moinsen-runapp-skill

name	moinsen_runapp-skill
description	Use when working with Flutter apps that use moinsen_runapp — for setup, configuration, state exposure, error reporting, HTTP monitoring, UI interaction (tap, scroll, text input), MCP server setup, and LLM-assisted debugging via CLI, VM Service extensions, or MCP tools.

moinsen_runapp — LLM Debug Bridge for Flutter

Drop-in runApp() replacement that gives LLM tools full visibility and control over a Flutter app: three-layer error catching, app-level logging, navigation tracking, screenshots, device context, lifecycle tracking, HTTP monitoring, state inspection, remote UI interaction, and an MCP server for AI agent integration.

When to Use This Skill

• Project has moinsen_runapp in pubspec.yaml
• User asks about Flutter error handling with LLM support
• User wants to make a Flutter app "debuggable by AI"
• User asks about exposing app state for debugging
• User asks about the moinsen_run CLI tool or ext.moinsen.* extensions
• User wants to remote-control a Flutter app (tap, scroll, enter text)
• User wants to connect an AI agent to a Flutter app via MCP
• User is configuring MCP servers for Flutter debugging

Quick Start (4 Steps)

1. Replace runApp()

import 'package:moinsen_runapp/moinsen_runapp.dart';

void main() {
  moinsenRunApp(child: const MyApp());
}

2. Add Navigator Observer

MaterialApp(
  navigatorObservers: [MoinsenNavigatorObserver.instance],
)

3. Log App Events

moinsenLog('Payment completed', source: 'checkout', level: 'info');
moinsenLog('API returned 500', source: 'api', level: 'error');

4. Expose State (Optional)

moinsenExposeState('cart', () => cartBloc.state.toJson());
moinsenExposeState('user', () => {'name': user.name, 'role': user.role});

That's it. The app now has error catching, logging, route tracking, device info, lifecycle tracking, HTTP monitoring, and LLM debugging support.

Enable UI Interaction (Opt-In)

moinsenRunApp(
  config: const RunAppConfig(enableInteraction: true),
  child: const MyApp(),
);

Registers 4 additional VM extensions for tap, scroll, text input, and element discovery. Only active in debug mode.

Custom Widget Support

RunAppConfig(
  enableInteraction: true,
  interactionConfig: InteractionConfig(
    isInteractiveWidget: (type) => type == MyCustomButton,
    shouldStopTraversal: (type) => type == MyCustomCard,
    extractText: (widget) {
      if (widget is MyLabel) return widget.title;
      return null;
    },
  ),
)

Built-in support for all standard Flutter widgets (buttons, text fields, switches, etc.).

With Async Initialization

void main() {
  moinsenRunApp(
    init: () async {
      await Firebase.initializeApp();
      await Hive.initFlutter();
    },
    onError: (error, stack) => Sentry.captureException(error, stackTrace: stack),
    config: const RunAppConfig(
      releaseScreenVariant: ErrorScreenVariant.minimal,
      logToFile: true,
    ),
    child: const MyApp(),
  );
}

If init throws, the error is caught and logged — but the app always starts.

RunAppConfig Reference

Parameter	Default	Description
deduplicationWindow	Duration(seconds: 2)	Time window for deduplicating identical errors
maxLoggedErrors	50	Max unique errors tracked before evicting oldest
logBufferCapacity	200	Max app-level log entries retained
logToFile	false	Write errors to disk (auto-rotates at 1 MB)
logFilePath	null	Explicit path; auto-resolved via path_provider if null
screenshotMaxDimension	null	Cap screenshot resolution (physical pixels)
monitorHttp	true	Intercept all dart:io HTTP traffic
httpBufferCapacity	100	Max HTTP requests retained in ring buffer
enableInteraction	false	Enable UI interaction extensions (tap, scroll, text, elements)
interactionConfig	InteractionConfig()	Callbacks for custom widget support (only when interaction enabled)
releaseScreenVariant	friendly	Error screen: friendly, minimal, or illustrated
releaseScreenBuilder	null	Custom release error screen (overrides variant)
debugScreenBuilder	null	Custom debug error screen (overrides built-in)

State Exposure Patterns

State snapshots are lazy — functions are only called when an LLM queries state.

