https://www.fernandohermida.com/tags/langchain/Recent content in Langchain on Fernando HermidaHugoen-usMon, 10 Aug 2026 00:00:00 +0000https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/01-hello-world-langchain/Sat, 25 Jul 2026 00:00:00 +0000https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/01-hello-world-langchain/A first LangChain chain, from prompt template to LCEL pipe, with a local model swap, response inspection, tests, type-checking, and tracing added around it.https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/02-agent-loops-in-python/Mon, 10 Aug 2026 00:00:00 +0000https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/02-agent-loops-in-python/What actually happens between an LLM call and a tool call: the read-act-observe loop that turns a plain language model into an agent.https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/03-tool-calling-with-langchain/Mon, 10 Aug 2026 00:00:00 +0000https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/03-tool-calling-with-langchain/How create_agent and the @tool decorator collapse a hand-rolled tool-calling loop into a few lines, and what that trade-off actually costs you.https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/07-structured-output-as-a-guardrail/Mon, 10 Aug 2026 00:00:00 +0000https://www.fernandohermida.com/posts/agentic-ai-engineering-journey/07-structured-output-as-a-guardrail/How binding a Pydantic schema to a model or agent turns a probably-shaped response into a validated object, and what still isn’t guaranteed once it is.