{"abstract":"Media data is appended before its required decoder initialization data.","category":"Streaming segment lifecycle","checks":4,"contract":"Plan append operations for one media segment: append its non-None initialization segment first only when not already loaded.","evaluation_group":"xmed-init-segment-before-media","failed_approach":"Appending initialization before every segment redundantly resets unchanged decoder state.","family":"xmed-init-segment-before-media","id":"FA-11136","implementations":{"attempt":{"sha256":"04cdf3a339794a9fe6920d31fb0797f33cb09f34d655bd147b08afb900d3d744","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(loaded_init, required_init, media):\n    return ([[\"init\",required_init]] if required_init is not None else [])+[[\"media\",media]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*('old', 'new', 's1')),[['init', 'new'], ['media', 's1']])\ncheck('fixture 2',solve(*('same', 'same', 's2')),[['media', 's2']])\ncheck('fixture 3',solve(*(None, None, 's3')),[['media', 's3']])\ncheck('fixture 4',solve(*(None, 'init', 's4')),[['init', 'init'], ['media', 's4']])\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":"9fff7f1e799a3fa969ef180edfb73a06f7adff5cd3abf5032df57a7a5695ceee","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(loaded_init, required_init, media):\n    return [[\"media\",media]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*('old', 'new', 's1')),[['init', 'new'], ['media', 's1']])\ncheck('fixture 2',solve(*('same', 'same', 's2')),[['media', 's2']])\ncheck('fixture 3',solve(*(None, None, 's3')),[['media', 's3']])\ncheck('fixture 4',solve(*(None, 'init', 's4')),[['init', 'init'], ['media', 's4']])\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":"344ec7e95781d5997379f0b4887560c2083b353e98b0b8b7ebdcabc07704c536","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(loaded_init, required_init, media):\n    return ([] if required_init is None or required_init==loaded_init else [[\"init\",required_init]])+[[\"media\",media]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*('old', 'new', 's1')),[['init', 'new'], ['media', 's1']])\ncheck('fixture 2',solve(*('same', 'same', 's2')),[['media', 's2']])\ncheck('fixture 3',solve(*(None, None, 's3')),[['media', 's3']])\ncheck('fixture 4',solve(*(None, 'init', 's4')),[['init', 'init'], ['media', 's4']])\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":" 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":"xmed-init-segment-before-media","generated_at":"2026-09-29T14:38:45.316607+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic local media controller stage; metadata and downloaded data are supplied explicitly. No external player, service or codec is required.","repair":"Preserve the media contract: Plan append operations for one media segment: append its non-None initialization segment first only when not already loaded.","root_cause":"Media data is appended before its required decoder initialization data.","sha256":"7975bd6738905ad3ff89f11c1e00f8c051e7add4a566fd0843d5d88bca569247","title":"Init segment before media · case 01","variant":1,"variant_policy":"The five numbered cases rerun the same authored boundary fixtures; they are reproducibility runs, not independent input variants.","verification":{"attempt":{"elapsed_ms":36.637,"exit_code":1,"observations":[{"actual":[["init","new"],["media","s1"]],"check":"fixture 1","expected":[["init","new"],["media","s1"]],"passed":true},{"actual":[["init","same"],["media","s2"]],"check":"fixture 2","expected":[["media","s2"]],"passed":false},{"actual":[["media","s3"]],"check":"fixture 3","expected":[["media","s3"]],"passed":true},{"actual":[["init","init"],["media","s4"]],"check":"fixture 4","expected":[["init","init"],["media","s4"]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[\"init\", \"new\"], [\"media\", \"s1\"]], \"expected\": [[\"init\", \"new\"], [\"media\", \"s1\"]], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [[\"init\", \"same\"], [\"media\", \"s2\"]], \"expected\": [[\"media\", \"s2\"]], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [[\"media\", \"s3\"]], \"expected\": [[\"media\", \"s3\"]], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[\"init\", \"init\"], [\"media\", \"s4\"]], \"expected\": [[\"init\", \"init\"], [\"media\", \"s4\"]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.583,"exit_code":1,"observations":[{"actual":[["media","s1"]],"check":"fixture 1","expected":[["init","new"],["media","s1"]],"passed":false},{"actual":[["media","s2"]],"check":"fixture 2","expected":[["media","s2"]],"passed":true},{"actual":[["media","s3"]],"check":"fixture 3","expected":[["media","s3"]],"passed":true},{"actual":[["media","s4"]],"check":"fixture 4","expected":[["init","init"],["media","s4"]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[\"media\", \"s1\"]], \"expected\": [[\"init\", \"new\"], [\"media\", \"s1\"]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [[\"media\", \"s2\"]], \"expected\": [[\"media\", \"s2\"]], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[\"media\", \"s3\"]], \"expected\": [[\"media\", \"s3\"]], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[\"media\", \"s4\"]], \"expected\": [[\"init\", \"init\"], [\"media\", \"s4\"]], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.452,"exit_code":0,"observations":[{"actual":[["init","new"],["media","s1"]],"check":"fixture 1","expected":[["init","new"],["media","s1"]],"passed":true},{"actual":[["media","s2"]],"check":"fixture 2","expected":[["media","s2"]],"passed":true},{"actual":[["media","s3"]],"check":"fixture 3","expected":[["media","s3"]],"passed":true},{"actual":[["init","init"],["media","s4"]],"check":"fixture 4","expected":[["init","init"],["media","s4"]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[\"init\", \"new\"], [\"media\", \"s1\"]], \"expected\": [[\"init\", \"new\"], [\"media\", \"s1\"]], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [[\"media\", \"s2\"]], \"expected\": [[\"media\", \"s2\"]], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[\"media\", \"s3\"]], \"expected\": [[\"media\", \"s3\"]], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[\"init\", \"init\"], [\"media\", \"s4\"]], \"expected\": [[\"init\", \"init\"], [\"media\", \"s4\"]], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}