You Can Learn AI Agent Harness & Loop Engineering In 19 Min, with LLM Ops, Eval, Tracing and RAG.
They went viral not because they're complicated but because they're simple building blocks, and once you see them you can prompt your way to building real systems.
🎬YouTube: https://t.co/6QZENmmeJr
Here's the whole thing in one picture.
An LLM is a powerful brain that knows everything about humanity and nothing about you or the software you're running.
The harness is the set of tools you put on that horse so it runs where you want.
Memory gives it context: who you are, what happened before, how to act.
The loop lets it call tools again and again, with guardrails so it knows when to stop.
Eval and LLM Ops trace every run, score it, and feed the fixes back in so the system keeps improving itself.
Master these four and you can read almost any AI agent repo or paper and actually know what's going on.
You Can Build Anything. You Can Learn Anything. 💪
Chapters:
Intro: the 4 AI agent buzzwords
What an AI agent run actually is
The memory system: procedural, semantic, episodic
What "harness" really means (the horse)
Storing and updating memory (databases, skills, summarizer agent)
Retrieval: RAG, SQL vs semantic search
Tool calling and why agents loop
Loop engineering and end-loop guardrails
A Claude Code hooks example
Eval and LLM Ops: why you need them
Tracing every run (Langfuse, LangSmith)
Evaluation: LLM as a judge
Diagnosing what broke
The gate: ship the fix or fix the bug
Zoom out: the full system