{"abstract":"Boundary-like substrings inside part bodies remain payload data.","category":"HTTP ranges","checks":6,"contract":"Return position of first delimiter at start or immediately after CRLF, or -1. Delimiter bytes are --boundary; interior lookalikes are ignored.","evaluation_group":"s3-http_ranges-multipart-client","failed_approach":"The partial repair uses return body.find(\"\\r\\n--\"+boundary)+2 if \"\\r\\n--\"+boundary in body else -1, which still violates the stated contract.","family":"s3-http_ranges-multipart-client-line-anchoring","id":"FA-26796","implementations":{"attempt":{"sha256":"6e538e164d89d94cbea4ea22c9bb8aa0dca1d58d87cb821a965029dfb50b4faf","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(body, boundary):\n    return body.find(\"\\r\\n--\"+boundary)+2 if \"\\r\\n--\"+boundary in body else -1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-line-anchoring fixture 0', solve(\"x--b\"+str(N),\"b\"+str(N)), -1)\ncheck('multipart-client-line-anchoring fixture 1', solve(\"--b\"+str(N),\"b\"+str(N)), 0)\ncheck('multipart-client-line-anchoring fixture 2', solve(\"abc\\r\\n--b\",\"b\"), 5)\ncheck('multipart-client-line-anchoring fixture 3', solve(\"abc\",\"b\"), -1)\ncheck('multipart-client-line-anchoring fixture 4', solve(\"\",\"b\"), -1)\ncheck('multipart-client-line-anchoring fixture 5', solve(\"x--b\\r\\n--b\",\"b\"), 6)\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":"0b516975fcf62584597afc4f54d78034682f43aa979ba3407bf4082562ad0412","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(body, boundary):\n    return body.find(\"--\"+boundary)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-line-anchoring fixture 0', solve(\"x--b\"+str(N),\"b\"+str(N)), -1)\ncheck('multipart-client-line-anchoring fixture 1', solve(\"--b\"+str(N),\"b\"+str(N)), 0)\ncheck('multipart-client-line-anchoring fixture 2', solve(\"abc\\r\\n--b\",\"b\"), 5)\ncheck('multipart-client-line-anchoring fixture 3', solve(\"abc\",\"b\"), -1)\ncheck('multipart-client-line-anchoring fixture 4', solve(\"\",\"b\"), -1)\ncheck('multipart-client-line-anchoring fixture 5', solve(\"x--b\\r\\n--b\",\"b\"), 6)\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":"800e4cd2f0724309b30d9a3c42256fcf4ba0e6a0cc165d7b13cdd44a62b96259","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(body, boundary):\n    if body.startswith(\"--\"+boundary): return 0\n    p=body.find(\"\\r\\n--\"+boundary)\n    return p+2 if p>=0 else -1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-line-anchoring fixture 0', solve(\"x--b\"+str(N),\"b\"+str(N)), -1)\ncheck('multipart-client-line-anchoring fixture 1', solve(\"--b\"+str(N),\"b\"+str(N)), 0)\ncheck('multipart-client-line-anchoring fixture 2', solve(\"abc\\r\\n--b\",\"b\"), 5)\ncheck('multipart-client-line-anchoring fixture 3', solve(\"abc\",\"b\"), -1)\ncheck('multipart-client-line-anchoring fixture 4', solve(\"\",\"b\"), -1)\ncheck('multipart-client-line-anchoring fixture 5', solve(\"x--b\\r\\n--b\",\"b\"), 6)\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-multipart-client-line-anchoring","generated_at":"2026-09-29T14:41:19.223056+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: if body.startswith(\"--\"+boundary): return 0\np=body.find(\"\\r\\n--\"+boundary)\nreturn p+2 if p>=0 else -1","root_cause":"The multipart-client-line-anchoring decision uses return body.find(\"--\"+boundary).","sha256":"f744484684ffdafda3c3cc10a7efb6807428464685d265086096ee948936c103","title":"Boundary-like substrings inside part bodies remain payload data · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":38.001,"exit_code":1,"observations":[{"actual":-1,"check":"multipart-client-line-anchoring fixture 0","expected":-1,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 1","expected":0,"passed":false},{"actual":5,"check":"multipart-client-line-anchoring fixture 2","expected":5,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 3","expected":-1,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 4","expected":-1,"passed":true},{"actual":6,"check":"multipart-client-line-anchoring fixture 5","expected":6,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-line-anchoring fixture 0\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 1\", \"actual\": -1, \"expected\": 0, \"passed\": false}, {\"check\": \"multipart-client-line-anchoring fixture 2\", \"actual\": 5, \"expected\": 5, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 3\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 4\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 5\", \"actual\": 6, \"expected\": 6, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.853,"exit_code":1,"observations":[{"actual":1,"check":"multipart-client-line-anchoring fixture 0","expected":-1,"passed":false},{"actual":0,"check":"multipart-client-line-anchoring fixture 1","expected":0,"passed":true},{"actual":5,"check":"multipart-client-line-anchoring fixture 2","expected":5,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 3","expected":-1,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 4","expected":-1,"passed":true},{"actual":1,"check":"multipart-client-line-anchoring fixture 5","expected":6,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-line-anchoring fixture 0\", \"actual\": 1, \"expected\": -1, \"passed\": false}, {\"check\": \"multipart-client-line-anchoring fixture 1\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 2\", \"actual\": 5, \"expected\": 5, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 3\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 4\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 5\", \"actual\": 1, \"expected\": 6, \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":41.909,"exit_code":0,"observations":[{"actual":-1,"check":"multipart-client-line-anchoring fixture 0","expected":-1,"passed":true},{"actual":0,"check":"multipart-client-line-anchoring fixture 1","expected":0,"passed":true},{"actual":5,"check":"multipart-client-line-anchoring fixture 2","expected":5,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 3","expected":-1,"passed":true},{"actual":-1,"check":"multipart-client-line-anchoring fixture 4","expected":-1,"passed":true},{"actual":6,"check":"multipart-client-line-anchoring fixture 5","expected":6,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-line-anchoring fixture 0\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 1\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 2\", \"actual\": 5, \"expected\": 5, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 3\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 4\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"multipart-client-line-anchoring fixture 5\", \"actual\": 6, \"expected\": 6, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}