Why I Didn't Use LangChain — The Design Logic Behind a Custom FSM Orchestration Engine
LangChain, LangGraph, CrewAI, PydanticAI — no shortage of AI orchestration frameworks. I evaluated all of them and built my own. Not NIH syndrome. When you need failure-mode-driven mutation strategies, phase-aware multi-model routing with different temperatures, and adaptive evolution based on trajectory analysis, the abstraction layers of general-purpose frameworks become obstacles to route around.