Agent Frameworks, Runtimes, and Harnesses- oh my!

LangChain's team proposes a taxonomy for AI agent tooling: frameworks (like LangChain) provide abstractions and mental models for building with LLMs; runtimes (like LangGraph) handle production infrastructure concerns such as durable execution, streaming, and persistence; harnesses (like DeepAgents) are batteries-included solutions with default prompts and opinionated tooling. The distinctions help developers understand when to use each layer, though the boundaries remain somewhat fluid as the space evolves.