{"abstract":"row gather returns the pointer end as an inclusive bound.","category":"Sparse tensor canonicalization","checks":6,"contract":"Return columns in the selected CSR row using its half-open pointer interval.","contract_signature":"ptr,columns,row","evaluation_group":"w3-sparse-tensor-canonicalization-csr-row-gather","failed_approach":"The first offset belongs to the row; advancing it loses the first stored column.","family":"w3-sparse-tensor-canonicalization-csr-row-gather","id":"FA-100526","implementations":{"attempt":{"sha256":"4bd3ac13469e0701628cc0bf894562411439d0816d30d59eb55170fe9c415efb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(ptr,columns,row):\n    return columns[ptr[row]+1:ptr[row+1]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('middle row',solve([0,2,2,4],[1,3,0,2],1),[])\ncheck('nonempty',solve([0,2,4],[1,3,0,2],1),[0,2])\ncheck('empty',solve([0,0],[],0),[])\ncheck('last entry',solve([0,1],[N],0),[N])\ncheck('leading empty',solve([0,0,2],[N,4],0),[])\ncheck('second row',solve([0,1,3],[2,1,4],1),[1,4])\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":"f79a81b2029f47baca6e9776ce669578d2183272fd683d0883a41a2886f64419","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(ptr,columns,row):\n    return columns[ptr[row]:ptr[row+1]+1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('middle row',solve([0,2,2,4],[1,3,0,2],1),[])\ncheck('nonempty',solve([0,2,4],[1,3,0,2],1),[0,2])\ncheck('empty',solve([0,0],[],0),[])\ncheck('last entry',solve([0,1],[N],0),[N])\ncheck('leading empty',solve([0,0,2],[N,4],0),[])\ncheck('second row',solve([0,1,3],[2,1,4],1),[1,4])\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 are toy integer-valued COO or CSR contracts; they make no claim about a framework API, floating point policy, or large tensor performance. 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-sparse-tensor-canonicalization-csr-row-gather","generated_at":"2026-09-30T16:48:36.730807+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small offline sparse-array operation has explicit coordinate and storage semantics.","root_cause":"CSR row segments use start-inclusive, end-exclusive offsets.","sha256":"02ebf7a4514bb7a75254d87e4e2e29e592387c5b558c947f69c9e31f8c8551c7","title":"Sparse tensor: row gather returns the pointer end as an inclusive bound · 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":27.691,"exit_code":1,"observations":[{"actual":[],"check":"middle row","expected":[],"passed":true},{"actual":[2],"check":"nonempty","expected":[0,2],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[],"check":"last entry","expected":[1],"passed":false},{"actual":[],"check":"leading empty","expected":[],"passed":true},{"actual":[4],"check":"second row","expected":[1,4],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"middle row\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"nonempty\", \"actual\": [2], \"expected\": [0, 2], \"passed\": false}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"last entry\", \"actual\": [], \"expected\": [1], \"passed\": false}, {\"check\": \"leading empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"second row\", \"actual\": [4], \"expected\": [1, 4], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.655,"exit_code":1,"observations":[{"actual":[0],"check":"middle row","expected":[],"passed":false},{"actual":[0,2],"check":"nonempty","expected":[0,2],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[1],"check":"last entry","expected":[1],"passed":true},{"actual":[1],"check":"leading empty","expected":[],"passed":false},{"actual":[1,4],"check":"second row","expected":[1,4],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"middle row\", \"actual\": [0], \"expected\": [], \"passed\": false}, {\"check\": \"nonempty\", \"actual\": [0, 2], \"expected\": [0, 2], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"last entry\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"leading empty\", \"actual\": [1], \"expected\": [], \"passed\": false}, {\"check\": \"second row\", \"actual\": [1, 4], \"expected\": [1, 4], \"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."}}