Architecture & API design interview questions
MVVM, TCA, unidirectional flow, DI, module boundaries.
10 sections, 25 questions. Each question has a clear answer, the common traps and likely follow-ups.
- 15.1 · Presentation patterns
Every architecture answers the same few questions: where does state live, who is allowed to change it, and how do you test it. The names differ; the trade-offs… - 15.2 · Navigation & composition
Two questions shape the codebase more than the choice of UI pattern: who decides which screen comes next, and who decides which object a screen talks to. - 15.3 · Modules & legacy
Boundaries are the part of architecture that outlives any pattern. Where you put them decides what teams can change independently, and how you can retire the… - 15.4 · Error modelling
Errors are part of an API. How you model them decides whether callers can react correctly, or just show “Something went wrong”. - 15.5 · API design
An API is a promise to every caller you will never meet. The cost of a bad name or a leaky type is paid every time it is used, and every time you try to change… - 15.6 · Principles & platforms
Principles are heuristics for managing change. Applied with judgement they save you from a tangle; applied as rules they produce layers of nothing. - 15.7 · State in practice
The first pass explained why one-way state is predictable. In practice the hard parts are everything around the pure function: effects that finish out of… - 15.8 · Injection in practice
The first pass said to inject through initialisers. The questions that follow in a real codebase are about the shape of what you inject, how long it lives, how… - 15.9 · Compatibility
API evolution is more than deprecation: some harmless-looking source changes break binaries, and an ordinary import can leak more than you meant. - 15.10 · Misuse and failure
The best API makes the wrong call impossible or loud. That is a choice about types, ownership and failure mode.