{"abstract":"Retry rewinds into a prefix preceding the request body","category":"HTTP retries","checks":7,"contract":"Events open(list of integer bytes, starting index), mutate(index,byte), read(count), retry, close. Opening freezes bytes and origin. Reads advance within the frozen representation. Retry rewinds to origin. Reads after close return closed; retry after close returns closed. Output read chunks or status markers.","contract_signature":"events","evaluation_group":"s3-http_retries-replay-snapshot","failed_approach":"The attempted repair changes the faulty site to origin = max(0,e[2]-1) but still violates a regression oracle.","family":"s3-http_retries-replay-snapshot-origin","id":"FA-29346","implementations":{"attempt":{"sha256":"ef29ac1d870e5a372d0c12ffba169f17f4148b1bcef52a60ce0573a77c61f4f8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    body = (); live = []; origin = 0; pos = 0; closed = True; out = []\n    for e in events:\n        if e[0] == 'open':\n            live = list(e[1])\n            body = tuple(live)\n            origin = max(0,e[2]-1)\n            pos = origin\n            closed = False\n        elif e[0] == 'mutate':\n            live[e[1]] = e[2]\n        elif e[0] == 'close':\n            closed = True\n        elif e[0] == 'read':\n            if closed:\n                out.append('closed')\n                continue\n            chunk = list(body[pos:pos+e[1]])\n            pos += len(chunk)\n            out.append(chunk)\n        elif e[0] == 'retry':\n            if closed:\n                out.append('closed')\n                continue\n            pos = origin\n            out.append('rewound')\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [])\ncheck('1', solve([('open',[N,N+1,N+2],1),('read',1),('retry',),('read',2)]), [[N+1],'rewound',[N+1,N+2]])\ncheck('2', solve([('open',[N,N+1,N+2],0),('read',2),('read',1),('read',1)]), [[N,N+1],[N+2],[]])\ncheck('3', solve([('open',[N,N+1],0),('mutate',0,99),('retry',),('read',2)]), ['rewound',[N,N+1]])\ncheck('4', solve([('open',[],0),('read',0),('retry',),('read',1)]), [[],'rewound',[]])\ncheck('5', solve([('open',[N,N+1],0),('close',),('read',1),('retry',)]), ['closed','closed'])\ncheck('6', solve([('open',[N],0),('read',1),('close',),('read',1),('retry',),('open',[N+2],0),('read',1)]), [[N],'closed','closed',[N+2]])\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":"d8e88f7a89a39e56836fccf7f797e0371ba8c59af7ef7dc52156608430f2f042","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    body = (); live = []; origin = 0; pos = 0; closed = True; out = []\n    for e in events:\n        if e[0] == 'open':\n            live = list(e[1])\n            body = tuple(live)\n            origin = 0\n            pos = origin\n            closed = False\n        elif e[0] == 'mutate':\n            live[e[1]] = e[2]\n        elif e[0] == 'close':\n            closed = True\n        elif e[0] == 'read':\n            if closed:\n                out.append('closed')\n                continue\n            chunk = list(body[pos:pos+e[1]])\n            pos += len(chunk)\n            out.append(chunk)\n        elif e[0] == 'retry':\n            if closed:\n                out.append('closed')\n                continue\n            pos = origin\n            