🧱 Clean Architecture in .NET: Why It Still Matters at Scale

After years of building and maintaining .NET systems, one thing becomes clear:

most technical debt comes from blurred boundaries, not bad code.
Clean Architecture helps prevent that by enforcing a simple but powerful rule:
👉 business logic must not depend on frameworks, databases, or delivery mechanisms.

In a well-structured .NET application:
• Domain contains the core business rules and invariants
• Application defines use cases and orchestration
• Infrastructure handles EF Core, messaging, external services
• Presentation exposes APIs or UI via ASP.NET Core

The real value isn’t the folder structure — it’s the direction of dependencies.
Why it works in real-world .NET systems:
✔ Business logic is testable without databases or web servers
✔ Framework upgrades don’t ripple through the entire codebase
✔ Teams can evolve infrastructure independently of core logic
✔ Refactoring becomes safer as requirements change

Common pitfalls I still see:
⚠ Overengineering simple CRUD apps
⚠ Anemic domain models with logic pushed into services
⚠ Infrastructure concerns leaking into the domain

A practical rule of thumb:
If you can replace EF Core or ASP.NET Core without rewriting your business rules, your architecture is doing its job.
Architecture is not about perfection — it’s about making change cheaper over time.