{"abstract":"Concatenated clips restart their timestamps at zero and overlap earlier clips.","category":"Media timeline seeking","checks":4,"contract":"Clips are [duration,local timestamped frames], with nonnegative durations and local timestamps inside each clip. Concatenate timelines using full declared clip durations.","contract_signature":"clips","evaluation_group":"xmed-clip-concatenation-offset-by-duration","failed_approach":"Adding clip index uses item count instead of elapsed media duration.","family":"xmed-clip-concatenation-offset-by-duration","id":"FA-11271","implementations":{"attempt":{"sha256":"a31c8073173e5afebf895d2756f33564e21c4a7a3d7a0dd0a5b6a0f024342ac2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(clips):\n    return [[t+i,value] for i,(duration,frames) in enumerate(clips) for t,value in frames]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([[5, [[0, 'a'], [3, 'b']]], [4, [[0, 'c'], [2, 'd']]]],)),[[0, 'a'], [3, 'b'], [5, 'c'], [7, 'd']])\ncheck('fixture 2',solve(*([],)),[])\ncheck('fixture 3',solve(*([[2, [[0, 'a']]]],)),[[0, 'a']])\ncheck('fixture 4',solve(*([[0, []], [3, [[1, 'x']]]],)),[[1, 'x']])\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":"b9c7ff64572c17011e2e7bca04868c0ffd9b405649814fc972e3dcf0f4175c93","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(clips):\n    return [[t,value] for duration,frames in clips for t,value in frames]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([[5, [[0, 'a'], [3, 'b']]], [4, [[0, 'c'], [2, 'd']]]],)),[[0, 'a'], [3, 'b'], [5, 'c'], [7, 'd']])\ncheck('fixture 2',solve(*([],)),[])\ncheck('fixture 3',solve(*([[2, [[0, 'a']]]],)),[[0, 'a']])\ncheck('fixture 4',solve(*([[0, []], [3, [[1, 'x']]]],)),[[1, 'x']])\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-clip-concatenation-offset-by-duration","generated_at":"2026-09-29T14:38:46.459546+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.","root_cause":"Concatenated clips restart their timestamps at zero and overlap earlier clips.","sha256":"5a85aee7dffd8dfa9ef7da6b85fd428e2f381b134b154fb80c012067758a4fac","title":"Clip concatenation offset by duration · case 01","variant":1,"variant_policy":"The five numbered cases rerun the same authored boundary fixtures; they are reproducibility runs, not independent input variants.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":37.925,"exit_code":1,"observations":[{"actual":[[0,"a"],[3,"b"],[1,"c"],[3,"d"]],"check":"fixture 1","expected":[[0,"a"],[3,"b"],[5,"c"],[7,"d"]],"passed":false},{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[[0,"a"]],"check":"fixture 3","expected":[[0,"a"]],"passed":true},{"actual":[[2,"x"]],"check":"fixture 4","expected":[[1,"x"]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[0, \"a\"], [3, \"b\"], [1, \"c\"], [3, \"d\"]], \"expected\": [[0, \"a\"], [3, \"b\"], [5, \"c\"], [7, \"d\"]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[0, \"a\"]], \"expected\": [[0, \"a\"]], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[2, \"x\"]], \"expected\": [[1, \"x\"]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.704,"exit_code":1,"observations":[{"actual":[[0,"a"],[3,"b"],[0,"c"],[2,"d"]],"check":"fixture 1","expected":[[0,"a"],[3,"b"],[5,"c"],[7,"d"]],"passed":false},{"actual":[],"check":"fixture 2","expected":[],"passed":true},{"actual":[[0,"a"]],"check":"fixture 3","expected":[[0,"a"]],"passed":true},{"actual":[[1,"x"]],"check":"fixture 4","expected":[[1,"x"]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[0, \"a\"], [3, \"b\"], [0, \"c\"], [2, \"d\"]], \"expected\": [[0, \"a\"], [3, \"b\"], [5, \"c\"], [7, \"d\"]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[0, \"a\"]], \"expected\": [[0, \"a\"]], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[1, \"x\"]], \"expected\": [[1, \"x\"]], \"passed\": true}], \"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."}}