diff --git a/ylgamehall/Source/Resource/LobbyZipUpgrader.swift b/ylgamehall/Source/Resource/LobbyZipUpgrader.swift
index cefb417..4a215eb 100644
--- a/ylgamehall/Source/Resource/LobbyZipUpgrader.swift
+++ b/ylgamehall/Source/Resource/LobbyZipUpgrader.swift
@@ -28,18 +28,17 @@ public actor LobbyZipUpgrader {
         case stagingMoveFailed(any Error)
     }
 
-    private let session: URLSession
+    public init() {}
 
-    public init(session: URLSession = LobbyZipUpgrader.defaultSession) {
-        self.session = session
-    }
-
-    /// 默认 URLSession：下载用 60s 超时（zip 大约 11 MB，4G 网络约 10s）。
-    nonisolated public static var defaultSession: URLSession {
+    /// URLSession 配置：60s 单请求 / 300s 总体（zip 约 11 MB，4G 约 10s）。
+    /// 每次 upgradeIfNeeded 用此 config 临时建 session，绑 download delegate 接收
+    /// didWriteData 进度回调；ad-hoc delegate（`session.download(from:delegate:)`）
+    /// 不会触发 URLSessionDownloadDelegate 的 download-specific 方法，必须走 session 级。
+    nonisolated private static var defaultConfig: URLSessionConfiguration {
         let cfg = URLSessionConfiguration.default
         cfg.timeoutIntervalForRequest = 60
         cfg.timeoutIntervalForResource = 300
-        return URLSession(configuration: cfg)
+        return cfg
     }
 
     /// 比较远端 game_version 与本地 version.xml。需要升级则下载 + 解压 + 原子 rename。
@@ -61,15 +60,23 @@ public actor LobbyZipUpgrader {
             return .noop
         }
 
-        // 1. 下载到 tmp（URLSession 默认管理临时位置），delegate 上报 0…1 进度
+        // 1. 下载到 tmp（URLSession 默认管理临时位置），delegate 上报 0…1 进度。
+        //    delegate 必须在 URLSession init 时绑定，否则 didWriteData 不会被调用
+        //    （async API `download(from:delegate:)` 的 ad-hoc delegate 只收 task-level 回调）。
         let progressDelegate = DownloadProgressDelegate(onProgress: onProgress)
+        let opQueue = OperationQueue()
+        opQueue.maxConcurrentOperationCount = 1
+        let session = URLSession(
+            configuration: Self.defaultConfig,
+            delegate: progressDelegate,
+            delegateQueue: opQueue
+        )
+        defer { session.invalidateAndCancel() }
+
         let downloadedURL: URL
         let response: URLResponse
         do {
-            (downloadedURL, response) = try await session.download(
-                from: zipURL,
-                delegate: progressDelegate
-            )
+            (downloadedURL, response) = try await session.download(from: zipURL)
         } catch {
             throw UpgradeError.downloadFailed(error)
         }
diff --git a/ylgamehall/Source/Resource/SubGameDownloader.swift b/ylgamehall/Source/Resource/SubGameDownloader.swift
index 27311a2..68c662e 100644
--- a/ylgamehall/Source/Resource/SubGameDownloader.swift
+++ b/ylgamehall/Source/Resource/SubGameDownloader.swift
@@ -36,17 +36,17 @@ public actor SubGameDownloader {
         case stagingMoveFailed(any Error)
     }
 
-    private let session: URLSession
+    public init() {}
 
-    public init(session: URLSession = SubGameDownloader.defaultSession) {
-        self.session = session
-    }
-
-    nonisolated public static var defaultSession: URLSession {
+    /// URLSession 配置：60s 单请求 / 300s 总体（zip 体量约 1-10 MB）。
+    /// 每次 ensureReady 用此 config 临时建 session，绑 download delegate 接收
+    /// didWriteData 进度回调；ad-hoc delegate（`session.download(from:delegate:)`）
+    /// 不会触发 URLSessionDownloadDelegate 的 download-specific 方法，必须走 session 级。
+    nonisolated private static var defaultConfig: URLSessionConfiguration {
         let cfg = URLSessionConfiguration.default
         cfg.timeoutIntervalForRequest = 60
         cfg.timeoutIntervalForResource = 300
-        return URLSession(configuration: cfg)
+        return cfg
     }
 
     /// 确保 `{Caches}/{request.gameDir}/{request.gameStart}/index.html` 已就绪。
@@ -72,15 +72,23 @@ public actor SubGameDownloader {
             throw DownloadError.badDownloadURL(request.downloadURL)
         }
 
-        // 1. 下载到 tmp
+        // 1. 下载到 tmp。delegate 必须在 URLSession init 时绑定，否则
+        //    URLSessionDownloadDelegate.didWriteData 不会被调用（async API
+        //    `download(from:delegate:)` 的 ad-hoc delegate 只收 task-level 回调）。
         let progressDelegate = DownloadProgressDelegate(onProgress: onProgress)
+        let opQueue = OperationQueue()
+        opQueue.maxConcurrentOperationCount = 1
+        let session = URLSession(
+            configuration: Self.defaultConfig,
+            delegate: progressDelegate,
+            delegateQueue: opQueue
+        )
+        defer { session.invalidateAndCancel() }
+
         let downloadedURL: URL
         let response: URLResponse
         do {
-            (downloadedURL, response) = try await session.download(
-                from: zipURL,
-                delegate: progressDelegate
-            )
+            (downloadedURL, response) = try await session.download(from: zipURL)
         } catch {
             throw DownloadError.downloadFailed(error)
         }