out.append('rewound')\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [])\ncheck('1', solve([('open',[N,N+1,N+2],1),('read',1),('retry',),('read',2)]), [[N+1],'rewound',[N+1,N+2]])\ncheck('2', solve([('open',[N,N+1,N+2],0),('read',2),('read',1),('read',1)]), [[N,N+1],[N+2],[]])\ncheck('3', solve([('open',[N,N+1],0),('mutate',0,99),('retry',),('read',2)]), ['rewound',[N,N+1]])\ncheck('4', solve([('open',[],0),('read',0),('retry',),('read',1)]), [[],'rewound',[]])\ncheck('5', solve([('open',[N,N+1],0),('close',),('read',1),('retry',)]), ['closed','closed'])\ncheck('6', solve([('open',[N],0),('read',1),('close',),('read',1),('retry',),('open',[N+2],0),('read',1)]), [[N],'closed','closed',[N+2]])\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-replay-snapshot-origin","generated_at":"2026-09-29T14:41:42.764608+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":"Retry rewinds into a prefix preceding the request body","sha256":"90fb8004c8024502318c7a7423dc5be19b0f57f46bea7a61c98f3d13e8cdafd4","title":"Replay source snapshot: Retry rewinds into a prefix preceding the request body · 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":41.677,"exit_code":1,"observations":[{"actual":[],"check":"0","expected":[],"passed":true},{"actual":[[1],"rewound",[1,2]],"check":"1","expected":[[2],"rewound",[2,3]],"passed":false},{"actual":[[1,2],[3],[]],"check":"2","expected":[[1,2],[3],[]],"passed":true},{"actual":["rewound",[1,2]],"check":"3","expected":["rewound",[1,2]],"passed":true},{"actual":[[],"rewound",[]],"check":"4","expected":[[],"rewound",[]],"passed":true},{"actual":["closed","closed"],"check":"5","expected":["closed","closed"],"passed":true},{"actual":[[1],"closed","closed",[3]],"check":"6","expected":[[1],"closed","closed",[3]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"1\", \"actual\": [[1], \"rewound\", [1, 2]], \"expected\": [[2], \"rewound\", [2, 3]], \"passed\": false}, {\"check\": \"2\", \"actual\": [[1, 2], [3], []], \"expected\": [[1, 2], [3], []], \"passed\": true}, {\"check\": \"3\", \"actual\": [\"rewound\", [1, 2]], \"expected\": [\"rewound\", [1, 2]], \"passed\": true}, {\"check\": \"4\", \"actual\": [[], \"rewound\", []], \"expected\": [[], \"rewound\", []], \"passed\": true}, {\"check\": \"5\", \"actual\": [\"closed\", \"closed\"], \"expected\": [\"closed\", \"closed\"], \"passed\": true}, {\"check\": \"6\", \"actual\": [[1], \"closed\", \"closed\", [3]], \"expected\": [[1], \"closed\", \"closed\", [3]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.338,"exit_code":1,"observations":[{"actual":[],"check":"0","expected":[],"passed":true},{"actual":[[1],"rewound",[1,2]],"check":"1","expected":[[2],"rewound",[2,3]],"passed":false},{"actual":[[1,2],[3],[]],"check":"2","expected":[[1,2],[3],[]],"passed":true},{"actual":["rewound",[1,2]],"check":"3","expected":["rewound",[1,2]],"passed":true},{"actual":[[],"rewound",[]],"check":"4","expected":[[],"rewound",[]],"passed":true},{"actual":["closed","closed"],"check":"5","expected":["closed","closed"],"passed":true},{"actual":[[1],"closed","closed",[3]],"check":"6","expected":[[1],"closed","closed",[3]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"1\", \"actual\": [[1], \"rewound\", [1, 2]], \"expected\": [[2], \"rewound\", [2, 3]], \"passed\": false}, {\"check\": \"2\", \"actual\": [[1, 2], [3], []], \"expected\": [[1, 2], [3], []], \"passed\": true}, {\"check\": \"3\", \"actual\": [\"rewound\", [1, 2]], \"expected\": [\"rewound\", [1, 2]], \"passed\": true}, {\"check\": \"4\", \"actual\": [[], \"rewound\", []], \"expected\": [[], \"rewound\", []], \"passed\": true}, {\"check\": \"5\", \"actual\": [\"closed\", \"closed\"], \"expected\": [\"closed\", \"closed\"], \"passed\": true}, {\"check\": \"6\", \"actual\": [[1], \"closed\", \"closed\", [3]], \"expected\": [[1], \"closed\", \"closed\", [3]], \"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."}}