Swift App Architecture (iOS / macOS)

Pick the smallest architecture a feature actually needs, and keep state ownership, module boundaries, and test seams explicit. Grounded in Apple's SwiftUI + Observation frameworks; TCA specifics from pointfree's swift-composable-architecture.

• KMP counterpart: mvi-architecture — if the domain/state lives in shared Kotlin (commonMain), the iOS layer is a thin view over a shared store; don't rebuild the reducer in Swift.
• State mechanics: swiftui-observation (@Observable, @State, @Environment, @Bindable tracking rules). This skill is about structure; that one is about the machinery.
• Test seams / DI: swift-protocol-di-testing. Navigation: navigation. Concurrency in models: swift-concurrency.

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