fix(updater): drive download/install/restart from backend to avoid hang

The 3.16/3.16.1 update flow was frontend-driven: downloadAndInstall()
then relaunchApp(). relaunch() routed through AppHandle::restart(), and
the old WebView had to keep running JS after the .app bundle was already
swapped — an unstable window that could hang the update or leave the old
version running until a manual restart.

Move the whole download -> install -> cleanup -> restart chain into a new
backend command install_update_and_restart, so it no longer depends on the
old WebView running JS after the bundle is swapped.

Platform-aware install ordering (install() behaves differently per OS):
- Windows: install() launches the external installer and exits the process
  internally, so cleanup + single-instance destroy must run before install.
  Surface a recovery hint on failure since the proxy may already be stopped.
- macOS/Linux: install() returns, so install first then cleanup — an install
  failure no longer wrongly stops the proxy / reverts takeover.

Eliminate the restart vs single-instance race: restart_process() destroys
the single-instance lock (remove socket on macOS, ReleaseMutex on Windows)
before tauri::process::restart(), so the freshly spawned process can't
connect to the old listener and exit itself.

Also remove the now-dead frontend update plumbing (relaunchApp,
UpdateHandle, mapUpdateHandle) and surface backend errors in the toast.

Adapted from the original af4271f4 while rebasing onto #4069: the
ExitRequested handler changes were dropped entirely — the classifier from
#4069 already routes RESTART_EXIT_CODE to Tauri's default restart flow,
and the original should_restart branch (prevent_exit + async cleanup)
would have reintroduced the window-state deadlock that #4069 fixed.
install_update_and_restart bypasses ExitRequested entirely, so the two
fixes compose cleanly.

src-tauri/src/commands/settings.rs

@@ -1,6 +1,7 @@
 #![allow(non_snake_case)]
 
 use tauri::AppHandle;
+use tauri_plugin_updater::UpdaterExt;
 
 fn merge_settings_for_save(
     mut incoming: crate::settings::AppSettings,
@@ -84,6 +85,66 @@ pub async fn restart_app(app: AppHandle) -> Result<bool, String> {
     Ok(true)
 }
 
+/// 下载并安装应用更新，然后由后端直接重启应用。
+///
+/// macOS 更新会原地替换 `.app` bundle。如果先返回前端、再让旧 WebView 调
+/// `process.relaunch()`，旧进程可能已经处在 bundle 被替换后的不稳定窗口期。
+/// 这里把退出清理、安装和重启串在同一个后端流程中，避免依赖旧前端继续执行。
+#[tauri::command]
+pub async fn install_update_and_restart(app: AppHandle) -> Result<bool, String> {
+    let updater = app
+        .updater_builder()
+        .build()
+        .map_err(|e| format!("初始化更新器失败: {e}"))?;
+
+    let Some(update) = updater
+        .check()
+        .await
+        .map_err(|e| format!("检查更新失败: {e}"))?
+    else {
+        return Ok(false);
+    };
+
+    log::info!("开始下载应用更新: {}", update.version);
+    let bytes = update
+        .download(|_, _| {}, || {})
+        .await
+        .map_err(|e| format!("下载更新失败: {e}"))?;
+
+    log::info!("开始安装应用更新: {}", update.version);
+
+    #[cfg(target_os = "windows")]
+    {
+        // Windows updater 会在 install() 内启动安装器并直接退出当前进程。
+        // 因此清理只能放在 install 前执行。
+        crate::save_window_state_before_exit(&app);
+        crate::cleanup_before_exit(&app).await;
+        crate::destroy_single_instance_lock(&app);
+        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
+        update.install(bytes).map_err(|e| {
+            format!(
+                "Windows 更新安装失败: {e}。已执行退出前清理，代理或 Live 接管可能已暂停；请重启应用或重新开启代理后再试。"
+            )
+        })?;
+        return Ok(true);
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        // macOS/Linux install() 会返回；先安装，避免安装失败时误停代理/撤回接管。
+        update
+            .install(bytes)
+            .map_err(|e| format!("安装更新失败: {e}"))?;
+
+        crate::save_window_state_before_exit(&app);
+        crate::cleanup_before_exit(&app).await;
+
+        log::info!("应用更新安装完成，正在重启应用");
+        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
+        crate::restart_process(&app);
+    }
+}
+
 /// 获取 app_config_dir 覆盖配置 (从 Store)
 #[tauri::command]
 pub async fn get_app_config_dir_override(app: AppHandle) -> Result<Option<String>, String> {

src-tauri/src/lib.rs

@@ -1165,6 +1165,7 @@ pub fn run() {
             commands::get_log_config,
             commands::set_log_config,
             commands::restart_app,
+            commands::install_update_and_restart,
             commands::check_for_updates,
             commands::is_portable_mode,
             commands::copy_text_to_clipboard,
@@ -1962,6 +1963,22 @@ pub fn save_window_state_before_exit(app_handle: &tauri::AppHandle) {
     }
 }
 
