feat(live): add support for voice activity start and end events

src/app/components/chat/chat.component.spec.ts

@@ -1985,6 +1985,17 @@ describe('ChatComponent', () => {
         };
         expect((component as any).isEmptyMetadataEvent(event)).toBeFalse();
       });
+
+      it('returns false when a marker event signals voiceActivity', () => {
+        const event = {
+          id: 'vad-1',
+          author: 'agent',
+          usageMetadata: {totalTokenCount: 1},
+          voiceActivity: {voiceActivityType: 'ACTIVITY_START'},
+          actions: {...EMPTY_ACTIONS},
+        };
+        expect((component as any).isEmptyMetadataEvent(event)).toBeFalse();
+      });
     });
 
     describe('actionsAreEmpty', () => {

src/app/components/chat/chat.component.ts

@@ -1407,6 +1407,7 @@ export class ChatComponent implements OnInit, AfterViewInit, OnDestroy {
       && apiEvent.output === undefined
       && apiEvent.inputTranscription === undefined
       && apiEvent.outputTranscription === undefined
+      && apiEvent.voiceActivity === undefined
       && !apiEvent.errorMessage
       && !apiEvent.errorCode
       && !apiEvent.systemInstructionChanged

src/app/components/event-content/event-content.component.html

@@ -44,6 +44,22 @@
       [tooltipTitle]="'Turn Complete'"
     ></app-hover-info-button>
     }
+    @if (uiEvent.event.voiceActivity?.voiceActivityType === 'ACTIVITY_START') {
+    <app-hover-info-button
+      [icon]="'mic'"
+      [text]="'Voice Activity Start'"
+      [tooltipContent]="uiEvent.event.voiceActivity?.audioOffset ? 'Started at ' + uiEvent.event.voiceActivity!.audioOffset : 'Started'"
+      [tooltipTitle]="'Voice Activity Start'"
+    ></app-hover-info-button>
+    }
+    @if (uiEvent.event.voiceActivity?.voiceActivityType === 'ACTIVITY_END') {
+    <app-hover-info-button
+      [icon]="'mic_off'"
+      [text]="'Voice Activity End'"
+      [tooltipContent]="uiEvent.event.voiceActivity?.audioOffset ? 'Ended at ' + uiEvent.event.voiceActivity!.audioOffset : 'Ended'"
+      [tooltipTitle]="'Voice Activity End'"
+    ></app-hover-info-button>
+    }
     @if (uiEvent.event.interrupted) {
     <app-hover-info-button
       [icon]="'report'"

src/app/components/event-content/event-content.component.spec.ts

@@ -0,0 +1,115 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {ComponentFixture, TestBed} from '@angular/core/testing';
+import {MatDialog} from '@angular/material/dialog';
+import {By} from '@angular/platform-browser';
+import {NoopAnimationsModule} from '@angular/platform-browser/animations';
+// 1p-ONLY-IMPORTS: import {beforeEach, describe, expect, it}
+
+import {UiEvent} from '../../core/models/UiEvent';
+import {initTestBed} from '../../testing/utils';
+import {ChatPanelMessagesInjectionToken, CHAT_PANEL_MESSAGES} from '../chat-panel/chat-panel.component.i18n';
+import {EventContentComponent} from './event-content.component';
+
+describe('EventContentComponent', () => {
+  let component: EventContentComponent;
+  let fixture: ComponentFixture<EventContentComponent>;
+
+  beforeEach(async () => {
+    initTestBed();
+
+    await TestBed.configureTestingModule({
+      imports: [EventContentComponent, NoopAnimationsModule],
+      providers: [
+        {
+          provide: ChatPanelMessagesInjectionToken,
+          useValue: CHAT_PANEL_MESSAGES,
+        },
+        {
+          provide: MatDialog,
+          useValue: {open: () => ({afterClosed: () => ({subscribe: () => {}})})},
+        },
+      ],
+    }).compileComponents();
+
+    fixture = TestBed.createComponent(EventContentComponent);
+    component = fixture.componentInstance;
+  });
+
+  describe('Voice Activity Events', () => {
+    it('renders Voice Activity Start chip with mic icon and tooltip', () => {
+      component.uiEvent = new UiEvent({
+        role: 'bot',
+        event: {
+          id: 'vad-start-1',
+          voiceActivity: {
+            voiceActivityType: 'ACTIVITY_START',
+            audioOffset: '1.5s',
+          },
+        } as any,
+      });
+      component.index = 0;
+      fixture.detectChanges();
+
+      const buttons = fixture.debugElement.queryAll(By.css('app-hover-info-button'));
+      const startBtn = buttons.find(b => b.componentInstance.text === 'Voice Activity Start');
+      expect(startBtn).toBeTruthy();
+      expect(startBtn?.componentInstance.icon).toBe('mic');
+      expect(startBtn?.componentInstance.tooltipContent).toBe('Started at 1.5s');
+    });
+
+    it('renders Voice Activity End chip with mic_off icon and tooltip', () => {
+      component.uiEvent = new UiEvent({
+        role: 'bot',
+        event: {
+          id: 'vad-end-1',
+          voiceActivity: {
+            voiceActivityType: 'ACTIVITY_END',
+            audioOffset: '3.2s',
+          },
+        } as any,
+      });
+      component.index = 1;
+      fixture.detectChanges();
+
+      const buttons = fixture.debugElement.queryAll(By.css('app-hover-info-button'));
+      const endBtn = buttons.find(b => b.componentInstance.text === 'Voice Activity End');
+      expect(endBtn).toBeTruthy();
+      expect(endBtn?.componentInstance.icon).toBe('mic_off');
+      expect(endBtn?.componentInstance.tooltipContent).toBe('Ended at 3.2s');
+    });
+
+    it('renders default tooltip when audio offset is missing', () => {
+      component.uiEvent = new UiEvent({
+        role: 'bot',
+        event: {
+          id: 'vad-start-2',
+          voiceActivity: {
+            voiceActivityType: 'ACTIVITY_START',
+          },
+        } as any,
+      });
+      component.index = 0;
+      fixture.detectChanges();
+
+      const buttons = fixture.debugElement.queryAll(By.css('app-hover-info-button'));
+      const startBtn = buttons.find(b => b.componentInstance.text === 'Voice Activity Start');
+      expect(startBtn?.componentInstance.tooltipContent).toBe('Started');
+    });
+  });
+});

src/app/core/models/types.ts

@@ -71,12 +71,18 @@ export declare interface LlmRequest {
   contents: GenAiContent[];
 }
 
+export declare interface VoiceActivity {
+  voiceActivityType?: string;
+  audioOffset?: string;
+}
+
 export declare interface LlmResponse {
   content: GenAiContent;
   error?: string;
   errorMessage?: string;
   errorCode?: string;
   longRunningToolIds?: string[];
+  voiceActivity?: VoiceActivity;
 }
 
 export enum NodeStatus {