"""公共配置：统一从环境变量或 Flask config 读取配置项。"""
import os
from flask import current_app


def get_config(key: str, default: str = "") -> str:
    """从环境变量获取配置（优先级：环境变量 > Flask config）。"""
    value = os.environ.get(key, "")
    if value:
        return value
    try:
        return current_app.config.get(key, default)
    except RuntimeError:
        return default