Building a Cross-Border Price-Comparison Agent: A Live Build Log

Short summary

A dev shipped a cross-border shopping agent using LangChain + BuyWhere MCP solving production problems: stale pricing, geo-blocking, currency reconciliation. Key patterns: mode=offer for live prices (not mode=product), find_similar for repricing (not discovery), system prompt as consistency layer. Measured: 1.2–2.4s latency, 73% CTR on top results over 1,800 queries. Includes reference repo and case-study notebook.

• •Shipped cross-border shopping agent with three production iterations revealing design patterns
• •Core insight: mode=offer vs mode=product distinction; find_similar for repricing, not discovery
• •Measured results: 1.2–2.4s response time, 73% CTR, 1,800 queries tracked; setup guide and repo included

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