{"abstract":"At low resolutions single-module bars vanish, making the symbol unreadable.","category":"Barcode symbology encoding","checks":8,"contract":"Render a module string (\"1\" bar, \"0\" space) at xn/xd device pixels per module after `quiet` leading quiet-zone modules. Module boundary k lies at round-half-up((quiet + k) * X), computed from the exact fraction so errors do not accumulate. Adjacent bar modules merge into one bar [start, end); bar width reduction shaves `bwr` pixels from the right edge of each bar, but a bar is never narrower than 1 pixel.","contract_signature":"mods, xn, xd, bwr, quiet","evaluation_group":"w2-barcode-symbology-encoding-device-pixel-rendering","failed_approach":"Clamping only negative widths still allows zero-width bars.","family":"w2-barcode-symbology-encoding-device-pixel-rendering-min-width","id":"FA-79761","implementations":{"attempt":{"sha256":"8a03bd6a0d79544ad90c299ddf95bf791a15f8821805d611611e1b8d968ad0e8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(mods, xn, xd, bwr, quiet):\n    X = Fraction(xn, xd)\n    def edge(i):\n        return math.floor((quiet + i) * X + Fraction(1, 2))\n    bars = []\n    i = 0\n    n = len(mods)\n    while i < n:\n        if mods[i] == '1':\n            j = i\n            while j < n and mods[j] == '1':\n                j += 1\n            s, e = edge(i), edge(j) - bwr\n            if e < s:\n                e = s\n            bars.append([s, e])\n            i = j\n        else:\n            i += 1\n    return bars\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[[('010111110', 11, 5, 2, 0), [[2, 3], [7, 16]]], [('1100111001', 1, 1, 1, 10), [[10, 11], [14, 16], [19, 20]]], [('0001111', 2, 1, 0, 1), [[8, 16]]], [('011', 5, 2, 1, 10), [[28, 32]]], [('00001010', 1, 1, 0, 1), [[5, 6], [7, 8]]], [('101100101', 11, 5, 0, 0), [[0, 2], [4, 9], [13, 15], [18, 20]]], [('00101', 3, 1, 0, 0), [[6, 9], [12, 15]]], [('11000100', 4, 3, 2, 1), [[1, 2], [8, 9]]]], [[('1', 4, 3, 1, 0), [[0, 1]]], [('00010000011', 11, 5, 2, 10), [[29, 30], [42, 44]]], [('0010101000110', 7, 3, 0, 0), [[5, 7], [9, 12], [14, 16], [23, 28]]], [('1111', 9, 4, 2, 3), [[7, 14]]], [('1100001111', 9, 4, 0, 0), [[0, 5], [14, 23]]], [('000010010001', 9, 4, 1, 0), [[9, 10], [16, 17], [25, 26]]], [('0011000', 3, 1, 2, 3), [[15, 19]]], [('10000111', 9, 4, 2, 3), [[7, 8], [18, 23]]]], [[('001', 7, 3, 2, 10), [[28, 29]]], [('1100000101000', 1, 1, 1, 1), [[1, 2], [8, 9], [10, 11]]], [('11000100111001', 5, 2, 1, 10), [[25, 29], [38, 39], [45, 52], [58, 59]]], [('1101101001', 3, 1, 0, 3), [[9, 15], [18, 24], [27, 30], [36, 39]]], [('100110010100', 1, 1, 0, 1), [[1, 2], [4, 6], [8, 9], [10, 11]]], [('101100', 4, 3, 1, 10), [[13, 14], [16, 18]]], [('0110001110', 2, 1, 0, 10), [[22, 26], [32, 38]]], [('00010110011', 7, 3, 2, 3), [[14, 15], [19, 21], [28, 31]]]], [[('101110001000', 9, 4, 2, 0), [[0, 1], [5, 9], [18, 19]]], [('110101100', 5, 2, 2, 0), [[0, 3], [8, 9], [13, 16]]], [('01100', 2, 1, 0, 0), [[2, 6]]], [('10110', 5, 2, 0, 0), [[0, 3], [5, 10]]], [('01110000', 2, 1, 0, 3), [[8, 14]]], [('00101011101', 7, 3, 1, 10), [[28, 29], [33, 34], [37, 43], [47, 48]]], [('10111010100111', 5, 2, 0, 1), [[3, 5], [8, 15], [18, 20], [23, 25], [30, 38]]], [('0000101000', 7, 3, 2, 3), [[16, 17], [21, 22]]]], [[('11111000001', 1, 1, 1, 0), [[0, 4], [10, 11]]], [('100', 1, 1, 2, 0), [[0, 1]]], [('011110111', 9, 4, 1, 10), [[25, 33], [36, 42]]], [('111', 4, 3, 2, 10), [[13, 15]]], [('10111101000110', 7, 3, 0, 3), [[7, 9], [12, 21], [23, 26], [33, 37]]], [('0111110010101', 