{"abstract":"Thumbnails are one pixel narrower than expected whenever the exact width has a fractional part of one half or more.","category":"Image orientation metadata","checks":8,"contract":"Input [stored_w, stored_h, tag, box_w, box_h]. Compute the displayed thumbnail size: tags 5..8 swap the displayed dimensions (other values, including invalid tags, do not). Scale = min(box_w/dw, box_h/dh, 1) exactly (never upscale); each side is rounded half up and is at least 1 pixel.","contract_signature":"x","evaluation_group":"w2-image-orientation-metadata-thumbnail-fit","failed_approach":"Python round uses banker's rounding and rounds 2.5 down to 2.","family":"w2-image-orientation-metadata-thumbnail-fit-width-rounding","id":"FA-78986","implementations":{"attempt":{"sha256":"1f82d021164d695ca163d7807717b0089465820d2537154c615b772089b93c93","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(x):\n    w, h, tag, bw, bh = x\n    if tag in (5, 6, 7, 8):\n        w, h = h, w\n    s = min(Fraction(bw, w), Fraction(bh, h), Fraction(1))\n    tw = max(1, round(w * s))\n    th = max(1, math.floor(h * s + Fraction(1, 2)))\n    return [tw, th]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[[[2477, 3237, 0, 10, 10], [8, 10]], [[5, 2, 1, 10, 1], [3, 1]], [[25, 2, 6, 76, 343], [2, 25]], [[3, 1, 6, 10, 10], [1, 3]], [[5, 2, 2, 10, 2], [5, 2]], [[15, 10, 8, 361, 38], [10, 15]], [[5, 4158, 8, 2, 2], [2, 1]], [[57, 33, 9, 10, 5], [9, 5]]], [[[25, 56, 7, 397, 12], [27, 12]], [[9, 2, 1, 20, 1], [5, 1]], [[5, 2, 1, 10, 1], [3, 1]], [[5, 2, 1, 19, 25], [5, 2]], [[25, 7, 2, 2, 145], [2, 1]], [[17, 50, 7, 72, 27], [50, 17]], [[15, 2, 0, 2, 2], [2, 1]], [[58, 7, 2, 168, 2], [17, 2]]], [[[5, 19, 6, 165, 2], [8, 2]], [[13, 6, 1, 40, 3], [7, 3]], [[5, 2, 1, 10, 1], [3, 1]], [[152, 2, 2, 2, 10], [2, 1]], [[12, 1369, 3, 1, 30], [1, 30]], [[15, 1, 1, 11, 291], [11, 1]], [[25, 7, 7, 10, 345], [7, 25]], [[35, 7, 6, 66, 19], [4, 19]]], [[[25, 7, 8, 10, 10], [3, 10]], [[5, 2, 1, 10, 1], [3, 1]], [[1283, 2, 6, 10, 2], [1, 2]], [[5, 2, 6, 18, 92], [2, 5]], [[5, 2, 8, 2, 10], [2, 5]], [[25, 1230, 1, 10, 10], [1, 10]], [[3, 5, 2, 2, 22], [2, 3]], [[15, 44, 8, 10, 2], [6, 2]]], [[[25, 1721, 9, 40, 380], [6, 380]], [[9, 2, 1, 20, 1], [5, 1]], [[5, 2, 1, 10, 1], [3, 1]], [[1251, 51, 3, 2, 2], [2, 1]], [[3903, 7, 9, 364, 10], [364, 1]], [[3907, 2, 8, 28, 202], [1, 202]], [[25, 2, 4, 54, 2], [25, 2]], [[5, 212, 3, 281, 108], [3, 108]]]]\nlabels = [\"regression: width rounding\", \"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":"ae69a2f1f89c2aea0c907a9647a84652fc2d9d5adfa5c59f0f1ebb8d6156cd73","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(x):\n    w, h, tag, bw, bh = x\n    if tag in (5, 6, 7, 8):\n        w, h = h, w\n    s = min(Fraction(bw, w), Fraction(bh, h), Fraction(1))\n    tw = max(1, math.floor(w * s))\n    th = max(1, math.floor(h * s + Fraction(1, 2)))\n    return [tw, th]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[[[2477, 3237, 0, 10, 10], [8, 10]], [[5, 2, 1, 10, 1], [3, 1]], [[25, 2, 6, 76, 343], [2, 25]], [[3, 1, 6, 10, 10], [1, 3]], [[5, 2, 2, 10, 2], [5, 2]], [[15, 10, 8, 361, 38], [10, 15]], [[5, 4158, 8, 2, 2], [2, 1]], [[57, 33, 9, 10, 5], [9, 5]]], [[[25, 56, 7, 397, 12], [27, 12]], [[9, 2, 1, 20, 1], [5, 1]], [[5, 2, 1, 10, 1], [3, 1]], [[5, 2, 1, 19, 25], [5, 2]], [[25, 7, 2, 2, 145], [2, 1]], [[17, 50, 7, 72, 27], [50, 17]], [[15, 2, 0, 2, 2], [2, 1]], [[58, 7, 2, 168, 2], [17, 2]]], [[[5, 19, 6, 165, 2], [8, 2]], [[13, 6, 1, 40, 3], [7, 3]], [[5, 2, 1, 10, 1], [3, 1]], [[152, 2, 2, 2, 10], [2, 1]], [[12, 1369, 3, 1, 30], [1, 30]], [[15, 1, 1, 11, 291], [11, 1]], [[25, 7, 7, 10, 345], [7, 25]], [[35, 7, 6, 66, 19], [4, 19]]], [[[25, 7, 8, 10, 10], [3, 10]], [[5, 2, 1, 10, 1], [3, 1]], [[1283, 2, 6, 10, 2], [1, 2]], [[5, 2, 6, 18, 92], [2, 5]], [[5, 2, 8, 2, 10], [2, 5]], [[25, 1230, 1, 10, 