fix: handle notification timeout correctly when set to 0 (#16849)

- Fix timeout logic to properly handle explicit timeout of 0
- Change condition from falsy check to undefined check to preserve 0 value if set explicitly
- Add unit tests for getTimeout method covering various timeout scenarios
- Add sample commands demonstrating persistent and vanishing notifications

Contributed on behalf of STMicroelectronics

Author: ndoschek

examples/api-samples/src/browser/menu/sample-menu-contribution.ts

@@ -58,6 +58,14 @@ const SampleSelectDialog: Command = {
     id: 'sample-command-select-dialog',
     label: 'Sample Select Component Dialog'
 };
+const SamplePersistentNotification: Command = {
+    id: 'sample-persistent-notification',
+    label: 'Sample Persistent Notification (No Timeout)'
+};
+const SampleVanishingNotification: Command = {
+    id: 'sample-vanishing-notification',
+    label: 'Sample Vanishing Notification (500ms Timeout)'
+};
 
 @injectable()
 export class SampleCommandContribution implements CommandContribution {
@@ -218,6 +226,22 @@ export class SampleCommandContribution implements CommandContribution {
                     });
             }
         });
+        commands.registerCommand(SamplePersistentNotification, {
+            execute: () => {
+                this.messageService.info(
+                    'This notification will stay visible until you dismiss it manually.',
+                    { timeout: 0 }
+                );
+            }
+        });
+        commands.registerCommand(SampleVanishingNotification, {
+            execute: () => {
+                this.messageService.info(
+                    'This notification will stay visible for 500ms.',
+                    { timeout: 500 }
+                );
+            }
+        });
     }
 
 }

packages/messages/src/browser/notifications-manager.spec.ts

@@ -0,0 +1,112 @@
+// *****************************************************************************
+// Copyright (C) 2026 STMicroelectronics and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0.
+//
+// This Source Code may also be made available under the following Secondary
+// Licenses when the conditions for such availability set forth in the Eclipse
+// Public License v. 2.0 are satisfied: GNU General Public License, version 2
+// with the GNU Classpath Exception which is available at
+// https://www.gnu.org/software/classpath/license.html.
+//
+// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
+// *****************************************************************************
+
+import { enableJSDOM } from '@theia/core/lib/browser/test/jsdom';
+let disableJSDOM = enableJSDOM();
+import { FrontendApplicationConfigProvider } from '@theia/core/lib/browser/frontend-application-config-provider';
+FrontendApplicationConfigProvider.set({});
+
+import { expect } from 'chai';
+import { Message } from '@theia/core/lib/common';
+import { NotificationManager } from './notifications-manager';
+import { NotificationPreferences } from '../common/notification-preferences';
+import { NotificationContentRenderer } from './notification-content-renderer';
+
+disableJSDOM();
+
+describe('NotificationManager', () => {
+
+    const DEFAULT_TIMEOUT = 30000;
+
+    class TestableNotificationManager extends NotificationManager {
+        public testGetTimeout(plainMessage: Message): number {
+            return this.getTimeout(plainMessage);
+        }
+    }
+
+    function createNotificationManager(preferenceTimeout: number = DEFAULT_TIMEOUT): TestableNotificationManager {
+        const manager = new TestableNotificationManager();
+        (manager as unknown as { preferences: Partial<NotificationPreferences> }).preferences = {
+            'notification.timeout': preferenceTimeout
+        };
+        (manager as unknown as { contentRenderer: NotificationContentRenderer }).contentRenderer = new NotificationContentRenderer();
+        return manager;
+    }
+
+    before(() => {
+        disableJSDOM = enableJSDOM();
+    });
+
+    after(() => {
+        disableJSDOM();
+    });
+
+    describe('getTimeout', () => {
+
+        let manager: TestableNotificationManager = createNotificationManager();
+
+        it('should return preference timeout when no options are provided', () => {
+            const message: Message = { text: 'Test message' };
+            expect(manager.testGetTimeout(message)).to.equal(DEFAULT_TIMEOUT);
+        });
+
+        it('should return preference timeout when options are provided without timeout', () => {
+            const message: Message = { text: 'Test message', options: {} };
+            expect(manager.testGetTimeout(message)).to.equal(DEFAULT_TIMEOUT);
+        });
+
+        it('should return explicit timeout when provided', () => {
+            const message: Message = { text: 'Test message', options: { timeout: 5000 } };
+            expect(manager.testGetTimeout(message)).to.equal(5000);
+        });
+
+        it('should return 0 when timeout is explicitly set to 0', () => {
+            const message: Message = { text: 'Test message', options: { timeout: 0 } };
+            expect(manager.testGetTimeout(message)).to.equal(0);
+        });
+
+        it('should return 0 when actions are present regardless of timeout', () => {
+            const message: Message = { text: 'Test message', actions: ['OK'], options: { timeout: 5000 } };
+            expect(manager.testGetTimeout(message)).to.equal(0);
+        });
+
+        it('should return 0 when actions are present and no timeout is set', () => {
+            const message: Message = { text: 'Test message', actions: ['OK', 'Cancel'] };
+            expect(manager.testGetTimeout(message)).to.equal(0);
+        });
+
+        it('should return negative timeout when explicitly set', () => {
+            const message: Message = { text: 'Test message', options: { timeout: -1 } };
+            expect(manager.testGetTimeout(message)).to.equal(-1);
+        });
+
+        it('should return explicit timeout even if custom preference timeout is available', () => {
+            const customTimeout = 60000;
+            manager = createNotificationManager(customTimeout);
+            const message: Message = { text: 'Test message', options: { timeout: 5000 } };
+            expect(manager.testGetTimeout(message)).to.equal(5000);
+        });
+
+        it('should return custom preference timeout if no timeout is set', () => {
+            const customTimeout = 60000;
+            manager = createNotificationManager(customTimeout);
+            const message: Message = { text: 'Test message' };
+            expect(manager.testGetTimeout(message)).to.equal(customTimeout);
+        });
+
+    });
+
+});

packages/messages/src/browser/notifications-manager.ts

@@ -229,7 +229,7 @@ export class NotificationManager extends MessageClient {
             // Ignore the timeout if at least one action is set, and we wait for user interaction.
             return 0;
         }
-        return plainMessage.options && plainMessage.options.timeout || this.preferences['notification.timeout'];
+        return plainMessage.options?.timeout !== undefined ? plainMessage.options.timeout : this.preferences['notification.timeout'];
     }
     protected isExpandable(message: string, source: string | undefined, actions: string[]): boolean {
         if (!actions.length && source) {