{"abstract":"One-of union accepts values matching both branches.","category":"Tool call schema validation","checks":6,"contract":"One-of is valid when exactly one predicate matches.","contract_signature":"value, predicates","evaluation_group":"w3-schema-oneof-exclusive-branch","failed_approach":"Rejecting all values matching multiple branches but not counting zero matches admits invalid values.","family":"w3-tool-call-schema-validation-oneof-exclusive-branch","id":"FA-99816","implementations":{"attempt":{"sha256":"6682672fa65f15d680d400cae2f1727d95c713fe1229c58efb4ce32f461b7b7c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(value, predicates):\n    return sum(bool(p(value)) for p in predicates)<=1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('only first',solve(N,[lambda x:type(x)is int,lambda x:x<0]),True)\ncheck('both match',solve(N,[lambda x:type(x)is int,lambda x:x>0]),False)\ncheck('only second',solve(-N,[lambda x:type(x)is str,lambda x:x<0]),True)\ncheck('no branch',solve(None,[lambda x:type(x)is int,lambda x:type(x)is str]),False)\ncheck('empty branches',solve(N,[]),False)\ncheck('one predicate',solve('x',[lambda x:type(x)is str]),True)\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":"9e4ab63ab51a54efd0958c3c21396c7b1290be83bce282dd18c4a1879fac0c15","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(value, predicates):\n    return any(p(value) for p in predicates)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('only first',solve(N,[lambda x:type(x)is int,lambda x:x<0]),True)\ncheck('both match',solve(N,[lambda x:type(x)is int,lambda x:x>0]),False)\ncheck('only second',solve(-N,[lambda x:type(x)is str,lambda x:x<0]),True)\ncheck('no branch',solve(None,[lambda x:type(x)is int,lambda x:type(x)is str]),False)\ncheck('empty branches',solve(N,[]),False)\ncheck('one predicate',solve('x',[lambda x:type(x)is str]),True)\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":"Self-contained toy JSON-like schema contract over in-memory Python values; no compatibility with a production schema standard or callable binding is claimed. 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-tool-call-schema-validation-oneof-exclusive-branch","generated_at":"2026-09-30T16:48:28.522211+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Tool argument validation prevents malformed structured payloads from entering a deterministic downstream operation.","root_cause":"The union uses any-match semantics, which belongs to an any-of rule.","sha256":"ec49b33e46c4f988dd4dc750d0ea1c9f466a64ad79eac505b73c5df06c0defb0","title":"One-of union accepts values matching both branches · 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":26.855,"exit_code":1,"observations":[{"actual":true,"check":"only first","expected":true,"passed":true},{"actual":false,"check":"both match","expected":false,"passed":true},{"actual":true,"check":"only second","expected":true,"passed":true},{"actual":true,"check":"no branch","expected":false,"passed":false},{"actual":true,"check":"empty branches","expected":false,"passed":false},{"actual":true,"check":"one predicate","expected":true,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"only first\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"both match\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"only second\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"no branch\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"empty branches\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"one predicate\", \"actual\": true, \"expected\": true, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":29.286,"exit_code":1,"observations":[{"actual":true,"check":"only first","expected":true,"passed":true},{"actual":true,"check":"both match","expected":false,"passed":false},{"actual":true,"check":"only second","expected":true,"passed":true},{"actual":false,"check":"no branch","expected":false,"passed":true},{"actual":false,"check":"empty branches","expected":false,"passed":true},{"actual":true,"check":"one predicate","expected":true,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"only first\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"both match\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"only second\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"no branch\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"empty branches\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"one predicate\", \"actual\": true, \"expected\": true, \"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."}}