One flagship project

Learn — what gets graded is judgment, not feature count. Pick by target: backend or infra means a real API with the boring parts done, or a distributed component from scratch; product means a deployed app with real users; data means a pipeline that runs on a schedule.

Do — build exactly one, over four to eight weeks.

Check —

• A stranger clones it and runs it in under five minutes from the README alone
• Deployed and reachable at a URL
• CI runs tests on every push
• The README states one design decision you would defend, and its trade-off
• There is one number in it: throughput, p99, cost, or rows/sec
• The commit history shows iteration, not one 12,000-line initial commit

Ship — repo, live URL, and a short write-up of what broke and how you found it.

What does not count: a tutorial clone, a to-do app, anything whose hardest decision was the CSS framework. Interviewers have seen those for a decade.