public actor LocalRepository {
    private var cache: [String: Record] = [:]
    private let cacheFileURL: URL

    public init(directory: URL = .documentsDirectory) {
        self.cacheFileURL = directory.appendingPathComponent("cache.json")
        // Synchronous cache load during init (actor isolation not yet active)
        // init中の同期キャッシュ読み込み（actor分離がまだアクティブでないため）
        self.cache = Self.loadCacheSynchronously(from: cacheFileURL)
    }

    public func save(_ record: Record) throws {
        cache[record.id] = record
        try persistToFile()
    }

    public func loadAll() -> [Record] {
        Array(cache.values)
    }

    public func find(by id: String) -> Record? {
        cache[id]
    }

    private func persistToFile() throws {
        let data = try JSONEncoder().encode(Array(cache.values))
        try data.write(to: cacheFileURL)
    }

    private static func loadCacheSynchronously(from url: URL) -> [String: Record] {
        guard let data = try? Data(contentsOf: url),
              let records = try? JSONDecoder().decode([Record].self, from: data) else {
            return [:]
        }
        return Dictionary(uniqueKeysWithValues: records.map { ($0.id, $0) })
    }
}

let repository = LocalRepository()

// All calls are async due to actor isolation
// actor分離により、すべての呼び出しは非同期
let records = await repository.loadAll()
try await repository.save(newRecord)
let found = await repository.find(by: "question-1")