{"abstract":"A key between breakpoints gets a future band.","category":"Spreadsheet calculation semantics","checks":7,"contract":"Unique sorted integer [key,value] rows define bands. Return value at greatest key <= query or #N/A below all keys or for empty rows.","contract_signature":"rows, query","evaluation_group":"model-ea9cb61a7e8af11c","failed_approach":"Requiring an exact match discards legitimate interior band queries.","family":"z-spreadsheets-approximate-lookup-bracket","id":"FA-11356","implementations":{"attempt":{"sha256":"31aca71f25503b44a0fd4fc4c7fc58cc69e97011f3ba160d592c53173711e791","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, query):\n    return next((v for k,v in rows if k == query), '#N/A')\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows = [[0, 'low'], [10*N, 'high']]\ncheck('interior near upper endpoint', solve(rows, 10*N-1), 'low')\ncheck('below minimum', solve(rows, -N), '#N/A')\ncheck('minimum inclusive', solve(rows, 0), 'low')\ncheck('upper inclusive', solve(rows, 10*N), 'high')\ncheck('above maximum', solve(rows, 20*N), 'high')\ncheck('empty table', solve([], N), '#N/A')\ncheck('single band interior', solve([[N, 'only']], N+1), 'only')\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":"7f72fdc17aaa3e8dae11b848b1c4ed0fca5801a72fb1c6b703a4d8ac953e79d1","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, query):\n    return min(rows, key=lambda r: abs(r[0]-query))[1] if rows else '#N/A'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows = [[0, 'low'], [10*N, 'high']]\ncheck('interior near upper endpoint', solve(rows, 10*N-1), 'low')\ncheck('below minimum', solve(rows, -N), '#N/A')\ncheck('minimum inclusive', solve(rows, 0), 'low')\ncheck('upper inclusive', solve(rows, 10*N), 'high')\ncheck('above maximum', solve(rows, 20*N), 'high')\ncheck('empty table', solve([], N), '#N/A')\ncheck('single band interior', solve([[N, 'only']], N+1), 'only')\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":"z-spreadsheets-approximate-lookup-bracket","generated_at":"2026-09-29T14:38:47.243060+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This isolated spreadsheet model makes cell semantics explicit; it does not claim compatibility with every workbook engine.","root_cause":"Nearest distance substitutes for floor-band lookup.","sha256":"983385118622d9f22ff48498602f500e6555a7b522c4c2c8aa6657cf2200bbbd","title":"Approximate lookup selects a nearest value instead of the lower bracket · 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":37.591,"exit_code":1,"observations":[{"actual":"#N/A","check":"interior near upper endpoint","expected":"low","passed":false},{"actual":"#N/A","check":"below minimum","expected":"#N/A","passed":true},{"actual":"low","check":"minimum inclusive","expected":"low","passed":true},{"actual":"high","check":"upper inclusive","expected":"high","passed":true},{"actual":"#N/A","check":"above maximum","expected":"high","passed":false},{"actual":"#N/A","check":"empty table","expected":"#N/A","passed":true},{"actual":"#N/A","check":"single band interior","expected":"only","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"interior near upper endpoint\", \"actual\": \"#N/A\", \"expected\": \"low\", \"passed\": false}, {\"check\": \"below minimum\", \"actual\": \"#N/A\", \"expected\": \"#N/A\", \"passed\": true}, {\"check\": \"minimum inclusive\", \"actual\": \"low\", \"expected\": \"low\", \"passed\": true}, {\"check\": \"upper inclusive\", \"actual\": \"high\", \"expected\": \"high\", \"passed\": true}, {\"check\": \"above maximum\", \"actual\": \"#N/A\", \"expected\": \"high\", \"passed\": false}, {\"check\": \"empty table\", \"actual\": \"#N/A\", \"expected\": \"#N/A\", \"passed\": true}, {\"check\": \"single band interior\", \"actual\": \"#N/A\", \"expected\": \"only\", \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.582,"exit_code":1,"observations":[{"actual":"high","check":"interior near upper endpoint","expected":"low","passed":false},{"actual":"low","check":"below minimum","expected":"#N/A","passed":false},{"actual":"low","check":"minimum inclusive","expected":"low","passed":true},{"actual":"high","check":"upper inclusive","expected":"high","passed":true},{"actual":"high","check":"above maximum","expected":"high","passed":true},{"actual":"#N/A","check":"empty table","expected":"#N/A","passed":true},{"actual":"only","check":"single band interior","expected":"only","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"interior near upper endpoint\", \"actual\": \"high\", \"expected\": \"low\", \"passed\": false}, {\"check\": \"below minimum\", \"actual\": \"low\", \"expected\": \"#N/A\", \"passed\": false}, {\"check\": \"minimum inclusive\", \"actual\": \"low\", \"expected\": \"low\", \"passed\": true}, {\"check\": \"upper inclusive\", \"actual\": \"high\", \"expected\": \"high\", \"passed\": true}, {\"check\": \"above maximum\", \"actual\": \"high\", \"expected\": \"high\", \"passed\": true}, {\"check\": \"empty table\", \"actual\": \"#N/A\", \"expected\": \"#N/A\", \"passed\": true}, {\"check\": \"single band interior\", \"actual\": \"only\", \"expected\": \"only\", \"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."}}