configure-auth skill | PlugMCP

configure-auth

by dotnet5.7k

Install

The skill file stays in the publisher's repository.

Paste the copied command in a terminal. It installs this SKILL.md into that agent.

npx skills add dotnet/skills --skill configure-auth -a cursor -y

Download skill plugins/dotnet-blazor/skills/configure-auth/SKILL.md on GitHub

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Questions

How do I install configure-auth?: Download plugins/dotnet-blazor/skills/configure-auth/SKILL.md from the publisher, or copy the path and open the repository. PlugMCP lists the skill and does not host the file.
Where does configure-auth live?: The publisher keeps it at https://github.com/dotnet/skills.
Which agents can use configure-auth?: Claude, Cursor, and Codex can read a SKILL.md you add from the publisher's repository.

license: MIT name: configure-auth description: > Add authentication and authorization to a Blazor Web App, accounting for the app's render mode. USE WHEN the user needs [Authorize] on pages, AuthorizeView, role or policy-based access, login/logout Identity pages, or AuthenticationStateProvider. Also USE WHEN auth state is null after WebAssembly loads, SignInManager throws in an interactive component, NotAuthorized content never renders in static SSR, or HttpContext.User is null in an interactive component. DO NOT USE for general component authoring (see author-component), for prerendering concerns unrelated to auth (see support-prerendering), or for managing non-auth cascading state (see coordinate-components).

Configure Auth

Step 1 — Read AGENTS.md

Read AGENTS.md at the workspace root for the project's interactivity mode and scope before making changes.

Step 2 — Register auth services in Program.cs

// Program.cs (server project)
builder.Services.AddCascadingAuthenticationState();
builder.Services.AddAuthorization();

builder.Services.AddAuthentication(options =>
{
    options.DefaultScheme = IdentityConstants.ApplicationScheme;
    options.DefaultSignInScheme = IdentityConstants.ExternalScheme;
})
.AddIdentityCookies();

builder.Services.AddIdentityCore<ApplicationUser>()
    .AddRoles<IdentityRole>()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddSignInManager()
    .AddDefaultTokenProviders();

<!DOCTYPE html>
<html>
<head>
    <HeadOutlet @rendermode="RenderModeForPage" />
</head>
<body>
    <Routes @rendermode="RenderModeForPage" />
    <script src="_framework/blazor.web.js"></script>
</body>
</html>

@code {
    [CascadingParameter]
    public HttpContext HttpContext { get; set; } = default!;

    private IComponentRenderMode? RenderModeForPage =>
        HttpContext.AcceptsInteractiveRouting()
            ? InteractiveServer   // replace with the app's render mode
            : null;
}

<Router AppAssembly="typeof(Program).Assembly">
    <Found Context="routeData">
        <AuthorizeRouteView RouteData="routeData"
                            DefaultLayout="typeof(Layout.MainLayout)">
            <NotAuthorized>
                @if (context.User.Identity?.IsAuthenticated != true)
                {
                    <RedirectToLogin />
                }
                else
                {
                    <p>You are not authorized to access this resource.</p>
                }
            </NotAuthorized>
        </AuthorizeRouteView>
        <FocusOnNavigate RouteData="routeData" Selector="h1" />
    </Found>
</Router>

@page "/admin"
@attribute [Authorize]

@attribute [Authorize(Roles = "Admin")]
@attribute [Authorize(Policy = "RequireManager")]

<AuthorizeView>
    <Authorized>Welcome, @context.User.Identity?.Name!</Authorized>
    <NotAuthorized><a href="Account/Login">Log in</a></NotAuthorized>
</AuthorizeView>

<AuthorizeView Roles="Admin,Manager">
    <Authorized>Admin content here</Authorized>
</AuthorizeView>

[CascadingParameter]
private Task<AuthenticationState>? AuthState { get; set; }

protected override async Task OnInitializedAsync()
{
    if (AuthState is not null)
    {
        var state = await AuthState;
        var isAdmin = state.User.IsInRole("Admin");
    }
}

@page "/Account/Login"
@attribute [ExcludeFromInteractiveRouting]

builder.Services.AddAuthenticationStateSerialization();

builder.Services.AddAuthenticationStateDeserialization();

builder.Services.AddAuthenticationStateSerialization(options =>
    options.SerializeAllClaims = true);

Render mode	HttpContext.User	SignInManager	Auth state source	Key requirement
Static SSR	Available	Works	Server pipeline	Use middleware for redirects, `<NotAuthorized>` does NOT render
Server (interactive)	NOT available	Throws	`CascadingAuthenticationState`	Use `[Authorize]` + `AuthorizeView`, not `HttpContext`
WebAssembly	NOT available	Throws	Serialized from server	`AddAuthenticationStateSerialization` / `Deserialization`
Auto	NOT available after WASM	Throws	Serialized from server	Same as WebAssembly; register in both Program.cs files

Mistake	Symptom	Fix
Using `HttpContext.User` in interactive component	Null or stale claims	Use `[CascadingParameter] Task<AuthenticationState>`
`SignInManager` in interactive component	`InvalidOperationException`	Move to static SSR page with `[ExcludeFromInteractiveRouting]`
Missing `AddAuthenticationStateSerialization`	Anonymous user after WASM loads	Add to server Program.cs; add `Deserialization` to client Program.cs
`<NotAuthorized>` in static SSR layout	Content never shown	Static SSR uses middleware pipeline; redirect via `LoginPath` or `RedirectToLogin` component
Global interactivity without `AcceptsInteractiveRouting`	Identity pages crash	Add `AcceptsInteractiveRouting()` check in App.razor (Step 3)
Missing `AddCascadingAuthenticationState()`	`Task<AuthenticationState>` is null	Register in Program.cs (Step 2)

configure-auth

Install

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Configure Auth

Step 1 — Read AGENTS.md

Step 2 — Register auth services in Program.cs

Step 3 — Wire App.razor for auth and render mode

Step 4 — Protect pages and components

[Authorize] attribute on pages

AuthorizeView for conditional UI

Access auth state in code

Step 5 — Identity pages must stay static SSR

Step 6 — Auth state in WebAssembly / Auto mode

Render Mode × Auth Matrix

Common Mistakes