Agent
Also called AI agent
A model, a loop and some tools. The model asks for a tool, a program runs it and hands back the result, and this repeats until the model says it has finished.
The loop is what changes your job. A chat reply is one answer you can read before anything happens. An agent takes many actions before you look, so your attention moves from what it said to what it did.
Say it to your agent
“Work on this as an agent, not a chat. Run bun test yourself, read the failures, fix them, and keep going until it exits 0. Do not paste code for me to apply.”