Handling concurrency / optimistic concurrency?

Short answer: Return 409 Conflict if concurrency exception is caught. Model Binding & Validation

Example code

Use RowVersion / ETag to detect concurrent edits. Example with EF Core: modelBuilder.Entity<Product>() .Property(p => p.RowVersion).IsRowVersion();

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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.