diff --git a/apps/readest-app/src/__tests__/services/native-app-service-share.test.ts b/apps/readest-app/src/__tests__/services/native-app-service-share.test.ts
new file mode 100644
index 00000000..1bb8ee09
--- /dev/null
+++ b/apps/readest-app/src/__tests__/services/native-app-service-share.test.ts
@@ -0,0 +1,110 @@
+import { describe, test, expect, vi, beforeEach } from 'vitest';
+
+const osTypeMock = vi.fn().mockReturnValue('macos');
+const writeTextFileMock = vi.fn().mockResolvedValue(undefined);
+const writeFileMock = vi.fn().mockResolvedValue(undefined);
+const saveDialogMock = vi.fn().mockResolvedValue('/tmp/exported.md');
+const shareFileMock = vi.fn().mockResolvedValue(undefined);
+
+vi.mock('@tauri-apps/plugin-os', () => ({
+  type: () => osTypeMock(),
+}));
+
+vi.mock('@tauri-apps/plugin-fs', () => ({
+  exists: vi.fn().mockResolvedValue(false),
+  mkdir: vi.fn().mockResolvedValue(undefined),
+  readTextFile: vi.fn().mockResolvedValue(''),
+  readFile: vi.fn().mockResolvedValue(new Uint8Array()),
+  writeTextFile: (...args: unknown[]) => writeTextFileMock(...args),
+  writeFile: (...args: unknown[]) => writeFileMock(...args),
+  readDir: vi.fn().mockResolvedValue([]),
+  remove: vi.fn().mockResolvedValue(undefined),
+  copyFile: vi.fn().mockResolvedValue(undefined),
+  stat: vi.fn().mockResolvedValue({ size: 0 }),
+  BaseDirectory: {},
+}));
+
+vi.mock('@tauri-apps/api/core', () => ({
+  invoke: vi.fn().mockResolvedValue(undefined),
+  convertFileSrc: (p: string) => `asset://${p}`,
+}));
+
+vi.mock('@tauri-apps/plugin-dialog', () => ({
+  open: vi.fn().mockResolvedValue(null),
+  save: (...args: unknown[]) => saveDialogMock(...args),
+  ask: vi.fn().mockResolvedValue(true),
+}));
+
+vi.mock('@tauri-apps/api/path', () => ({
+  join: (...parts: string[]) => Promise.resolve(parts.join('/')),
+  basename: (p: string) => Promise.resolve(p.split('/').pop() ?? p),
+  appDataDir: () => Promise.resolve('/tmp/app-data'),
+  appConfigDir: () => Promise.resolve('/tmp/app-config'),
+  appCacheDir: () => Promise.resolve('/tmp/app-cache'),
+  appLogDir: () => Promise.resolve('/tmp/app-log'),
+  tempDir: () => Promise.resolve('/tmp'),
+}));
+
+vi.mock('@choochmeque/tauri-plugin-sharekit-api', () => ({
+  shareFile: (...args: unknown[]) => shareFileMock(...args),
+}));
+
+vi.mock('@/utils/bridge', () => ({
+  copyURIToPath: vi.fn().mockResolvedValue({ path: '' }),
+  getStorefrontRegionCode: vi.fn().mockResolvedValue({ regionCode: null }),
+}));
+
+vi.mock('@/utils/file', () => ({
+  NativeFile: class {},
+  RemoteFile: class {},
+}));
+
+vi.mock('@/utils/files', () => ({
+  copyFiles: vi.fn().mockResolvedValue(undefined),
+}));
+
+vi.mock('@/services/settingsService', () => ({
+  getDefaultViewSettings: vi.fn().mockReturnValue({}),
+  loadSettings: vi.fn().mockResolvedValue({ migrationVersion: 99999999 }),
+  saveSettings: vi.fn().mockResolvedValue(undefined),
+}));
+
+async function loadServiceWithOS(os: 'macos' | 'windows' | 'linux' | 'ios' | 'android') {
+  osTypeMock.mockReturnValue(os);
+  vi.resetModules();
+  const mod = await import('@/services/nativeAppService');
+  return new mod.NativeAppService();
+}
+
+describe('NativeAppService.saveFile share gating', () => {
+  beforeEach(() => {
+    writeTextFileMock.mockClear();
+    writeFileMock.mockClear();
+    saveDialogMock.mockClear();
+    shareFileMock.mockClear();
+  });
+
+  test('uses native share on macOS when share=true', async () => {
+    const service = await loadServiceWithOS('macos');
+    await service.saveFile('notes.md', 'hello', { share: true, mimeType: 'text/markdown' });
+    expect(shareFileMock).toHaveBeenCalledTimes(1);
+    expect(saveDialogMock).not.toHaveBeenCalled();
+  });
+
+  // Regression: on Windows the sharekit plugin's share UI blocks the main
+  // thread waiting on cancel/complete callbacks that may never fire, freezing
+  // the app. See issue #4343. Windows must fall through to the save dialog.
