{
  "experiment": "synthetic caption structure audit",
  "performed_date": "2026-09-20",
  "fixtures": 6,
  "seeded_structural_failures": 4,
  "structural_failures_flagged": 4,
  "semantic_errors_flagged": 0,
  "semantic_ground_truth": "For semantic_error fixture, intended source sentence is: The meeting starts at ten.",
  "rules": [
    "nonpositive_duration",
    "overlap",
    "empty_text",
    "long_line"
  ],
  "long_line_threshold_characters": 42,
  "threshold_note": "Our editorial heuristic, not a platform specification.",
  "limits": [
    "Six deliberately constructed fixtures; no estimate of real-world error rate.",
    "No speech model or commercial caption editor tested.",
    "Does not evaluate word accuracy, names, punctuation, reading speed, sync with audio, accessibility compliance, or all malformed SRT inputs.",
    "A clean structural result is not publication approval."
  ],
  "results": [
    {
      "fixture": "clean",
      "flags": [],
      "expected_match": true
    },
    {
      "fixture": "reversed",
      "flags": [
        [
          "1",
          "nonpositive_duration"
        ]
      ],
      "expected_match": true
    },
    {
      "fixture": "overlap",
      "flags": [
        [
          "2",
          "overlap"
        ]
      ],
      "expected_match": true
    },
    {
      "fixture": "empty",
      "flags": [
        [
          "1",
          "empty_text"
        ]
      ],
      "expected_match": true
    },
    {
      "fixture": "long_line",
      "flags": [
        [
          "1",
          "long_line"
        ]
      ],
      "expected_match": true
    },
    {
      "fixture": "semantic_error",
      "flags": [],
      "expected_match": true
    }
  ]
}