​
🚀 Features

  • 🎙️ Two-way voice conversations with AI agents
  • 🔊 Voice Activity Detection (VAD) for natural conversations
  • 🧠 Custom actions that allow agents to trigger code in your app
  • 📱 Cross-platform - works on iOS, Android, and Web
  • 🔌 Audio session management for handling interruptions and device changes
  • 📝 Real-time transcripts of both user and agent speech
  • 🚦 Rich state management with ValueNotifiers for UI integration

​
Installation

Add the package to your pubspec.yaml:

dependencies:
  agents:
    git:
      url: https://github.com/playht/agents-client-sdk-flutter.git
      ref: main

Then save, or run:

flutter pub get

​
Platform Configuration

​
iOS

  1. Add the following to your Info.plist:
<key>NSMicrophoneUsageDescription</key>
<string>We need access to your microphone to enable voice conversations with the AI agent.</string>
  1. Add the following to your Podfile, since we depend on permission_handler to manage permissions and audio_session to manage audio sessions.
post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= [
        '$(inherited)',
        # audio_session settings
        'AUDIO_SESSION_MICROPHONE=0',
        # For microphone access
        'PERMISSION_MICROPHONE=1'
    end
  end
end
  1. Due to an issue of the Onnx Runtime getting stripped by XCode when archived, you need to follow these steps in XCode for the voice activity detector (VAD) to work on iOS builds:
    • Under “Targets”, choose “Runner” (or your project’s name)
    • Go to “Build Settings” tab
    • Filter for “Deployment”
    • Set “Stripped Linked Product” to “No”
    • Set “Strip Style” to “Non-Global-Symbols”

​
Android

  1. Add the following permissions to your AndroidManifest.xml:
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
  1. Add the following to android/gradle.properties (unless they’re already there):
android.useAndroidX=true
android.enableJetifier=true
  1. Add the following settings to android/app/build.gradle:
android {
    compileSdkVersion 34
    ...
}

​
Web

For VAD to work on web platforms, please following the instructions here.

​
Getting Started

​
1. Create an Agent on PlayAI

Follow the instructions here to create an agent on PlayAI.

​
2. Implement the Agent in Your Flutter App

final agent = Agent(
  // Replace with your agent ID from PlayAI
  agentId: 'your-agent-id-here',
  // Customize your agent's behavior
  prompt: 'You are a helpful assistant who speaks in a friendly, casual tone.',
  // Define actions the agent can take in your app
  actions: [
    AgentAction(
      name: 'show_weather',
      triggerInstructions: 'Trigger this when the user asks about weather.',
      argumentSchema: {
        'city': AgentActionParameter(
          type: 'string',
          description: 'The city to show weather for',
        ),
      },
      callback: (data) async {
        final city = data['city'] as String;
        // In a real app, you would fetch weather data here
        return 'Weather data fetched for $city!';
      },
    ),
  ],
  // Configure callbacks to respond to agent events
  callbackConfig: AgentCallbackConfig(
    // Get user speech transcript
    onUserTranscript: (text) {
      setState(() => _messages.add(ChatMessage(text, isUser: true)));
    },
    // Get agent speech transcript
    onAgentTranscript: (text) {
      setState(() => _messages.add(ChatMessage(text, isUser: false)));
    },
    // Handle any errors
    onError: (error, isFatal) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Error: $error')),
      );
    },
  ),
);

​
3. Connect the Agent to Start a Conversation

await agent.connect();

​
4. Mute and Unmute the User during a Conversation

await agent.muteUser();
await agent.unmuteUser();

​
5. Disconnect the Agent

await agent.disconnect();

