Most people learn system design backwards.

The usual path is a list of eighty interview questions and a diagram of Twitter. You memorise the answer without ever learning why a cache belongs on that line, so the first follow-up question ends the conversation.

SysAlchemy Labs goes the other way. You start with a client, a server, and a database, and you do not get another box until you have earned it. By the time a queue appears on your canvas, you can say what it is holding and what breaks without it.

Every lab is graded by rules, not by a language model. The critique names the missing path and points at the lesson that explains it. It can tell you that you scored 59 because clients are talking straight to the database — and it will say the same thing tomorrow, because a rule is not a mood.