--- paths:

• "**/*.swift"
• "**/Package.swift"

---

Swift Coding Style

This file extends [common/coding-style.md](../common/coding-style.md) with Swift specific content.

Formatting

• **SwiftFormat** for auto-formatting, **SwiftLint** for style enforcement
• `swift-format` is bundled with Xcode 16+ as an alternative

Immutability

• Prefer `let` over `var` — define everything as `let` and only change to `var` if the compiler requires it
• Use `struct` with value semantics by default; use `class` only when identity or reference semantics are needed

Naming

Follow [Apple API Design Guidelines](https://www.swift.org/documentation/api-design-guidelines/):

• Clarity at the point of use — omit needless words
• Name methods and properties for their roles, not their types
• Use `static let` for constants over global constants

Error Handling

Use typed throws (Swift 6+) and pattern matching:

func load(id: String) throws(LoadError) -> Item {
    guard let data = try? read(from: path) else {
        throw .fileNotFound(id)
    }
    return try decode(data)
}

Concurrency

Enable Swift 6 strict concurrency checking. Prefer:

• `Sendable` value types for data crossing isolation boundaries
• Actors for shared mutable state
• Structured concurrency (`async let`, `TaskGroup`) over unstructured `Task {}`