swift-actor-persistence

# Swift Actors for Thread-Safe Persistence Patterns for building thread-safe data persistence layers using Swift actors. Combines in-memory caching with file-backed storage, leveraging the actor model to eliminate data races at compile time. ## When to Activate - Building a data persistence layer in Swift 5.5+ - Need thread-safe access to shared mutable state - Want to eliminate manual synchronization (locks, DispatchQueues) - Building offline-first apps with local storage ## Core Pattern ### Actor-Based Repository The actor model guarantees serialized access — no data races, enforced by the compiler. ```swift public actor LocalRepository<T: Codable & Identifiable> where T.ID == String { private var cache: [String: T] = [:] private let fileURL: URL public init(directory: URL = .documentsDirectory, filename: String = "data.json") { self.fileURL = directory.appendingPathComponent(filename) // Synchronous load during init (actor isolation not yet active) self.cache = Self.loadSynchronously(from: fileURL) } // MARK: - Public API public func save(_ item: T) throws { cache[item.id] = item try persistToFile() } public func delete(_ id: String) throws { cache[id] = nil try persistToFile() } public func find(by id: String) -> T? { cache[id] } public func loadAll() -> [T] { Array(cache.values) } // MARK: - Private private func persistToFile(...