chore(firebaseai): clean up the model usage in example. Using flash lite for all regular…

packages/firebase_ai/firebase_ai/example/lib/constants.dart

@@ -0,0 +1,33 @@
+// 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.
+
+/// Centralized model identifiers used across the example app.
+abstract final class ExampleModels {
+  /// Default fast multimodal model.
+  static const String flashLite = 'gemini-3.5-flash-lite';
+
+  /// Multimodal text and image generation model.
+  static const String flashImage = 'gemini-3.1-flash-image';
+
+  /// Text-to-speech audio model preview.
+  static const String flashTTS = 'gemini-3.1-flash-tts-preview';
+
+  /// Live bidirectional audio streaming model for Agent Platform.
+  static const String liveAgentPlatform =
+      'gemini-live-2.5-flash-preview-native-audio-09-2025';
+
+  /// Live bidirectional audio streaming model for Google AI.
+  static const String liveGoogleAI =
+      'gemini-2.5-flash-native-audio-preview-09-2025';
+}

packages/firebase_ai/firebase_ai/example/lib/main.dart

@@ -21,16 +21,19 @@ import 'package:flutter/material.dart';
 // Import after file is generated through flutterfire_cli.
 // import 'package:firebase_ai_example/firebase_options.dart';
 
+import 'constants.dart';
 import 'pages/bidi_page.dart';
+import 'pages/capabilities_page.dart';
 import 'pages/chat_page.dart';
 import 'pages/function_calling_page.dart';
-import 'pages/image_generation_page.dart';
-import 'pages/capabilities_page.dart';
-import 'pages/server_template_page.dart';
 import 'pages/grounding_page.dart';
+import 'pages/image_generation_page.dart';
 import 'pages/integration_test_page.dart';
+import 'pages/server_template_page.dart';
 import 'pages/tts_page.dart';
 
+export 'constants.dart';
+
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   // Enable this line instead once have the firebase_options.dart generated and
@@ -72,10 +75,10 @@ class _GenerativeAISampleState extends State<GenerativeAISample> {
       final agentPlatformInstance =
           FirebaseAI.agentPlatform(location: 'global');
       _currentModel =
-          agentPlatformInstance.generativeModel(model: 'gemini-3.5-flash-lite');
+          agentPlatformInstance.generativeModel(model: ExampleModels.flashLite);
     } else {
       final googleAI = FirebaseAI.googleAI();
-      _currentModel = googleAI.generativeModel(model: 'gemini-3.5-flash-lite');
+      _currentModel = googleAI.generativeModel(model: ExampleModels.flashLite);
     }
   }
 

packages/firebase_ai/firebase_ai/example/lib/pages/bidi_page.dart

@@ -18,12 +18,13 @@ import 'package:flutter/material.dart';
 import 'package:firebase_ai/firebase_ai.dart';
 import 'package:waveform_flutter/waveform_flutter.dart';
 
+import '../constants.dart';
 import '../utils/audio_input.dart';
 import '../utils/audio_output.dart';
 import '../utils/video_input.dart';
-import '../widgets/message_widget.dart';
 import '../widgets/audio_visualizer.dart';
 import '../widgets/camera_previews.dart';
+import '../widgets/message_widget.dart';
 
 // ============================================================================
 // MEDIA MANAGER
@@ -257,12 +258,12 @@ class BidiSessionController extends ChangeNotifier {
 
     _liveModel = useVertexBackend
         ? FirebaseAI.agentPlatform().liveGenerativeModel(
-            model: 'gemini-live-2.5-flash-preview-native-audio-09-2025',
+            model: ExampleModels.liveAgentPlatform,
             liveGenerationConfig: config,
             tools: tools,
           )
         : FirebaseAI.googleAI().liveGenerativeModel(
-            model: 'gemini-2.5-flash-native-audio-preview-09-2025',
+            model: ExampleModels.liveGoogleAI,
             liveGenerationConfig: config,
             tools: tools,
           );

packages/firebase_ai/firebase_ai/example/lib/pages/chat_page.dart

@@ -14,6 +14,7 @@
 
 import 'package:flutter/material.dart';
 import 'package:firebase_ai/firebase_ai.dart';
+import '../constants.dart';
 import '../widgets/message_widget.dart';
 
