multi_device_preview_marionette 1.0.0

Exposes multi_device_preview commands (devices, input sync, restart, screenshots, trackpad scroll) as Marionette MCP tools for AI agents.

multi_device_preview_marionette

Lets AI agents drive multi_device_preview through Marionette MCP: every preview command becomes an MCP tool with a typed schema.

Tool	What it does
multiDevicePreview.getState	Devices (preset, text scale, size, screen key, out-of-sync) and sync state
multiDevicePreview.listPresets	Preset ids
multiDevicePreview.setSync	Turns input sync on or off
multiDevicePreview.restart	Rebuilds every app from scratch
multiDevicePreview.setDevice / addDevice / removeDevice	Changes the devices
multiDevicePreview.saveScreenshot	Writes a PNG of all devices, or one, to a file
multiDevicePreview.panZoom	Scrolls with a trackpad gesture, mirrored like a real one

Setup

flutter pub add dev:multi_device_preview_marionette dev:marionette_flutter

In the preview entry point, initialize Marionette before runMultiDevicePreview:

import 'package:flutter/foundation.dart';
import 'package:marionette_flutter/marionette_flutter.dart';
import 'package:multi_device_preview/multi_device_preview.dart';
import 'package:multi_device_preview_marionette/multi_device_preview_marionette.dart';

void main() {
  final controller = MultiDevicePreviewController();
  if (!kReleaseMode) {
    MarionetteBinding.ensureInitialized(
      multiDevicePreviewMarionetteConfiguration,
    );
    registerMultiDevicePreviewMarionetteExtensions(controller);
  }
  runMultiDevicePreview(
    controller: controller,
    appBuilder: (context, slot) => const MyApp(),
  );
}

multiDevicePreviewMarionetteConfiguration uses CompactionMode.none, so get_interactive_elements reports every element and an agent can compare sizes and text scales across devices. Pass your own MarionetteConfiguration to customize it.

Tips for agents

• Each device screen has the key multi_device_preview.screen.<n>. Pass it in ancestor_keys to look at, or act on, a single device. Without it, keys and texts match the first device, and the action is mirrored to the others while input sync is on.
• Prefer multiDevicePreview.saveScreenshot over take_screenshots: several devices easily exceed the size of an MCP response.
• macOS stops rendering a window hidden behind other windows; keep the preview window visible, or saveScreenshot reports an error.
• bounds from Marionette: x/y are positions in the scaled window, width/height are logical sizes inside the device.

License

MIT