{"abstract":"Playback starts at the beginning of the callback instead of the scheduled offset.","category":"Audio playback scheduling","checks":4,"contract":"Render exactly nonnegative size samples for a sound starting after nonnegative delay frames, with silence before start and after source end.","evaluation_group":"xaud-scheduled-start-silence-prefix","failed_approach":"Appending delay silence postpones silence rather than the sound onset.","family":"xaud-scheduled-start-silence-prefix","id":"FA-11011","implementations":{"attempt":{"sha256":"b2534cfbf33860d16c1eb2401376fae957b7e5e8e7ec0bb9fba2984066ae9787","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(samples, delay, size):\n    return list(samples[:max(0,size-delay)])+[0]*min(delay,size)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([1, 2], 2, 5)),[0, 0, 1, 2, 0])\ncheck('fixture 2',solve(*([1, 2], 0, 2)),[1, 2])\ncheck('fixture 3',solve(*([1], 4, 2)),[0, 0])\ncheck('fixture 4',solve(*([], 1, 3)),[0, 0, 0])\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":"bde25f98f33725ec78a2c7861bfcbe04380b919932ea6ce71dbf547b79ecb099","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(samples, delay, size):\n    return list(samples[:size])+[0]*max(0,size-len(samples))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([1, 2], 2, 5)),[0, 0, 1, 2, 0])\ncheck('fixture 2',solve(*([1, 2], 0, 2)),[1, 2])\ncheck('fixture 3',solve(*([1], 4, 2)),[0, 0])\ncheck('fixture 4',solve(*([], 1, 3)),[0, 0, 0])\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":"ba36cf38795c7c8c4c0675170a06e19897934a0fdbdfee5eaa59f06454474afc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(samples, delay, size):\n    return ([0]*delay+list(samples))[:size]+[0]*max(0,size-delay-len(samples))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([1, 2], 2, 5)),[0, 0, 1, 2, 0])\ncheck('fixture 2',solve(*([1, 2], 0, 2)),[1, 2])\ncheck('fixture 3',solve(*([1], 4, 2)),[0, 0])\ncheck('fixture 4',solve(*([], 1, 3)),[0, 0, 0])\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":"xaud-scheduled-start-silence-prefix","generated_at":"2026-09-29T14:38:44.215437+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A pure Python local audio pipeline stage with explicit sample formats and frame conventions; no real-time device or signal-spectrum claims.","repair":"Apply the explicit PCM/playback contract: Render exactly nonnegative size samples for a sound starting after nonnegative delay frames, with silence before start and after source end.","root_cause":"Playback starts at the beginning of the callback instead of the scheduled offset.","sha256":"d78faf69e94c8abdf0056c25e11d4241e681429f21da09836049205bbb1e2fa8","title":"Scheduled start silence prefix · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.636,"exit_code":1,"observations":[{"actual":[1,2,0,0],"check":"fixture 1","expected":[0,0,1,2,0],"passed":false},{"actual":[1,2],"check":"fixture 2","expected":[1,2],"passed":true},{"actual":[0,0],"check":"fixture 3","expected":[0,0],"passed":true},{"actual":[0],"check":"fixture 4","expected":[0,0,0],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [1, 2, 0, 0], \"expected\": [0, 0, 1, 2, 0], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0], \"expected\": [0, 0, 0], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.475,"exit_code":1,"observations":[{"actual":[1,2,0,0,0],"check":"fixture 1","expected":[0,0,1,2,0],"passed":false},{"actual":[1,2],"check":"fixture 2","expected":[1,2],"passed":true},{"actual":[1,0],"check":"fixture 3","expected":[0,0],"passed":false},{"actual":[0,0,0],"check":"fixture 4","expected":[0,0,0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [1, 2, 0, 0, 0], \"expected\": [0, 0, 1, 2, 0], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [1, 0], \"expected\": [0, 0], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [0, 0, 0], \"expected\": [0, 0, 0], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.665,"exit_code":0,"observations":[{"actual":[0,0,1,2,0],"check":"fixture 1","expected":[0,0,1,2,0],"passed":true},{"actual":[1,2],"check":"fixture 2","expected":[1,2],"passed":true},{"actual":[0,0],"check":"fixture 3","expected":[0,0],"passed":true},{"actual":[0,0,0],"check":"fixture 4","expected":[0,0,0],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [0, 0, 1, 2, 0], \"expected\": [0, 0, 1, 2, 0], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0, 0, 0], \"expected\": [0, 0, 0], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}