ADR-0001: Modular monolith and domain dependency direction

• Status: Accepted
• Date: 2026-07-15

Context

Switchyard coordinates many local capabilities but ships and evolves as one coherent product. Premature services would add deployment and consistency costs without independent scaling or ownership needs.

Decision

Build one modular Go monolith grouped by bounded context. Dependencies flow from transports/adapters to application use cases to domain models. Infrastructure implements ports owned by consuming application packages. Domains do not read each other’s tables and collaborate only through explicit interfaces or typed events. Composition uses manual constructor injection.

Consequences

The product remains easy to build and operate while package boundaries stay enforceable. Cross-domain features require explicit contracts. Architecture checks will reject forbidden imports and miscellaneous shared packages.