What if you never had to write application logic again?

I recently showed that an agent can be built in 200 lines of code. What if we took that agent and have it handle web requests?

The result - a web server with zero application logic - is fascinating. It has no routes, no controllers, no business logic. Just a prompt and an AI agent that handles every HTTP request dynamically.

Every few months, a new state-of-the-art AI model is released. The technical reports are polished, the loss curves are smooth, and every decision seems obvious in hindsight. It all looks so clean.

But the reality is far more chaotic.

The team at Hugging Face just pulled back the curtain with their Smol Training Playbook, an incredibly detailed account of training their 3B parameter SmolLM3 model. Far from being a story of flawless execution, it’s a drama of debugging sessions, unexpected failures, and hard-won lessons.

Building a fully functioning coding agent is not nearly as hard as you might think.

When you watch an agent autonomously editing files, running commands, recovering from errors, and adapting its strategy on the fly, it feels like magic. Like there must be some secret sauce you’re missing.

But there isn’t. The core of an agent is surprisingly simple: an LLM, a loop, and enough context. Everything else is just good engineering.