{"abstract":"An empty payload reports k data bytes in its last codeword.","category":"Error-correcting codes","checks":8,"contract":"Frame a payload of the given number of bytes into shortened RS(n, k) codewords: cw = ceil(payload / k) codewords, the last one carries payload - (cw - 1)*k data bytes (shortened, zero padding not transmitted), and each codeword adds n - k parity bytes. An empty payload uses no codewords. Return [cw, last data bytes, bytes sent]; invalid parameters return None.","contract_signature":"payload, n, k","evaluation_group":"w2-error_correcting_codes-rs-framing","failed_approach":"Returning None for an empty payload treats a valid request as an error.","family":"w2-error_correcting_codes-rs-framing-empty-payload","id":"FA-72311","implementations":{"attempt":{"sha256":"6f14882181cb436124e93e376f34026de3cc39780de3ea58b1f545160f7b53ba","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(payload, n, k):\n    if payload < 0 or not 0 < k < n:\n        return None\n    cw = -(-payload // k)\n    last = payload - (cw - 1) * k if cw else None\n    sent = payload + cw * (n - k)\n    return [cw, last, sent]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [1, 255, 239]', [1, 255, 239], [1, 1, 17]], ['control [239, 255, 239]', [239, 255, 239], [1, 239, 255]], ['control [240, 255, 239]', [240, 255, 239], [2, 1, 272]], ['control [478, 255, 239]', [478, 255, 239], [2, 239, 510]], ['control [1000, 255, 223]', [1000, 255, 223], [5, 108, 1160]], ['control [223, 255, 223]', [223, 255, 223], [1, 223, 255]], ['control [5, 15, 11]', [5, 15, 11], [1, 5, 9]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [223, 255, 223]', [223, 255, 223], [1, 223, 255]], ['control [5, 15, 11]', [5, 15, 11], [1, 5, 9]], ['control [11, 15, 11]', [11, 15, 11], [1, 11, 15]], ['control [12, 15, 11]', [12, 15, 11], [2, 1, 20]], ['control [33, 15, 11]', [33, 15, 11], [3, 11, 45]], ['control [100, 204, 188]', [100, 204, 188], [1, 100, 116]], ['control [188, 204, 188]', [188, 204, 188], [1, 188, 204]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [100, 204, 188]', [100, 204, 188], [1, 100, 116]], ['control [188, 204, 188]', [188, 204, 188], [1, 188, 204]], ['control [376, 204, 188]', [376, 204, 188], [2, 188, 408]], ['control [-1, 15, 11]', [-1, 15, 11], None], ['control [5, 11, 11]', [5, 11, 11], None], ['control [22, 7, 4]', [22, 7, 4], [6, 2, 40]], ['control [1, 7, 4]', [1, 7, 4], [1, 1, 4]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [22, 7, 4]', [22, 7, 4], [6, 2, 40]], ['control [1, 7, 4]', [1, 7, 4], [1, 1, 4]], ['control [1, 255, 239]', [1, 255, 239], [1, 1, 17]], ['control [239, 255, 239]', [239, 255, 239], [1, 239, 255]], ['control [240, 255, 239]', [240, 255, 239], [2, 1, 272]], ['control [478, 255, 239]', [478, 255, 239], [2, 239, 510]], ['control [1000, 255, 223]', [1000, 255, 223], [5, 108, 1160]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [478, 255, 239]', [478, 255, 239], [2, 239, 510]], ['control [1000, 255, 223]', [1000, 255, 223], [5, 108, 1160]], ['control [223, 255, 223]', [223, 255, 223], [1, 223, 255]], ['control [5, 15, 11]', [5, 15, 11], [1, 5, 9]], ['control [11, 15, 11]', [11, 15, 11], [1, 11, 15]], ['control [12, 15, 11]', [12, 15, 11], [2, 1, 20]], ['control [33, 15, 11]', [33, 15, 11], [3, 11, 45]]]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, 