Track product prices across ecommerce sites and alert on offers or target-price hits. Use when a user wants to monitor one or many product URLs or item queries, compare current vs previous prices, detect discounts, and generate alert-ready summaries with product name, old/new price, percent drop, and direct link.

跟踪电商平台上的产品价格，当出现优惠或达到目标价格时发出提醒。适用于用户希望监控一个或多个产品网址或商品查询，比较当前与过往价格，检测折扣，并生成包含产品名称、原价/现价、降价百分比及直接链接的预警摘要。