dotnet-spectre-console

Imported from wshaddix/dotnet-skills (skills/dotnet-spectre-console/SKILL.md). Install upstream with npx skills add wshaddix/dotnet-skills --skill dotnet-spectre-console. Copyright stays with the author.

dotnet-spectre-console

Spectre.Console for building rich console output (tables, trees, progress bars, prompts, markup, live displays) and Spectre.Console.Cli for structured command-line application parsing. Cross-platform across Windows, macOS, and Linux terminals.

Version assumptions: .NET 8.0+ baseline. Spectre.Console 0.54.0 (latest stable). Spectre.Console.Cli 0.53.1 (latest stable). Both packages target net8.0+ and netstandard2.0.

Scope boundary: This skill owns rich console output and Spectre.Console.Cli command parsing. Full TUI applications (windows, menus, dialogs, views) are owned by [skill:dotnet-terminal-gui]. System.CommandLine parsing is owned by [skill:dotnet-system-commandline]. CLI application architecture and distribution are owned by [skill:dotnet-cli-architecture] and [skill:dotnet-cli-distribution].

Cross-references: [skill:dotnet-terminal-gui] for full TUI alternative, [skill:dotnet-system-commandline] for System.CommandLine scope boundary, [skill:dotnet-cli-architecture] for CLI structure, [skill:dotnet-csharp-async-patterns] for async patterns, [skill:dotnet-csharp-dependency-injection] for DI with Spectre.Console.Cli, [skill:dotnet-accessibility] for TUI accessibility limitations and screen reader considerations.

Package References

<ItemGroup>
  <!-- Rich console output: markup, tables, trees, progress, prompts, live displays -->
  <PackageReference Include="Spectre.Console" Version="0.54.0" />

  <!-- CLI command framework (adds command parsing, settings, DI support) -->
  <PackageReference Include="Spectre.Console.Cli" Version="0.53.1" />
</ItemGroup>

Spectre.Console.Cli has a dependency on Spectre.Console -- install both only when you need the CLI framework. For rich output only, Spectre.Console alone is sufficient.

Markup and Styling

Spectre.Console uses a BBCode-inspired markup syntax for styled console output.

Basic Markup

using Spectre.Console;

// Styled text with markup tags
AnsiConsole.MarkupLine("[bold red]Error:[/] File not found.");
AnsiConsole.MarkupLine("[green]Success![/] Build completed in [blue]2.3s[/].");
AnsiConsole.MarkupLine("[underline]https://example.com[/]");
AnsiConsole.MarkupLine("[dim italic]This is subtle text[/]");

// Nested styles
AnsiConsole.MarkupLine("[bold [red on white]Warning:[/] check config[/]");

// Escape brackets with double brackets
AnsiConsole.MarkupLine("Use [[bold]] for bold text.");

Figlet Text

AnsiConsole.Write(
    new FigletText("Hello!")
        .Color(Color.Green)
        .Centered());

Rule (Horizontal Line)

// Simple rule
AnsiConsole.Write(new Rule());

// Titled rule
AnsiConsole.Write(new Rule("[yellow]Section Title[/]"));

// Aligned rule
AnsiConsole.Write(new Rule("[blue]Left Aligned[/]").LeftJustified());

Tables

var table = new Table();

// Add columns
table.AddColumn("Name");
table.AddColumn(new TableColumn("Age").Centered());
table.AddColumn(new TableColumn("City").RightAligned());

// Add rows
table.AddRow("Alice", "30", "Seattle");
table.AddRow("[green]Bob[/]", "25", "Portland");
table.AddRow("Charlie", "35", "Vancouver");

// Styling
table.Border(TableBorder.Rounded);
table.BorderColor(Color.Grey);
table.Title("[underline]Team Members[/]");
table.Caption("[dim]Updated daily[/]");

// Column configuration
table.Columns[0].PadLeft(2);
table.Columns[0].NoWrap();

AnsiConsole.Write(table);

Nested Tables

var innerTable = new Table()
    .AddColumn("Detail")
    .AddColumn("Value")
    .AddRow("Role", "Developer")
    .AddRow("Level", "Senior");

var outerTable = new Table()
    .AddColumn("Name")
    .AddColumn("Info")
    .AddRow("Alice", innerTable);

AnsiConsole.Write(outerTable);

Trees

var tree = new Tree("Solution");

// Add nodes
var srcNode = tree.AddNode("[yellow]src[/]");
var apiNode = srcNode.AddNode("Api");
apiNode.AddNode("Controllers/");
apiNode.AddNode("Program.cs");

var libNode = srcNode.AddNode("Library");
libNode.AddNode("Services/");

var testNode = tree.AddNode("[blue]tests[/]");
testNode.AddNode("Api.Tests/");

