scalar

name	scalar
description	Generates and configures Scalar OpenAPI UI for API documentation. Use when: Adding API documentation to services, configuring OpenAPI endpoints, customizing documentation themes
allowed-tools	Read, Edit, Write, Glob, Grep, Bash, mcp__context7__resolve-library-id, mcp__context7__query-docs

Scalar Skill

Scalar replaces Swagger/Swashbuckle as the OpenAPI documentation UI in this codebase. All services use .NET 10's built-in AddOpenApi() with Scalar's MapScalarApiReference() for the UI. The project enforces Purple theme consistency across all microservices.

Quick Start

Standard Service Configuration

// Program.cs - Service setup
builder.Services.AddOpenApi();

var app = builder.Build();
app.MapOpenApi();

if (app.Environment.IsDevelopment())
{
    app.MapScalarApiReference(options =>
    {
        options
            .WithTitle("Blueprint Service")
            .WithTheme(ScalarTheme.Purple)
            .WithDefaultHttpClient(ScalarTarget.CSharp, ScalarClient.HttpClient);
    });
}

API Gateway with Aggregated Documentation

// Aggregated OpenAPI from all services
app.MapGet("/openapi/aggregated.json", async (OpenApiAggregationService service) =>
{
    var spec = await service.GetAggregatedOpenApiAsync();
    return Results.Json(spec);
})
.ExcludeFromDescription();

app.MapScalarApiReference(options =>
{
    options
        .WithTitle("Sorcha API Gateway - All Services")
        .WithTheme(ScalarTheme.Purple)
        .WithDefaultHttpClient(ScalarTarget.CSharp, ScalarClient.HttpClient)
        .WithOpenApiRoutePattern("/openapi/aggregated.json");
});

Key Concepts

Concept	Usage	Example
AddOpenApi()	Register OpenAPI services	builder.Services.AddOpenApi()
MapOpenApi()	Expose /openapi/v1.json	app.MapOpenApi()
MapScalarApiReference()	Mount Scalar UI at /scalar	See examples above
ScalarTheme	Visual theme enum	ScalarTheme.Purple
ScalarTarget	Code generation target	ScalarTarget.CSharp
ScalarClient	HTTP client library	ScalarClient.HttpClient

Common Patterns

Document Endpoints for Scalar

app.MapPost("/api/wallets", handler)
    .WithName("CreateWallet")
    .WithSummary("Create a new wallet")
    .WithDescription("Creates an HD wallet with the specified algorithm")
    .WithTags("Wallets");

Rich OpenAPI Descriptions with Markdown

builder.Services.AddOpenApi(options =>
{
    options.AddDocumentTransformer((document, context, ct) =>
    {
        document.Info.Title = "Register Service API";
        document.Info.Version = "1.0.0";
        document.Info.Description = """
            # Register Service
            
            ## Overview
            Provides a **distributed ledger** for immutable transactions.
            
            ## Key Features
            - Cryptographic signatures
            - Chain integrity verification
            """;
        return Task.CompletedTask;
    });
});

See Also

• patterns
• workflows

Related Skills

• See the minimal-apis skill for endpoint documentation patterns
• See the aspire skill for service discovery integration
• See the yarp skill for API Gateway configuration

Documentation Resources

Fetch latest Scalar documentation with Context7.

How to use Context7:

1. Use mcp__context7__resolve-library-id to search for "scalar"
2. Prefer website documentation (/websites/guides_scalar) over source repositories
3. Query with mcp__context7__query-docs using the resolved library ID

Library ID: /websites/guides_scalar

Recommended Queries:

• "Scalar .NET ASP.NET Core configuration options themes"
• "Scalar themes available dark mode customization"
• "Scalar API reference configuration fluent API"