"""聊天策略模块。"""

from app.core.config import settings
from app.core.errors import AppError


def validate_text_message(*, modality: str, content: str) -> None:
    if modality != "text":
        raise AppError("unsupported_media_type", "当前阶段仅支持文本消息。")
    if len(content.encode("utf-8")) > settings.max_text_message_bytes:
        raise AppError("payload_too_large", "单条文本消息超过大小限制。")