ADR-004: Architectural layering

Date: 2026-04-28 Status: Accepted

Context

We want domain-led modularity with clear dependency direction, while avoiding heavy enterprise DDD patterns.

Decision

Adopt the layering:

• UI → Application → Domain → (Infrastructure implementations)

With explicit rules:

• Domain depends only on Shared.
• Application depends on Domain and Shared.
• Infrastructure depends on Domain and Shared.
• UI depends on Application, UI, Shared, and selected Domain types/value objects.

Consequences

• UI cannot shortcut to database/repositories.
• Business rules remain portable and testable.

Alternatives considered

• Fully anemic domain model (business rules drift into UI/infrastructure)
• Microservices (too heavy for early stage)