{"abstract":"Delta encoding subtracts the initial sample every time.","category":"Binary formats","checks":4,"contract":"Encode first integer unchanged and each later value minus its immediate predecessor.","evaluation_group":"model-f0f988d804ff3c7e","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-delta-previous","id":"FA-3731","implementations":{"attempt":{"sha256":"8befea8549d917a3ffc313e72de20372dfca0ba94864942ee23872e30da9a7e7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct\nfrom urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit\nfrom email.header import decode_header, make_header\nfrom email.utils import getaddresses\nfrom xml.etree import ElementTree as ET\nimport shlex, string, textwrap\n\nN = 1\nobservations = []\ndef solve(x):\n    try:\n        return [x[0]]+[v-x[0] for v in x[1:]] if x else []\n    except Exception as exc:\n        return {\"error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('boundary 1', solve([10, 12, 15]), [10, 2, 3])\ncheck('boundary 2', solve([2, 2, 2]), [2, 0, 0])\ncheck('boundary 3', solve([]), [])\ncheck('boundary 4', solve([5]), [5])\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":"8996c47a85055d750834a8ef1521bea59cc2c6c908359014d3fe10856635b825","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct\nfrom urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit\nfrom email.header import decode_header, make_header\nfrom email.utils import getaddresses\nfrom xml.etree import ElementTree as ET\nimport shlex, string, textwrap\n\nN = 1\nobservations = []\ndef solve(x):\n    try:\n        return x\n    except Exception as exc:\n        return {\"error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('boundary 1', solve([10, 12, 15]), [10, 2, 3])\ncheck('boundary 2', solve([2, 2, 2]), [2, 0, 0])\ncheck('boundary 3', solve([]), [])\ncheck('boundary 4', solve([5]), [5])\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"},"fixed":{"sha256":"357c05259cc7240c3e16878d64f57e5c053a119a1dedb5ebb1385a12f7676b4f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct\nfrom urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit\nfrom email.header import decode_header, make_header\nfrom email.utils import getaddresses\nfrom xml.etree import ElementTree as ET\nimport shlex, string, textwrap\n\nN = 1\nobservations = []\ndef solve(x):\n    try:\n        return [x[0]]+[x[i]-x[i-1] for i in range(1,len(x))] if x else []\n    except Exception as exc:\n        return {\"error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('boundary 1', solve([10, 12, 15]), [10, 2, 3])\ncheck('boundary 2', solve([2, 2, 2]), [2, 0, 0])\ncheck('boundary 3', solve([]), [])\ncheck('boundary 4', solve([5]), [5])\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":" 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":"xp-binary-delta-previous","generated_at":"2026-09-29T14:37:30.111275+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.","repair":"Implement the complete stated contract, including the boundary fixtures: Encode first integer unchanged and each later value minus its immediate predecessor.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Encode first integer unchanged and each later value minus its immediate predecessor.","sha256":"e63c8f6651f6a6b521c7d2b00cb65b29ce3e886e3e33c1b6c8add8ddb5ceeaed","title":"Delta encoding subtracts the initial sample every time · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":56.09,"exit_code":1,"observations":[{"actual":[10,2,5],"check":"boundary 1","expected":[10,2,3],"passed":false},{"actual":[2,0,0],"check":"boundary 2","expected":[2,0,0],"passed":true},{"actual":[],"check":"boundary 3","expected":[],"passed":true},{"actual":[5],"check":"boundary 4","expected":[5],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [10, 2, 5], \"expected\": [10, 2, 3], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [2, 0, 0], \"expected\": [2, 0, 0], \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [5], \"expected\": [5], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":53.949,"exit_code":1,"observations":[{"actual":[10,12,15],"check":"boundary 1","expected":[10,2,3],"passed":false},{"actual":[2,2,2],"check":"boundary 2","expected":[2,0,0],"passed":false},{"actual":[],"check":"boundary 3","expected":[],"passed":true},{"actual":[5],"check":"boundary 4","expected":[5],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [10, 12, 15], \"expected\": [10, 2, 3], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [2, 2, 2], \"expected\": [2, 0, 0], \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [5], \"expected\": [5], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":51.254,"exit_code":0,"observations":[{"actual":[10,2,3],"check":"boundary 1","expected":[10,2,3],"passed":true},{"actual":[2,0,0],"check":"boundary 2","expected":[2,0,0],"passed":true},{"actual":[],"check":"boundary 3","expected":[],"passed":true},{"actual":[5],"check":"boundary 4","expected":[5],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [10, 2, 3], \"expected\": [10, 2, 3], \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": [2, 0, 0], \"expected\": [2, 0, 0], \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [5], \"expected\": [5], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}