{"abstract":"A malformed Set Tempo event declaring length 4 or 2 is accepted as if it were valid.","category":"MIDI event timing","checks":8,"contract":"Input the bytes of a Set Tempo meta event: FF 51 03 followed by a 24-bit big-endian microseconds-per-quarter value (nonzero). Return [microseconds, bpm_x100] where bpm_x100 = 6000000000 / microseconds rounded half up. Anything else returns None.","contract_signature":"x","evaluation_group":"w2-midi-event-timing-set-tempo-meta","failed_approach":"Rejecting only lengths above three still accepts a declared length of two.","family":"w2-midi-event-timing-set-tempo-meta-meta-length-byte","id":"FA-81496","implementations":{"attempt":{"sha256":"de17dffbc4c42d6c11c469ba05eb0355646ac314eff1dc00b9244609b75e4381","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    if not isinstance(x, list) or len(x) != 6 or x[0] != 0xFF or x[1] != 0x51 or x[2] > 3:\n        return None\n    us = (x[3] << 16) | (x[4] << 8) | x[5]\n    if us == 0:\n        return None\n    centi = (12000000000 + us) // (2 * us)\n    return [us, centi]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[([255, 81, 3, 7, 161, 32], [500000, 12000]), ([255, 81, 3, 9, 39, 192], [600000, 10000]), ([255, 81, 3, 58, 152, 0], [3840000, 1563]), ([255, 81, 3, 11, 184, 0], [768000, 7813]), ([255, 81, 3, 2, 88, 0], [153600, 39063]), ([255, 81, 3, 0, 0, 1], [1, 6000000000]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None)], [([255, 81, 3, 11, 184, 0], [768000, 7813]), ([255, 81, 3, 2, 88, 0], [153600, 39063]), ([255, 81, 3, 0, 0, 1], [1, 6000000000]), ([255, 81, 3, 255, 255, 255], [16777215, 358]), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 0, 0, 0], None), ([255, 82, 3, 7, 161, 32], None), ([255, 81, 3, 7, 161], None)], [([255, 81, 3, 255, 255, 255], [16777215, 358]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 0, 0, 0], None), ([255, 82, 3, 7, 161, 32], None), ([255, 81, 3, 7, 161], None), ([255, 81, 3, 6, 26, 128], [400000, 15000]), ([255, 81, 3, 3, 13, 64], [200000, 30000])], [([255, 81, 3, 7, 161, 32], [500000, 12000]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 7, 161], None), ([255, 81, 3, 6, 26, 128], [400000, 15000]), ([255, 81, 3, 3, 13, 64], [200000, 30000]), ([255, 81, 3, 0, 3, 232], [1000, 6000000]), ([255, 81, 3, 15, 66, 64], [1000000, 6000])], [([255, 81, 3, 7, 161, 32], [500000, 12000]), ([255, 81, 3, 9, 39, 192], [600000, 10000]), ([255, 81, 3, 58, 152, 0], [3840000, 1563]), ([255, 81, 3, 11, 184, 0], [768000, 7813]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 0, 3, 232], [1000, 6000000]), ([255, 81, 3, 15, 66, 64], [1000000, 6000])]]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"oracle %d\" % i, solve(args), expected)\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":"00039af32c3a9fd942de0299db1134839b0f2b97f8bdc0995967ae8df6c9fef9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    if not isinstance(x, list) or len(x) != 6 or x[0] != 0xFF or x[1] != 0x51:\n        return None\n    us = (x[3] << 16) | (x[4] << 8) | x[5]\n    if us == 0:\n        return None\n    centi = (12000000000 + us) // (2 * us)\n    return [us, centi]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[([255, 81, 3, 7, 161, 32], [500000, 12000]), ([255, 81, 3, 9, 39, 192], [600000, 10000]), ([255, 81, 3, 58, 152, 0], [3840000, 1563]), ([255, 81, 3, 11, 184, 0], [768000, 7813]), ([255, 81, 3, 2, 88, 0], [153600, 39063]), ([255, 81, 3, 0, 0, 1], [1, 6000000000]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None)], [([255, 81, 3, 11, 184, 0], [768000, 7813]), ([255, 81, 3, 2, 88, 0], [153600, 39063]), ([255, 81, 3, 0, 0, 1], [1, 6000000000]), ([255, 81, 3, 255, 255, 255], [16777215, 358]), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 0, 0, 0], None), ([255, 82, 3, 7, 161, 32], None), ([255, 81, 3, 7, 161], None)], [([255, 81, 3, 255, 255, 255], [16777215, 358]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 0, 0, 0], None), ([255, 82, 3, 7, 161, 32], None), ([255, 81, 3, 7, 161], None), ([255, 81, 3, 6, 26, 128], [400000, 15000]), ([255, 81, 3, 3, 13, 64], [200000, 30000])], [([255, 81, 3, 7, 161, 32], [500000, 12000]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 7, 161], None), ([255, 81, 3, 6, 26, 128], [400000, 15000]), ([255, 81, 3, 3, 13, 64], [200000, 