{"abstract":"Ipv4 and ipv6 endpoint identities remain distinct.","category":"Network routing","checks":4,"contract":"Bounded offline decision model: ipv4 and ipv6 endpoint identities remain distinct. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.","contract_signature":"a, b","evaluation_group":"xh-ipv4-and-ipv6-endpoint-identities-remain-distinct","failed_approach":"The attempted repair uses `a == b` and still violates a separate fixture.","family":"xh-ipv4-and-ipv6-endpoint-identities-remain-distinct","id":"FA-7181","implementations":{"attempt":{"sha256":"a54b75c950ab2797d7e20ff6f3a16613a783f5f420325ecc13e542a61413d331","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport ipaddress\nimport re\nfrom urllib.parse import urlsplit, urljoin\nN = 1\nobservations = []\ndef solve(a, b):\n    return a == b\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve('2001:db8::1', '2001:db8:0:0:0:0:0:1'), True)\", \"check('fixture 2', solve('::ffff:192.0.2.1', '192.0.2.1'), False)\", \"check('fixture 3', solve('::1', '::1'), True)\", \"check('fixture 4', solve('192.0.2.1', '192.0.2.2'), False)\"]\nfor _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:\n    exec(_line)\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":"a6db31b3b08150876fc3dee6ad8b60ed63a80d14d06259f31adc4b467a38bb72","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport ipaddress\nimport re\nfrom urllib.parse import urlsplit, urljoin\nN = 1\nobservations = []\ndef solve(a, b):\n    return a.split(\":\")[-1] == b.split(\":\")[-1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve('2001:db8::1', '2001:db8:0:0:0:0:0:1'), True)\", \"check('fixture 2', solve('::ffff:192.0.2.1', '192.0.2.1'), False)\", \"check('fixture 3', solve('::1', '::1'), True)\", \"check('fixture 4', solve('192.0.2.1', '192.0.2.2'), False)\"]\nfor _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:\n    exec(_line)\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":"Bounded deterministic policy model over validated inputs; not a complete protocol stack or an interoperability claim. The five variants rotate the same explicit fixture set. 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":"xh-ipv4-and-ipv6-endpoint-identities-remain-distinct","generated_at":"2026-09-29T14:38:09.132953+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic network routing model isolates the ipv4-and-ipv6-endpoint-identities-remain-distinct policy at a network component boundary.","root_cause":"The faulty implementation uses `a.split(\":\")[-1] == b.split(\":\")[-1]` for the ipv4-and-ipv6-endpoint-identities-remain-distinct decision.","sha256":"a6222cbeefbddec5f5df2fb1e3824cbedd3e5477ac252d90a046afd4c6acb440","title":"Ipv4 and ipv6 endpoint identities remain distinct · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":43.419,"exit_code":1,"observations":[{"actual":false,"check":"fixture 2","expected":false,"passed":true},{"actual":true,"check":"fixture 3","expected":true,"passed":true},{"actual":false,"check":"fixture 4","expected":false,"passed":true},{"actual":false,"check":"fixture 1","expected":true,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": false, \"expected\": true, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":51.899,"exit_code":1,"observations":[{"actual":true,"check":"fixture 2","expected":false,"passed":false},{"actual":true,"check":"fixture 3","expected":true,"passed":true},{"actual":false,"check":"fixture 4","expected":false,"passed":true},{"actual":true,"check":"fixture 1","expected":true,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"fixture 1\", \"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."}}