{"abstract":"Upstream attempt history preserves equal statuses.","category":"Proxy forwarding","checks":4,"contract":"Given attempts, upstream attempt history preserves equal statuses. Return the protocol decision or transformed value; fields are validated and fixtures state boundary outcomes.","evaluation_group":"xh-upstream-attempt-history-preserves-equal-statuses","failed_approach":"The attempted repair uses `[{\"attempt\":1,\"status\":attempts[-1][0],\"elapsed\":attempts[-1][1]}] if attempts else []` and still violates a separate fixture.","family":"xh-upstream-attempt-history-preserves-equal-statuses","id":"FA-7076","implementations":{"attempt":{"sha256":"26467563fbdb794944db75402ed66628028bc480922e8f4a567cbbd798d046fb","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(attempts):\n    return [{\"attempt\":1,\"status\":attempts[-1][0],\"elapsed\":attempts[-1][1]}] if attempts else []\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve([(502, 2), (502, 2), (200, 1)]), [{'attempt': 1, 'status': 502, 'elapsed': 2}, {'attempt': 2, 'status': 502, 'elapsed': 2}, {'attempt': 3, 'status': 200, 'elapsed': 1}])\", \"check('fixture 2', solve([]), [])\", \"check('fixture 3', solve([(200, 1)]), [{'attempt': 1, 'status': 200, 'elapsed': 1}])\", \"check('fixture 4', solve([(503, 2), (200, 3)]), [{'attempt': 1, 'status': 503, 'elapsed': 2}, {'attempt': 2, 'status': 200, 'elapsed': 3}])\"]\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":"3c2d54cb7860fa0f7b9ee89ade20d4fc031ae0edeeaa74bf1a9f8a93453b8802","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(attempts):\n    return [{\"attempt\":i+1,\"status\":status,\"elapsed\":elapsed} for i,(status,elapsed) in enumerate(dict.fromkeys(attempts))]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve([(502, 2), (502, 2), (200, 1)]), [{'attempt': 1, 'status': 502, 'elapsed': 2}, {'attempt': 2, 'status': 502, 'elapsed': 2}, {'attempt': 3, 'status': 200, 'elapsed': 1}])\", \"check('fixture 2', solve([]), [])\", \"check('fixture 3', solve([(200, 1)]), [{'attempt': 1, 'status': 200, 'elapsed': 1}])\", \"check('fixture 4', solve([(503, 2), (200, 3)]), [{'attempt': 1, 'status': 503, 'elapsed': 2}, {'attempt': 2, 'status': 200, 'elapsed': 3}])\"]\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":"7d1f19651ea9848773c9e304039228417922c8aa24c060c2782508998adbf065","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(attempts):\n    return [{\"attempt\":i+1,\"status\":status,\"elapsed\":elapsed} for i,(status,elapsed) in enumerate(attempts)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\n_fixtures = [\"check('fixture 1', solve([(502, 2), (502, 2), (200, 1)]), [{'attempt': 1, 'status': 502, 'elapsed': 2}, {'attempt': 2, 'status': 502, 'elapsed': 2}, {'attempt': 3, 'status': 200, 'elapsed': 1}])\", \"check('fixture 2', solve([]), [])\", \"check('fixture 3', solve([(200, 1)]), [{'attempt': 1, 'status': 200, 'elapsed': 1}])\", \"check('fixture 4', solve([(503, 2), (200, 3)]), [{'attempt': 1, 'status': 503, 'elapsed': 2}, {'attempt': 2, 'status': 200, 'elapsed': 3}])\"]\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-upstream-attempt-history-preserves-equal-statuses","generated_at":"2026-09-29T14:38:08.062766+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic proxy forwarding model isolates the upstream-attempt-history-preserves-equal-statuses policy at a network component boundary.","repair":"Apply the explicit upstream-attempt-history-preserves-equal-statuses contract, including the tested boundary and negative cases.","root_cause":"The faulty implementation uses `[{\"attempt\":i+1,\"status\":status,\"elapsed\":elapsed} for i,(status,elapsed) in enumerate(dict.fromkeys(attempts))]` for the upstream-attempt-history-preserves-equal-statuses decision.","sha256":"adea1382659483d39fb7f611d3000643ac34b46e116698adf327fdf4a3894d03","title":"Upstream attempt history preserves equal statuses · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":33.036,"exit_code":1,"observations":[{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[{"attempt":1,"elapsed":1,"status":200}],"check":"fixture 3","expected":[{"attempt":1,"elapsed":1,"status":200}],"passed":true},{"actual":[{"attempt":1,"elapsed":3,"status":200}],"check":"fixture 4","expected":[{"attempt":1,"elapsed":2,"status":503},{"attempt":2,"elapsed":3,"status":200}],"passed":false},{"actual":[{"attempt":1,"elapsed":1,"status":200}],"check":"fixture 1","expected":[{"attempt":1,"elapsed":2,"status":502},{"attempt":2,"elapsed":2,"status":502},{"attempt":3,"elapsed":1,"status":200}],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"expected\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 3}], \"expected\": [{\"attempt\": 1, \"status\": 503, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 200, \"elapsed\": 3}], \"passed\": false}, {\"check\": \"fixture 1\", \"actual\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"expected\": [{\"attempt\": 1, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 3, \"status\": 200, \"elapsed\": 1}], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":33.089,"exit_code":1,"observations":[{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[{"attempt":1,"elapsed":1,"status":200}],"check":"fixture 3","expected":[{"attempt":1,"elapsed":1,"status":200}],"passed":true},{"actual":[{"attempt":1,"elapsed":2,"status":503},{"attempt":2,"elapsed":3,"status":200}],"check":"fixture 4","expected":[{"attempt":1,"elapsed":2,"status":503},{"attempt":2,"elapsed":3,"status":200}],"passed":true},{"actual":[{"attempt":1,"elapsed":2,"status":502},{"attempt":2,"elapsed":1,"status":200}],"check":"fixture 1","expected":[{"attempt":1,"elapsed":2,"status":502},{"attempt":2,"elapsed":2,"status":502},{"attempt":3,"elapsed":1,"status":200}],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"expected\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [{\"attempt\": 1, \"status\": 503, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 200, \"elapsed\": 3}], \"expected\": [{\"attempt\": 1, \"status\": 503, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 200, \"elapsed\": 3}], \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": [{\"attempt\": 1, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 200, \"elapsed\": 1}], \"expected\": [{\"attempt\": 1, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 3, \"status\": 200, \"elapsed\": 1}], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":35.533,"exit_code":0,"observations":[{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[{"attempt":1,"elapsed":1,"status":200}],"check":"fixture 3","expected":[{"attempt":1,"elapsed":1,"status":200}],"passed":true},{"actual":[{"attempt":1,"elapsed":2,"status":503},{"attempt":2,"elapsed":3,"status":200}],"check":"fixture 4","expected":[{"attempt":1,"elapsed":2,"status":503},{"attempt":2,"elapsed":3,"status":200}],"passed":true},{"actual":[{"attempt":1,"elapsed":2,"status":502},{"attempt":2,"elapsed":2,"status":502},{"attempt":3,"elapsed":1,"status":200}],"check":"fixture 1","expected":[{"attempt":1,"elapsed":2,"status":502},{"attempt":2,"elapsed":2,"status":502},{"attempt":3,"elapsed":1,"status":200}],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"expected\": [{\"attempt\": 1, \"status\": 200, \"elapsed\": 1}], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [{\"attempt\": 1, \"status\": 503, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 200, \"elapsed\": 3}], \"expected\": [{\"attempt\": 1, \"status\": 503, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 200, \"elapsed\": 3}], \"passed\": true}, {\"check\": \"fixture 1\", \"actual\": [{\"attempt\": 1, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 3, \"status\": 200, \"elapsed\": 1}], \"expected\": [{\"attempt\": 1, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 2, \"status\": 502, \"elapsed\": 2}, {\"attempt\": 3, \"status\": 200, \"elapsed\": 1}], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}