+  test('falls through to save dialog on Windows when share=true', async () => {
+    const service = await loadServiceWithOS('windows');
+    await service.saveFile('notes.md', 'hello', { share: true, mimeType: 'text/markdown' });
+    expect(shareFileMock).not.toHaveBeenCalled();
+    expect(saveDialogMock).toHaveBeenCalledTimes(1);
+  });
+
+  test('falls through to save dialog on Linux when share=true', async () => {
+    const service = await loadServiceWithOS('linux');
+    await service.saveFile('notes.md', 'hello', { share: true, mimeType: 'text/markdown' });
+    expect(shareFileMock).not.toHaveBeenCalled();
+    expect(saveDialogMock).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/apps/readest-app/src/services/appService.ts b/apps/readest-app/src/services/appService.ts
index 415e81c3..a08c2550 100644
--- a/apps/readest-app/src/services/appService.ts
+++ b/apps/readest-app/src/services/appService.ts
@@ -42,6 +42,7 @@ export abstract class BaseAppService implements AppService {
   isAppDataSandbox = false;
   isAndroidApp = false;
   isIOSApp = false;
+  isWindowsApp = false;
   isMobileApp = false;
   isPortableApp = false;
   isDesktopApp = false;
diff --git a/apps/readest-app/src/services/nativeAppService.ts b/apps/readest-app/src/services/nativeAppService.ts
index d1802f9b..1ad061a2 100644
--- a/apps/readest-app/src/services/nativeAppService.ts
+++ b/apps/readest-app/src/services/nativeAppService.ts
@@ -444,6 +444,7 @@ export class NativeAppService extends BaseAppService {
   override isIOSApp = OS_TYPE === 'ios';
   override isMacOSApp = OS_TYPE === 'macos';
   override isLinuxApp = OS_TYPE === 'linux';
+  override isWindowsApp = OS_TYPE === 'windows';
   override isMobileApp = ['android', 'ios'].includes(OS_TYPE);
   override isDesktopApp = ['macos', 'windows', 'linux'].includes(OS_TYPE);
   override isAppImage = Boolean(window.__READEST_IS_APPIMAGE);
@@ -642,8 +643,12 @@ export class NativeAppService extends BaseAppService {
   ): Promise<boolean> {
     try {
       const ext = filename.split('.').pop() || '';
-      // Linux desktop has no system share sheet; always fall through to saveDialog.
-      const wantShare = !this.isLinuxApp && (this.isIOSApp || options?.share);
+      // Linux desktop has no system share sheet; Windows WebView2's native
+      // share UI (via tauri-plugin-sharekit) blocks the main thread waiting
+      // on complete/cancel callbacks that may never fire when the user
+      // dismisses the picker, freezing the app (issue #4343). Both fall
+      // through to saveDialog instead.
+      const wantShare = !this.isLinuxApp && !this.isWindowsApp && (this.isIOSApp || options?.share);
       if (wantShare) {
         let shareablePath = options?.filePath;
         if (!shareablePath) {
diff --git a/apps/readest-app/src/types/system.ts b/apps/readest-app/src/types/system.ts
index 4a06e71e..c4903f4b 100644
--- a/apps/readest-app/src/types/system.ts
+++ b/apps/readest-app/src/types/system.ts
@@ -89,6 +89,7 @@ export interface AppService {
   isIOSApp: boolean;
   isMacOSApp: boolean;
   isLinuxApp: boolean;
+  isWindowsApp: boolean;
   isPortableApp: boolean;
   isDesktopApp: boolean;
   isAppImage: boolean;