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":"7cf94c9042590656d81c9b51b5fe46a50f93641ab75542dea5648562f767e874","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(payload, n, k):\n    if payload < 0 or not 0 < k < n:\n        return None\n    cw = -(-payload // k)\n    last = payload - (cw - 1) * k\n    sent = payload + cw * (n - k)\n    return [cw, last, sent]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [1, 255, 239]', [1, 255, 239], [1, 1, 17]], ['control [239, 255, 239]', [239, 255, 239], [1, 239, 255]], ['control [240, 255, 239]', [240, 255, 239], [2, 1, 272]], ['control [478, 255, 239]', [478, 255, 239], [2, 239, 510]], ['control [1000, 255, 223]', [1000, 255, 223], [5, 108, 1160]], ['control [223, 255, 223]', [223, 255, 223], [1, 223, 255]], ['control [5, 15, 11]', [5, 15, 11], [1, 5, 9]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [223, 255, 223]', [223, 255, 223], [1, 223, 255]], ['control [5, 15, 11]', [5, 15, 11], [1, 5, 9]], ['control [11, 15, 11]', [11, 15, 11], [1, 11, 15]], ['control [12, 15, 11]', [12, 15, 11], [2, 1, 20]], ['control [33, 15, 11]', [33, 15, 11], [3, 11, 45]], ['control [100, 204, 188]', [100, 204, 188], [1, 100, 116]], ['control [188, 204, 188]', [188, 204, 188], [1, 188, 204]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [100, 204, 188]', [100, 204, 188], [1, 100, 116]], ['control [188, 204, 188]', [188, 204, 188], [1, 188, 204]], ['control [376, 204, 188]', [376, 204, 188], [2, 188, 408]], ['control [-1, 15, 11]', [-1, 15, 11], None], ['control [5, 11, 11]', [5, 11, 11], None], ['control [22, 7, 4]', [22, 7, 4], [6, 2, 40]], ['control [1, 7, 4]', [1, 7, 4], [1, 1, 4]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [22, 7, 4]', [22, 7, 4], [6, 2, 40]], ['control [1, 7, 4]', [1, 7, 4], [1, 1, 4]], ['control [1, 255, 239]', [1, 255, 239], [1, 1, 17]], ['control [239, 255, 239]', [239, 255, 239], [1, 239, 255]], ['control [240, 255, 239]', [240, 255, 239], [2, 1, 272]], ['control [478, 255, 239]', [478, 255, 239], [2, 239, 510]], ['control [1000, 255, 223]', [1000, 255, 223], [5, 108, 1160]]], [['regression [0, 255, 239]', [0, 255, 239], [0, 0, 0]], ['control [478, 255, 239]', [478, 255, 239], [2, 239, 510]], ['control [1000, 255, 223]', [1000, 255, 223], [5, 108, 1160]], ['control [223, 255, 223]', [223, 255, 223], [1, 223, 255]], ['control [5, 15, 11]', [5, 15, 11], [1, 5, 9]], ['control [11, 15, 11]', [11, 15, 11], [1, 11, 15]], ['control [12, 15, 11]', [12, 15, 11], [2, 1, 20]], ['control [33, 15, 11]', [33, 15, 11], [3, 11, 45]]]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, 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 of the named code under the stated contract; not a production codec. 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-error_correcting_codes-rs-framing-empty-payload","generated_at":"2026-09-29T14:48:37.319344+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Link layers size FEC frames and transmit budgets from the payload length.","root_cause":"The zero-codeword case falls through the general formula (payload - (0 - 1)*k).","sha256":"efbd5558b3c4f4996d584a56f07be63d9d24834a620c8305045f8e55d343e9a7","title":"RS framing reports a full last codeword for an empty payload · 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":40.115,"exit_code":1,"observations":[{"actual":[0,null,0],"check":"regression [0, 255, 