{"abstract":"Some pad codewords are one higher than the reference encoder produces.","category":"Barcode symbology encoding","checks":8,"contract":"Data Matrix ASCII encodation into `capacity` data codewords: two consecutive ASCII digits become 130 + their value; ASCII 0..127 becomes ord + 1; 128..255 becomes Upper Shift 235 then ord - 127; higher code points are unencodable. Too many codewords -> overflow. Padding: the first pad is 129; each later pad at 1-based position p is 129 + ((149 * p) mod 253) + 1, minus 254 if above 254.","contract_signature":"text, capacity","evaluation_group":"w2-barcode-symbology-encoding-datamatrix-ascii","failed_approach":"Wrapping above 255 lets 255 through, which is not a valid pad.","family":"w2-barcode-symbology-encoding-datamatrix-ascii-pad-wrap","id":"FA-79811","implementations":{"attempt":{"sha256":"2e2994c88a5c54ebf33464d4b519fc0ac78d5984b3bf1b6f4a7c7e0aac1ffeeb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(text, capacity):\n    cw = []\n    i = 0\n    while i < len(text):\n        c = text[i]\n        if c in '0123456789' and i + 1 < len(text) and text[i + 1] in '0123456789':\n            cw.append(130 + int(text[i:i + 2]))\n            i += 2\n            continue\n        o = ord(c)\n        if o > 255:\n            return {'error': 'unencodable'}\n        if o > 127:\n            cw += [235, o - 127]\n        else:\n            cw.append(o + 1)\n        i += 1\n    if len(cw) > capacity:\n        return {'error': 'overflow'}\n    if len(cw) < capacity:\n        cw.append(129)\n    while len(cw) < capacity:\n        p = len(cw) + 1\n        v = 129 + ((149 * p) % 253) + 1\n        if v > 255:\n            v -= 255\n        cw.append(v)\n    return cw\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[[('', 6), [129, 175, 70, 220, 115, 11]], [('é99AB0', 10), [235, 106, 229, 66, 67, 49, 129, 56, 206, 101]], [('\\x80', 4), [235, 1, 129, 220]], [('0AB12', 3), {'error': 'overflow'}], [('ABé', 1), {'error': 'overflow'}], [('AB€€', 10), {'error': 'unencodable'}], [('ÿAB', 5), [235, 128, 66, 67, 129]], [('99x', 5), [229, 121, 129, 220, 115]]], [[('0', 9), [49, 129, 70, 220, 115, 11, 161, 56, 206]], [('0 5', 12), [49, 33, 54, 129, 115, 11, 161, 56, 206, 101, 251, 147]], [('ABxx', 2), {'error': 'overflow'}], [(' AB', 4), [33, 66, 67, 129]], [('', 2), [129, 175]], [('x€', 10), {'error': 'unencodable'}], [(' 125', 1), {'error': 'overflow'}], [('0', 4), [49, 129, 70, 220]]], [[('', 4), [129, 175, 70, 220]], [('x', 5), [121, 129, 70, 220, 115]], [('éé', 3), {'error': 'overflow'}], [('é\\x80\\x80', 3), {'error': 'overflow'}], [('99ÿé', 7), [229, 235, 128, 235, 106, 129, 161]], [('0', 2), [49, 129]], [('99é0', 5), [229, 235, 106, 49, 129]], [('x99AB', 11), [121, 229, 66, 67, 129, 11, 161, 56, 206, 101, 251]]], [[('0xÿ', 8), [49, 121, 235, 128, 129, 11, 161, 56]], [(' 12', 9), [33, 142, 129, 220, 115, 11, 161, 56, 206]], [('\\x8012x5', 1), {'error': 'overflow'}], [(' €ÿ\\x80', 5), {'error': 'unencodable'}], [('AB€x', 2), {'error': 'unencodable'}], [('€ ', 4), {'error': 'unencodable'}], [('\\x80x0', 5), [235, 1, 121, 49, 129]], [('', 6), [129, 175, 70, 220, 115, 11]]], [[('xÿ ', 8), [121, 235, 128, 33, 129, 11, 161, 56]], [('x5AB', 12), [121, 54, 66, 67, 129, 11, 161, 56, 206, 101, 251, 147]], [('990', 1), {'error': 'overflow'}], [('599AB€', 8), {'error': 'unencodable'}], [('\\x80€ 0', 8), {'error': 'unencodable'}], [('AB\\x805AB', 8), [66, 67, 235, 1, 54, 66, 67, 129]], [('€99', 7), {'error': 'unencodable'}], [('\\x80ÿ', 9), [235, 1, 235, 128, 129, 11, 161, 56, 206]]]]\nlabels = [\"regression: randomised pad wraparound\", \"repair trap\", \"combined fault\", \"control\", \"control\", \"boundary\", \"boundary\", \"control\"]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"%s %d\" % (labels[i % len(labels)], 