30000]), ([255, 81, 3, 0, 3, 232], [1000, 6000000]), ([255, 81, 3, 15, 66, 64], [1000000, 6000])], [([255, 81, 3, 7, 161, 32], [500000, 12000]), ([255, 81, 3, 9, 39, 192], [600000, 10000]), ([255, 81, 3, 58, 152, 0], [3840000, 1563]), ([255, 81, 3, 11, 184, 0], [768000, 7813]), ([255, 81, 4, 7, 161, 32], None), ([255, 81, 2, 7, 161, 32], None), ([255, 81, 3, 0, 3, 232], [1000, 6000000]), ([255, 81, 3, 15, 66, 64], [1000000, 6000])]]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"oracle %d\" % i, solve(args), expected)\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":"A deterministic bounded teaching model with a stipulated toy contract; it is not a complete Standard MIDI File or MIDI 1.0/2.0 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":"w2-midi-event-timing-set-tempo-meta-meta-length-byte","generated_at":"2026-09-29T14:50:03.639390+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"MIDI sequencers, file readers and synth drivers depend on exact event ordering and tick/time arithmetic.","root_cause":"The length byte of the meta event is not validated.","sha256":"314631fdeeff25d77ea7c6763ec4e24cc151f1526f51d40aa911ff8a31f749f9","title":"Set Tempo meta event to BPM: declared length of the tempo event not checked · 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":40.527,"exit_code":1,"observations":[{"actual":[500000,12000],"check":"oracle 0","expected":[500000,12000],"passed":true},{"actual":[600000,10000],"check":"oracle 1","expected":[600000,10000],"passed":true},{"actual":[3840000,1563],"check":"oracle 2","expected":[3840000,1563],"passed":true},{"actual":[768000,7813],"check":"oracle 3","expected":[768000,7813],"passed":true},{"actual":[153600,39063],"check":"oracle 4","expected":[153600,39063],"passed":true},{"actual":[1,6000000000],"check":"oracle 5","expected":[1,6000000000],"passed":true},{"actual":null,"check":"oracle 6","expected":null,"passed":true},{"actual":[500000,12000],"check":"oracle 7","expected":null,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 0\", \"actual\": [500000, 12000], \"expected\": [500000, 12000], \"passed\": true}, {\"check\": \"oracle 1\", \"actual\": [600000, 10000], \"expected\": [600000, 10000], \"passed\": true}, {\"check\": \"oracle 2\", \"actual\": [3840000, 1563], \"expected\": [3840000, 1563], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [768000, 7813], \"expected\": [768000, 7813], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [153600, 39063], \"expected\": [153600, 39063], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [1, 6000000000], \"expected\": [1, 6000000000], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [500000, 12000], \"expected\": null, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.605,"exit_code":1,"observations":[{"actual":[500000,12000],"check":"oracle 0","expected":[500000,12000],"passed":true},{"actual":[600000,10000],"check":"oracle 1","expected":[600000,10000],"passed":true},{"actual":[3840000,1563],"check":"oracle 2","expected":[3840000,1563],"passed":true},{"actual":[768000,7813],"check":"oracle 3","expected":[768000,7813],"passed":true},{"actual":[153600,39063],"check":"oracle 4","expected":[153600,39063],"passed":true},{"actual":[1,6000000000],"check":"oracle 5","expected":[1,6000000000],"passed":true},{"actual":[500000,12000],"check":"oracle 6","expected":null,"passed":false},{"actual":[500000,12000],"check":"oracle 7","expected":null,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 0\", \"actual\": [500000, 12000], \"expected\": [500000, 12000], \"passed\": true}, {\"check\": \"oracle 1\", \"actual\": [600000, 10000], \"expected\": [600000, 10000], \"passed\": true}, {\"check\": \"oracle 2\", \"actual\": [3840000, 1563], \"expected\": [3840000, 1563], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [768000, 7813], \"expected\": [768000, 7813], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [153600, 39063], \"expected\": [153600, 39063], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [1, 6000000000], \"expected\": [1, 6000000000], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [500000, 12000], \"expected\": null, \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [500000, 12000], \"expected\": null, \"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."}}