{"abstract":"Distinct two-column groups collapse together because their concatenated or delimiter-separated key strings coincide.","category":"Storage and queries","checks":7,"contract":"Rows contain [first_string,second_string,integer_amount]. Group by exact ordered pairs and return sorted [first,second,total] rows. Components may be empty or contain delimiter characters; input occurrences are all counted.","evaluation_group":"model-d592b0a7c6bd306d","failed_approach":"Adding a delimiter only works when inputs cannot contain that delimiter; arbitrary strings still collide.","family":"store-compound-group-key","id":"FA-156","implementations":{"attempt":{"sha256":"a8e216e9981c196b06ee04d592d3d7e0a3d9c0184de175d06ce3369fff3259e7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    groups = {}\n    for first, second, amount in rows:\n        key = first + '|' + second\n        if key not in groups:\n            groups[key] = [first, second, 0]\n        groups[key][2] += amount\n    return sorted(groups.values())\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('unseparated component boundaries collide', solve([['ab', 'c', N], ['a', 'bc', N+1]]), [['a', 'bc', N+1], ['ab', 'c', N]])\ncheck('delimiter occurs inside either component', solve([['a|b', 'c', N], ['a', 'b|c', N+1]]), [['a', 'b|c', N+1], ['a|b', 'c', N]])\ncheck('empty components are ordered, not interchangeable', solve([['', 'x', N], ['x', '', N+1]]), [['', 'x', N], ['x', '', N+1]])\ncheck('delimiter-only boundaries remain distinct', solve([['|', '', N], ['', '|', 2*N]]), [['', '|', 2*N], ['|', '', N]])\ncheck('identical composite keys aggregate', solve([['team', str(N), N], ['team', str(N), N+2]]), [['team', str(N), 2*N+2]])\ncheck('signed contributions stay within their group', solve([['a', 'b', N], ['a', 'b', -N], ['a', 'c', 2*N]]), [['a', 'b', 0], ['a', 'c', 2*N]])\ncheck('empty relation', solve([]), [])\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":"2db9f43033f2d61c0ca37f99172329b6b7ee4a841da186134cb257bc0092f7b5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    groups = {}\n    for first, second, amount in rows:\n        key = first + second\n        if key not in groups:\n            groups[key] = [first, second, 0]\n        groups[key][2] += amount\n    return sorted(groups.values())\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('unseparated component boundaries collide', solve([['ab', 'c', N], ['a', 'bc', N+1]]), [['a', 'bc', N+1], ['ab', 'c', N]])\ncheck('delimiter occurs inside either component', solve([['a|b', 'c', N], ['a', 'b|c', N+1]]), [['a', 'b|c', N+1], ['a|b', 'c', N]])\ncheck('empty components are ordered, not interchangeable', solve([['', 'x', N], ['x', '', N+1]]), [['', 'x', N], ['x', '', N+1]])\ncheck('delimiter-only boundaries remain distinct', solve([['|', '', N], ['', '|', 2*N]]), [['', '|', 2*N], ['|', '', N]])\ncheck('identical composite keys aggregate', solve([['team', str(N), N], ['team', str(N), N+2]]), [['team', str(N), 2*N+2]])\ncheck('signed contributions stay within their group', solve([['a', 'b', N], ['a', 'b', -N], ['a', 'c', 2*N]]), [['a', 'b', 0], ['a', 'c', 2*N]])\ncheck('empty relation', solve([]), [])\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"},"fixed":{"sha256":"9ed01820ab1d31e043f730b7b347f544d27141e475a33bac0701902e91a93b92","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    groups = {}\n    for first, second, amount in rows:\n        key = (first, second)\n        if key not in groups:\n            groups[key] = [first, second, 0]\n        groups[key][2] += amount\n    return sorted(groups.values())\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('unseparated component boundaries collide', solve([['ab', 'c', N], ['a', 'bc', N+1]]), [['a', 'bc', N+1], ['ab', 'c', N]])\ncheck('delimiter occurs inside either component', solve([['a|b', 