{"abstract":"Policy route fallback occurs only after no policy match.","category":"Network routing","checks":4,"contract":"Given decisions, default, policy route fallback occurs only after no policy match. Return the protocol decision or transformed value; fields are validated and fixtures state boundary outcomes.","evaluation_group":"xh-policy-route-fallback-occurs-only-after-no-policy-match","failed_approach":"The attempted repair uses `next((d for d in decisions if d not in (\"continue\",\"drop\")),default)` and still violates a separate fixture.","family":"xh-policy-route-fallback-occurs-only-after-no-policy-match","id":"FA-7191","implementations":{"attempt":{"sha256":"47681d5910a2d06e20d2989315e32ee1bc516dcf7f1d006cf4d48e2e690ff9e5","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(decisions, default):\n    return next((d for d in decisions if d not in (\"continue\",\"drop\")),default)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve(['continue', 'route-a'], 'default'), 'route-a')\", \"check('fixture 2', solve(['drop', 'route-a'], 'default'), 'drop')\", \"check('fixture 3', solve(['continue'], 'default'), 'default')\", \"check('fixture 4', solve([], 'default'), 'default')\"]\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":"8ed8f860eb8642fb3852e366caab089e54ee5ea614c0596dd7bbe76da074d2a3","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(decisions, default):\n    return decisions[0] if decisions else default\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve(['continue', 'route-a'], 'default'), 'route-a')\", \"check('fixture 2', solve(['drop', 'route-a'], 'default'), 'drop')\", \"check('fixture 3', solve(['continue'], 'default'), 'default')\", \"check('fixture 4', solve([], 'default'), 'default')\"]\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"},"fixed":{"sha256":"5c5d9c6ae40413fb8a756c25d5cdac724adf53b497849b35151354d2f235ce63","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(decisions, default):\n    return next((d for d in decisions if d != \"continue\"),default)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve(['continue', 'route-a'], 'default'), 'route-a')\", \"check('fixture 2', solve(['drop', 'route-a'], 'default'), 'drop')\", \"check('fixture 3', solve(['continue'], 'default'), 'default')\", \"check('fixture 4', solve([], 'default'), 'default')\"]\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-policy-route-fallback-occurs-only-after-no-policy-match","generated_at":"2026-09-29T14:38:09.201002+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic network routing model isolates the policy-route-fallback-occurs-only-after-no-policy-match policy at a network component boundary.","repair":"Apply the explicit policy-route-fallback-occurs-only-after-no-policy-match contract, including the tested boundary and negative cases.","root_cause":"The faulty implementation uses `decisions[0] if decisions else default` for the policy-route-fallback-occurs-only-after-no-policy-match decision.","sha256":"e899642dc6a40b86f845a851ac0ced673d8301ef193f6f2f90907346a54fbe2f","title":"Policy route fallback occurs only after no policy match · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":42.906,"exit_code":1,"observations":[{"actual":"route-a","check":"fixture 2","expected":"drop","passed":false},{"actual":"default","check":"fixture 3","expected":"default","passed":true},{"actual":"default","check":"fixture 4","expected":"default","passed":true},{"actual":"route-a","check":"fixture 1","expected":"route-a","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": \"route-a\", \"expected\": \"drop\", \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": \"default\", \"expected\": \"default\", \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": \"default\", \"expected\": \"default\", \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": \"route-a\", \"expected\": \"route-a\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.661,"exit_code":1,"observations":[{"actual":"drop","check":"fixture 2","expected":"drop","passed":true},{"actual":"continue","check":"fixture 3","expected":"default","passed":false},{"actual":"default","check":"fixture 4","expected":"default","passed":true},{"actual":"continue","check":"fixture 1","expected":"route-a","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": \"drop\", \"expected\": \"drop\", \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": \"continue\", \"expected\": \"default\", \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": \"default\", \"expected\": \"default\", \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": \"continue\", \"expected\": \"route-a\", \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":44.911,"exit_code":0,"observations":[{"actual":"drop","check":"fixture 2","expected":"drop","passed":true},{"actual":"default","check":"fixture 3","expected":"default","passed":true},{"actual":"default","check":"fixture 4","expected":"default","passed":true},{"actual":"route-a","check":"fixture 1","expected":"route-a","passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": \"drop\", \"expected\": \"drop\", \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": \"default\", \"expected\": \"default\", \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": \"default\", \"expected\": \"default\", \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": \"route-a\", \"expected\": \"route-a\", \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}