{"abstract":"Low nibble loses its adaptive sign bit.","category":"PCM sample encoding","checks":8,"contract":"Extract adaptive PCM nibble codes in declared within-octet order; valid count is in nibbles and remaining codes are returned separately as padding.","contract_signature":"octets, high_first, valid_nibbles","evaluation_group":"s3-pcm-pcm-nibble-block-order","failed_approach":"Leaving the entire octet mixes neighboring sample codes.","family":"s3-pcm-pcm-nibble-block-order-low-mask","id":"FA-49776","implementations":{"attempt":{"sha256":"675e59cefa5085f0a7759203842447d603a5dfbf17baf4f7afc91fcc85269576","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(octets, high_first, valid_nibbles):\n    values=[]\n    for byte in octets:\n        high=(byte>>4)&15\n        low=byte&255\n        values.extend([high,low] if high_first else [low,high])\n    count=min(max(valid_nibbles,0),len(values))\n    return [values[:count],values[count:]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([24, 242], True, 3)), [[1, 8, 15], [2]])\ncheck('oracle 2', solve(*([18, 52], False, 4)), [[2, 1, 4, 3], []])\ncheck('oracle 3', solve(*([427], True, 2)), [[10, 11], []])\ncheck('oracle 4', solve(*([], False, 0)), [[], []])\ncheck('oracle 5', solve(*([128], False, 1)), [[0], [8]])\ncheck('oracle 6', solve(*([255], True, 0)), [[], [15, 15]])\ncheck('oracle 7', solve(*([87, 121], False, 8)), [[7, 5, 9, 7], []])\nif N == 1: check('variant packet 1', solve(*[[24, 242, 24, 242], True, 6]), [[1, 8, 15, 2, 1, 8], [15, 2]])\nif N == 2: check('variant packet 2', solve(*[[24, 242, 24, 242, 24, 242], True, 9]), [[1, 8, 15, 2, 1, 8, 15, 2, 1], [8, 15, 2]])\nif N == 3: check('variant packet 3', solve(*[[24, 242, 24, 242, 24, 242, 24, 242], True, 12]), [[1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2], [1, 8, 15, 2]])\nif N == 4: check('variant packet 4', solve(*[[24, 242, 24, 242, 24, 242, 24, 242, 24, 242], True, 15]), [[1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15], [2, 1, 8, 15, 2]])\nif N == 5: check('variant packet 5', solve(*[[24, 242, 24, 242, 24, 242, 24, 242, 24, 242, 24, 242], True, 18]), [[1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2, 1, 8], [15, 2, 1, 8, 15, 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":"0cb6d5aba6251820c14e137daeebd7f24d278209d7e708e2563421985e524342","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(octets, high_first, valid_nibbles):\n    values=[]\n    for byte in octets:\n        high=(byte>>4)&15\n        low=byte&7\n        values.extend([high,low] if high_first else [low,high])\n    count=min(max(valid_nibbles,0),len(values))\n    return [values[:count],values[count:]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([24, 242], True, 3)), [[1, 8, 15], [2]])\ncheck('oracle 2', solve(*([18, 52], False, 4)), [[2, 1, 4, 3], []])\ncheck('oracle 3', solve(*([427], True, 2)), [[10, 11], []])\ncheck('oracle 4', solve(*([], False, 0)), [[], []])\ncheck('oracle 5', solve(*([128], False, 1)), [[0], [8]])\ncheck('oracle 6', solve(*([255], True, 0)), [[], [15, 15]])\ncheck('oracle 7', solve(*([87, 121], False, 8)), [[7, 5, 9, 7], []])\nif N == 1: check('variant packet 1', solve(*[[24, 242, 24, 242], True, 6]), [[1, 8, 15, 2, 1, 8], [15, 2]])\nif N == 2: check('variant packet 2', solve(*[[24, 242, 24, 242, 24, 242], True, 9]), [[1, 8, 15, 2, 1, 8, 15, 2, 1], [8, 15, 2]])\nif N == 3: check('variant packet 3', solve(*[[24, 242, 24, 242, 24, 242, 24, 242], True, 12]), [[1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2], [1, 8, 15, 2]])\nif N == 4: check('variant packet 4', solve(*[[24, 242, 24, 242, 24, 242, 24, 242, 24, 242], True, 15]), [[1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15], [2, 1, 8, 15, 2]])\nif N == 5: check('variant packet 5', solve(*[[24, 242, 24, 242, 24, 242, 24, 242, 24, 242, 24, 242], True, 18]), [[1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2, 1, 8, 15, 2, 1, 8], [15, 2, 1, 8, 15, 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 finite model; no claim of hardware timing or full file-format conformance. 