The AI Coding Guidelines Nobody Needed (And What They Taught Me)

In the fall of 2024, my team started using Aider as our coding assistant, one of the first CLI-based AI coding tools out there. I was tasked with creating front-end guidelines to be used as LLM context. This was essentially what we'd now call an agents.md or a skills file, but back then none of that existed yet. We were just experimenting.

The motivation was simple: LLM output at the time could be inconsistent, and we wanted it to write code in a style that matched our team's conventions. So I set out to put together a set of concise, token-efficient guidelines written in Markdown.

My process looked something like this: I'd read through open-source style guides (Google's HTML/CSS guide, for example), strip out the parts that weren't relevant to us, then hand the result to Claude or ChatGPT with a prompt to make it more concise within a token budget. After a few rounds of that back-and-forth, I'd usually land somewhere I was happy with.

Going into this, I had two goals in mind. First, give the LLM better context for our project. Second, produce something I could hand to a junior dev as a quick reference. The guides needed to be concise but still readable for a human.

Looking back, we probably didn't need most of what I wrote. Like I said, we didn't really know what we were doing, and this was new territory for the whole team. The only ones that proved genuinely useful were the opinionated ones. As the lead front-end dev, I have some personal rules I enforce across the team (like no max-width media queries) and that kind of thing is hard for an LLM to guess on its own. Out of everything I wrote, we still use three guidelines today: one for design tokens, one for our custom Tailwind implementation, and a general CSS styling guide.

Even though most of these are pretty useless now (AI tooling has advanced so much since late 2024), I don't think it was a waste of time. Creating those guidelines taught me two things that still matter: the importance of giving your AI assistant good context, and how to think about token management.

If you want to see the retired guidelines, I put them up on GitHub.