Practice
Reading about trade-offs is not the same as making them
Each scenario gives you a realistic problem and asks you to reason through it. You'll hit decision points, make choices, and see what actually happened and why.
Design
Reasoning under uncertainty before the system exists. Requirements accumulate mid-build — you won't know what it needs to become until it's almost too late to change.
Diagnose
Reasoning under incomplete information after symptoms appear. You never start with the problem — you start with a complaint, a metric, or a failed job.
Change
Reasoning under live constraint with rollback risk. Every scenario has a system that cannot go down, a deadline, and at least one option that looks safe but isn't.
Operate Under Pressure
Reasoning when the system is correct but the environment is hostile. The system isn't broken — the constraints changed. These test whether you understand what your system was actually designed for.