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-pcm-pcm-nibble-block-order-low-mask","generated_at":"2026-09-29T14:45:03.104004+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline PCM interchange uses these exact bounded packet and sample representation decisions.","root_cause":"Low nibble loses its adaptive sign bit.","sha256":"defc6b35c264110da2446cf2d5e7862bcf2d45598d1f561b068f5faed91d77dd","title":"Pcm nibble block order: low mask · 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":42.923,"exit_code":1,"observations":[{"actual":[[1,24,15],[242]],"check":"oracle 1","expected":[[1,8,15],[2]],"passed":false},{"actual":[[18,1,52,3],[]],"check":"oracle 2","expected":[[2,1,4,3],[]],"passed":false},{"actual":[[10,171],[]],"check":"oracle 3","expected":[[10,11],[]],"passed":false},{"actual":[[],[]],"check":"oracle 4","expected":[[],[]],"passed":true},{"actual":[[128],[8]],"check":"oracle 5","expected":[[0],[8]],"passed":false},{"actual":[[],[15,255]],"check":"oracle 6","expected":[[],[15,15]],"passed":false},{"actual":[[87,5,121,7],[]],"check":"oracle 7","expected":[[7,5,9,7],[]],"passed":false},{"actual":[[1,24,15,242,1,24],[15,242]],"check":"variant packet 1","expected":[[1,8,15,2,1,8],[15,2]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[1, 24, 15], [242]], \"expected\": [[1, 8, 15], [2]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[18, 1, 52, 3], []], \"expected\": [[2, 1, 4, 3], []], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [[10, 171], []], \"expected\": [[10, 11], []], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[128], [8]], \"expected\": [[0], [8]], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[], [15, 255]], \"expected\": [[], [15, 15]], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [[87, 5, 121, 7], []], \"expected\": [[7, 5, 9, 7], []], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [[1, 24, 15, 242, 1, 24], [15, 242]], \"expected\": [[1, 8, 15, 2, 1, 8], [15, 2]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.079,"exit_code":1,"observations":[{"actual":[[1,0,15],[2]],"check":"oracle 1","expected":[[1,8,15],[2]],"passed":false},{"actual":[[2,1,4,3],[]],"check":"oracle 2","expected":[[2,1,4,3],[]],"passed":true},{"actual":[[10,3],[]],"check":"oracle 3","expected":[[10,11],[]],"passed":false},{"actual":[[],[]],"check":"oracle 4","expected":[[],[]],"passed":true},{"actual":[[0],[8]],"check":"oracle 5","expected":[[0],[8]],"passed":true},{"actual":[[],[15,7]],"check":"oracle 6","expected":[[],[15,15]],"passed":false},{"actual":[[7,5,1,7],[]],"check":"oracle 7","expected":[[7,5,9,7],[]],"passed":false},{"actual":[[1,0,15,2,1,0],[15,2]],"check":"variant packet 1","expected":[[1,8,15,2,1,8],[15,2]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[1, 0, 15], [2]], \"expected\": [[1, 8, 15], [2]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[2, 1, 4, 3], []], \"expected\": [[2, 1, 4, 3], []], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [[10, 3], []], \"expected\": [[10, 11], []], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[0], [8]], \"expected\": [[0], [8]], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [[], [15, 7]], \"expected\": [[], [15, 15]], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [[7, 5, 1, 7], []], \"expected\": [[7, 5, 9, 7], []], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [[1, 0, 15, 2, 1, 0], [15, 2]], \"expected\": [[1, 8, 15, 2, 1, 8], [15, 2]], \"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."}}