​
Key Features

​
Monitor the Agent’s State

  1. AgentState: The agent can be in one of four states:
  • idle: Not connected to a conversation
  • connecting: In the process of establishing a connection
  • connected: Connected and ready to converse
  • disconnecting: In the process of ending a conversation
  1. Agent also exposes ValueListenables which you can listen to for changes in the agent’s state.
ValueListenableBuilder<AgentState>(
  valueListenable: agent.isUserSpeakingNotifier,
  builder: (context, isUserSpeaking, _) => Text('User is speaking: $isUserSpeaking'),
)
  1. Pass callbacks as AgentCallbackConfig to the Agent constructor to handle events from the agent.
final config = AgentCallbackConfig(
  onUserTranscript: (text) => print('User just said: $text'),
  onAgentTranscript: (text) => print('Agent just said: $text'),
)

final agent = Agent(
  // ...
  callbackConfig: config,
);

​
Agent Actions

One of the most exciting features of the PlayAI Agents SDK is the ability to define custom actions that allow the agent to interact with your app.

AgentAction(
  name: 'open_settings',
  triggerInstructions: 'Trigger this when the user asks to open settings',
  argumentSchema: {
    'section': AgentActionParameter(
      type: 'string',
      description: 'The settings section to open',
    ),
  },
  callback: (data) async {
    final section = data['section'] as String;
    // Navigate to settings section in your app
    return 'Opened $section settings';
  },
)

​
Developer Messages

Send contextual information to the agent during a conversation to inform it of changes in your app.

// When user navigates to a new screen
void _onNavigate(String routeName) {
  agent.sendDeveloperMessage(
    'User navigated to $routeName screen. You can now discuss the content on this page.',
  );
}

// When relevant data changes
void _onCartUpdated(List<Product> products) {
  agent.sendDeveloperMessage(
    'User\'s cart has been updated, now containing: ${products.map((p) => p.name).join(", ")}.',
  );
}

​
Error Handling

The package uses a robust error handling system with specific exception types:

try {
  await agent.connect();
} on MicrophonePermissionDenied {
  // Handle microphone permission issues
} on WebSocketConnectionError catch (e) {
  // Handle connection issues
} on ServerError catch (e) {
  // Handle server-side errors
  if (e.isFatal) {
    // Handle fatal errors
  }
} on AgentException catch (e) {
  // Handle all other agent exceptions
  print('Error code: ${e.code}, Message: ${e.readableMessage}');
}

​
Lifecycle Management

Don’t forget to dispose of the agent when it’s no longer needed to free up resources.

@override
void dispose() {
  // Clean up resources
  agent.dispose();
  super.dispose();
}

​
UI Integration Examples

​
Mute Button

ValueListenableBuilder<bool>(
  valueListenable: agent.isMutedNotifier,
  builder: (context, isMuted, _) => IconButton(
    icon: Icon(isMuted ? Icons.mic_off : Icons.mic),
    onPressed: () => isMuted ? agent.unmuteUser() : agent.muteUser(),
    tooltip: isMuted ? 'Unmute' : 'Mute',
  ),
)

​
Speaking Indicator

ValueListenableBuilder<bool>(
  valueListenable: agent.isAgentSpeakingNotifier,
  builder: (context, isSpeaking, _) => AnimatedContainer(
    duration: const Duration(milliseconds: 300),
    width: 40,
    height: 40,
    decoration: BoxDecoration(
      shape: BoxShape.circle,
      color: isSpeaking ? Colors.blue : Colors.grey.shade300,
    ),
    child: Center(
      child: Icon(
        Icons.record_voice_over,
        size: 24,
        color: Colors.white,
      ),
    ),
  ),
)

​
Tips for Effective Usage

  1. Prompt Engineering: Craft clear, specific prompts to guide agent behavior
  2. Action Design: Design actions with clear trigger instructions and parameter descriptions
  3. Context Management: Use sendDeveloperMessage to keep the agent updated on app state
  4. Error Handling: Implement comprehensive error handling for a smooth user experience
  5. UI Feedback: Use the provided ValueListenables to give clear feedback on conversation state

​
Acknowledgments

  • Voice Activity Detection powered by vad
  • Audio session management by audio_session