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":"fd0738d7b8410603acbf79c0a02bd7d8cfb1f984d8315a7e34a76c689b6ea5df","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(text, capacity):\n    cw = []\n    i = 0\n    while i < len(text):\n        c = text[i]\n        if c in '0123456789' and i + 1 < len(text) and text[i + 1] in '0123456789':\n            cw.append(130 + int(text[i:i + 2]))\n            i += 2\n            continue\n        o = ord(c)\n        if o > 255:\n            return {'error': 'unencodable'}\n        if o > 127:\n            cw += [235, o - 127]\n        else:\n            cw.append(o + 1)\n        i += 1\n    if len(cw) > capacity:\n        return {'error': 'overflow'}\n    if len(cw) < capacity:\n        cw.append(129)\n    while len(cw) < capacity:\n        p = len(cw) + 1\n        v = 129 + ((149 * p) % 253) + 1\n        if v > 254:\n            v -= 253\n        cw.append(v)\n    return cw\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[[('', 6), [129, 175, 70, 220, 115, 11]], [('é99AB0', 10), [235, 106, 229, 66, 67, 49, 129, 56, 206, 101]], [('\\x80', 4), [235, 1, 129, 220]], [('0AB12', 3), {'error': 'overflow'}], [('ABé', 1), {'error': 'overflow'}], [('AB€€', 10), {'error': 'unencodable'}], [('ÿAB', 5), [235, 128, 66, 67, 129]], [('99x', 5), [229, 121, 129, 220, 115]]], [[('0', 9), [49, 129, 70, 220, 115, 11, 161, 56, 206]], [('0 5', 12), [49, 33, 54, 129, 115, 11, 161, 56, 206, 101, 251, 147]], [('ABxx', 2), {'error': 'overflow'}], [(' AB', 4), [33, 66, 67, 129]], [('', 2), [129, 175]], [('x€', 10), {'error': 'unencodable'}], [(' 125', 1), {'error': 'overflow'}], [('0', 4), [49, 129, 70, 220]]], [[('', 4), [129, 175, 70, 220]], [('x', 5), [121, 129, 70, 220, 115]], [('éé', 3), {'error': 'overflow'}], [('é\\x80\\x80', 3), {'error': 'overflow'}], [('99ÿé', 7), [229, 235, 128, 235, 106, 129, 161]], [('0', 2), [49, 129]], [('99é0', 5), [229, 235, 106, 49, 129]], [('x99AB', 11), [121, 229, 66, 67, 129, 11, 161, 56, 206, 101, 251]]], [[('0xÿ', 8), [49, 121, 235, 128, 129, 11, 161, 56]], [(' 12', 9), [33, 142, 129, 220, 115, 11, 161, 56, 206]], [('\\x8012x5', 1), {'error': 'overflow'}], [(' €ÿ\\x80', 5), {'error': 'unencodable'}], [('AB€x', 2), {'error': 'unencodable'}], [('€ ', 4), {'error': 'unencodable'}], [('\\x80x0', 5), [235, 1, 121, 49, 129]], [('', 6), [129, 175, 70, 220, 115, 11]]], [[('xÿ ', 8), [121, 235, 128, 33, 129, 11, 161, 56]], [('x5AB', 12), [121, 54, 66, 67, 129, 11, 161, 56, 206, 101, 251, 147]], [('990', 1), {'error': 'overflow'}], [('599AB€', 8), {'error': 'unencodable'}], [('\\x80€ 0', 8), {'error': 'unencodable'}], [('AB\\x805AB', 8), [66, 67, 235, 1, 54, 66, 67, 129]], [('€99', 7), {'error': 'unencodable'}], [('\\x80ÿ', 9), [235, 1, 235, 128, 129, 11, 161, 56, 206]]]]\nlabels = [\"regression: randomised pad wraparound\", \"repair trap\", \"combined fault\", \"control\", \"control\", \"boundary\", \"boundary\", \"control\"]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"%s %d\" % (labels[i % len(labels)], 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 contract; it makes no claim of conformance to any published specification. 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-barcode-symbology-encoding-datamatrix-ascii-pad-wrap","generated_at":"2026-09-29T14:49:47.984207+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Retail, logistics, pharmacy and document workflows depend on encoders that produce exactly the module pattern, code-set switches, separators and quiet zones scanners expect; one misplaced module or separator makes a label unreadable or, worse, scan as different data.","root_cause":"Values above 254 are reduced by 253 instead of 254.","sha256":"0c7fddd578b0f134421a2378ed2d613d9c901453964cf70dae8ac27b535813a1","title":"Randomised pad wraps by 253 · 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":39.355,"exit_code":1,"observations":[{"actual":[129,175,69,220,114,10],"check":"regression: randomised pad wraparound 