# Someone just explained the entire agent stack - harness, loop engineering, ev...
Canonical: https://social-archive.org/yena/8Ws2gFa258
Original URL: https://x.com/dunik_7/status/2072615317293907999
Author: dunik
Platform: x
## Content
Someone just explained the entire agent stack - harness, loop engineering, evals, LLM ops, tracing - in 19 minutes. It's clearer than most $500 courses, and it's free. harness → the structure around the model. loops → why the agent keeps going. evals → the "no" that catches it when it's wrong. tracing → how you find what actually broke. That's the whole machine the article below breaks down, drawn out in one sitting. Watch it first to see the shape of it - then read the guide below to actually build one.