Interact with Windows notifications from a thread

Co-authored-by: Fedor Indutny <79877362+indutny-signal@users.noreply.github.com>

app/WindowsNotifications.main.ts

@@ -1,55 +1,78 @@
 // Copyright 2017 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-import { ipcMain as ipc } from 'electron';
+import { ipcMain as ipc, app } from 'electron';
 import type { IpcMainInvokeEvent } from 'electron';
+import { join } from 'node:path';
+import { Worker } from 'node:worker_threads';
 
-import {
-  Notifier,
-  sendDummyKeystroke,
-} from '@indutny/simple-windows-notifications';
-
-import { createLogger } from '../ts/logging/log.std.js';
 import { AUMID } from './startup_config.main.js';
-import type { WindowsNotificationData } from '../ts/services/notifications.preload.js';
+import type {
+  WindowsNotificationWorkerDataType,
+  WindowsNotificationRequestType,
+  WindowsNotificationData,
+} from '../ts/types/notifications.std.js';
+import { WindowsNotificationDataSchema } from '../ts/types/notifications.std.js';
 import OS from '../ts/util/os/osMain.node.js';
-import { renderWindowsToast } from './renderWindowsToast.std.js';
+import { createLogger } from '../ts/logging/log.std.js';
-
-export { sendDummyKeystroke };
 
 const log = createLogger('WindowsNotifications');
 
+let worker: Worker | undefined;
+
 if (OS.isWindows()) {
-  const notifier = new Notifier(AUMID);
+  const scriptPath = join(
-
+    app.getAppPath(),
-  const NOTIFICATION_ID = {
+    'app',
-    group: 'group',
+    'WindowsNotificationsWorker.node.js'
-    tag: 'tag',
-  };
-
-  ipc.handle(
-    'windows-notifications:show',
-    (_event: IpcMainInvokeEvent, data: WindowsNotificationData) => {
-      try {
-        // First, clear all previous notifications - we want just one
-        // notification at a time
-        notifier.remove(NOTIFICATION_ID);
-        notifier.show(renderWindowsToast(data), NOTIFICATION_ID);
-      } catch (error) {
-        log.error(
-          `Windows Notifications: Failed to show notification: ${error.stack}`
-        );
-      }
-    }
   );
 
-  ipc.handle('windows-notifications:clear-all', () => {
+  worker = new Worker(scriptPath, {
-    try {
+    workerData: {
-      notifier.remove(NOTIFICATION_ID);
+      AUMID,
-    } catch (error) {
+    } satisfies WindowsNotificationWorkerDataType,
-      log.error(
-        `Windows Notifications: Failed to clear notifications: ${error.stack}`
-      );
-    }
   });
 }
+
+export function sendDummyKeystroke(): void {
+  if (worker == null) {
+    log.warn('sendDummyKeystroke without worker');
+    return;
+  }
+  worker.postMessage({
+    command: 'sendDummyKeystroke',
+  } satisfies WindowsNotificationRequestType);
+}
+
+export function show(notificationData: WindowsNotificationData): void {
+  if (worker == null) {
+    log.warn('show without worker');
+    return;
+  }
+  worker.postMessage({
+    command: 'show',
+    notificationData,
+  } satisfies WindowsNotificationRequestType);
+}
+
+ipc.handle(
+  'windows-notifications:show',
+  (_event: IpcMainInvokeEvent, data: unknown) => {
+    try {
+      const notificationData = WindowsNotificationDataSchema.parse(data);
+      show(notificationData);
+    } catch (error) {
+      log.error('failed to parse notification data', error.stack);
+    }
+  }
+);
+
+ipc.handle('windows-notifications:clear-all', () => {
+  if (worker == null) {
+    log.warn('clear all without worker');
+    return;
+  }
+  worker.postMessage({
+    command: 'clearAll',
+  } satisfies WindowsNotificationRequestType);
+});

