How would you design a plugin architecture with SOLID principles?

Short answer: Define plugin contracts with interfaces (DIP). Load plugins dynamically using reflection or MEF. Use DI to inject dependencies into plugins. Ensure plugins follow SRP with focused responsibilities. Use Factory or Strategy patterns to instantiate plugins. Keep core system closed for modification but open for extension (OCP). Separate cross-cutting concerns externally. Practical .NET Questions

Real-world example (ShopNest)

Open/Closed in ShopNest: add a new payment method by adding a class, not by editing a giant switch in CheckoutService.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.