{"abstract":"A sliding manifest window loses discontinuity history when old segments disappear.","category":"Streaming segment lifecycle","checks":4,"contract":"Each segment marks whether a discontinuity precedes it. When pruning sequences below keep_from, advance the retained-window discontinuity base by only pruned markers.","contract_signature":"base, segments, keep_from","evaluation_group":"xmed-discontinuity-base-increments-on-prune","failed_approach":"Including the first retained segment marker counts it both in the base and retained list.","family":"xmed-discontinuity-base-increments-on-prune","id":"FA-11116","implementations":{"attempt":{"sha256":"c21b2f2a73ddd2ec5f276a80465138355349da629313113617979c484c59058f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(base, segments, keep_from):\n    return base+sum(bool(discontinuity) for sequence,discontinuity in segments if sequence<=keep_from)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*(3, [[10, False], [11, True], [12, True]], 12)),4)\ncheck('fixture 2',solve(*(0, [[1, True]], 1)),0)\ncheck('fixture 3',solve(*(2, [], 10)),2)\ncheck('fixture 4',solve(*(1, [[2, True], [3, True]], 4)),3)\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":"233430fc60f94f3118dd3a3ce7590ef175797c87f5236380becd1b759427eb72","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(base, segments, keep_from):\n    return base\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*(3, [[10, False], [11, True], [12, True]], 12)),4)\ncheck('fixture 2',solve(*(0, [[1, True]], 1)),0)\ncheck('fixture 3',solve(*(2, [], 10)),2)\ncheck('fixture 4',solve(*(1, [[2, True], [3, True]], 4)),3)\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-discontinuity-base-increments-on-prune","generated_at":"2026-09-29T14:38:45.037532+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":"A sliding manifest window loses discontinuity history when old segments disappear.","sha256":"331abf521fa7f33247054bcec84020e5e86e95066175fc2ec0bd79e8eee8b409","title":"Discontinuity base increments on prune · 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":39.986,"exit_code":1,"observations":[{"actual":5,"check":"fixture 1","expected":4,"passed":false},{"actual":1,"check":"fixture 2","expected":0,"passed":false},{"actual":2,"check":"fixture 3","expected":2,"passed":true},{"actual":3,"check":"fixture 4","expected":3,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 5, \"expected\": 4, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": 1, \"expected\": 0, \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": 3, \"expected\": 3, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.871,"exit_code":1,"observations":[{"actual":3,"check":"fixture 1","expected":4,"passed":false},{"actual":0,"check":"fixture 2","expected":0,"passed":true},{"actual":2,"check":"fixture 3","expected":2,"passed":true},{"actual":1,"check":"fixture 4","expected":3,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 3, \"expected\": 4, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": 1, \"expected\": 3, \"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."}}