// Styling
tree.Style = Style.Parse("dim");

AnsiConsole.Write(tree);

Panels

var panel = new Panel("This is [green]important[/] content.")
    .Header("[bold]Notice[/]")
    .Border(BoxBorder.Rounded)
    .BorderColor(Color.Blue)
    .Padding(2, 1)    // horizontal, vertical
    .Expand();         // fill available width

AnsiConsole.Write(panel);

Composing Renderables with Columns

AnsiConsole.Write(new Columns(
    new Panel("Left panel").Expand(),
    new Panel("Right panel").Expand()));

Progress Displays

Progress Bars

await AnsiConsole.Progress()
    .AutoClear(false)       // keep completed tasks visible
    .HideCompleted(false)
    .Columns(
        new TaskDescriptionColumn(),
        new ProgressBarColumn(),
        new PercentageColumn(),
        new RemainingTimeColumn(),
        new SpinnerColumn())
    .StartAsync(async ctx =>
    {
        var downloadTask = ctx.AddTask("[green]Downloading[/]", maxValue: 100);
        var extractTask = ctx.AddTask("[blue]Extracting[/]", maxValue: 100);

        while (!ctx.IsFinished)
        {
            await Task.Delay(50);
            downloadTask.Increment(1.5);

            if (downloadTask.Value > 50)
            {
                extractTask.Increment(0.8);
            }
        }
    });

Status Spinners

await AnsiConsole.Status()
    .Spinner(Spinner.Known.Dots)
    .SpinnerStyle(Style.Parse("green bold"))
    .StartAsync("Processing...", async ctx =>
    {
        await Task.Delay(1000);
        ctx.Status("Compiling...");
        ctx.Spinner(Spinner.Known.Star);
        await Task.Delay(1000);
        ctx.Status("Publishing...");
        await Task.Delay(1000);
    });

Prompts

Text Prompt

// Simple typed input
var name = AnsiConsole.Ask<string>("What's your [green]name[/]?");
var age = AnsiConsole.Ask<int>("What's your [green]age[/]?");

// With default value
var city = AnsiConsole.Prompt(
    new TextPrompt<string>("Enter [green]city[/]:")
        .DefaultValue("Seattle")
        .ShowDefaultValue());

// Secret input (password)
var password = AnsiConsole.Prompt(
    new TextPrompt<string>("Enter [green]password[/]:")
        .Secret());

// With validation
var email = AnsiConsole.Prompt(
    new TextPrompt<string>("Enter [green]email[/]:")
        .Validate(input =>
            input.Contains('@') && input.Contains('.')
                ? ValidationResult.Success()
                : ValidationResult.Error("[red]Invalid email address[/]")));

// Optional (allow empty)
var nickname = AnsiConsole.Prompt(
    new TextPrompt<string>("Enter [green]nickname[/] (optional):")
        .AllowEmpty());

Confirmation Prompt

bool proceed = AnsiConsole.Confirm("Continue with deployment?");

Selection Prompt

var fruit = AnsiConsole.Prompt(
    new SelectionPrompt<string>()
        .Title("Pick a [green]fruit[/]:")
        .PageSize(10)
        .EnableSearch()
        .WrapAround()
        .AddChoices("Apple", "Banana", "Orange", "Mango", "Grape"));

// Grouped choices
var country = AnsiConsole.Prompt(
    new SelectionPrompt<string>()
        .Title("Select [green]destination[/]:")
        .AddChoiceGroup("Europe", "France", "Italy", "Spain")
        .AddChoiceGroup("Asia", "Japan", "Thailand", "Vietnam"));

Multi-Selection Prompt

var toppings = AnsiConsole.Prompt(
    new MultiSelectionPrompt<string>()
        .Title("Choose [green]toppings[/]:")
        .PageSize(10)
        .Required()
        .InstructionsText("[grey](Press [blue]<space>[/] to toggle, [green]<enter>[/] to accept)[/]")
        .AddChoices("Cheese", "Pepperoni", "Mushrooms", "Olives", "Onions"));

Live Displays

Live displays update in-place for dynamic content that changes over time.

var table = new Table()
    .AddColumn("Time")
    .AddColumn("Status");

await AnsiConsole.Live(table)
    .AutoClear(false)
    .Overflow(VerticalOverflow.Ellipsis)
    .Cropping(VerticalOverflowCropping.Bottom)
    .StartAsync(async ctx =>
    {
        table.AddRow(DateTime.Now.ToString("T"), "[yellow]Starting...[/]");
        ctx.Refresh();
        await Task.Delay(1000);

        table.AddRow(DateTime.Now.ToString("T"), "[green]Processing...[/]");
        ctx.Refresh();
        await Task.Delay(1000);

        table.AddRow(DateTime.Now.ToString("T"), "[blue]Complete![/]");
        ctx.Refresh();
    });

Replacing the Target

await AnsiConsole.Live(new Markup("[yellow]Initializing...[/]"))
    .StartAsync(async ctx =>
    {
        await Task.Delay(1000);
        ctx.UpdateTarget(new Markup("[green]Ready![/]"));
        await Task.Delay(1000);
        ctx.UpdateTarget(
            new Panel("Final result: [bold]42[/]")
                .Header("Done")
                .Border(BoxBorder.Rounded));
    });

Spectre.Console.Cli Framework

Spectre.Console.Cli provides a structured command-line parsing framework with command hierarchies, typed settings, validation, and automatic help generation.