10], [1, 10]], [[3, 5, 2, 2, 22], [2, 3]], [[15, 44, 8, 10, 2], [6, 2]]], [[[25, 1721, 9, 40, 380], [6, 380]], [[9, 2, 1, 20, 1], [5, 1]], [[5, 2, 1, 10, 1], [3, 1]], [[1251, 51, 3, 2, 2], [2, 1]], [[3903, 7, 9, 364, 10], [364, 1]], [[3907, 2, 8, 28, 202], [1, 202]], [[25, 2, 4, 54, 2], [25, 2]], [[5, 212, 3, 281, 108], [3, 108]]]]\nlabels = [\"regression: width rounding\", \"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-image-orientation-metadata-thumbnail-fit-width-rounding","generated_at":"2026-09-29T14:49:40.484964+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Camera, phone and scanner images carry an orientation hint separately from the stored pixels; galleries, thumbnailers, editors and upload pipelines must interpret it consistently or photos appear sideways, mirrored or doubly rotated.","root_cause":"The scaled width is floored.","sha256":"f58e42ab171e39caec17a20a2e08c84e5ac5de6d0c6019a21312efb6a5f6d4c4","title":"Thumbnail width is truncated instead of rounded · 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":39.747,"exit_code":1,"observations":[{"actual":[8,10],"check":"regression: width rounding 0","expected":[8,10],"passed":true},{"actual":[2,1],"check":"repair trap 1","expected":[3,1],"passed":false},{"actual":[2,25],"check":"combined fault 2","expected":[2,25],"passed":true},{"actual":[1,3],"check":"control 3","expected":[1,3],"passed":true},{"actual":[5,2],"check":"control 4","expected":[5,2],"passed":true},{"actual":[10,15],"check":"boundary 5","expected":[10,15],"passed":true},{"actual":[2,1],"check":"boundary 6","expected":[2,1],"passed":true},{"actual":[9,5],"check":"control 7","expected":[9,5],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: width rounding 0\", \"actual\": [8, 10], \"expected\": [8, 10], \"passed\": true}, {\"check\": \"repair trap 1\", \"actual\": [2, 1], \"expected\": [3, 1], \"passed\": false}, {\"check\": \"combined fault 2\", \"actual\": [2, 25], \"expected\": [2, 25], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [1, 3], \"expected\": [1, 3], \"passed\": true}, {\"check\": \"control 4\", \"actual\": [5, 2], \"expected\": [5, 2], \"passed\": true}, {\"check\": \"boundary 5\", \"actual\": [10, 15], \"expected\": [10, 15], \"passed\": true}, {\"check\": \"boundary 6\", \"actual\": [2, 1], \"expected\": [2, 1], \"passed\": true}, {\"check\": \"control 7\", \"actual\": [9, 5], \"expected\": [9, 5], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.098,"exit_code":1,"observations":[{"actual":[7,10],"check":"regression: width rounding 0","expected":[8,10],"passed":false},{"actual":[2,1],"check":"repair trap 1","expected":[3,1],"passed":false},{"actual":[2,25],"check":"combined fault 2","expected":[2,25],"passed":true},{"actual":[1,3],"check":"control 3","expected":[1,3],"passed":true},{"actual":[5,2],"check":"control 4","expected":[5,2],"passed":true},{"actual":[10,15],"check":"boundary 5","expected":[10,15],"passed":true},{"actual":[2,1],"check":"boundary 6","expected":[2,1],"passed":true},{"actual":[8,5],"check":"control 7","expected":[9,5],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: width rounding 0\", \"actual\": [7, 10], \"expected\": [8, 10], \"passed\": false}, {\"check\": \"repair trap 1\", \"actual\": [2, 1], \"expected\": [3, 1], \"passed\": false}, {\"check\": \"combined fault 2\", \"actual\": [2, 25], \"expected\": [2, 25], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [1, 3], \"expected\": [1, 3], \"passed\": true}, {\"check\": \"control 4\", \"actual\": [5, 2], \"expected\": [5, 2], \"passed\": true}, {\"check\": \"boundary 5\", \"actual\": [10, 15], \"expected\": [10, 15], \"passed\": true}, {\"check\": \"boundary 6\", \"actual\": [2, 1], \"expected\": [2, 1], \"passed\": true}, {\"check\": \"control 7\", \"actual\": [8, 5], \"expected\": [9, 5], \"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."}}