Add project files.

wishlist/wishlist.Client/PersistentAuthenticationStateProvider.cs

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+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Authorization;
+using System.Security.Claims;
+
+namespace wishlist.Client
+{
+    // This is a client-side AuthenticationStateProvider that determines the user's authentication state by
+    // looking for data persisted in the page when it was rendered on the server. This authentication state will
+    // be fixed for the lifetime of the WebAssembly application. So, if the user needs to log in or out, a full
+    // page reload is required.
+    //
+    // This only provides a user name and email for display purposes. It does not actually include any tokens
+    // that authenticate to the server when making subsequent requests. That works separately using a
+    // cookie that will be included on HttpClient requests to the server.
+    internal class PersistentAuthenticationStateProvider : AuthenticationStateProvider
+    {
+        private static readonly Task<AuthenticationState> defaultUnauthenticatedTask =
+            Task.FromResult(new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity())));
+
+        private readonly Task<AuthenticationState> authenticationStateTask = defaultUnauthenticatedTask;
+
+        public PersistentAuthenticationStateProvider(PersistentComponentState state)
+        {
+            if (!state.TryTakeFromJson<UserInfo>(nameof(UserInfo), out var userInfo) || userInfo is null)
+            {
+                return;
+            }
+
+            Claim[] claims = [
+                new Claim(ClaimTypes.NameIdentifier, userInfo.UserId),
+                new Claim(ClaimTypes.Name, userInfo.Email),
+                new Claim(ClaimTypes.Email, userInfo.Email)];
+
+            authenticationStateTask = Task.FromResult(
+                new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity(claims,
+                    authenticationType: nameof(PersistentAuthenticationStateProvider)))));
+        }
+
+        public override Task<AuthenticationState> GetAuthenticationStateAsync() => authenticationStateTask;
+    }
+}