maui-labs: Skill for Claude Code

Comet Go — Single-File App Development

Comet Go is a single-file app experience for .NET MAUI using the Comet MVU framework. The user writes ONE .cs file, runs maui go, and it live-reloads on their device.

How It Works

1. User writes a single .cs file with a MainPage : View class
2. maui go starts GoDevServer → Roslyn compiles to DLL (OutputKind.DynamicallyLinkedLibrary)
3. DLL is sent over WebSocket to the companion app
4. Companion app loads via Assembly.Load → MetadataUpdater.ApplyUpdate for hot reload
5. Scaffold new apps with: maui go create <AppName>

Required Imports

Every Comet Go file MUST start with:

#:package Comet

using Comet;
using Microsoft.Maui;
using Microsoft.Maui.Graphics;
using static Comet.CometControls;

• using static Comet.CometControls; enables VStack(...), Text(...), Button(...) etc. as top-level functions
• Add using System; if you need Math, Convert, DateTime, or TimeSpan directly
• Action and Func<T> resolve without using System; via implicit usings

App Structure

namespace MyApp;

public class MainPage : View
{
    readonly Reactive<int> count = new(0);

    [Body]
    View body() =>
        VStack(spacing: 16f,
            Text(() => $"Count: {count.Value}"),
            Button("Tap", () => count.Value++)
        );
}

CRITICAL: VStack/HStack Spacing Parameter

VStack(0, ...) is ambiguous between VStack(float?, params View[]) and VStack(LayoutAlignment, params View[]).

• ✅ VStack(spacing: 0f, ...) — named parameter (clearest)
• ✅ VStack(16f, ...) — float literal with f suffix
• ❌ VStack(0, ...) — CS0121 ambiguous call
• ❌ VStack(16, ...) — may be ambiguous

Always use f suffix or spacing: named parameter.

Available Controls (via using static Comet.CometControls)

Layout

VStack(float? spacing, params View[] children)     // vertical stack
HStack(float? spacing, params View[] children)     // horizontal stack
ZStack(params View[] children)                      // overlay stack
Grid(object[] columns, object[] rows, params View[] children)
ScrollView(View content)
Border(View content)
Spacer()                                            // flexible space