim. 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":"s3-http_retries-file-replay-integrity-identity-snapshot","generated_at":"2026-09-29T14:41:49.614133+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline deterministic model of HTTP request retries.","root_cause":"Identity snapshot violates retry transition semantics","sha256":"602ee4c4c1428b70d7c8cd260f482693dea5ea64e226356547401acd5c652d2a","title":"File-backed request replay integrity: Identity snapshot violates retry transition semantics · 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":44.415,"exit_code":1,"observations":[{"actual":[[],0],"check":"0","expected":[[],0],"passed":true},{"actual":[[2,2,0,"rewound",1],3],"check":"1","expected":[[2,2,0,"rewound",1],3],"passed":true},{"actual":[["changed","invalid"],0],"check":"2","expected":[["changed","invalid"],0],"passed":true},{"actual":[["changed","invalid"],0],"check":"3","expected":[["changed","invalid"],0],"passed":true},{"actual":[["changed","invalid"],0],"check":"4","expected":[["changed","invalid"],0],"passed":true},{"actual":[[0,"rewound","invalid","invalid"],0],"check":"5","expected":[[0,"rewound","invalid","invalid"],0],"passed":true},{"actual":[[1],2],"check":"6","expected":[[1],2],"passed":true},{"actual":[["changed","invalid","invalid"],1],"check":"7","expected":[["rewound","invalid","invalid"],1],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [[], 0], \"expected\": [[], 0], \"passed\": true}, {\"check\": \"1\", \"actual\": [[2, 2, 0, \"rewound\", 1], 3], \"expected\": [[2, 2, 0, \"rewound\", 1], 3], \"passed\": true}, {\"check\": \"2\", \"actual\": [[\"changed\", \"invalid\"], 0], \"expected\": [[\"changed\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"3\", \"actual\": [[\"changed\", \"invalid\"], 0], \"expected\": [[\"changed\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"4\", \"actual\": [[\"changed\", \"invalid\"], 0], \"expected\": [[\"changed\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"5\", \"actual\": [[0, \"rewound\", \"invalid\", \"invalid\"], 0], \"expected\": [[0, \"rewound\", \"invalid\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"6\", \"actual\": [[1], 2], \"expected\": [[1], 2], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"changed\", \"invalid\", \"invalid\"], 1], \"expected\": [[\"rewound\", \"invalid\", \"invalid\"], 1], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.437,"exit_code":1,"observations":[{"actual":[[],0],"check":"0","expected":[[],0],"passed":true},{"actual":[[2,2,0,"rewound",1],3],"check":"1","expected":[[2,2,0,"rewound",1],3],"passed":true},{"actual":[["changed","invalid"],0],"check":"2","expected":[["changed","invalid"],0],"passed":true},{"actual":[["changed","invalid"],0],"check":"3","expected":[["changed","invalid"],0],"passed":true},{"actual":[["changed","invalid"],0],"check":"4","expected":[["changed","invalid"],0],"passed":true},{"actual":[[0,"rewound","invalid","invalid"],0],"check":"5","expected":[[0,"rewound","invalid","invalid"],0],"passed":true},{"actual":[[1],2],"check":"6","expected":[[1],2],"passed":true},{"actual":[["changed","invalid","invalid"],1],"check":"7","expected":[["rewound","invalid","invalid"],1],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [[], 0], \"expected\": [[], 0], \"passed\": true}, {\"check\": \"1\", \"actual\": [[2, 2, 0, \"rewound\", 1], 3], \"expected\": [[2, 2, 0, \"rewound\", 1], 3], \"passed\": true}, {\"check\": \"2\", \"actual\": [[\"changed\", \"invalid\"], 0], \"expected\": [[\"changed\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"3\", \"actual\": [[\"changed\", \"invalid\"], 0], \"expected\": [[\"changed\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"4\", \"actual\": [[\"changed\", \"invalid\"], 0], \"expected\": [[\"changed\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"5\", \"actual\": [[0, \"rewound\", \"invalid\", \"invalid\"], 0], \"expected\": [[0, \"rewound\", \"invalid\", \"invalid\"], 0], \"passed\": true}, {\"check\": \"6\", \"actual\": [[1], 2], \"expected\": [[1], 2], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"changed\", \"invalid\", \"invalid\"], 1], \"expected\": [[\"rewound\", \"invalid\", \"invalid\"], 1], \"passed\": false}], \"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."}}