7, 3, 0, 10), [[26, 37], [42, 44], [47, 49], [51, 54]]], [('1', 5, 2, 0, 3), [[8, 10]]], [('001000011', 1, 1, 1, 1), [[3, 4], [8, 9]]]]]\nlabels = [\"regression: minimum bar width\", \"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":"8fa35c1f842e5382a903c4bef2728b49bf00fb2586e16f9172ea84a2cc7cb7e5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(mods, xn, xd, bwr, quiet):\n    X = Fraction(xn, xd)\n    def edge(i):\n        return math.floor((quiet + i) * X + Fraction(1, 2))\n    bars = []\n    i = 0\n    n = len(mods)\n    while i < n:\n        if mods[i] == '1':\n            j = i\n            while j < n and mods[j] == '1':\n                j += 1\n            s, e = edge(i), edge(j) - bwr\n            if e - s < 0:\n                e = s\n            bars.append([s, e])\n            i = j\n        else:\n            i += 1\n    return bars\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[[('010111110', 11, 5, 2, 0), [[2, 3], [7, 16]]], [('1100111001', 1, 1, 1, 10), [[10, 11], [14, 16], [19, 20]]], [('0001111', 2, 1, 0, 1), [[8, 16]]], [('011', 5, 2, 1, 10), [[28, 32]]], [('00001010', 1, 1, 0, 1), [[5, 6], [7, 8]]], [('101100101', 11, 5, 0, 0), [[0, 2], [4, 9], [13, 15], [18, 20]]], [('00101', 3, 1, 0, 0), [[6, 9], [12, 15]]], [('11000100', 4, 3, 2, 1), [[1, 2], [8, 9]]]], [[('1', 4, 3, 1, 0), [[0, 1]]], [('00010000011', 11, 5, 2, 10), [[29, 30], [42, 44]]], [('0010101000110', 7, 3, 0, 0), [[5, 7], [9, 12], [14, 16], [23, 28]]], [('1111', 9, 4, 2, 3), [[7, 14]]], [('1100001111', 9, 4, 0, 0), [[0, 5], [14, 23]]], [('000010010001', 9, 4, 1, 0), [[9, 10], [16, 17], [25, 26]]], [('0011000', 3, 1, 2, 3), [[15, 19]]], [('10000111', 9, 4, 2, 3), [[7, 8], [18, 23]]]], [[('001', 7, 3, 2, 10), [[28, 29]]], [('1100000101000', 1, 1, 1, 1), [[1, 2], [8, 9], [10, 11]]], [('11000100111001', 5, 2, 1, 10), [[25, 29], [38, 39], [45, 52], [58, 59]]], [('1101101001', 3, 1, 0, 3), [[9, 15], [18, 24], [27, 30], [36, 39]]], [('100110010100', 1, 1, 0, 1), [[1, 2], [4, 6], [8, 9], [10, 11]]], [('101100', 4, 3, 1, 10), [[13, 14], [16, 18]]], [('0110001110', 2, 1, 0, 10), [[22, 26], [32, 38]]], [('00010110011', 7, 3, 2, 3), [[14, 15], [19, 21], [28, 31]]]], [[('101110001000', 9, 4, 2, 0), [[0, 1], [5, 9], [18, 19]]], [('110101100', 5, 2, 2, 0), [[0, 3], [8, 9], [13, 16]]], [('01100', 2, 1, 0, 0), [[2, 6]]], [('10110', 5, 2, 0, 0), [[0, 3], [5, 10]]], [('01110000', 2, 1, 0, 3), [[8, 14]]], [('00101011101', 7, 3, 1, 10), [[28, 29], [33, 34], [37, 43], [47, 48]]], [('10111010100111', 5, 2, 0, 1), [[3, 5], [8, 15], [18, 20], [23, 25], [30, 38]]], [('0000101000', 7, 3, 2, 3), [[16, 17], [21, 22]]]], [[('11111000001', 1, 1, 1, 0), [[0, 4], [10, 11]]], [('100', 1, 1, 2, 0), [[0, 1]]], [('011110111', 9, 4, 1, 10), [[25, 33], [36, 42]]], [('111', 4, 3, 2, 10), [[13, 15]]], [('10111101000110', 7, 3, 0, 3), [[7, 9], [12, 21], [23, 26], [33, 37]]], [('0111110010101', 7, 3, 0, 10), [[26, 37], [42, 44], [47, 49], [51, 54]]], [('1', 5, 2, 0, 3), [[8, 10]]], [('001000011', 1, 1, 1, 1), [[3, 4], [8, 9]]]]]\nlabels = [\"regression: minimum bar width\", \"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-device-pixel-rendering-min-width","generated_at":"2026-09-29T14:49:47.576833+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":"Bars reduced to zero width are kept at zero instead of being clamped to one pixel.","sha256":"d507775e62c2e8bb9128469aa40e0da2d3dc67ef32422ca0f976530e05504f77","title":"Narrow bars disappear after width reduction · 