flutter_agent_kit 0.0.1

Flutter bindings for Google's Agent Development Kit (ADK) for Kotlin — build on-device and cloud AI agents with tool calling, from Dart.

example/lib/main.dart

import 'dart:math';

import 'package:flutter/material.dart';
import 'package:flutter_agent_kit/flutter_agent_kit.dart';

void main() {
  runApp(const ExampleApp());
}

/// Demo app for `flutter_agent_kit`: a chat screen, one Dart-defined tool
/// (`roll_dice`), and a switch for whether the conversation survives an app
/// restart. See docs/v1-implementation-plan.md for what this is and isn't
/// meant to show.
class ExampleApp extends StatelessWidget {
  const ExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'flutter_agent_kit example',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
      ),
      home: const ChatPage(),
    );
  }
}

/// Native errors (e.g. from a misconfigured Firebase project) carry a full
/// stack trace after the first line — only the first line is useful in a
/// chat bubble.
String _firstLine(Object error) => error.toString().split('\n').first;

class _ChatMessage {
  _ChatMessage.user(this.text) : isUser = true, isPending = false;
  _ChatMessage.assistant() : isUser = false, text = '', isPending = true;

  final bool isUser;
  String text;
  bool isPending;
}

class ChatPage extends StatefulWidget {
  const ChatPage({super.key});

  @override
  State<ChatPage> createState() => _ChatPageState();
}

class _ChatPageState extends State<ChatPage> {
  final _textController = TextEditingController();
  final _messages = <_ChatMessage>[];

  late Agent _agent;
  bool _rememberChat = false;
  bool _sending = false;

  @override
  void initState() {
    super.initState();
    _agent = _buildAgent();
  }

  Agent _buildAgent() {
    return Agent(
      instructions: 'You are a helpful assistant. Use the roll_dice tool when asked to roll a die.',
      model: const AgentModelConfig.cloud(),
      session: _rememberChat
          ? const AgentSessionConfig.persistent()
          : const AgentSessionConfig.memory(),
      tools: [
        AgentTool(
          name: 'roll_dice',
          description: 'Rolls a standard six-sided die and returns the result.',
          parametersSchema: const {'type': 'object', 'properties': {}},
          execute: (args) async => {'result': Random().nextInt(6) + 1},
        ),
      ],
    );
  }

  Future<void> _toggleRememberChat(bool value) async {
    final oldAgent = _agent;
    setState(() {
      _rememberChat = value;
      _messages.clear();
      _agent = _buildAgent();
    });
    await oldAgent.dispose();
  }

  Future<void> _send() async {
    final text = _textController.text.trim();
    if (text.isEmpty || _sending) return;
    _textController.clear();

    final assistantMessage = _ChatMessage.assistant();
    setState(() {
      _messages.add(_ChatMessage.user(text));
      _messages.add(assistantMessage);
      _sending = true;
    });

    try {
      await for (final event in _agent.send(text)) {
        setState(() {
          switch (event) {
            case AgentTextDelta(:final text):
              assistantMessage.text += text;
            case AgentFinalResponse(:final text):
              assistantMessage
                ..text = text
                ..isPending = false;
            case AgentToolCall(:final toolName):
              assistantMessage.text = 'Using $toolName…';
            case AgentError(:final message):
              assistantMessage
                ..text = 'Error: ${_firstLine(message)}'
                ..isPending = false;
          }
        });
      }
    } catch (error) {
      setState(() {
        assistantMessage
          ..text = 'Error: ${_firstLine(error)}'
          ..isPending = false;
      });
    } finally {
      setState(() => _sending = false);
    }
  }

  @override
  void dispose() {
    _agent.dispose();
    _textController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('flutter_agent_kit example')),
      body: Column(
        children: [
          SwitchListTile(
            title: const Text('Remember this conversation after restart'),
            value: _rememberChat,
            onChanged: _sending ? null : _toggleRememberChat,
          ),
          const Divider(height: 1),
          Expanded(
            child: ListView.builder(
              padding: const EdgeInsets.all(12),
              itemCount: _messages.length,
              itemBuilder: (context, index) {
                final message = _messages[index];
                return Align(
                  alignment: message.isUser
                      ? Alignment.centerRight
                      : Alignment.centerLeft,
                  child: Container(
                    constraints: BoxConstraints(
                      maxWidth: MediaQuery.of(context).size.width * 0.75,
                    ),
                    margin: const EdgeInsets.symmetric(vertical: 4),
                    padding: const EdgeInsets.symmetric(
                      horizontal: 14,
                      vertical: 10,
                    ),
                    decoration: BoxDecoration(
                      color: message.isUser
                          ? Theme.of(context).colorScheme.primaryContainer
                          : Theme.of(context)
                                .colorScheme
                                .surfaceContainerHighest,
                      borderRadius: BorderRadius.circular(14),
                    ),
                    child: Text(
                      message.text.isEmpty && message.isPending
                          ? '…'
                          : message.text,
                    ),
                  ),
                );
              },
            ),
          ),
          SafeArea(
            minimum: const EdgeInsets.all(8),
            child: Row(
              children: [
                Expanded(
                  child: TextField(
                    controller: _textController,
                    decoration: const InputDecoration(
                      hintText: 'Message',
                      border: OutlineInputBorder(),
                    ),
                    onSubmitted: (_) => _send(),
                  ),
                ),
                const SizedBox(width: 8),
                IconButton.filled(
                  onPressed: _sending ? null : _send,
                  icon: const Icon(Icons.send),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}