Cheat Sheet
| Question | Core Idea | Senior Signal |
|---|---|---|
| Q206 | Utility types | Use derived types for real relationships, but do not hide domain meaning. |
| Q207 | Mapped types | Map over keys when field state, config, permissions, or handlers must stay synchronized. |
| Q208 | Conditional types | Use infer to extract inner types and watch distributive union behavior. |
| Q209-Q210 | String and module contracts | Type stable string conventions and keep third-party declarations narrow. |