'c', N], ['a', 'b|c', N+1]]), [['a', 'b|c', N+1], ['a|b', 'c', N]])\ncheck('empty components are ordered, not interchangeable', solve([['', 'x', N], ['x', '', N+1]]), [['', 'x', N], ['x', '', N+1]])\ncheck('delimiter-only boundaries remain distinct', solve([['|', '', N], ['', '|', 2*N]]), [['', '|', 2*N], ['|', '', N]])\ncheck('identical composite keys aggregate', solve([['team', str(N), N], ['team', str(N), N+2]]), [['team', str(N), 2*N+2]])\ncheck('signed contributions stay within their group', solve([['a', 'b', N], ['a', 'b', -N], ['a', 'c', 2*N]]), [['a', 'b', 0], ['a', 'c', 2*N]])\ncheck('empty relation', solve([]), [])\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":" 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":"store-compound-group-key","generated_at":"2026-09-29T14:36:50.997534+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Models compound keys in aggregation caches and client-side query engines. The fixtures expose both simple concatenation collisions and delimiter collisions without relying on hash collisions or randomized behavior.","repair":"Use the two original string components as a tuple key and retain their separate identities in the output.","root_cause":"A lossy serialization is used as group identity without escaping delimiters or preserving component boundaries.","sha256":"9fbdf33e253b53c132c3c407089e1c8103921611185c85fc5ab99b982779e2b7","title":"String-encoded composite keys merge unrelated groups · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":34.279,"exit_code":1,"observations":[{"actual":[["a","bc",2],["ab","c",1]],"check":"unseparated component boundaries collide","expected":[["a","bc",2],["ab","c",1]],"passed":true},{"actual":[["a|b","c",3]],"check":"delimiter occurs inside either component","expected":[["a","b|c",2],["a|b","c",1]],"passed":false},{"actual":[["","x",1],["x","",2]],"check":"empty components are ordered, not interchangeable","expected":[["","x",1],["x","",2]],"passed":true},{"actual":[["|","",3]],"check":"delimiter-only boundaries remain distinct","expected":[["","|",2],["|","",1]],"passed":false},{"actual":[["team","1",4]],"check":"identical composite keys aggregate","expected":[["team","1",4]],"passed":true},{"actual":[["a","b",0],["a","c",2]],"check":"signed contributions stay within their group","expected":[["a","b",0],["a","c",2]],"passed":true},{"actual":[],"check":"empty relation","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"unseparated component boundaries collide\", \"actual\": [[\"a\", \"bc\", 2], [\"ab\", \"c\", 1]], \"expected\": [[\"a\", \"bc\", 2], [\"ab\", \"c\", 1]], \"passed\": true}, {\"check\": \"delimiter occurs inside either component\", \"actual\": [[\"a|b\", \"c\", 3]], \"expected\": [[\"a\", \"b|c\", 2], [\"a|b\", \"c\", 1]], \"passed\": false}, {\"check\": \"empty components are ordered, not interchangeable\", \"actual\": [[\"\", \"x\", 1], [\"x\", \"\", 2]], \"expected\": [[\"\", \"x\", 1], [\"x\", \"\", 2]], \"passed\": true}, {\"check\": \"delimiter-only boundaries remain distinct\", \"actual\": [[\"|\", \"\", 3]], \"expected\": [[\"\", \"|\", 2], [\"|\", \"\", 1]], \"passed\": false}, {\"check\": \"identical composite keys aggregate\", \"actual\": [[\"team\", \"1\", 4]], \"expected\": [[\"team\", \"1\", 4]], \"passed\": true}, {\"check\": \"signed contributions stay within their group\", \"actual\": [[\"a\", \"b\", 0], [\"a\", \"c\", 2]], \"expected\": [[\"a\", \"b\", 0], [\"a\", \"c\", 2]], \"passed\": true}, {\"check\": \"empty relation\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":31.676,"exit_code":1,"observations":[{"actual":[["ab","c",3]],"check":"unseparated component boundaries collide","expected":[["a","bc",2],["ab","c",1]],"passed":false},{"actual":[["a","b|c",2],["a|b","c",1]],"check":"delimiter occurs inside either