{"abstract":"Each multipart range begins with its own absolute seek.","category":"HTTP ranges","checks":6,"contract":"Return ordered abstract I/O operations: seek target if cursor differs, then read length even for zero length; equal cursor avoids redundant seek.","evaluation_group":"s3-http_ranges-stream-transfer","failed_approach":"The partial repair uses return [[\"seek\",target],[\"read\",length]], which still violates the stated contract.","family":"s3-http_ranges-stream-seek-before-read","id":"FA-26601","implementations":{"attempt":{"sha256":"a8e740235c674195d14e53ecb6fca72c9d9956dcfbf96c4e5ee4e934f2195712","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(current, target, length):\n    return [[\"seek\",target],[\"read\",length]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-seek-before-read fixture 0', solve(0,N,N), [[\"seek\",N],[\"read\",N]])\ncheck('stream-seek-before-read fixture 1', solve(N,N,N), [[\"read\",N]])\ncheck('stream-seek-before-read fixture 2', solve(N,0,N), [[\"seek\",0],[\"read\",N]])\ncheck('stream-seek-before-read fixture 3', solve(0,0,0), [[\"read\",0]])\ncheck('stream-seek-before-read fixture 4', solve(0,N,0), [[\"seek\",N],[\"read\",0]])\ncheck('stream-seek-before-read fixture 5', solve(2*N,N,1), [[\"seek\",N],[\"read\",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":"eeb6f52417abdb5b6e88ac905a74ec69651ece00c050bf6989dc20fac2c285dd","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(current, target, length):\n    return [[\"read\",length]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-seek-before-read fixture 0', solve(0,N,N), [[\"seek\",N],[\"read\",N]])\ncheck('stream-seek-before-read fixture 1', solve(N,N,N), [[\"read\",N]])\ncheck('stream-seek-before-read fixture 2', solve(N,0,N), [[\"seek\",0],[\"read\",N]])\ncheck('stream-seek-before-read fixture 3', solve(0,0,0), [[\"read\",0]])\ncheck('stream-seek-before-read fixture 4', solve(0,N,0), [[\"seek\",N],[\"read\",0]])\ncheck('stream-seek-before-read fixture 5', solve(2*N,N,1), [[\"seek\",N],[\"read\",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"},"fixed":{"sha256":"d619ac6f383ffa3a95569cae004dba8fe05e352a8be1ee62313191cfcceab558","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(current, target, length):\n    return ([] if current==target else [[\"seek\",target]])+[[\"read\",length]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-seek-before-read fixture 0', solve(0,N,N), [[\"seek\",N],[\"read\",N]])\ncheck('stream-seek-before-read fixture 1', solve(N,N,N), [[\"read\",N]])\ncheck('stream-seek-before-read fixture 2', solve(N,0,N), [[\"seek\",0],[\"read\",N]])\ncheck('stream-seek-before-read fixture 3', solve(0,0,0), [[\"read\",0]])\ncheck('stream-seek-before-read fixture 4', solve(0,N,0), [[\"seek\",N],[\"read\",0]])\ncheck('stream-seek-before-read fixture 5', solve(2*N,N,1), [[\"seek\",N],[\"read\",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":"Deterministic simplified range service, with stipulated local policies and already parsed trusted inputs; not a complete HTTP implementation. 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_ranges-stream-seek-before-read","generated_at":"2026-09-29T14:41:17.521120+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Range responses combine representation identity, conditional requests, framing, and partial-object state.","repair":"Apply the bounded decision exactly: return ([] if current==target else [[\"seek\",target]])+[[\"read\",length]]","root_cause":"The stream-seek-before-read decision uses return [[\"read\",length]].","sha256":"a52e7a4b01a07e58cb970d5244bd2b2b26bc3f6c822879d8490d02e284a83ac9","title":"Each multipart range begins with its own absolute seek · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":45.284,"exit_code":1,"observations":[{"actual":[["seek",1],["read",1]],"check":"stream-seek-before-read fixture 0","expected":[["seek",1],["read",1]],"passed":true},{"actual":[["seek",1],["read",1]],"check":"stream-seek-before-read fixture 1","expected":[["read",1]],"passed":false},{"actual":[["seek",0],["read",1]],"check":"stream-seek-before-read fixture 2","expected":[["seek",0],["read",1]],"passed":true},{"actual":[["seek",0],["read",0]],"check":"stream-seek-before-read fixture 3","expected":[["read",0]],"passed":false},{"actual":[["seek",1],["read",0]],"check":"stream-seek-before-read