We run a practice platform for coding interviews with an AI assistant in the editor. That's the format Meta, Shopify, Canva, Stripe and a growing list of companies now use. From the start our assistant had one rule above all others: it never contributes an idea. Not a design, not a data structure, not a fix.

We were wrong about that rule. This is how we found out, and where we think the line actually is.

Two goals that pulled apart

We wanted two things. Users who are stuck should get help. A stuck user is a frustrated user, and frustrated users leave. And the practice has to make you do the work the interview grades. Otherwise it is not practice.

Those felt like opposites. Help means ideas. And if the ideas come from the agent, you didn't have them.

Our first answer: no ideas from the agent

So we picked a side. The assistant writes code when you say what to build. It never says what to build. If you ask it to "implement the solution", it asks you which approach you want.…