app/WindowsNotificationsWorker.node.ts

@@ -0,0 +1,83 @@
+// Copyright 2025 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { parentPort, workerData } from 'node:worker_threads';
+
+import {
+  Notifier,
+  sendDummyKeystroke,
+} from '@indutny/simple-windows-notifications';
+
+import { createLogger } from '../ts/logging/log.std.js';
+import {
+  WindowsNotificationWorkerDataSchema,
+  WindowsNotificationRequestSchema,
+} from '../ts/types/notifications.std.js';
+import OS from '../ts/util/os/osMain.node.js';
+import { missingCaseError } from '../ts/util/missingCaseError.std.js';
+import { renderWindowsToast } from './renderWindowsToast.std.js';
+
+if (!parentPort) {
+  throw new Error('Must run as a worker thread');
+}
+
+if (!OS.isWindows()) {
+  throw new Error('Runs only on Windows');
+}
+
+const port = parentPort;
+
+const log = createLogger('WindowsNotificationsWorker');
+
+const { AUMID } = WindowsNotificationWorkerDataSchema.parse(workerData);
+const notifier = new Notifier(AUMID);
+
+const NOTIFICATION_ID = {
+  group: 'group',
+  tag: 'tag',
+};
+
+port.on('message', (message: unknown) => {
+  const request = WindowsNotificationRequestSchema.parse(message);
+
+  if (request.command === 'show') {
+    try {
+      // First, clear all previous notifications - we want just one
+      // notification at a time
+      notifier.remove(NOTIFICATION_ID);
+      notifier.show(
+        renderWindowsToast(request.notificationData),
+        NOTIFICATION_ID
+      );
+    } catch (error) {
+      log.error(
+        `Windows Notifications: Failed to show notification: ${error.stack}`
+      );
+    }
+    return;
+  }
+
+  if (request.command === 'clearAll') {
+    try {
+      notifier.remove(NOTIFICATION_ID);
+    } catch (error) {
+      log.error(
+        `Windows Notifications: Failed to clear notifications: ${error.stack}`
+      );
+    }
+    return;
+  }
+
+  if (request.command === 'sendDummyKeystroke') {
+    try {
+      sendDummyKeystroke();
+    } catch (error) {
+      log.error(
+        `Windows Notifications: Failed to send dummy keystroke: ${error.stack}`
+      );
+    }
+    return;
+  }
+
+  throw missingCaseError(request);
+});

app/main.main.ts

@@ -47,6 +47,7 @@ import { strictAssert } from '../ts/util/assert.std.js';
 import { drop } from '../ts/util/drop.std.js';
 import type { ThemeSettingType } from '../ts/types/StorageUIKeys.std.js';
 import { ThemeType } from '../ts/types/Util.std.js';
+import { NotificationType } from '../ts/types/notifications.std.js';
 import * as Errors from '../ts/types/errors.std.js';
 import { resolveCanonicalLocales } from '../ts/util/resolveCanonicalLocales.std.js';
 import { createLogger } from '../ts/logging/log.std.js';
@@ -136,7 +137,10 @@ import { safeParseLoose, safeParseUnknown } from '../ts/util/schemas.std.js';
 import { getAppErrorIcon } from '../ts/util/getAppErrorIcon.node.js';
 import { promptOSAuth } from '../ts/util/os/promptOSAuthMain.main.js';
 import { appRelaunch } from '../ts/util/relaunch.main.js';
-import { sendDummyKeystroke } from './WindowsNotifications.main.js';
+import {
+  sendDummyKeystroke,
+  show as showWindowsNotification,
+} from './WindowsNotifications.main.js';
 
 const { chmod, realpath, writeFile } = fsExtra;
 const { get, pick, isNumber, isBoolean, some, debounce, noop } = lodash;
@@ -926,7 +930,10 @@ async function createWindow() {
       !windowState.shouldQuit() &&
       (usingTrayIcon || OS.isMacOS())
     ) {
-      if (usingTrayIcon) {
+      if (!usingTrayIcon) {
+        return;
+      }
+
       const shownTrayNotice = ephemeralConfig.get('shown-tray-notice');
       if (shownTrayNotice) {
         log.info('close: not showing tray notice');
@@ -936,6 +943,20 @@ async function createWindow() {
       ephemeralConfig.set('shown-tray-notice', true);
       log.info('close: showing tray notice');
 
+      if (OS.isWindows()) {
+        showWindowsNotification({
+          type: NotificationType.MinimizedToTray,
+          token: 'unused',
+          heading: getResolvedMessagesLocale().i18n(
+            'icu:minimizeToTrayNotification--title'
+          ),
+          body: getResolvedMessagesLocale().i18n(
+            'icu:minimizeToTrayNotification--body'
+          ),
+        });
+        return;
+      }
+
       const n = new Notification({
         title: getResolvedMessagesLocale().i18n(
           'icu:minimizeToTrayNotification--title'
@@ -946,7 +967,6 @@ async function createWindow() {
       });
 
       n.show();
-      }
       return;
     }
 

app/renderWindowsToast.std.tsx

@@ -4,9 +4,10 @@
 import React from 'react';
 import { renderToStaticMarkup } from 'react-dom/server';
 