fixture 4","expected":[["seek",1],["read",0]],"passed":true},{"actual":[["seek",1],["read",1]],"check":"stream-seek-before-read fixture 5","expected":[["seek",1],["read",1]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-seek-before-read fixture 0\", \"actual\": [[\"seek\", 1], [\"read\", 1]], \"expected\": [[\"seek\", 1], [\"read\", 1]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 1\", \"actual\": [[\"seek\", 1], [\"read\", 1]], \"expected\": [[\"read\", 1]], \"passed\": false}, {\"check\": \"stream-seek-before-read fixture 2\", \"actual\": [[\"seek\", 0], [\"read\", 1]], \"expected\": [[\"seek\", 0], [\"read\", 1]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 3\", \"actual\": [[\"seek\", 0], [\"read\", 0]], \"expected\": [[\"read\", 0]], \"passed\": false}, {\"check\": \"stream-seek-before-read fixture 4\", \"actual\": [[\"seek\", 1], [\"read\", 0]], \"expected\": [[\"seek\", 1], [\"read\", 0]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 5\", \"actual\": [[\"seek\", 1], [\"read\", 1]], \"expected\": [[\"seek\", 1], [\"read\", 1]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.259,"exit_code":1,"observations":[{"actual":[["read",1]],"check":"stream-seek-before-read fixture 0","expected":[["seek",1],["read",1]],"passed":false},{"actual":[["read",1]],"check":"stream-seek-before-read fixture 1","expected":[["read",1]],"passed":true},{"actual":[["read",1]],"check":"stream-seek-before-read fixture 2","expected":[["seek",0],["read",1]],"passed":false},{"actual":[["read",0]],"check":"stream-seek-before-read fixture 3","expected":[["read",0]],"passed":true},{"actual":[["read",0]],"check":"stream-seek-before-read fixture 4","expected":[["seek",1],["read",0]],"passed":false},{"actual":[["read",1]],"check":"stream-seek-before-read fixture 5","expected":[["seek",1],["read",1]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-seek-before-read fixture 0\", \"actual\": [[\"read\", 1]], \"expected\": [[\"seek\", 1], [\"read\", 1]], \"passed\": false}, {\"check\": \"stream-seek-before-read fixture 1\", \"actual\": [[\"read\", 1]], \"expected\": [[\"read\", 1]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 2\", \"actual\": [[\"read\", 1]], \"expected\": [[\"seek\", 0], [\"read\", 1]], \"passed\": false}, {\"check\": \"stream-seek-before-read fixture 3\", \"actual\": [[\"read\", 0]], \"expected\": [[\"read\", 0]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 4\", \"actual\": [[\"read\", 0]], \"expected\": [[\"seek\", 1], [\"read\", 0]], \"passed\": false}, {\"check\": \"stream-seek-before-read fixture 5\", \"actual\": [[\"read\", 1]], \"expected\": [[\"seek\", 1], [\"read\", 1]], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":39.565,"exit_code":0,"observations":[{"actual":[["seek",1],["read",1]],"check":"stream-seek-before-read fixture 0","expected":[["seek",1],["read",1]],"passed":true},{"actual":[["read",1]],"check":"stream-seek-before-read fixture 1","expected":[["read",1]],"passed":true},{"actual":[["seek",0],["read",1]],"check":"stream-seek-before-read fixture 2","expected":[["seek",0],["read",1]],"passed":true},{"actual":[["read",0]],"check":"stream-seek-before-read fixture 3","expected":[["read",0]],"passed":true},{"actual":[["seek",1],["read",0]],"check":"stream-seek-before-read fixture 4","expected":[["seek",1],["read",0]],"passed":true},{"actual":[["seek",1],["read",1]],"check":"stream-seek-before-read fixture 5","expected":[["seek",1],["read",1]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-seek-before-read fixture 0\", \"actual\": [[\"seek\", 1], [\"read\", 1]], \"expected\": [[\"seek\", 1], [\"read\", 1]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 1\", \"actual\": [[\"read\", 1]], \"expected\": [[\"read\", 1]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 2\", \"actual\": [[\"seek\", 0], [\"read\", 1]], \"expected\": [[\"seek\", 0], [\"read\", 1]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 3\", \"actual\": [[\"read\", 0]], \"expected\": [[\"read\", 0]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 4\", \"actual\": [[\"seek\", 1], [\"read\", 0]], \"expected\": [[\"seek\", 1], [\"read\", 0]], \"passed\": true}, {\"check\": \"stream-seek-before-read fixture 5\", \"actual\": [[\"seek\", 1], [\"read\", 1]], \"expected\": [[\"seek\", 1], [\"read\", 1]], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}