...    items.append((ctime or 0, author, text))

    items.sort(key=lambda x: (x[0] or 0))
    return items

data = json.loads(INPUT.read_text(encoding="utf-8", errors="replace"))

# Manche Exporte sind Liste, manche haben Wrapper
conversations = data if isinstance(data, list) else data.get("conversations") or data.get("data") or []
if not isinstance(conversations, list):
    raise SystemExit("Unbekanntes...