Appduct for Flutter

Call functions inside your running Flutter app from a terminal, a test runner or an AI agent. You register a few functions, called tools, with a name, a description and an input schema. The appduct CLI and its MCP server list and call them over an encrypted connection. Only the tools you register are reachable.

Works on Android, iOS, macOS, Windows and Linux. Flutter web isn't supported.

Requirements

• Flutter 3.38 or newer, iOS 15 or newer, Android 7.0 (API 24) or newer.
• The appduct CLI on your computer: npm install -g appduct (Node 20 or newer).

Getting started

flutter pub add appduct

Start Appduct before runApp, and register a tool:

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

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  Appduct.ensureInitialized();

  Appduct.instance.registerTool(
    'seed_cart',
    description: 'Fill the cart with test items.',
    inputSchema: {
      'type': 'object',
      'properties': {
        'items': {'type': 'number'},
      },
      'required': ['items'],
    },
    handler: (args, context) => {'added': (args['items'] as num).toInt()},
  );

  runApp(const ShopApp());
}

Then give the app a URL scheme and the permissions to reach your computer: a scheme on Android, iOS and macOS, INTERNET in the main Android manifest, NSLocalNetworkUsageDescription on iOS and the network client entitlement on macOS. The Flutter setup guide has each step.

With the app running in debug mode on a simulator or emulator, connect and call the tool:

appduct sessions link --open ios-sim     # or: --open android
appduct tools call seed_cart --input '{"items":3}'

Things to know

• Read numbers as num. A JSON number arrives as an int or a double, so use args['items'] as num, not as double.
• Move heavy work to Isolate.run. Handlers run on the main isolate. A long computation inside one freezes your UI.
• Create the futures a handler awaits inside the handler. A future created earlier that fails doesn't reach your try/catch, and the call ends with tool_timeout.

Register tools in Dart explains each of these.

Release builds

Appduct is in debug and profile builds. A release build leaves it out, and your Appduct.* calls do nothing. To include it in an internal build, or to leave it out of debug and profile builds, set a define:

flutter build apk --release --dart-define=APPDUCT_ENABLED=true

Pin an included build to your key with APPDUCT_PINS and APPDUCT_TRUST through --dart-define-from-file. See Ship Appduct in a release build and Security. Check the built app with appduct doctor <file> --assert-absent.

Learn more

• Documentation: guides and reference for every platform
• Write tools: schemas, timeouts, groups and events
• Connect an agent over MCP

License

MIT. Made at Callstack.