Gateway Builder

The provided fragment is a high-level architectural specification for gateway implementations (interface-first, business-model-centric, DI-friendly). It is internally consistent with its stated purpose and follows best practices for gateway design. However, it does not include any actual code, interfaces, or concrete gateway implementations to evaluate for security properties beyond the stated design philosophy. As a result, there is no observable malicious behavior or data exfiltration patterns, but also no concrete security controls to audit. The risk profile is low in this fragment, with potential for proper implementation to introduce typical integration risks if defaults, DI wiring, or external clients are mishandled in the future.