Vertical Slice Architecture (VSA) Core Principles 1. Organize by feature, not by layer — Each feature is a self-contained vertical slice containing its endpoint, handler, request/response types, and validation. No more jumping between Controllers/, Services/, Repositories/ folders. 2. Minimize cross-feature coupling — Features should not reference each other directly. Shared concerns go in a or directory. 3. One file per feature is fine — A simple CRUD endpoint doesn't need 5 files spread across layers. Start with everything in one file, extract only when complexity demands it. 4. The handler…