AI can write useful scripts. It can also write scripts that read your SSH keys and POST them somewhere interesting.

The problem isn’t malice. AI doesn’t want to exfiltrate your data. It just doesn’t know what’s sensitive. Ask it to “find configuration files” and it might helpfully include ~/.aws/credentials in its search. Ask it to “clean up temporary files” and who knows what it considers temporary.

Running arbitrary AI-generated code requires trust you probably shouldn’t extend.

Don’t think about a pink elephant.

You just did. Your brain had to summon the elephant to know what not to think about. The instruction defeated itself.

Large language models have the same problem, except they can’t even try to comply.

How LLMs Process Text

When you write “don’t use jargon,” the model processes every token in that sentence. Including “jargon.” That token activates associations, weights, patterns learned from training data. The concept is now present in the context window, influencing what comes next.

This is an instructions file. It lives in your repository root. Your AI coding assistant reads it before touching your code.

You can call it CLAUDE.md or AGENTS.md or INSTRUCTIONS.md or whatever your tooling expects. The name doesn’t matter. What matters is that you’re encoding expectations that would otherwise live in your head.

What follows is a starting point. Steal it, modify it, delete the parts that don’t apply. Add what’s missing.

There’s a dirty secret about AI-assisted coding: it’s often too helpful.

Ask an AI to implement a feature and it will, quickly and confidently. It’ll reach across your codebase, modify whatever it needs, create new utilities that duplicate existing ones, and deliver working code that makes you slightly uncomfortable.

The code works. But it doesn’t belong.

After months of working with AI coding assistants, I’ve started to recognize the pattern. The AI isn’t bad at coding. It’s bad at not coding. It lacks the instinct that experienced developers have: the pause before typing, the “wait, where should this actually live?” moment, the awareness that every line you write exists in a larger context.