0","expected":[129,175,70,220,115,11],"passed":false},{"actual":[235,106,229,66,67,49,129,55,206,100],"check":"repair trap 1","expected":[235,106,229,66,67,49,129,56,206,101],"passed":false},{"actual":[235,1,129,220],"check":"combined fault 2","expected":[235,1,129,220],"passed":true},{"actual":{"error":"overflow"},"check":"control 3","expected":{"error":"overflow"},"passed":true},{"actual":{"error":"overflow"},"check":"control 4","expected":{"error":"overflow"},"passed":true},{"actual":{"error":"unencodable"},"check":"boundary 5","expected":{"error":"unencodable"},"passed":true},{"actual":[235,128,66,67,129],"check":"boundary 6","expected":[235,128,66,67,129],"passed":true},{"actual":[229,121,129,220,114],"check":"control 7","expected":[229,121,129,220,115],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: randomised pad wraparound 0\", \"actual\": [129, 175, 69, 220, 114, 10], \"expected\": [129, 175, 70, 220, 115, 11], \"passed\": false}, {\"check\": \"repair trap 1\", \"actual\": [235, 106, 229, 66, 67, 49, 129, 55, 206, 100], \"expected\": [235, 106, 229, 66, 67, 49, 129, 56, 206, 101], \"passed\": false}, {\"check\": \"combined fault 2\", \"actual\": [235, 1, 129, 220], \"expected\": [235, 1, 129, 220], \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"error\": \"overflow\"}, \"expected\": {\"error\": \"overflow\"}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"error\": \"overflow\"}, \"expected\": {\"error\": \"overflow\"}, \"passed\": true}, {\"check\": \"boundary 5\", \"actual\": {\"error\": \"unencodable\"}, \"expected\": {\"error\": \"unencodable\"}, \"passed\": true}, {\"check\": \"boundary 6\", \"actual\": [235, 128, 66, 67, 129], \"expected\": [235, 128, 66, 67, 129], \"passed\": true}, {\"check\": \"control 7\", \"actual\": [229, 121, 129, 220, 114], \"expected\": [229, 121, 129, 220, 115], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.713,"exit_code":1,"observations":[{"actual":[129,175,71,220,116,12],"check":"regression: randomised pad wraparound 0","expected":[129,175,70,220,115,11],"passed":false},{"actual":[235,106,229,66,67,49,129,57,206,102],"check":"repair trap 1","expected":[235,106,229,66,67,49,129,56,206,101],"passed":false},{"actual":[235,1,129,220],"check":"combined fault 2","expected":[235,1,129,220],"passed":true},{"actual":{"error":"overflow"},"check":"control 3","expected":{"error":"overflow"},"passed":true},{"actual":{"error":"overflow"},"check":"control 4","expected":{"error":"overflow"},"passed":true},{"actual":{"error":"unencodable"},"check":"boundary 5","expected":{"error":"unencodable"},"passed":true},{"actual":[235,128,66,67,129],"check":"boundary 6","expected":[235,128,66,67,129],"passed":true},{"actual":[229,121,129,220,116],"check":"control 7","expected":[229,121,129,220,115],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: randomised pad wraparound 0\", \"actual\": [129, 175, 71, 220, 116, 12], \"expected\": [129, 175, 70, 220, 115, 11], \"passed\": false}, {\"check\": \"repair trap 1\", \"actual\": [235, 106, 229, 66, 67, 49, 129, 57, 206, 102], \"expected\": [235, 106, 229, 66, 67, 49, 129, 56, 206, 101], \"passed\": false}, {\"check\": \"combined fault 2\", \"actual\": [235, 1, 129, 220], \"expected\": [235, 1, 129, 220], \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"error\": \"overflow\"}, \"expected\": {\"error\": \"overflow\"}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"error\": \"overflow\"}, \"expected\": {\"error\": \"overflow\"}, \"passed\": true}, {\"check\": \"boundary 5\", \"actual\": {\"error\": \"unencodable\"}, \"expected\": {\"error\": \"unencodable\"}, \"passed\": true}, {\"check\": \"boundary 6\", \"actual\": [235, 128, 66, 67, 129], \"expected\": [235, 128, 66, 67, 129], \"passed\": true}, {\"check\": \"control 7\", \"actual\": [229, 121, 129, 220, 116], \"expected\": [229, 121, 129, 220, 115], \"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."}}