// Bloc / Cubit
moinsenExposeState('auth', () => authBloc.state.toJson());

// Riverpod
moinsenExposeState('settings', () => ref.read(settingsProvider).toJson());

// Provider / ChangeNotifier
moinsenExposeState('cart', () => {
  'items': cartModel.items.length,
  'total': cartModel.totalPrice,
});

// Remove when no longer needed
moinsenHideState('cart');

Error Reporting Integration

// Sentry
onError: (error, stack) => Sentry.captureException(error, stackTrace: stack),

// Crashlytics
onError: (error, stack) => FirebaseCrashlytics.instance.recordError(error, stack),

// Manual reporting from catch blocks:
try {
  await api.fetchData();
} catch (e, stack) {
  moinsenReportError(e, stack, source: 'api');
}

CLI Quick Reference

Run with dart run moinsen_runapp:moinsen_run <command>.

Observation Commands

Command	Description
(default)	Start flutter run with JSON line streaming
errors	Get deduplicated error report
prompt	LLM-ready markdown bug report
logs	Recent log entries (--last N)
route	Current route + navigation history
device	Device/environment info (screen, locale, a11y)
lifecycle	App lifecycle state + transitions
network	HTTP traffic (--errors, --last N)
inspect	Registered app state (inspect [key])
screenshot	Capture screen as PNG
context	Full LLM-ready context report (--with-screenshot, --with-tree)
status	Check if app is running
state	Widget tree dump
analyze	Run flutter analyze

Interaction Commands (require enableInteraction: true)

Command	Description
elements	Get all interactive elements currently on screen
tap	Tap element (--key, --text, --type, or --x/--y)
enter-text	Type into text field (--key/--text/--type + --input)
scroll-to	Scroll until element visible (--key or --text)

Control Commands

Command	Description
navigate	Push (--push /route) or pop (--pop)
reload	Hot reload
restart	Hot restart
stop	Stop the running app

MCP Server

The moinsen_mcp executable exposes all capabilities as 21 MCP tools for AI agents.

Setup

# Global install (recommended)
dart pub global activate moinsen_runapp
moinsen_mcp

# Or from a project
dart run moinsen_runapp:moinsen_mcp

Claude Code / Cursor Integration

With global installation (recommended):

{
  "mcpServers": {
    "moinsen": {
      "command": "moinsen_mcp"
    }
  }
}

Without global installation:

{
  "mcpServers": {
    "moinsen": {
      "command": "dart",
      "args": ["run", "moinsen_runapp:moinsen_mcp"],
      "cwd": "/path/to/your-flutter-project"
    }
  }
}

CLI Options

Flag	Default	Description
--log-level, -l	INFO	Log level (FINEST, FINE, INFO, WARNING, SEVERE)
--log-file	stderr	Path to log file

Typical MCP Workflow

1. connect(uri: "ws://127.0.0.1:8181/ws")    — connect to running app
2. observe()                                    — full context + screenshot
3. get_interactive_elements()                   — see what's tappable
4. tap(key: "login_button")                     — interact
5. interact_and_verify(action: "tap", key: "submit")  — action + screenshot
6. disconnect()

MCP Tool Reference (21 Tools)

Category	Tools
Connection	connect, disconnect
Observation	get_errors, clear_errors, get_logs, get_route, get_device_info, get_lifecycle, get_network, get_state, take_screenshot, get_prompt
Interaction	get_interactive_elements, tap, enter_text, scroll_to
Control	navigate, hot_reload, hot_restart
Composite	observe (full context + screenshot in one call), interact_and_verify (action + verification screenshot)

MCP Usage Patterns

Quick health check: connect -> observe -> disconnect

Automated form filling:

connect -> get_interactive_elements -> enter_text(key: "email", input: "...") -> tap(key: "submit") -> take_screenshot -> disconnect

Debug a crash:

connect -> get_errors -> get_logs -> get_network -> get_route -> take_screenshot -> disconnect

VM Service Extensions

All registered under ext.moinsen.* in debug mode.

