{"abstract":"Connection nominated fields are removed case insensitively.","category":"Proxy forwarding","checks":4,"contract":"Bounded offline decision model: connection nominated fields are removed case insensitively. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.","contract_signature":"headers, tokens","evaluation_group":"xh-connection-nominated-fields-are-removed-case-insensitively","failed_approach":"The attempted repair uses `{k:v for k,v in headers.items() if k not in tokens}` and still violates a separate fixture.","family":"xh-connection-nominated-fields-are-removed-case-insensitively","id":"FA-6956","implementations":{"attempt":{"sha256":"2ba5530d45b7ac26fbc2135e6fe065a739ed028bf9d85ac83758539453ae2894","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(headers, tokens):\n    return {k:v for k,v in headers.items() if k not in tokens}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve({'Connection': 'X', 'X': 'v', 'End': 'e'}, ['x']), {'End': 'e'})\", \"check('fixture 2', solve({}, []), {})\", \"check('fixture 3', solve({'end': 'e'}, []), {'end': 'e'})\", \"check('fixture 4', solve({'x': 'v'}, ['X']), {})\"]\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":"f9d48f58f4e049318ac08d216cc976a16c80a24a134c961357047f64d602048a","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(headers, tokens):\n    return {k:v for k,v in headers.items() if k.lower() != \"connection\"}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve({'Connection': 'X', 'X': 'v', 'End': 'e'}, ['x']), {'End': 'e'})\", \"check('fixture 2', solve({}, []), {})\", \"check('fixture 3', solve({'end': 'e'}, []), {'end': 'e'})\", \"check('fixture 4', solve({'x': 'v'}, ['X']), {})\"]\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-connection-nominated-fields-are-removed-case-insensitively","generated_at":"2026-09-29T14:38:07.131720+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic proxy forwarding model isolates the connection-nominated-fields-are-removed-case-insensitively policy at a network component boundary.","root_cause":"The faulty implementation uses `{k:v for k,v in headers.items() if k.lower() != \"connection\"}` for the connection-nominated-fields-are-removed-case-insensitively decision.","sha256":"623232b64260b1a9dd9ce5a25c2e37e617e549d3aebcaacffa71f64ea80941c5","title":"Connection nominated fields are removed case insensitively · 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":37.8,"exit_code":1,"observations":[{"actual":{},"check":"fixture 2","expected":{},"passed":true},{"actual":{"end":"e"},"check":"fixture 3","expected":{"end":"e"},"passed":true},{"actual":{"x":"v"},"check":"fixture 4","expected":{},"passed":false},{"actual":{"Connection":"X","End":"e","X":"v"},"check":"fixture 1","expected":{"End":"e"},"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": {\"end\": \"e\"}, \"expected\": {\"end\": \"e\"}, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": {\"x\": \"v\"}, \"expected\": {}, \"passed\": false}, {\"check\": \"fixture 1\", \"actual\": {\"Connection\": \"X\", \"X\": \"v\", \"End\": \"e\"}, \"expected\": {\"End\": \"e\"}, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":132.237,"exit_code":1,"observations":[{"actual":{},"check":"fixture 2","expected":{},"passed":true},{"actual":{"end":"e"},"check":"fixture 3","expected":{"end":"e"},"passed":true},{"actual":{"x":"v"},"check":"fixture 4","expected":{},"passed":false},{"actual":{"End":"e","X":"v"},"check":"fixture 1","expected":{"End":"e"},"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": {\"end\": \"e\"}, \"expected\": {\"end\": \"e\"}, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": {\"x\": \"v\"}, \"expected\": {}, \"passed\": false}, {\"check\": \"fixture 1\", \"actual\": {\"X\": \"v\", \"End\": \"e\"}, \"expected\": {\"End\": \"e\"}, \"passed\": false}], \"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."}}