-import type { WindowsNotificationData } from '../ts/services/notifications.preload.js';
+import {
-
+  type WindowsNotificationData,
-import { NotificationType } from '../ts/types/notifications.std.js';
+  NotificationType,
+} from '../ts/types/notifications.std.js';
 import { missingCaseError } from '../ts/util/missingCaseError.std.js';
 import {
   cancelPresentingRoute,
@@ -78,6 +79,8 @@ export function renderWindowsToast({
     launch = showWindowRoute.toAppUrl({});
   } else if (type === NotificationType.IsPresenting) {
     launch = cancelPresentingRoute.toAppUrl({});
+  } else if (type === NotificationType.MinimizedToTray) {
+    launch = showWindowRoute.toAppUrl({});
   } else {
     throw missingCaseError(type);
   }

ts/services/notifications.preload.ts

@@ -53,13 +53,6 @@ export type NotificationClickData = Readonly<{
   messageId: string | undefined;
   storyId: string | undefined;
 }>;
-export type WindowsNotificationData = {
-  avatarPath?: string;
-  body: string;
-  heading: string;
-  token: string;
-  type: NotificationType;
-};
 
 // The keys and values don't match here. This is because the values correspond to old
 //   setting names. In the future, we may wish to migrate these to match.
@@ -230,6 +223,9 @@ class NotificationService extends EventEmitter {
           window.reduxActions?.calling?.cancelPresenting();
         } else if (type === NotificationType.IncomingCall) {
           window.IPC.showWindow();
+        } else if (type === NotificationType.MinimizedToTray) {
+          // Unused since the notification is shown by main process instead
+          window.IPC.showWindow();
         } else {
           throw missingCaseError(type);
         }

ts/types/notifications.std.ts

@@ -1,10 +1,50 @@
 // Copyright 2025 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
+import z from 'zod';
+
 export enum NotificationType {
   IncomingCall = 'IncomingCall',
   IncomingGroupCall = 'IncomingGroupCall',
   IsPresenting = 'IsPresenting',
   Message = 'Message',
   Reaction = 'Reaction',
+  MinimizedToTray = 'MinimizedToTray',
 }
+
+export const WindowsNotificationDataSchema = z.object({
+  avatarPath: z.string().optional(),
+  body: z.string(),
+  heading: z.string(),
+  token: z.string(),
+  type: z.nativeEnum(NotificationType),
+});
+
+export type WindowsNotificationData = z.infer<
+  typeof WindowsNotificationDataSchema
+>;
+
+export const WindowsNotificationWorkerDataSchema = z.object({
+  AUMID: z.string(),
+});
+
+export type WindowsNotificationWorkerDataType = z.infer<
+  typeof WindowsNotificationWorkerDataSchema
+>;
+
+export const WindowsNotificationRequestSchema = z.union([
+  z.object({
+    command: z.literal('show'),
+    notificationData: WindowsNotificationDataSchema,
+  }),
+  z.object({
+    command: z.literal('clearAll'),
+  }),
+  z.object({
+    command: z.literal('sendDummyKeystroke'),
+  }),
+]);
+
+export type WindowsNotificationRequestType = z.infer<
+  typeof WindowsNotificationRequestSchema
+>;

ts/windows/main/phase1-ipc.preload.ts

@@ -20,7 +20,7 @@ import { strictAssert } from '../../util/assert.std.js';
 import { drop } from '../../util/drop.std.js';
 import { explodePromise } from '../../util/explodePromise.std.js';
 import { DataReader } from '../../sql/Client.preload.js';
-import type { WindowsNotificationData } from '../../services/notifications.preload.js';
+import type { WindowsNotificationData } from '../../types/notifications.std.js';
 import { finish3dsValidation } from '../../services/donations.preload.js';
 import { AggregatedStats } from '../../textsecure/WebsocketResources.preload.js';
 import { UNAUTHENTICATED_CHANNEL_NAME } from '../../textsecure/SocketManager.preload.js';