def safe_context_param(context_str: str) -> str:
    """确保上下文参数可以安全地序列化为JSON"""
    if not context_str:
        return ""

    # 移除ECharts代码块，这些对上下文没有帮助且容易导致格式错误
    import re

    # 移除 ```echarts 代码块
    cleaned = re.sub(r"```echarts[\s\S]*?```", "", context_str)
    # 移除其他代码块
    cleaned = re.sub(r"```[\s\S]*?```", "", cleaned)

    # 清理可能导致JSON解析问题的字符
    cleaned = str(cleaned).replace('"', "'").replace("\\", "/").strip()
    # 移除多余的空行和空格
    cleaned = re.sub(r"\n\s*\n", "\n", cleaned)  # 移除连续空行
    cleaned = re.sub(r" +", " ", cleaned)  # 合并多个空格

    # 限制上下文长度，避免过长导致序列化问题
    max_length = 2000
    if len(cleaned) > max_length:
        cleaned = cleaned[:max_length] + "... [上下文已截断]"

    return cleaned.strip()