diff --git a/Tun/Punchnet/AsyncOneShot.swift b/Tun/Punchnet/Concurrency/AsyncOneShot.swift
similarity index 100%
rename from Tun/Punchnet/AsyncOneShot.swift
rename to Tun/Punchnet/Concurrency/AsyncOneShot.swift
diff --git a/Tun/Punchnet/OnceContinuation.swift b/Tun/Punchnet/Concurrency/OnceContinuation.swift
similarity index 100%
rename from Tun/Punchnet/OnceContinuation.swift
rename to Tun/Punchnet/Concurrency/OnceContinuation.swift
diff --git a/Tun/Punchnet/Concurrency/PeriodicWorker.swift b/Tun/Punchnet/Concurrency/PeriodicWorker.swift
new file mode 100644
index 0000000..2398a21
--- /dev/null
+++ b/Tun/Punchnet/Concurrency/PeriodicWorker.swift
@@ -0,0 +1,197 @@
+//
+//  PeriodicWorker.swift
+//  Tun
+//
+//  Created by Codex on 2026/5/20.
+//
+
+import Foundation
+
+public actor PeriodicWorker {
+    public typealias Operation = @Sendable () async throws -> Void
+    public typealias ErrorHandler = @Sendable (Error) async -> Void
+
+    public enum Mode: Sendable {
+        case fixedDelay
+        case fixedRate
+    }
+
+    public enum ErrorPolicy: Sendable {
+        case keepRunning(delay: Duration?)
+        case stop
+    }
+
+    public struct Configuration: Sendable {
+        public var interval: Duration
+        public var tolerance: Duration?
+        public var runImmediately: Bool
+        public var mode: Mode
+        public var errorPolicy: ErrorPolicy
+
+        public init(
+            interval: Duration,
+            tolerance: Duration? = nil,
+            runImmediately: Bool = true,
+            mode: Mode = .fixedDelay,
+            errorPolicy: ErrorPolicy = .keepRunning(delay: .seconds(5))
+        ) {
+            self.interval = interval
+            self.tolerance = tolerance
+            self.runImmediately = runImmediately
+            self.mode = mode
+            self.errorPolicy = errorPolicy
+        }
+    }
+
+    private let configuration: Configuration
+    private let operation: Operation
+    private let onError: ErrorHandler
+
+    private var task: Task<Void, Never>?
+    private var generation: UInt64 = 0
+
+    public init(configuration: Configuration, operation: @escaping Operation, onError: @escaping ErrorHandler = { _ in }) {
+        self.configuration = configuration
+        self.operation = operation
+        self.onError = onError
+    }
+
+    public func start() {
+        guard self.task == nil else {
+            return
+        }
+
+        self.generation &+= 1
+        let currentGeneration = self.generation
+        let configuration = self.configuration
+        let operation = self.operation
+        let onError = self.onError
+
+        self.task = Task {
+            switch configuration.mode {
+            case .fixedDelay:
+                await Self.runFixedDelay(
+                    configuration: configuration,
+                    operation: operation,
+                    onError: onError
+                )
+            case .fixedRate:
+                await Self.runFixedRate(
+                    configuration: configuration,
+                    operation: operation,
+                    onError: onError
+                )
+            }
+            self.clearIfCurrent(generation: currentGeneration)
+        }
+    }
+
+    public func stop() async {
+        self.generation &+= 1
+
+        let task = self.task
+        self.task = nil
+
+        task?.cancel()
+        await task?.value
+    }
+
+    public var isRunning: Bool {
+        self.task != nil
+    }
+
+    private func clearIfCurrent(generation: UInt64) {
+        guard self.generation == generation else {
+            return
+        }
+
+        self.task = nil
+    }
+
+    private static func runFixedDelay(configuration: Configuration, operation: @escaping Operation, onError: @escaping ErrorHandler) async {
+        if !configuration.runImmediately {
+            guard await sleep(interval: configuration.interval, tolerance: configuration.tolerance) else {
+                return
+            }
+        }
+
+        while !Task.isCancelled {
+            let shouldContinue = await runOperation(
+                operation: operation,
+                onError: onError,
+                errorPolicy: configuration.errorPolicy
+            )
+            guard shouldContinue else {
+                return
+            }
+
+            guard await sleep(interval: configuration.interval, tolerance: configuration.tolerance) else {
+                return
+            }
+        }
+    }
+
+    private static func runFixedRate(configuration: Configuration, operation: @escaping Operation, onError: @escaping ErrorHandler) async {
+        var nextRun = ContinuousClock.now
+        if !configuration.runImmediately {
+            nextRun = nextRun.advanced(by: configuration.interval)
+        }
+
+        while !Task.isCancelled {
+            let now = ContinuousClock.now
+            if nextRun > now {
+                let delay = now.duration(to: nextRun)
+                guard await sleep(interval: delay, tolerance: configuration.tolerance) else {
+                    return
+                }
+            }
+
+            let shouldContinue = await runOperation(
+                operation: operation,
+                onError: onError,
+                errorPolicy: configuration.errorPolicy
+            )
+            guard shouldContinue else {
+                return
+            }
+
+            let afterRun = ContinuousClock.now
+            repeat {
+                nextRun = nextRun.advanced(by: configuration.interval)
+            } while nextRun <= afterRun
+        }
+    }
+
+    private static func runOperation(operation: @escaping Operation, onError: @escaping ErrorHandler, errorPolicy: ErrorPolicy) async -> Bool {
+        do {
+            try Task.checkCancellation()
+            try await operation()
+            return true
+        } catch is CancellationError {
+            return false
+        } catch {
+            await onError(error)
+
+            switch errorPolicy {
+            case .keepRunning(let delay):
+                if let delay {
+                    return await sleep(interval: delay, tolerance: nil)
+                }
+                return true
+            case .stop:
+                return false
+            }
+        }
+    }
+
+    private static func sleep(interval: Duration, tolerance: Duration?) async -> Bool {
+        do {
+            try await Task.sleep(for: interval, tolerance: tolerance)
+            return true
+        } catch is CancellationError {
+            return false
+        } catch {
+            return false
+        }
+    }
+}
diff --git a/Tun/Punchnet/SDLAsyncTimerStream.swift b/Tun/Punchnet/Concurrency/SDLAsyncTimerStream.swift
similarity index 100%
rename from Tun/Punchnet/SDLAsyncTimerStream.swift
rename to Tun/Punchnet/Concurrency/SDLAsyncTimerStream.swift