Observation Extensions (13, always active)

Extension	Returns
getErrors	{errors: [...], totalCount, uniqueCount}
clearErrors	{cleared: true}
getInfo	{package, errorCount, uniqueErrors, platform}
getLogs	{logs: [...], capacity, size}
getPrompt	{prompt: "# Enhanced Bug Report\n..."}
screenshot	{screenshot: "<base64>", width, height}
getRoute	{currentRoute, observerInstalled, history: [...]}
navigate	{navigated: true, action, route} (params: route, pop)
getContext	{errors, logs, route, device, lifecycle, network, state}
getDeviceInfo	{os, logicalWidth, logicalHeight, devicePixelRatio, locale, ...}
getLifecycle	{currentState, uptime_ms, history: [...]}
getNetwork	{totalCount, errorCount, avgDuration_ms, requests: [...]}
getState	{registeredKeys: [...], states: {...}} (param: key)

Interaction Extensions (4, require enableInteraction: true)

Extension	Params	Returns
getInteractiveElements	(none)	{elements: [{type, key, text, bounds, visible}], count}
tap	key/text/type/x+y	{success: true} or {success: false, error}
enterText	key/text/type + input	{success: true} or {success: false, error}
scrollTo	key/text	{success: true} or {success: false, error}

Widget matching precedence: coordinates (x+y) > key > text > type. All params are strings.

InteractionConfig Reference

Callback	Purpose
isInteractiveWidget(Type)	Mark custom widgets as interactive
shouldStopTraversal(Type)	Stop traversing children of this widget
extractText(Widget)	Extract text from custom widgets

Built-in interactive widgets: ElevatedButton, TextButton, FilledButton, OutlinedButton, IconButton, FloatingActionButton, TextField, TextFormField, Checkbox, Switch, Radio, Slider, GestureDetector, InkWell, DropdownButton, PopupMenuButton, and their ListTile variants.

Troubleshooting

Navigation not tracked / route returns null:

• Forgot MoinsenNavigatorObserver.instance in navigatorObservers
• Using Navigator 2.0 (Router) — observer is for Navigator 1.0 only

HTTP requests not showing:

• monitorHttp: false in config
• Custom HttpOverrides set after moinsenRunApp() — chain via MoinsenHttpOverrides(previous: yourOverrides)

CLI commands fail with "No running app found":

• App not started with moinsen_run start, or .moinsen_run.json stale

Interaction commands return errors:

• enableInteraction: false (default) — must enable
• App not in debug mode
• Widget not found — use elements to see what's on screen

elements returns empty list:

• No interactive widgets on screen
• Elements obscured by overlays
• Custom widgets not registered via InteractionConfig

MCP: "Not connected to any app":

• Call connect first with the VM service URI

MCP: "No isolate with ext.moinsen.getErrors found":

• App doesn't use moinsenRunApp()
• App in release mode — extensions only register in debug mode

MCP: Connection drops after hot restart:

• Hot restart reinitializes the VM — reconnect after hot_restart

Architecture Notes

• No custom binding — uses dart:developer.registerExtension and GestureBinding.instance, compatible with any Flutter binding
• Interaction is opt-in — enableInteraction: false by default
• Widget matching — sealed class with 4 strategies: CoordinatesMatcher (fastest), KeyMatcher, TextMatcher, TypeStringMatcher
• MCP transport — stdio only, auto-discovers moinsen-enabled isolate

Platform Support

Platform	Supported
iOS / Android / macOS / Windows / Linux	Yes
Web	No (dart:io required)

Package Info

• Package: moinsen_runapp
• Version: 0.6.0
• Executables: moinsen_run (CLI), moinsen_mcp (MCP server)
• Repository: https://github.com/moinsen-dev/moinsen_runapp
• License: MIT