1 min lesson
Have a default deployable stack
Put yourself in this case: "On the onsite small project, you have a feature idea that is too big for the time box. What is the strongest opening move?" Give the clearest next step.
Step 1 of 2
Have a default deployable stackfluency beats novelty
Pick one stack you can stand up from memory and rehearse it cold. Setup friction is the most common way candidates lose time live and it reads as a builder who does not actually build. The specific stack matters less than your fluency in it.
npx create-next-app@latest demo --ts --app cd demo # build the slice with Cursor Agent, run locally npm run dev # ship a public URL so the demo survives a flaky onsite network npx vercel --prod
When you get the onsite project, narrate your scope cut in the first ten minutes: “Here is the full idea, here is the one slice I will get working in the time and here is what I am deliberately faking.” That sentence shows shipping bias and judgment before you have written a line, which is exactly the builder-PM signal the loop is looking for.
Do not let the agent run the session. Accepting large diffs you have not read produces a demo that breaks under the first question. Steer in small, verified steps so you can always explain what every part does.