Hexagonal Architecture is Not a Layered Architecture: Topology, Safety, and When to Walk Away

Hexagonal (Ports & Adapters) is misunderstood as layered architecture with a different hat. It's a fundamentally different dependency topology — radially inward instead of vertically downward. This article breaks down the topological difference, why Cockburn's original model only had two ports, where the safety boundaries actually live, and when this architecture is overkill.