+/// 主动释放 single-instance 锁。
+///
+/// macOS single-instance 使用 `/tmp/{identifier}.sock`。我们有若干路径会直接
+/// `std::process::exit(0)`，不会触发插件挂在 `RunEvent::Exit` 上的清理钩子。
+/// 重启前主动 destroy 可以避免新进程误连旧 listener 后自行退出。
+pub fn destroy_single_instance_lock(app_handle: &tauri::AppHandle) {
+    #[cfg(any(target_os = "macos", target_os = "windows", target_os = "linux"))]
+    tauri_plugin_single_instance::destroy(app_handle);
+}
+
+/// 释放 single-instance 锁后重启当前应用。
+pub fn restart_process(app_handle: &tauri::AppHandle) -> ! {
+    destroy_single_instance_lock(app_handle);
+    tauri::process::restart(&app_handle.env());
+}
+
 #[cfg(test)]
 mod tests {
     use super::{classify_exit_request, ExitRequestAction};

src/components/settings/AboutSection.tsx

@@ -32,7 +32,6 @@ import type {
   ToolInstallationReport,
 } from "@/lib/api/settings";
 import { useUpdate } from "@/contexts/UpdateContext";
-import { relaunchApp } from "@/lib/updater";
 import { Badge } from "@/components/ui/badge";
 import { motion } from "framer-motion";
 import appIcon from "@/assets/icons/app-icon.png";
@@ -195,14 +194,8 @@ export function AboutSection({ isPortable }: AboutSectionProps) {
   );
   const [showInstallCommands, setShowInstallCommands] = useState(false);
 
-  const {
-    hasUpdate,
-    updateInfo,
-    updateHandle,
-    checkUpdate,
-    resetDismiss,
-    isChecking,
-  } = useUpdate();
+  const { hasUpdate, updateInfo, checkUpdate, resetDismiss, isChecking } =
+    useUpdate();
 
   const [wslShellByTool, setWslShellByTool] = useState<
     Record<string, WslShellPreference>
@@ -392,7 +385,7 @@ export function AboutSection({ isPortable }: AboutSectionProps) {
   }, [t, updateInfo?.availableVersion, version]);
 
   const handleCheckUpdate = useCallback(async () => {
-    if (hasUpdate && updateHandle) {
+    if (hasUpdate) {
       if (isPortable) {
         try {
           await settingsApi.checkUpdates();
@@ -405,11 +398,16 @@ export function AboutSection({ isPortable }: AboutSectionProps) {
       setIsDownloading(true);
       try {
         resetDismiss();
-        await updateHandle.downloadAndInstall();
-        await relaunchApp();
+        const installed = await settingsApi.installUpdateAndRestart();
+        if (!installed) {
+          toast.success(t("settings.upToDate"), { closeButton: true });
+        }
       } catch (error) {
         console.error("[AboutSection] Update failed", error);
-        toast.error(t("settings.updateFailed"));
+        toast.error(t("settings.updateFailed"), {
+          description: extractErrorMessage(error) || undefined,
+          closeButton: true,
+        });
         try {
           await settingsApi.checkUpdates();
         } catch (fallbackError) {
@@ -433,7 +431,7 @@ export function AboutSection({ isPortable }: AboutSectionProps) {
       console.error("[AboutSection] Check update failed", error);
       toast.error(t("settings.checkUpdateFailed"));
     }
-  }, [checkUpdate, hasUpdate, isPortable, resetDismiss, t, updateHandle]);
+  }, [checkUpdate, hasUpdate, isPortable, resetDismiss, t]);
 
   const handleCopyInstallCommands = useCallback(async () => {
     try {

src/contexts/UpdateContext.tsx

@@ -6,14 +6,13 @@ import React, {
   useCallback,
   useRef,
 } from "react";
-import type { UpdateInfo, UpdateHandle } from "../lib/updater";
+import type { UpdateInfo } from "../lib/updater";
 import { checkForUpdate } from "../lib/updater";
 
 interface UpdateContextValue {
   // 更新状态
   hasUpdate: boolean;
   updateInfo: UpdateInfo | null;
-  updateHandle: UpdateHandle | null;
   isChecking: boolean;
   error: string | null;
 
@@ -34,7 +33,6 @@ export function UpdateProvider({ children }: { children: React.ReactNode }) {
 
   const [hasUpdate, setHasUpdate] = useState(false);
   const [updateInfo, setUpdateInfo] = useState<UpdateInfo | null>(null);
-  const [updateHandle, setUpdateHandle] = useState<UpdateHandle | null>(null);
   const [isChecking, setIsChecking] = useState(false);
   const [error, setError] = useState<string | null>(null);
   const [isDismissed, setIsDismissed] = useState(false);
@@ -72,7 +70,6 @@ export function UpdateProvider({ children }: { children: React.ReactNode }) {
       if (result.status === "available") {
         setHasUpdate(true);
         setUpdateInfo(result.info);
-        setUpdateHandle(result.update);
 