Basic Command App

using Spectre.Console.Cli;

var app = new CommandApp<GreetCommand>();
return app.Run(args);

// Command with typed settings
public sealed class GreetSettings : CommandSettings
{
    [CommandArgument(0, "<name>")]
    [Description("The person to greet")]
    public string Name { get; init; } = string.Empty;

    [CommandOption("-c|--count")]
    [Description("Number of times to greet")]
    [DefaultValue(1)]
    public int Count { get; init; }

    [CommandOption("--shout")]
    [Description("Greet in uppercase")]
    public bool Shout { get; init; }
}

public sealed class GreetCommand : Command<GreetSettings>
{
    public override int Execute(CommandContext context, GreetSettings settings)
    {
        for (int i = 0; i < settings.Count; i++)
        {
            var greeting = $"Hello, {settings.Name}!";
            AnsiConsole.MarkupLine(settings.Shout
                ? $"[bold]{greeting.ToUpperInvariant()}[/]"
                : greeting);
        }
        return 0;  // exit code
    }
}

Command Hierarchy with Branches

var app = new CommandApp();
app.Configure(config =>
{
    config.AddBranch<RemoteSettings>("remote", remote =>
    {
        remote.AddCommand<RemoteAddCommand>("add")
            .WithDescription("Add a remote");
        remote.AddCommand<RemoteRemoveCommand>("remove")
            .WithDescription("Remove a remote");
    });

    config.AddCommand<CloneCommand>("clone")
        .WithDescription("Clone a repository");
});

return app.Run(args);

// Shared settings for the branch -- inherited by subcommands
public class RemoteSettings : CommandSettings
{
    [CommandOption("-v|--verbose")]
    [Description("Verbose output")]
    public bool Verbose { get; init; }
}

// Subcommand settings inherit from branch settings
public sealed class RemoteAddSettings : RemoteSettings
{
    [CommandArgument(0, "<name>")]
    public string Name { get; init; } = string.Empty;

    [CommandArgument(1, "<url>")]
    public string Url { get; init; } = string.Empty;
}

public sealed class RemoteAddCommand : Command<RemoteAddSettings>
{
    public override int Execute(CommandContext context, RemoteAddSettings settings)
    {
        if (settings.Verbose)
        {
            AnsiConsole.MarkupLine($"[dim]Adding remote...[/]");
        }
        AnsiConsole.MarkupLine($"Added remote [green]{settings.Name}[/] -> {settings.Url}");
        return 0;
    }
}

Settings Validation

public sealed class DeploySettings : CommandSettings
{
    [CommandArgument(0, "<environment>")]
    public string Environment { get; init; } = string.Empty;

    [CommandOption("--timeout")]
    [DefaultValue(30)]
    public int TimeoutSeconds { get; init; }

    public override ValidationResult Validate()
    {
        var validEnvs = new[] { "dev", "staging", "prod" };
        if (!validEnvs.Contains(Environment, StringComparer.OrdinalIgnoreCase))
        {
            return ValidationResult.Error(
                $"Environment must be one of: {string.Join(", ", validEnvs)}");
        }

        if (TimeoutSeconds <= 0)
        {
            return ValidationResult.Error("Timeout must be positive");
        }

        return ValidationResult.Success();
    }
}

Async Commands

public sealed class FetchCommand : AsyncCommand<FetchSettings>
{
    public override async Task<int> ExecuteAsync(
        CommandContext context, FetchSettings settings)
    {
        await AnsiConsole.Status()
            .StartAsync("Fetching data...", async ctx =>
            {
                await Task.Delay(2000); // simulate work
            });

        AnsiConsole.MarkupLine("[green]Done![/]");
        return 0;
    }
}

Dependency Injection with ITypeRegistrar

using Microsoft.Extensions.DependencyInjection;
using Spectre.Console.Cli;

// Set up DI container
var services = new ServiceCollection();
services.AddSingleton<IGreetingService, GreetingService>();
services.AddSingleton<IAnsiConsole>(AnsiConsole.Console);

var registrar = new TypeRegistrar(services);
var app = new CommandApp<GreetCommand>(registrar);
return app.Run(args);

