Reasoning Checkpoint
A design challenge, worked through in writing — no auto-grading, just a real attempt.
The Challenge
A new backend developer starts at BlueTicket next Monday — on a brand-new laptop. John asks Anna to write the complete "Set up BlueTicket from zero" guide, from an empty laptop to the app running locally, using everything from this Act.
The project uses Node.js 20 (in .nvmrc), npm with a committed package-lock.json, and needs DATABASE_URL, REDIS_URL, PAYMENT_API_KEY and SMS_API_KEY to run.
What Your Guide Needs
- List the tools to install first (editor and extensions, Git, a Node version manager) and why each is needed.
- Give the exact commands, in order, from cloning the repository to opening the app in a browser.
- Explain how the new developer gets the environment variables — and which kinds of keys they should get.
- Include three safety rules about secrets, and explain why
.envmust never be committed. - Explain why the guide uses
npm ciinstead ofnpm install, and what to do if they see "Unsupported engine". - Add a short "Common problems" section with at least three problems and fixes.
Stuck? A Few Hints
- Follow the order of this Act: workbench, settings, dependencies, versions, docs.
- The new developer shouldn't have to ask anyone anything.
- Think about the three errors Anna hit on her own new laptop.
Before You Move On
A guide like this is one of the most valuable things a new team member can write — you see the gaps that experienced people have long forgotten. The final test is always the same: hand it to someone new and watch them follow it without asking a single question.