ColinTing/ddd-aggregate-practice — reverse-engineered prompt

I want this repo turned into a small Java practice project that shows Domain Driven Design aggregates in a way that is easy to read and learn from. Use the article linked in the README as the main guide, and look up the current write up online if you need to.

Please pick one simple business domain and model it properly with an aggregate root, entities or value objects where they make sense, and clear business rules that are enforced inside the aggregate instead of scattered around. I want to be able to see a few realistic actions a user might take, like creating something, changing it, and rejecting invalid state changes.

Keep it runnable with Gradle and make the code feel like a clean learning example, not a huge production app. Add tests that prove the aggregate rules work and fail when they should. A short README update explaining the domain, the aggregate boundary, and how to run the tests would be really helpful too.