{"abstract":"row shard offset ignores preceding shard lengths.","category":"Checkpoint tensor mapping","checks":6,"contract":"Return the sum of lengths before a valid shard index; invalid index returns -1.","contract_signature":"lengths, index","evaluation_group":"w3-checkpoint-tensor-mapping-row-offset","failed_approach":"Including the current extent returns the shard end offset.","family":"w3-checkpoint-tensor-mapping-row-offset","id":"FA-99191","implementations":{"attempt":{"sha256":"64ac2cbd9e8a424842ca4d9121f914d03a49729fdb9cf178278ffc4fcc30054e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(lengths, index):\n    return sum(lengths[:index+1]) if 0<=index<len(lengths) else -1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('second', solve(*([3, 3, 4], 1)), 3)\ncheck('first', solve(*([3, 3], 0)), 0)\ncheck('last', solve(*([2, 3, 3], 2)), 5)\ncheck('empty', solve(*([], 0)), -1)\ncheck('out of range', solve(*([3], 1)), -1)\ncheck('zero length', solve(*([0, 3], 1)), 0)\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":"8990cb44bcc2c7a42369dc0371da66fe56a7453ea2177e563aa5996ed4a87ffe","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(lengths, index):\n    return lengths[index] if 0<=index<len(lengths) else -1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('second', solve(*([3, 3, 4], 1)), 3)\ncheck('first', solve(*([3, 3], 0)), 0)\ncheck('last', solve(*([2, 3, 3], 2)), 5)\ncheck('empty', solve(*([], 0)), -1)\ncheck('out of range', solve(*([3], 1)), -1)\ncheck('zero length', solve(*([0, 3], 1)), 0)\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":"Inputs are already decoded Python values; this toy contract makes no claim about a framework, file format, or production checkpoint. 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-checkpoint-tensor-mapping-row-offset","generated_at":"2026-09-30T16:48:21.243162+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A bounded offline model of checkpoint tensor bookkeeping in a training workflow.","root_cause":"The local shard length is returned instead of its global starting offset.","sha256":"781cfec478b8d009fbd8c69e48fea0368b0f39fccf140bb1c9cc1ff297d69be8","title":"Checkpoint mapping: row shard offset ignores preceding shard lengths · 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":27.78,"exit_code":1,"observations":[{"actual":6,"check":"second","expected":3,"passed":false},{"actual":3,"check":"first","expected":0,"passed":false},{"actual":8,"check":"last","expected":5,"passed":false},{"actual":-1,"check":"empty","expected":-1,"passed":true},{"actual":-1,"check":"out of range","expected":-1,"passed":true},{"actual":3,"check":"zero length","expected":0,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"second\", \"actual\": 6, \"expected\": 3, \"passed\": false}, {\"check\": \"first\", \"actual\": 3, \"expected\": 0, \"passed\": false}, {\"check\": \"last\", \"actual\": 8, \"expected\": 5, \"passed\": false}, {\"check\": \"empty\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"out of range\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"zero length\", \"actual\": 3, \"expected\": 0, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":27.731,"exit_code":1,"observations":[{"actual":3,"check":"second","expected":3,"passed":true},{"actual":3,"check":"first","expected":0,"passed":false},{"actual":3,"check":"last","expected":5,"passed":false},{"actual":-1,"check":"empty","expected":-1,"passed":true},{"actual":-1,"check":"out of range","expected":-1,"passed":true},{"actual":3,"check":"zero length","expected":0,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"second\", \"actual\": 3, \"expected\": 3, \"passed\": true}, {\"check\": \"first\", \"actual\": 3, \"expected\": 0, \"passed\": false}, {\"check\": \"last\", \"actual\": 3, \"expected\": 5, \"passed\": false}, {\"check\": \"empty\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"out of range\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"zero length\", \"actual\": 3, \"expected\": 0, \"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."}}