// TypeRegistrar bridges Microsoft DI to Spectre.Console.Cli
public sealed class TypeRegistrar(IServiceCollection services) : ITypeRegistrar
{
    public ITypeResolver Build() => new TypeResolver(services.BuildServiceProvider());

    public void Register(Type service, Type implementation)
        => services.AddSingleton(service, implementation);

    public void RegisterInstance(Type service, object implementation)
        => services.AddSingleton(service, implementation);

    public void RegisterLazy(Type service, Func<object> factory)
        => services.AddSingleton(service, _ => factory());
}

public sealed class TypeResolver(IServiceProvider provider) : ITypeResolver
{
    public object? Resolve(Type? type)
        => type is null ? null : provider.GetService(type);
}

// Command receives services via constructor injection
public sealed class GreetCommand(IGreetingService greetingService) : Command<GreetSettings>
{
    public override int Execute(CommandContext context, GreetSettings settings)
    {
        var message = greetingService.GetGreeting(settings.Name);
        AnsiConsole.MarkupLine(message);
        return 0;
    }
}

Testable Console Output

Spectre.Console provides IAnsiConsole for testable output instead of writing directly to the real console.

// Production: use AnsiConsole.Console (the real console)
IAnsiConsole console = AnsiConsole.Console;

// Testing: use a recording console
var console = AnsiConsole.Create(new AnsiConsoleSettings
{
    Out = new AnsiConsoleOutput(new StringWriter())
});

// Use the abstraction instead of static AnsiConsole methods
console.MarkupLine("[green]Testable output[/]");
console.Write(new Table().AddColumn("Col").AddRow("Val"));

Agent Gotchas

1. Do not use AnsiConsole.Markup* in redirected output. When stdout is redirected (piped to a file or another process), ANSI escape codes corrupt the output. Check AnsiConsole.Profile.Capabilities.Ansi before using markup, or use IAnsiConsole with appropriate settings. See [skill:dotnet-csharp-async-patterns] for async pipeline patterns.
2. Do not assume ANSI support in CI environments. CI runners (GitHub Actions, Azure Pipelines) may not support ANSI escape codes. Set TERM=dumb or use AnsiConsole.Create() with ColorSystemSupport.NoColors for CI-safe output. Spectre.Console auto-detects capabilities, but explicit configuration prevents flaky rendering.
3. Do not mix AnsiConsole static calls with IAnsiConsole instance calls. Static AnsiConsole.Write() always targets the real console. When using DI with IAnsiConsole, consistently use the injected instance. Mixing the two produces duplicated or interleaved output.
4. Do not modify a renderable from a background thread during Live(). Live displays are not thread-safe. Mutate the target renderable only inside the Start/StartAsync callback, then call ctx.Refresh(). Concurrent mutations cause corrupted terminal output.
5. Do not use prompts in non-interactive contexts. TextPrompt, SelectionPrompt, and ConfirmationPrompt block waiting for user input. In CI or automated scripts, use environment variables or command-line arguments for input instead of prompts. Check AnsiConsole.Profile.Capabilities.Interactive before prompting.
6. Do not confuse Spectre.Console.Cli with System.CommandLine. They are independent frameworks with different APIs. Spectre.Console.Cli uses CommandSettings classes with [CommandArgument]/[CommandOption] attributes, while System.CommandLine uses Option<T> and Argument<T> builder pattern. Do not mix APIs. For System.CommandLine, see [skill:dotnet-system-commandline].
7. Do not forget ctx.Refresh() after modifying live display content. Changes to tables, trees, or panels inside a Live() callback are not rendered until ctx.Refresh() is called. Omitting it produces stale displays.
8. Do not hardcode color values without fallback. Terminals with limited color support silently degrade TrueColor values. Use named colors (Color.Green) when possible and test with NO_COLOR=1 environment variable to verify graceful degradation.

Prerequisites

• NuGet packages: Spectre.Console 0.54.0 for rich output; add Spectre.Console.Cli 0.53.1 for CLI framework
• Target framework: net8.0 or later (also supports netstandard2.0)
• Terminal: Any terminal emulator supporting ANSI escape sequences. Windows Terminal, iTerm2, or modern Linux terminal recommended for best experience (TrueColor, Unicode). Console output degrades gracefully on limited terminals.
• For DI with Spectre.Console.Cli: Microsoft.Extensions.DependencyInjection package for the ITypeRegistrar/ITypeResolver bridge

References

• Spectre.Console GitHub -- source code, issues, samples
• Spectre.Console Documentation -- official guides and API reference
• Spectre.Console NuGet -- package downloads and version history
• Spectre.Console.Cli NuGet -- CLI framework package
• Spectre.Console Examples -- official example projects