You've probably noticed something when using AI coding agents like Claude Code, Cursor, or Codex. The model doesn't just answer - it works. It reads a file, writes some code to search through it, reads another file, runs a check, and slowly pieces together an answer. It feels almost like watching someone think out loud. That intuition is important. Because a paper out of MIT CSAIL late last year - quietly titled Recursive Language Models - essentially formalizes exactly that

Most AI demos look impressive. Most AI agents in production quietly fail. The difference is rarely the model — it's everything built around it. Agentic AI refers to systems where a model takes autonomous, multi-step actions to complete a goal — browsing the web, writing and running code, calling APIs — acting, observing the result, and acting again, often over hours. Harness engineering is the discipline of building the system that makes those actions reliable. As LangChain p