Lessons Learned from Upgrading to LangChain 1.0 in Production

LangChain v1.0 offers a more coherent and thoughtfully designed framework for building LLM applications, though it presents some migration challenges. One significant change is the `create_agent` method, which drops Pydantic model support, necessitating a workaround to convert schemas to TypedDicts. While the new `deepagents` library offers advanced planning, its opinionated design and default middleware can add unnecessary latency for simpler tasks. A key beneficial feature is the improved support for structured output, enabling agents to reliably produce JSON that conforms to a defined schema. The article also highlights middleware as a powerful tool for context engineering and controlling agent execution loops.