{"abstract":"Forwarded chain appends current hop.","category":"Proxy forwarding","checks":4,"contract":"Bounded offline decision model: forwarded chain appends current hop. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.","evaluation_group":"xh-forwarded-chain-appends-current-hop","failed_approach":"The attempted repair uses `[hop]` and still violates a separate fixture.","family":"xh-forwarded-chain-appends-current-hop","id":"FA-6961","implementations":{"attempt":{"sha256":"d94e33500fab4199e08bed735131ea8be6fdc5f860a3b3cf360c6dd94a29323a","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(chain, hop):\n    return [hop]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve(['a'], 'b'), ['a', 'b'])\", \"check('fixture 2', solve([], 'a'), ['a'])\", \"check('fixture 3', solve(['a', 'b'], 'c'), ['a', 'b', 'c'])\", \"check('fixture 4', solve(['a'], 'a'), ['a', 'a'])\"]\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":"8fd45df04fbb206db0c2761991144a41ee4f0867aa5674a71db668c90991aa94","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(chain, hop):\n    return [hop]+chain\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve(['a'], 'b'), ['a', 'b'])\", \"check('fixture 2', solve([], 'a'), ['a'])\", \"check('fixture 3', solve(['a', 'b'], 'c'), ['a', 'b', 'c'])\", \"check('fixture 4', solve(['a'], 'a'), ['a', 'a'])\"]\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":"7ee23c1d522acf0f547619f7ca84e8d1f0c4daeb96f88ecc7bed71793b40678c","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(chain, hop):\n    return chain+[hop]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve(['a'], 'b'), ['a', 'b'])\", \"check('fixture 2', solve([], 'a'), ['a'])\", \"check('fixture 3', solve(['a', 'b'], 'c'), ['a', 'b', 'c'])\", \"check('fixture 4', solve(['a'], 'a'), ['a', 'a'])\"]\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-forwarded-chain-appends-current-hop","generated_at":"2026-09-29T14:38:07.128698+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic proxy forwarding model isolates the forwarded-chain-appends-current-hop policy at a network component boundary.","repair":"Apply the explicit forwarded-chain-appends-current-hop contract, including the tested boundary and negative cases.","root_cause":"The faulty implementation uses `[hop]+chain` for the forwarded-chain-appends-current-hop decision.","sha256":"6010cb891432cd212d5363524f7d6ecaf746ca53c24bcf82e9e6313095b20a8a","title":"Forwarded chain appends current hop · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":36.455,"exit_code":1,"observations":[{"actual":["a"],"check":"fixture 2","expected":["a"],"passed":true},{"actual":["c"],"check":"fixture 3","expected":["a","b","c"],"passed":false},{"actual":["a"],"check":"fixture 4","expected":["a","a"],"passed":false},{"actual":["b"],"check":"fixture 1","expected":["a","b"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [\"c\"], \"expected\": [\"a\", \"b\", \"c\"], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [\"a\"], \"expected\": [\"a\", \"a\"], \"passed\": false}, {\"check\": \"fixture 1\", \"actual\": [\"b\"], \"expected\": [\"a\", \"b\"], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":130.928,"exit_code":1,"observations":[{"actual":["a"],"check":"fixture 2","expected":["a"],"passed":true},{"actual":["c","a","b"],"check":"fixture 3","expected":["a","b","c"],"passed":false},{"actual":["a","a"],"check":"fixture 4","expected":["a","a"],"passed":true},{"actual":["b","a"],"check":"fixture 1","expected":["a","b"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [\"c\", \"a\", \"b\"], \"expected\": [\"a\", \"b\", \"c\"], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [\"a\", \"a\"], \"expected\": [\"a\", \"a\"], \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": [\"b\", \"a\"], \"expected\": [\"a\", \"b\"], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":33.468,"exit_code":0,"observations":[{"actual":["a"],"check":"fixture 2","expected":["a"],"passed":true},{"actual":["a","b","c"],"check":"fixture 3","expected":["a","b","c"],"passed":true},{"actual":["a","a"],"check":"fixture 4","expected":["a","a"],"passed":true},{"actual":["a","b"],"check":"fixture 1","expected":["a","b"],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [\"a\", \"b\", \"c\"], \"expected\": [\"a\", \"b\", \"c\"], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [\"a\", \"a\"], \"expected\": [\"a\", \"a\"], \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": [\"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}