{"abstract":"Weak etag comparison ignores weakness markers.","category":"HTTP caching","checks":4,"contract":"Bounded offline decision model: weak etag comparison ignores weakness markers. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.","evaluation_group":"xh-weak-etag-comparison-ignores-weakness-markers","failed_approach":"The attempted repair uses `left.lower().removeprefix('w/') == right.lower().removeprefix('w/')` and still violates a separate fixture.","family":"xh-weak-etag-comparison-ignores-weakness-markers","id":"FA-6791","implementations":{"attempt":{"sha256":"07c88a5186a2c41fde55b74132fff1b8a7356ce8fde2bf73c21607f78e42d09c","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(left, right):\n    return left.lower().removeprefix('w/') == right.lower().removeprefix('w/')\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = ['check(\\'fixture 1\\', solve(\\'W/\"a\"\\', \\'\"a\"\\'), True)', 'check(\\'fixture 2\\', solve(\\'\"A\"\\', \\'\"a\"\\'), False)', 'check(\\'fixture 3\\', solve(\\'\"a\"\\', \\'\"a\"\\'), True)', 'check(\\'fixture 4\\', solve(\\'\"b\"\\', \\'\"a\"\\'), 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":"d32d731a988fc2e368cecfe6642fd43edb5973689b2ecc4a79ed632ff2cd6bce","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(left, right):\n    return left == right\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = ['check(\\'fixture 1\\', solve(\\'W/\"a\"\\', \\'\"a\"\\'), True)', 'check(\\'fixture 2\\', solve(\\'\"A\"\\', \\'\"a\"\\'), False)', 'check(\\'fixture 3\\', solve(\\'\"a\"\\', \\'\"a\"\\'), True)', 'check(\\'fixture 4\\', solve(\\'\"b\"\\', \\'\"a\"\\'), 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"},"fixed":{"sha256":"988934ad5f517f23823fabc5f53328745295d77fbc50ed56cb4a722f4582a069","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(left, right):\n    return left.removeprefix('W/') == right.removeprefix('W/')\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = ['check(\\'fixture 1\\', solve(\\'W/\"a\"\\', \\'\"a\"\\'), True)', 'check(\\'fixture 2\\', solve(\\'\"A\"\\', \\'\"a\"\\'), False)', 'check(\\'fixture 3\\', solve(\\'\"a\"\\', \\'\"a\"\\'), True)', 'check(\\'fixture 4\\', solve(\\'\"b\"\\', \\'\"a\"\\'), 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-weak-etag-comparison-ignores-weakness-markers","generated_at":"2026-09-29T14:38:05.205619+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic http caching model isolates the weak-etag-comparison-ignores-weakness-markers policy at a network component boundary.","repair":"Apply the explicit weak-etag-comparison-ignores-weakness-markers contract, including the tested boundary and negative cases.","root_cause":"The faulty implementation uses `left == right` for the weak-etag-comparison-ignores-weakness-markers decision.","sha256":"890c612a250ff52c38e80c8d8fdfa862e935d1cd3a3f2b3893c37de90ac6c6da","title":"Weak etag comparison ignores weakness markers · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":38.98,"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"},"broken":{"elapsed_ms":36.2,"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"},"fixed":{"elapsed_ms":40.363,"exit_code":0,"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":true,"check":"fixture 1","expected":true,"passed":true}],"passed":true,"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\": true, \"expected\": true, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}