component","expected":[["a","b|c",2],["a|b","c",1]],"passed":true},{"actual":[["","x",3]],"check":"empty components are ordered, not interchangeable","expected":[["","x",1],["x","",2]],"passed":false},{"actual":[["|","",3]],"check":"delimiter-only boundaries remain distinct","expected":[["","|",2],["|","",1]],"passed":false},{"actual":[["team","1",4]],"check":"identical composite keys aggregate","expected":[["team","1",4]],"passed":true},{"actual":[["a","b",0],["a","c",2]],"check":"signed contributions stay within their group","expected":[["a","b",0],["a","c",2]],"passed":true},{"actual":[],"check":"empty relation","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"unseparated component boundaries collide\", \"actual\": [[\"ab\", \"c\", 3]], \"expected\": [[\"a\", \"bc\", 2], [\"ab\", \"c\", 1]], \"passed\": false}, {\"check\": \"delimiter occurs inside either component\", \"actual\": [[\"a\", \"b|c\", 2], [\"a|b\", \"c\", 1]], \"expected\": [[\"a\", \"b|c\", 2], [\"a|b\", \"c\", 1]], \"passed\": true}, {\"check\": \"empty components are ordered, not interchangeable\", \"actual\": [[\"\", \"x\", 3]], \"expected\": [[\"\", \"x\", 1], [\"x\", \"\", 2]], \"passed\": false}, {\"check\": \"delimiter-only boundaries remain distinct\", \"actual\": [[\"|\", \"\", 3]], \"expected\": [[\"\", \"|\", 2], [\"|\", \"\", 1]], \"passed\": false}, {\"check\": \"identical composite keys aggregate\", \"actual\": [[\"team\", \"1\", 4]], \"expected\": [[\"team\", \"1\", 4]], \"passed\": true}, {\"check\": \"signed contributions stay within their group\", \"actual\": [[\"a\", \"b\", 0], [\"a\", \"c\", 2]], \"expected\": [[\"a\", \"b\", 0], [\"a\", \"c\", 2]], \"passed\": true}, {\"check\": \"empty relation\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":31.68,"exit_code":0,"observations":[{"actual":[["a","bc",2],["ab","c",1]],"check":"unseparated component boundaries collide","expected":[["a","bc",2],["ab","c",1]],"passed":true},{"actual":[["a","b|c",2],["a|b","c",1]],"check":"delimiter occurs inside either component","expected":[["a","b|c",2],["a|b","c",1]],"passed":true},{"actual":[["","x",1],["x","",2]],"check":"empty components are ordered, not interchangeable","expected":[["","x",1],["x","",2]],"passed":true},{"actual":[["","|",2],["|","",1]],"check":"delimiter-only boundaries remain distinct","expected":[["","|",2],["|","",1]],"passed":true},{"actual":[["team","1",4]],"check":"identical composite keys aggregate","expected":[["team","1",4]],"passed":true},{"actual":[["a","b",0],["a","c",2]],"check":"signed contributions stay within their group","expected":[["a","b",0],["a","c",2]],"passed":true},{"actual":[],"check":"empty relation","expected":[],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"unseparated component boundaries collide\", \"actual\": [[\"a\", \"bc\", 2], [\"ab\", \"c\", 1]], \"expected\": [[\"a\", \"bc\", 2], [\"ab\", \"c\", 1]], \"passed\": true}, {\"check\": \"delimiter occurs inside either component\", \"actual\": [[\"a\", \"b|c\", 2], [\"a|b\", \"c\", 1]], \"expected\": [[\"a\", \"b|c\", 2], [\"a|b\", \"c\", 1]], \"passed\": true}, {\"check\": \"empty components are ordered, not interchangeable\", \"actual\": [[\"\", \"x\", 1], [\"x\", \"\", 2]], \"expected\": [[\"\", \"x\", 1], [\"x\", \"\", 2]], \"passed\": true}, {\"check\": \"delimiter-only boundaries remain distinct\", \"actual\": [[\"\", \"|\", 2], [\"|\", \"\", 1]], \"expected\": [[\"\", \"|\", 2], [\"|\", \"\", 1]], \"passed\": true}, {\"check\": \"identical composite keys aggregate\", \"actual\": [[\"team\", \"1\", 4]], \"expected\": [[\"team\", \"1\", 4]], \"passed\": true}, {\"check\": \"signed contributions stay within their group\", \"actual\": [[\"a\", \"b\", 0], [\"a\", \"c\", 2]], \"expected\": [[\"a\", \"b\", 0], [\"a\", \"c\", 2]], \"passed\": true}, {\"check\": \"empty relation\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}