         // 检查是否已经关闭过这个版本的提醒
         let dismissedVersion = localStorage.getItem(DISMISSED_VERSION_KEY);
@@ -89,7 +86,6 @@ export function UpdateProvider({ children }: { children: React.ReactNode }) {
       } else {
         setHasUpdate(false);
         setUpdateInfo(null);
-        setUpdateHandle(null);
         setIsDismissed(false);
         return false; // 已是最新
       }
@@ -132,7 +128,6 @@ export function UpdateProvider({ children }: { children: React.ReactNode }) {
   const value: UpdateContextValue = {
     hasUpdate,
     updateInfo,
-    updateHandle,
     isChecking,
     error,
     isDismissed,

src/lib/api/settings.ts

@@ -36,6 +36,10 @@ export const settingsApi = {
     return await invoke("restart_app");
   },
 
+  async installUpdateAndRestart(): Promise<boolean> {
+    return await invoke("install_update_and_restart");
+  },
+
   async checkUpdates(): Promise<void> {
     await invoke("check_for_updates");
   },

src/lib/updater.ts

@@ -1,22 +1,7 @@
 import { getVersion } from "@tauri-apps/api/app";
 
-// 可选导入：在未注册插件或非 Tauri 环境下，调用时会抛错，外层需做兜底
-// 我们按需加载并在运行时捕获错误，避免构建期类型问题
-// eslint-disable-next-line @typescript-eslint/consistent-type-imports
-import type { Update } from "@tauri-apps/plugin-updater";
-
 export type UpdateChannel = "stable" | "beta";
 
-export type UpdaterPhase =
-  | "idle"
-  | "checking"
-  | "available"
-  | "downloading"
-  | "installing"
-  | "restarting"
-  | "upToDate"
-  | "error";
-
 export interface UpdateInfo {
   currentVersion: string;
   availableVersion: string;
@@ -24,64 +9,11 @@ export interface UpdateInfo {
   pubDate?: string;
 }
 
-export interface UpdateProgressEvent {
-  event: "Started" | "Progress" | "Finished";
-  total?: number;
-  downloaded?: number;
-}
-
-export interface UpdateHandle {
-  version: string;
-  notes?: string;
-  date?: string;
-  downloadAndInstall: (
-    onProgress?: (e: UpdateProgressEvent) => void,
-  ) => Promise<void>;
-  download?: () => Promise<void>;
-  install?: () => Promise<void>;
-}
-
 export interface CheckOptions {
   timeout?: number;
   channel?: UpdateChannel;
 }
 
-function mapUpdateHandle(raw: Update): UpdateHandle {
-  return {
-    version: (raw as any).version ?? "",
-    notes: (raw as any).notes,
-    date: (raw as any).date,
-    async downloadAndInstall(onProgress?: (e: UpdateProgressEvent) => void) {
-      await (raw as any).downloadAndInstall((evt: any) => {
-        if (!onProgress) return;
-        const mapped: UpdateProgressEvent = {
-          event: evt?.event,
-        };
-        if (evt?.event === "Started") {
-          mapped.total = evt?.data?.contentLength ?? 0;
-          mapped.downloaded = 0;
-        } else if (evt?.event === "Progress") {
-          mapped.downloaded = evt?.data?.chunkLength ?? 0; // 累积由调用方完成
-        }
-        onProgress(mapped);
-      });
-    },
-    // 透传可选 API（若插件版本支持）
-    download: (raw as any).download
-      ? async () => {
-          // eslint-disable-next-line @typescript-eslint/no-unsafe-call
-          await (raw as any).download();
-        }
-      : undefined,
-    install: (raw as any).install
-      ? async () => {
-          // eslint-disable-next-line @typescript-eslint/no-unsafe-call
-          await (raw as any).install();
-        }
-      : undefined,
-  };
-}
-
 export async function getCurrentVersion(): Promise<string> {
   try {
     return await getVersion();
@@ -93,8 +25,7 @@ export async function getCurrentVersion(): Promise<string> {
 export async function checkForUpdate(
   opts: CheckOptions = {},
 ): Promise<
-  | { status: "up-to-date" }
-  | { status: "available"; info: UpdateInfo; update: UpdateHandle }
+  { status: "up-to-date" } | { status: "available"; info: UpdateInfo }
 > {
   // 动态引入，避免在未安装插件时导致打包期问题
   const { check } = await import("@tauri-apps/plugin-updater");
@@ -106,21 +37,12 @@ export async function checkForUpdate(
     return { status: "up-to-date" };
   }
 
-  const mapped = mapUpdateHandle(update);
   const info: UpdateInfo = {
     currentVersion,
-    availableVersion: mapped.version,
-    notes: mapped.notes,
-    pubDate: mapped.date,
+    availableVersion: (update as any).version ?? "",
+    notes: (update as any).notes,
+    pubDate: (update as any).date,
   };
 
-  return { status: "available", info, update: mapped };
+  return { status: "available", info };
 }
-
-export async function relaunchApp(): Promise<void> {
-  const { relaunch } = await import("@tauri-apps/plugin-process");
-  await relaunch();
-}
-
-// 旧的聚合更新流程已由调用方直接使用 updateHandle 取代
-// 如需单函数封装，可在需要时基于 checkForUpdate + updateHandle 复合调用