 class ChatPage extends StatefulWidget {
@@ -54,12 +55,12 @@ class _ChatPageState extends State<ChatPage> {
     );
     if (widget.useAgentPlatform) {
       _model = FirebaseAI.agentPlatform().generativeModel(
-        model: 'gemini-3.5-flash-lite',
+        model: ExampleModels.flashLite,
         generationConfig: generationConfig,
       );
     } else {
       _model = FirebaseAI.googleAI().generativeModel(
-        model: 'gemini-3.5-flash-lite',
+        model: ExampleModels.flashLite,
         generationConfig: generationConfig,
       );
     }

packages/firebase_ai/firebase_ai/example/lib/pages/function_calling_page.dart

@@ -15,6 +15,7 @@
 import 'package:flutter/material.dart';
 import 'package:firebase_ai/firebase_ai.dart';
 
+import '../constants.dart';
 import '../utils/function_call_utils.dart';
 import '../widgets/message_widget.dart';
 
@@ -240,21 +241,21 @@ class _FunctionCallingPageState extends State<FunctionCallingPage> {
         : FirebaseAI.googleAI();
 
     _functionCallModel = aiClient.generativeModel(
-      model: 'gemini-3.5-flash-lite',
+      model: ExampleModels.flashLite,
       generationConfig: generationConfig,
       tools: [
         Tool.functionDeclarations([fetchWeatherTool]),
       ],
     );
     _autoFunctionCallModel = aiClient.generativeModel(
-      model: 'gemini-3.5-flash-lite',
+      model: ExampleModels.flashLite,
       generationConfig: generationConfig,
       tools: [
         Tool.functionDeclarations([_autoFetchWeatherTool]),
       ],
     );
     _parallelAutoFunctionCallModel = aiClient.generativeModel(
-      model: 'gemini-3.5-flash-lite',
+      model: ExampleModels.flashLite,
       generationConfig: generationConfig,
       tools: [
         Tool.functionDeclarations(
@@ -263,21 +264,21 @@ class _FunctionCallingPageState extends State<FunctionCallingPage> {
       ],
     );
     _codeExecutionModel = aiClient.generativeModel(
-      model: 'gemini-3.5-flash-lite',
+      model: ExampleModels.flashLite,
       generationConfig: generationConfig,
       tools: [
         Tool.codeExecution(),
       ],
     );
     _complexSchemaModel = aiClient.generativeModel(
-      model: 'gemini-3.5-flash-lite',
+      model: ExampleModels.flashLite,
       generationConfig: generationConfig,
       tools: [
         Tool.functionDeclarations([_autoPlanVacationTool]),
       ],
     );
     _refDefJsonSchemaModel = aiClient.generativeModel(
-      model: 'gemini-3.5-flash-lite',
+      model: ExampleModels.flashLite,
       generationConfig: generationConfig,
       tools: [
         Tool.functionDeclarations([_autoProcessTransactionTool]),

packages/firebase_ai/firebase_ai/example/lib/pages/grounding_page.dart

@@ -14,6 +14,7 @@
 
 import 'package:flutter/material.dart';
 import 'package:firebase_ai/firebase_ai.dart';
+import '../constants.dart';
 import '../widgets/message_widget.dart';
 
 class GroundingPage extends StatefulWidget {
@@ -78,7 +79,7 @@ class _GroundingPageState extends State<GroundingPage> {
         : FirebaseAI.googleAI();
 
     _model = aiProvider.generativeModel(
-      model: 'gemini-3.5-flash',
+      model: ExampleModels.flashLite,
       tools: tools.isNotEmpty ? tools : null,
       toolConfig: toolConfig,
     );

packages/firebase_ai/firebase_ai/example/lib/pages/image_generation_page.dart

@@ -16,6 +16,7 @@ import 'dart:typed_data';
 import 'package:flutter/material.dart';
 import 'package:firebase_ai/firebase_ai.dart';
 
+import '../constants.dart';
 import '../widgets/message_widget.dart';
 
 class ImageGenerationPage extends StatefulWidget {
@@ -54,7 +55,7 @@ class _ImageGenerationPageState extends State<ImageGenerationPage> {
         : FirebaseAI.googleAI();
 
     _model = aiClient.generativeModel(
-      model: 'gemini-2.5-flash-image',
+      model: ExampleModels.flashImage,
       generationConfig: GenerationConfig(
         responseModalities: [ResponseModalities.text, ResponseModalities.image],
       ),