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":42.112,"exit_code":1,"observations":[{"actual":[[2,2],[7,16]],"check":"regression: minimum bar width 0","expected":[[2,3],[7,16]],"passed":false},{"actual":[[10,11],[14,16],[19,19]],"check":"repair trap 1","expected":[[10,11],[14,16],[19,20]],"passed":false},{"actual":[[8,16]],"check":"combined fault 2","expected":[[8,16]],"passed":true},{"actual":[[28,32]],"check":"control 3","expected":[[28,32]],"passed":true},{"actual":[[5,6],[7,8]],"check":"control 4","expected":[[5,6],[7,8]],"passed":true},{"actual":[[0,2],[4,9],[13,15],[18,20]],"check":"boundary 5","expected":[[0,2],[4,9],[13,15],[18,20]],"passed":true},{"actual":[[6,9],[12,15]],"check":"boundary 6","expected":[[6,9],[12,15]],"passed":true},{"actual":[[1,2],[8,8]],"check":"control 7","expected":[[1,2],[8,9]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: minimum bar width 0\", \"actual\": [[2, 2], [7, 16]], \"expected\": [[2, 3], [7, 16]], \"passed\": false}, {\"check\": \"repair trap 1\", \"actual\": [[10, 11], [14, 16], [19, 19]], \"expected\": [[10, 11], [14, 16], [19, 20]], \"passed\": false}, {\"check\": \"combined fault 2\", \"actual\": [[8, 16]], \"expected\": [[8, 16]], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [[28, 32]], \"expected\": [[28, 32]], \"passed\": true}, {\"check\": \"control 4\", \"actual\": [[5, 6], [7, 8]], \"expected\": [[5, 6], [7, 8]], \"passed\": true}, {\"check\": \"boundary 5\", \"actual\": [[0, 2], [4, 9], [13, 15], [18, 20]], \"expected\": [[0, 2], [4, 9], [13, 15], [18, 20]], \"passed\": true}, {\"check\": \"boundary 6\", \"actual\": [[6, 9], [12, 15]], \"expected\": [[6, 9], [12, 15]], \"passed\": true}, {\"check\": \"control 7\", \"actual\": [[1, 2], [8, 8]], \"expected\": [[1, 2], [8, 9]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.094,"exit_code":1,"observations":[{"actual":[[2,2],[7,16]],"check":"regression: minimum bar width 0","expected":[[2,3],[7,16]],"passed":false},{"actual":[[10,11],[14,16],[19,19]],"check":"repair trap 1","expected":[[10,11],[14,16],[19,20]],"passed":false},{"actual":[[8,16]],"check":"combined fault 2","expected":[[8,16]],"passed":true},{"actual":[[28,32]],"check":"control 3","expected":[[28,32]],"passed":true},{"actual":[[5,6],[7,8]],"check":"control 4","expected":[[5,6],[7,8]],"passed":true},{"actual":[[0,2],[4,9],[13,15],[18,20]],"check":"boundary 5","expected":[[0,2],[4,9],[13,15],[18,20]],"passed":true},{"actual":[[6,9],[12,15]],"check":"boundary 6","expected":[[6,9],[12,15]],"passed":true},{"actual":[[1,2],[8,8]],"check":"control 7","expected":[[1,2],[8,9]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: minimum bar width 0\", \"actual\": [[2, 2], [7, 16]], \"expected\": [[2, 3], [7, 16]], \"passed\": false}, {\"check\": \"repair trap 1\", \"actual\": [[10, 11], [14, 16], [19, 19]], \"expected\": [[10, 11], [14, 16], [19, 20]], \"passed\": false}, {\"check\": \"combined fault 2\", \"actual\": [[8, 16]], \"expected\": [[8, 16]], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [[28, 32]], \"expected\": [[28, 32]], \"passed\": true}, {\"check\": \"control 4\", \"actual\": [[5, 6], [7, 8]], \"expected\": [[5, 6], [7, 8]], \"passed\": true}, {\"check\": \"boundary 5\", \"actual\": [[0, 2], [4, 9], [13, 15], [18, 20]], \"expected\": [[0, 2], [4, 9], [13, 15], [18, 20]], \"passed\": true}, {\"check\": \"boundary 6\", \"actual\": [[6, 9], [12, 15]], \"expected\": [[6, 9], [12, 15]], \"passed\": true}, {\"check\": \"control 7\", \"actual\": [[1, 2], [8, 8]], \"expected\": [[1, 2], [8, 9]], \"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."}}