{"abstract":"A logical page is represented by its local offset instead of the physical slot in that page.","category":"KV cache position mapping","checks":6,"contract":"block_table maps logical page number to physical block base. Return base + (position modulo page_size). Missing page returns -1.","contract_signature":"block_table, position, page_size","evaluation_group":"w3-kv-map-paged-table-slot","failed_approach":"The first table entry works, but using only the page offset loses the selected block.","family":"w3-kv-cache-position-mapping-paged-table-slot","id":"FA-98561","implementations":{"attempt":{"sha256":"044e41b02620a171463e839d140cfd6b44db428f83185a755558802017691d4a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(block_table, position, page_size):\n    return block_table.get(position//page_size,-1) + position if position//page_size in block_table else -1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ntable={0:12,1:28,5:40}\ncheck('second page offset',solve(table,5,4),29)\ncheck('page zero',solve(table,3,4),15)\ncheck('missing page',solve(table,8,4),-1)\ncheck('mapped later page',solve(table,22,4),42)\ncheck('boundary next page',solve(table,4,4),28)\ncheck('empty table',solve({},0,4),-1)\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":"1b1f4908f7a79d4b00d563eeafcff621c6c80508f8e70750c4412d5f301608b2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(block_table, position, page_size):\n    return position%page_size if position//page_size in block_table else -1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ntable={0:12,1:28,5:40}\ncheck('second page offset',solve(table,5,4),29)\ncheck('page zero',solve(table,3,4),15)\ncheck('missing page',solve(table,8,4),-1)\ncheck('mapped later page',solve(table,22,4),42)\ncheck('boundary next page',solve(table,4,4),28)\ncheck('empty table',solve({},0,4),-1)\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-paged-table-slot","generated_at":"2026-09-30T16:48:14.544834+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 lookup computes a page-local offset but returns it without resolving the logical page through the block table.","sha256":"847d1f0cacb978035a44eb811b4ab5599cd06534098dfff8a6592ec6a718e77c","title":"Paged cache resolves through the sequence block table · case 01","variant":1,"variant_policy":"The same explicitly authored fixtures repeat across all five numbered records; runtime N is unused. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":27.04,"exit_code":1,"observations":[{"actual":33,"check":"second page offset","expected":29,"passed":false},{"actual":15,"check":"page zero","expected":15,"passed":true},{"actual":-1,"check":"missing page","expected":-1,"passed":true},{"actual":62,"check":"mapped later page","expected":42,"passed":false},{"actual":32,"check":"boundary next page","expected":28,"passed":false},{"actual":-1,"check":"empty table","expected":-1,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"second page offset\", \"actual\": 33, \"expected\": 29, \"passed\": false}, {\"check\": \"page zero\", \"actual\": 15, \"expected\": 15, \"passed\": true}, {\"check\": \"missing page\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"mapped later page\", \"actual\": 62, \"expected\": 42, \"passed\": false}, {\"check\": \"boundary next page\", \"actual\": 32, \"expected\": 28, \"passed\": false}, {\"check\": \"empty table\", \"actual\": -1, \"expected\": -1, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":27.817,"exit_code":1,"observations":[{"actual":1,"check":"second page offset","expected":29,"passed":false},{"actual":3,"check":"page zero","expected":15,"passed":false},{"actual":-1,"check":"missing page","expected":-1,"passed":true},{"actual":2,"check":"mapped later page","expected":42,"passed":false},{"actual":0,"check":"boundary next page","expected":28,"passed":false},{"actual":-1,"check":"empty table","expected":-1,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"second page offset\", \"actual\": 1, \"expected\": 29, \"passed\": false}, {\"check\": \"page zero\", \"actual\": 3, \"expected\": 15, \"passed\": false}, {\"check\": \"missing page\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"mapped later page\", \"actual\": 2, \"expected\": 42, \"passed\": false}, {\"check\": \"boundary next page\", \"actual\": 0, \"expected\": 28, \"passed\": false}, {\"check\": \"empty table\", \"actual\": -1, \"expected\": -1, \"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."}}