📝 How to really stop your agents from making the same mistakes LangChain has raised $160 million. Three years of development. A billion-dollar valuation. LangSmith, their testing platform, is genuinely sophisticated: trajectory evals, trace-to-dataset pipelines, LLM-as-judge, regression suites, unit test frameworks for tools. They have the pieces. Credit where it's due. But pieces aren't a practice. LangChain gives you testing tools. It never tells you what to test, in what order, or when…