AI Agent Skill HUB

gum-tool-viewmodels

Reference guide for Gum tool ViewModel conventions. Load this when working on ViewModels, XAML views, data binding, DependsOn, or visibility properties in the Gum tool.

447 stars
byvchelaru
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Best use case

gum-tool-viewmodels is best used when you need a repeatable AI agent workflow instead of a one-off prompt.

Reference guide for Gum tool ViewModel conventions. Load this when working on ViewModels, XAML views, data binding, DependsOn, or visibility properties in the Gum tool.

Teams using gum-tool-viewmodels should expect a more consistent output, faster repeated execution, less prompt rewriting.

When to use this skill

  • You want a reusable workflow that can be run more than once with consistent structure.

When not to use this skill

  • You only need a quick one-off answer and do not need a reusable workflow.
  • You cannot install or maintain the underlying files, dependencies, or repository context.

Installation

Claude Code / Cursor / Codex

$curl -o ~/.claude/skills/gum-tool-viewmodels/SKILL.md --create-dirs "https://raw.githubusercontent.com/vchelaru/Gum/main/.claude/skills/gum-tool-viewmodels/SKILL.md"

Manual Installation

  1. Download SKILL.md from GitHub
  2. Place it in .claude/skills/gum-tool-viewmodels/SKILL.md inside your project
  3. Restart your AI agent — it will auto-discover the skill

How gum-tool-viewmodels Compares

Feature / Agentgum-tool-viewmodelsStandard Approach
Platform SupportNot specifiedLimited / Varies
Context Awareness High Baseline
Installation ComplexityUnknownN/A

Frequently Asked Questions

What does this skill do?

Reference guide for Gum tool ViewModel conventions. Load this when working on ViewModels, XAML views, data binding, DependsOn, or visibility properties in the Gum tool.

Where can I find the source code?

You can find the source code on GitHub using the link provided at the top of the page.

SKILL.md Source

# Gum Tool ViewModel Conventions

## Base Classes

- **`ViewModel`** (`Gum/Mvvm/ViewModel.cs`) — base for all view models. Provides `Get<T>()`/`Set()` property storage, `NotifyPropertyChanged`, and `[DependsOn]` propagation.
- **`DialogViewModel`** (`Gum/Services/Dialogs/DialogViewModel.cs`) — extends `ViewModel` for dialogs. Adds `AffirmativeCommand`/`NegativeCommand`, `RequestClose` event, and `AffirmativeText`/`NegativeText`.

## Property Patterns

**Stored properties** use `Get<T>()`/`Set()`:

```csharp
public string Name
{
    get => Get<string>() ?? string.Empty;
    set => Set(value);
}
```

**Derived properties** must use `[DependsOn]` so changes to the source property automatically raise `PropertyChanged` for the derived property. Without this, the UI will not update.

```csharp
[DependsOn(nameof(SourceType))]
public bool IsLocalFile => SourceType == SourceType.LocalFile;
```

Multiple dependencies are expressed with multiple attributes:

```csharp
[DependsOn(nameof(IsPreviewLoaded))]
[DependsOn(nameof(IsLoading))]
public bool CanImport => IsPreviewLoaded && !IsLoading;
```

## Visibility: ViewModel Properties, Not Converters

Do **not** use `IValueConverter` in XAML for visibility or other transformations. Instead, expose a `System.Windows.Visibility` property on the ViewModel with `[DependsOn]`:

```csharp
[DependsOn(nameof(ErrorMessage))]
public Visibility ErrorMessageVisibility =>
    string.IsNullOrEmpty(ErrorMessage) ? Visibility.Collapsed : Visibility.Visible;
```

XAML then binds directly:

```xml
<TextBlock Visibility="{Binding ErrorMessageVisibility}" />
```

This keeps XAML simple and makes the logic unit-testable.

## Common Pitfalls

**Missing `[DependsOn]`**: If a getter computes from another property but lacks the attribute, the UI will show stale values. The `ViewModel` constructor scans for `[DependsOn]` via reflection at construction time — it only works if the attribute is present.

**Two-way derived properties**: Properties like `IsLocalFile` that both read from and write to a backing property need `[DependsOn]` for the read direction. The write direction (setter updating `SourceType`) works normally through `Set()`.

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