Functional Architecture in Swift

Use this skill for Swift architecture work where correctness, decoupling, and testability matter more than framework ceremony.

Core model

Partition the codebase into five concerns:

1. Inert domain
2. Pure decision logic
3. Application orchestration and feature-state management
4. Composition boundary
5. Infrastructure and source-of-truth boundaries

Keep the first two deterministic. Push IO, timers, persistence, networking, and hardware access to the last two.

Non-negotiables

• Domain types are immutable struct and enum values by default.