{"abstract":"Zero weight upstreams never receive traffic.","category":"Network routing","checks":4,"contract":"Bounded offline decision model: zero weight upstreams never receive traffic. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.","evaluation_group":"xh-zero-weight-upstreams-never-receive-traffic","failed_approach":"The attempted repair uses `[i for i,w in enumerate(weights) if w >= 0]` and still violates a separate fixture.","family":"xh-zero-weight-upstreams-never-receive-traffic","id":"FA-7131","implementations":{"attempt":{"sha256":"97af31cc34eea656c09ed78f752b431ae60716d5c58fea465c0bef0e40955539","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(weights):\n    return [i for i,w in enumerate(weights) if w >= 0]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve([0, 2, 0]), [1])\", \"check('fixture 2', solve([]), [])\", \"check('fixture 3', solve([1, 2]), [0, 1])\", \"check('fixture 4', solve([0]), [])\"]\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":"87cb62c6bb1112f95bf0b1c48f27cf5f6ab632daa543963fd215a9c6c9c3c757","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(weights):\n    return list(range(len(weights)))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve([0, 2, 0]), [1])\", \"check('fixture 2', solve([]), [])\", \"check('fixture 3', solve([1, 2]), [0, 1])\", \"check('fixture 4', solve([0]), [])\"]\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":"6d317ce1edf9ddc9ee2fe35b06685fb94f053e6089b529880eef7ec50bda8bbc","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(weights):\n    return [i for i,w in enumerate(weights) if w > 0]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve([0, 2, 0]), [1])\", \"check('fixture 2', solve([]), [])\", \"check('fixture 3', solve([1, 2]), [0, 1])\", \"check('fixture 4', solve([0]), [])\"]\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-zero-weight-upstreams-never-receive-traffic","generated_at":"2026-09-29T14:38:08.573726+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic network routing model isolates the zero-weight-upstreams-never-receive-traffic policy at a network component boundary.","repair":"Apply the explicit zero-weight-upstreams-never-receive-traffic contract, including the tested boundary and negative cases.","root_cause":"The faulty implementation uses `list(range(len(weights)))` for the zero-weight-upstreams-never-receive-traffic decision.","sha256":"7fa9e9283e708a4ca790f3301cd03d6cd29db6d7f4d2fef41d5e0b95e6741ce0","title":"Zero weight upstreams never receive traffic · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":36.789,"exit_code":1,"observations":[{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[0,1],"check":"fixture 3","expected":[0,1],"passed":true},{"actual":[0],"check":"fixture 4","expected":[],"passed":false},{"actual":[0,1,2],"check":"fixture 1","expected":[1],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [0, 1], \"expected\": [0, 1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0], \"expected\": [], \"passed\": false}, {\"check\": \"fixture 1\", \"actual\": [0, 1, 2], \"expected\": [1], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":34.428,"exit_code":1,"observations":[{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[0,1],"check":"fixture 3","expected":[0,1],"passed":true},{"actual":[0],"check":"fixture 4","expected":[],"passed":false},{"actual":[0,1,2],"check":"fixture 1","expected":[1],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [0, 1], \"expected\": [0, 1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0], \"expected\": [], \"passed\": false}, {\"check\": \"fixture 1\", \"actual\": [0, 1, 2], \"expected\": [1], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":36.835,"exit_code":0,"observations":[{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[0,1],"check":"fixture 3","expected":[0,1],"passed":true},{"actual":[],"check":"fixture 4","expected":[],"passed":true},{"actual":[1],"check":"fixture 1","expected":[1],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [0, 1], \"expected\": [0, 1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": [1], \"expected\": [1], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}