{"abstract":"missing shard indices are not detected.","category":"Checkpoint tensor mapping","checks":6,"contract":"Return values in shard order only when indices are exactly 0 through count-1; otherwise return [] (also for count zero).","contract_signature":"shards, count","evaluation_group":"w3-checkpoint-tensor-mapping-shard-gap","failed_approach":"Length-only validation accepts duplicate indices while omitting another shard.","family":"w3-checkpoint-tensor-mapping-shard-gap","id":"FA-99161","implementations":{"attempt":{"sha256":"2090ce9847154d48269d9cb2e50cff0f576107dfd5cbe82a6d6a5054e9eb3e32","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(shards, count):\n    return sum((v for i,v in sorted(shards)), []) if len(shards)==count else []\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('gap', solve(*([[0, [3]], [2, [2]]], 3)), [])\ncheck('complete', solve(*([[1, [1]], [0, [0]]], 2)), [0, 1])\ncheck('empty zero', solve(*([], 0)), [])\ncheck('unexpected', solve(*([[0, [3]]], 0)), [])\ncheck('duplicate', solve(*([[0, [1]], [0, [2]]], 2)), [])\ncheck('single', solve(*([[0, [3]]], 1)), [3])\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":"0cc34992cc4d533676c753a4cb03b81a822c343ab6d6aa32e50b4614f8d0b239","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(shards, count):\n    return sum((v for i,v in sorted(shards)), [])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('gap', solve(*([[0, [3]], [2, [2]]], 3)), [])\ncheck('complete', solve(*([[1, [1]], [0, [0]]], 2)), [0, 1])\ncheck('empty zero', solve(*([], 0)), [])\ncheck('unexpected', solve(*([[0, [3]]], 0)), [])\ncheck('duplicate', solve(*([[0, [1]], [0, [2]]], 2)), [])\ncheck('single', solve(*([[0, [3]]], 1)), [3])\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-shard-gap","generated_at":"2026-09-30T16:48:21.244187+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":"Matching shard count does not prove that every required index appears once.","sha256":"0e8b49a8109a53ce3c341c05723dc7d4ecad44fd77121f050aeeb9d8c1724f34","title":"Checkpoint mapping: missing shard indices are not detected · 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":28.463,"exit_code":1,"observations":[{"actual":[],"check":"gap","expected":[],"passed":true},{"actual":[0,1],"check":"complete","expected":[0,1],"passed":true},{"actual":[],"check":"empty zero","expected":[],"passed":true},{"actual":[],"check":"unexpected","expected":[],"passed":true},{"actual":[1,2],"check":"duplicate","expected":[],"passed":false},{"actual":[3],"check":"single","expected":[3],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"gap\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"complete\", \"actual\": [0, 1], \"expected\": [0, 1], \"passed\": true}, {\"check\": \"empty zero\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"unexpected\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"duplicate\", \"actual\": [1, 2], \"expected\": [], \"passed\": false}, {\"check\": \"single\", \"actual\": [3], \"expected\": [3], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.793,"exit_code":1,"observations":[{"actual":[3,2],"check":"gap","expected":[],"passed":false},{"actual":[0,1],"check":"complete","expected":[0,1],"passed":true},{"actual":[],"check":"empty zero","expected":[],"passed":true},{"actual":[3],"check":"unexpected","expected":[],"passed":false},{"actual":[1,2],"check":"duplicate","expected":[],"passed":false},{"actual":[3],"check":"single","expected":[3],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"gap\", \"actual\": [3, 2], \"expected\": [], \"passed\": false}, {\"check\": \"complete\", \"actual\": [0, 1], \"expected\": [0, 1], \"passed\": true}, {\"check\": \"empty zero\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"unexpected\", \"actual\": [3], \"expected\": [], \"passed\": false}, {\"check\": \"duplicate\", \"actual\": [1, 2], \"expected\": [], \"passed\": false}, {\"check\": \"single\", \"actual\": [3], \"expected\": [3], \"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."}}