239]","expected":[0,0,0],"passed":false},{"actual":[1,1,17],"check":"control [1, 255, 239]","expected":[1,1,17],"passed":true},{"actual":[1,239,255],"check":"control [239, 255, 239]","expected":[1,239,255],"passed":true},{"actual":[2,1,272],"check":"control [240, 255, 239]","expected":[2,1,272],"passed":true},{"actual":[2,239,510],"check":"control [478, 255, 239]","expected":[2,239,510],"passed":true},{"actual":[5,108,1160],"check":"control [1000, 255, 223]","expected":[5,108,1160],"passed":true},{"actual":[1,223,255],"check":"control [223, 255, 223]","expected":[1,223,255],"passed":true},{"actual":[1,5,9],"check":"control [5, 15, 11]","expected":[1,5,9],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [0, 255, 239]\", \"actual\": [0, null, 0], \"expected\": [0, 0, 0], \"passed\": false}, {\"check\": \"control [1, 255, 239]\", \"actual\": [1, 1, 17], \"expected\": [1, 1, 17], \"passed\": true}, {\"check\": \"control [239, 255, 239]\", \"actual\": [1, 239, 255], \"expected\": [1, 239, 255], \"passed\": true}, {\"check\": \"control [240, 255, 239]\", \"actual\": [2, 1, 272], \"expected\": [2, 1, 272], \"passed\": true}, {\"check\": \"control [478, 255, 239]\", \"actual\": [2, 239, 510], \"expected\": [2, 239, 510], \"passed\": true}, {\"check\": \"control [1000, 255, 223]\", \"actual\": [5, 108, 1160], \"expected\": [5, 108, 1160], \"passed\": true}, {\"check\": \"control [223, 255, 223]\", \"actual\": [1, 223, 255], \"expected\": [1, 223, 255], \"passed\": true}, {\"check\": \"control [5, 15, 11]\", \"actual\": [1, 5, 9], \"expected\": [1, 5, 9], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.219,"exit_code":1,"observations":[{"actual":[0,239,0],"check":"regression [0, 255, 239]","expected":[0,0,0],"passed":false},{"actual":[1,1,17],"check":"control [1, 255, 239]","expected":[1,1,17],"passed":true},{"actual":[1,239,255],"check":"control [239, 255, 239]","expected":[1,239,255],"passed":true},{"actual":[2,1,272],"check":"control [240, 255, 239]","expected":[2,1,272],"passed":true},{"actual":[2,239,510],"check":"control [478, 255, 239]","expected":[2,239,510],"passed":true},{"actual":[5,108,1160],"check":"control [1000, 255, 223]","expected":[5,108,1160],"passed":true},{"actual":[1,223,255],"check":"control [223, 255, 223]","expected":[1,223,255],"passed":true},{"actual":[1,5,9],"check":"control [5, 15, 11]","expected":[1,5,9],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [0, 255, 239]\", \"actual\": [0, 239, 0], \"expected\": [0, 0, 0], \"passed\": false}, {\"check\": \"control [1, 255, 239]\", \"actual\": [1, 1, 17], \"expected\": [1, 1, 17], \"passed\": true}, {\"check\": \"control [239, 255, 239]\", \"actual\": [1, 239, 255], \"expected\": [1, 239, 255], \"passed\": true}, {\"check\": \"control [240, 255, 239]\", \"actual\": [2, 1, 272], \"expected\": [2, 1, 272], \"passed\": true}, {\"check\": \"control [478, 255, 239]\", \"actual\": [2, 239, 510], \"expected\": [2, 239, 510], \"passed\": true}, {\"check\": \"control [1000, 255, 223]\", \"actual\": [5, 108, 1160], \"expected\": [5, 108, 1160], \"passed\": true}, {\"check\": \"control [223, 255, 223]\", \"actual\": [1, 223, 255], \"expected\": [1, 223, 255], \"passed\": true}, {\"check\": \"control [5, 15, 11]\", \"actual\": [1, 5, 9], \"expected\": [1, 5, 9], \"passed\": true}], \"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."}}