{"abstract":"A longer boundary prefix is not mistaken for the chosen delimiter.","category":"HTTP ranges","checks":6,"contract":"A delimiter line equals --boundary or --boundary--; lines are already stripped of CRLF. Return part, close, or payload.","evaluation_group":"s3-http_ranges-multipart-client","failed_approach":"The partial repair uses return \"close\" if line.endswith(\"--\") else (\"part\" if line==\"--\"+boundary else \"payload\"), which still violates the stated contract.","family":"s3-http_ranges-multipart-client-boundary-token-end","id":"FA-26801","implementations":{"attempt":{"sha256":"8720c05e4e1d92d1fbc2100fbaf96f4f91544aa966b0ef61486ff638b1ee11c9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(line, boundary):\n    return \"close\" if line.endswith(\"--\") else (\"part\" if line==\"--\"+boundary else \"payload\")\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-boundary-token-end fixture 0', solve(\"--b\"+str(N)+\"x\",\"b\"+str(N)), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 1', solve(\"unrelated--\",\"b\"), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 2', solve(\"--b--\",\"b\"), \"close\")\ncheck('multipart-client-boundary-token-end fixture 3', solve(\"--b\",\"b\"), \"part\")\ncheck('multipart-client-boundary-token-end fixture 4', solve(\"\",\"b\"), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 5', solve(\"--b-x\",\"b\"), \"payload\")\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":"352b7456195614d6a2db9bfb9cf80a9f95b3b285d944020bad944ba94fe0db10","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(line, boundary):\n    return \"part\" if line.startswith(\"--\"+boundary) else \"payload\"\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-boundary-token-end fixture 0', solve(\"--b\"+str(N)+\"x\",\"b\"+str(N)), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 1', solve(\"unrelated--\",\"b\"), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 2', solve(\"--b--\",\"b\"), \"close\")\ncheck('multipart-client-boundary-token-end fixture 3', solve(\"--b\",\"b\"), \"part\")\ncheck('multipart-client-boundary-token-end fixture 4', solve(\"\",\"b\"), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 5', solve(\"--b-x\",\"b\"), \"payload\")\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":"72bd7b2d6e3c9b9d87f4cca07a22c07cd8bafce2cc20f19b88d298e31b617af4","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(line, boundary):\n    return \"close\" if line==\"--\"+boundary+\"--\" else (\"part\" if line==\"--\"+boundary else \"payload\")\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-boundary-token-end fixture 0', solve(\"--b\"+str(N)+\"x\",\"b\"+str(N)), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 1', solve(\"unrelated--\",\"b\"), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 2', solve(\"--b--\",\"b\"), \"close\")\ncheck('multipart-client-boundary-token-end fixture 3', solve(\"--b\",\"b\"), \"part\")\ncheck('multipart-client-boundary-token-end fixture 4', solve(\"\",\"b\"), \"payload\")\ncheck('multipart-client-boundary-token-end fixture 5', solve(\"--b-x\",\"b\"), \"payload\")\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-boundary-token-end","generated_at":"2026-09-29T14:41:19.323062+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 \"close\" if line==\"--\"+boundary+\"--\" else (\"part\" if line==\"--\"+boundary else \"payload\")","root_cause":"The multipart-client-boundary-token-end decision uses return \"part\" if line.startswith(\"--\"+boundary) else \"payload\".","sha256":"51867721cd1f3370dd602086e6ab2bb6c1bf25c8f98e14c53a4ce3be0e65f2cd","title":"A longer boundary prefix is not mistaken for the chosen delimiter · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.189,"exit_code":1,"observations":[{"actual":"payload","check":"multipart-client-boundary-token-end fixture 0","expected":"payload","passed":true},{"actual":"close","check":"multipart-client-boundary-token-end fixture 1","expected":"payload","passed":false},{"actual":"close","check":"multipart-client-boundary-token-end fixture 2","expected":"close","passed":true},{"actual":"part","check":"multipart-client-boundary-token-end fixture 3","expected":"part","passed":true},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 4","expected":"payload","passed":true},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 5","expected":"payload","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-boundary-token-end fixture 0\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 1\", \"actual\": \"close\", \"expected\": \"payload\", \"passed\": false}, {\"check\": \"multipart-client-boundary-token-end fixture 2\", \"actual\": \"close\", \"expected\": \"close\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 3\", \"actual\": \"part\", \"expected\": \"part\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 4\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 5\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.12,"exit_code":1,"observations":[{"actual":"part","check":"multipart-client-boundary-token-end fixture 0","expected":"payload","passed":false},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 1","expected":"payload","passed":true},{"actual":"part","check":"multipart-client-boundary-token-end fixture 2","expected":"close","passed":false},{"actual":"part","check":"multipart-client-boundary-token-end fixture 3","expected":"part","passed":true},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 4","expected":"payload","passed":true},{"actual":"part","check":"multipart-client-boundary-token-end fixture 5","expected":"payload","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-boundary-token-end fixture 0\", \"actual\": \"part\", \"expected\": \"payload\", \"passed\": false}, {\"check\": \"multipart-client-boundary-token-end fixture 1\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 2\", \"actual\": \"part\", \"expected\": \"close\", \"passed\": false}, {\"check\": \"multipart-client-boundary-token-end fixture 3\", \"actual\": \"part\", \"expected\": \"part\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 4\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 5\", \"actual\": \"part\", \"expected\": \"payload\", \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":37.807,"exit_code":0,"observations":[{"actual":"payload","check":"multipart-client-boundary-token-end fixture 0","expected":"payload","passed":true},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 1","expected":"payload","passed":true},{"actual":"close","check":"multipart-client-boundary-token-end fixture 2","expected":"close","passed":true},{"actual":"part","check":"multipart-client-boundary-token-end fixture 3","expected":"part","passed":true},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 4","expected":"payload","passed":true},{"actual":"payload","check":"multipart-client-boundary-token-end fixture 5","expected":"payload","passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-boundary-token-end fixture 0\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 1\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 2\", \"actual\": \"close\", \"expected\": \"close\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 3\", \"actual\": \"part\", \"expected\": \"part\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 4\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}, {\"check\": \"multipart-client-boundary-token-end fixture 5\", \"actual\": \"payload\", \"expected\": \"payload\", \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}