{"abstract":"Writes land at an absolute index instead of an index relative to the cache origin.","category":"KV cache position mapping","checks":6,"contract":"For inclusive logical positions [origin, position], return (logical, slot_origin + logical - origin) pairs. position before origin yields an empty list.","contract_signature":"origin, slot_origin, position","evaluation_group":"w3-kv-map-absolute-base-offset","failed_approach":"Subtracting the origin but dropping the physical slot origin still addresses the wrong segment.","family":"w3-kv-cache-position-mapping-absolute-base-offset","id":"FA-98541","implementations":{"attempt":{"sha256":"32306e8f40e08a690fa15ab497086c1659ebba3d1d6a4ffc93ee894762e09594","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(origin, slot_origin, position):\n    return [(p, p-origin) for p in range(origin, position+1)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('shifted window',solve(N,7,N+2),[(N,7),(N+1,8),(N+2,9)])\ncheck('nonzero origin',solve(4,3,6),[(4,3),(5,4),(6,5)])\ncheck('origin only',solve(N,2,N),[(N,2)])\ncheck('empty range',solve(5,9,4),[])\ncheck('large origin',solve(100,0,101),[(100,0),(101,1)])\ncheck('different physical base',solve(2,20,3),[(2,20),(3,21)])\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":"2eba6b02359433cff93d3c9302809964df72c646f46bdb678d03b61b3b353b32","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(origin, slot_origin, position):\n    return [(p, p) for p in range(origin, position+1)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('shifted window',solve(N,7,N+2),[(N,7),(N+1,8),(N+2,9)])\ncheck('nonzero origin',solve(4,3,6),[(4,3),(5,4),(6,5)])\ncheck('origin only',solve(N,2,N),[(N,2)])\ncheck('empty range',solve(5,9,4),[])\ncheck('large origin',solve(100,0,101),[(100,0),(101,1)])\ncheck('different physical base',solve(2,20,3),[(2,20),(3,21)])\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":"These toy integer maps omit tensor layout, concurrency, device memory, and model-specific cache formats. 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":"w3-kv-cache-position-mapping-absolute-base-offset","generated_at":"2026-09-30T16:48:14.105953+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small in-memory model makes the cache address contract explicit for a serving component.","root_cause":"The address calculation writes the logical position itself as the physical slot, ignoring both origins.","sha256":"6e3f7d8af54391083994f6e748d8050eac4f03030671fd0e77c4741eced12697","title":"Absolute positions map relative to the cache origin · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":27.751,"exit_code":1,"observations":[{"actual":[[1,0],[2,1],[3,2]],"check":"shifted window","expected":[[1,7],[2,8],[3,9]],"passed":false},{"actual":[[4,0],[5,1],[6,2]],"check":"nonzero origin","expected":[[4,3],[5,4],[6,5]],"passed":false},{"actual":[[1,0]],"check":"origin only","expected":[[1,2]],"passed":false},{"actual":[],"check":"empty range","expected":[],"passed":true},{"actual":[[100,0],[101,1]],"check":"large origin","expected":[[100,0],[101,1]],"passed":true},{"actual":[[2,0],[3,1]],"check":"different physical base","expected":[[2,20],[3,21]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"shifted window\", \"actual\": [[1, 0], [2, 1], [3, 2]], \"expected\": [[1, 7], [2, 8], [3, 9]], \"passed\": false}, {\"check\": \"nonzero origin\", \"actual\": [[4, 0], [5, 1], [6, 2]], \"expected\": [[4, 3], [5, 4], [6, 5]], \"passed\": false}, {\"check\": \"origin only\", \"actual\": [[1, 0]], \"expected\": [[1, 2]], \"passed\": false}, {\"check\": \"empty range\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"large origin\", \"actual\": [[100, 0], [101, 1]], \"expected\": [[100, 0], [101, 1]], \"passed\": true}, {\"check\": \"different physical base\", \"actual\": [[2, 0], [3, 1]], \"expected\": [[2, 20], [3, 21]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":26.106,"exit_code":1,"observations":[{"actual":[[1,1],[2,2],[3,3]],"check":"shifted window","expected":[[1,7],[2,8],[3,9]],"passed":false},{"actual":[[4,4],[5,5],[6,6]],"check":"nonzero origin","expected":[[4,3],[5,4],[6,5]],"passed":false},{"actual":[[1,1]],"check":"origin only","expected":[[1,2]],"passed":false},{"actual":[],"check":"empty range","expected":[],"passed":true},{"actual":[[100,100],[101,101]],"check":"large origin","expected":[[100,0],[101,1]],"passed":false},{"actual":[[2,2],[3,3]],"check":"different physical base","expected":[[2,20],[3,21]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"shifted window\", \"actual\": [[1, 1], [2, 2], [3, 3]], \"expected\": [[1, 7], [2, 8], [3, 9]], \"passed\": false}, {\"check\": \"nonzero origin\", \"actual\": [[4, 4], [5, 5], [6, 6]], \"expected\": [[4, 3], [5, 4], [6, 5]], \"passed\": false}, {\"check\": \"origin only\", \"actual\": [[1, 1]], \"expected\": [[1, 2]], \"passed\": false}, {\"check\": \"empty range\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"large origin\", \"actual\": [[100, 100], [101, 101]], \"expected\": [[100, 0], [101, 1]], \"passed\": false}, {\"check\": \"different physical base\", \"actual\": [[2, 2], [3, 3]], \"expected\": [[2, 20], [3, 21]], \"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."}}