Adopt b2b.next's client patterns: services, page state, feedback

Ported from the owner's b2b.next and adapted from MudBlazor to the daisyUI
components:
- LocalizableComponentBase provides CascadingState, Navigation, Toast,
  IsLoading/IsDefaultDisabled, WhenOnline/StartOnlinePolling, and after-render
  jobs that actually run.
- CascadingState starts with initialised state and polls the online status
  with a PeriodicTimer. It reports errors through ILoggingService plus a toast,
  and disposes what it holds.
- New pieces:
  - ToastService + ToastHost, the snackbar, with AddResponseError/Success/
    Warning/Exception in SUtility;
  - ErrorViewer, which shows the validation messages plus AdditionalError(s);
  - LoggingService, which writes to the console and the IndexedDB client log.
- HttpService is rebuilt and registered:
  - auth levels Get/Post/Delete, *Anon and *TotallyAnon;
  - retry with backoff;
  - classified failures (FailureCodes) instead of exceptions;
  - HTTP 410 on cancel;
  - the "default" client.
  ReadWebResult and DefaultReadFromJsonAsync read its responses.
- ClientJsonContext is source-generated, and SUtility.DefaultSerializer and
  Blazored.LocalStorage use it.
- WebResult gains a C# 14 IsInvalid extension property.

The code follows the imported rules:
- Every service and async helper takes a CancellationToken last.
- Primary constructors replace constructor-plus-fields.
- MessagesService and IStorage return Task<WebResult> / Task<List<T>>.
  MessagesService is still mock, building its results in memory; the seed
  feed and thread moved to Faker.
- Index and ExpandMessage follow the page pattern: an offline guard with
  WhenOnline, LoadData, and early returns with toasts on the results they used
  to ignore. ExpandMessage reloads on route change and shows "not found"
  instead of a null message.
- Model and state collections are [], and the fake identity defaults moved
  out of the models.
- Components:
  - no ?. chains over initialised state;
  - [Inject] instead of @inject;
  - IsDefaultDisabled on the actions;
  - autocomplete on every text input;
  - Localizer[key, args] instead of string.Format;
  - the localizer no longer leaks its inner _pLocalizer.
- Settings → General gains a language picker (English/Italiano), and
  SetDefaultCulture limits the culture to those two.

Bugs fixed along the way:
- A compose with untouched (null) content passed the empty check.
- File errors were joined with <br/> and rendered as markup.
- ClientLogs.ErrorMessage() threw on warnings.
- CoalescingStringLocalizer[key, args] showed a raw "{0}" for missing keys.
- AppStatusService exposed a call to a JS function that doesn't exist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

Pages/Index.razor

@@ -27,7 +27,7 @@
 			{
 				<Content Message="message"
 							 OnMessageBoost="async (m) => await OnMessageBoost(m)" OnMessageDelete="async (m) => await OnMessageDelete(m)"
-							 OnMessageFavourite="async (m) => await OnMessageFavourite(m)" OnMessageReply="async (m) => await OnMessageReply(m)"
+							 OnMessageFavourite="async (m) => await OnMessageFavourite(m)" OnMessageReply="async (m) => await OnMessageSubmit(m)"
 							 OnMessageMediaDownload="async (m) => await OnMessageMediaDownload(m)"
 							 OnUserBlock="async (u) => await OnUserBlock(u)" OnUserDirectMessage="async (u) => await OnUserDirectMessage(u)" OnUserSilence="async (u) => await OnUserSilence(u)" />
 			}
@@ -58,55 +58,39 @@
 </div>
 
 @code {
-	[CascadingParameter] Task<AuthenticationState> AuthState { get; set; }
-	[CascadingParameter] CascadingState CascadingState { get; set; }
 	[Inject] IBlazorDownloadFileService BlazorDownloadFileService { get; set; }
 	[Inject] IStorage Storage { get; set; }
 	[Inject] ILocalStorageService LocalStorage { get; set; }
-	[Inject] HttpClient Http { get; set; }
 	[Inject] MessagesService MessagesService { get; set; }
 
 	TimelineType TimelineType { get; set; } = TimelineType.Home;
 	TimeSortingType TimeSortingType { get; set; } = TimeSortingType.Ascending;
-
-	IReadOnlyList<Claim> userClaim
-	{
-		get
-		{
-			var auth = AuthState.Result;
-			if (auth.User.Identity?.IsAuthenticated ?? false)
-				return auth.User.Claims.ToList();
-			return new List<Claim>();
-		}
-	}
-
-	List<Message> IncomingMessages { get; set; } = new();
-	List<Message> Messages { get; set; } = new();
-	string Response { get; set; }
+	List<Message> Messages { get; set; } = [];
 
 	protected override async Task OnInitializedAsync()
 	{
-		var filters = await LocalStorage.GetItemAsync<ActionBarFilter>(nameof(ActionBarFilter));
-		if (filters == default)
-			await LocalStorage.SetItemAsync(nameof(ActionBarFilter), new ActionBarFilter());
-		else
+		var filters = await LocalStorage.GetItemAsync<ActionBarFilter>(nameof(ActionBarFilter)) ?? new();
+		TimelineType = filters.TimelineType;
+		TimeSortingType = filters.TimeSortingType;
+
+		if (CascadingState.IsOffline)
 		{
-			TimelineType = filters.TimelineType;
-			TimeSortingType = filters.TimeSortingType;
+			WhenOnline(LoadData);
+			StartOnlinePolling();
+			IsLoading = false;
+			return;
 		}
 
-		Messages = await Storage.GetMessages();
-		//try
-		//{
-		//	var response = await Http.GetAsync("api/test");
-		//	Response = await response.Content.ReadAsStringAsync();
-		//}
-		//catch
-		//{
-		//}
+		await LoadData();
 		IsLoading = false;
 	}
 
+	// The feed: the mock one in IndexedDB until the app reads PrivaPub's timeline.
+	async Task LoadData()
+	{
+		Messages = await Storage.GetMessages();
+	}
+
 	void OnTimelineChanged(TimelineType timelineType)
 	{
 		TimelineType = timelineType;
@@ -117,143 +101,105 @@
 		TimeSortingType = timeSortingType;
 	}
 
+	// Covers replies too: the form carries the RootMessageId.
 	async Task OnMessageSubmit(MessageForm messageForm)
 	{
-		await Task.Run(() =>
+		var result = await MessagesService.SubmitMessage(messageForm, CascadingState.User);
+		if (result.IsInvalid)
 		{
-		});
-		var submitMessage = await MessagesService.SubmitMessage(messageForm);
-		Messages.Insert(0, new()
-			{
-				MessageId = Guid.NewGuid().ToString(),
-				Content = messageForm.Content?.ParseContent(messageForm.ContentType),
-				CreatedAt = DateTime.UtcNow,
-				MessageType = messageForm.MessageType,
-				Medias = messageForm.Media.Select(m => new Media
-				{
-					FileName = m.FileName,
-					AltText = m.AltText,
-					ContentType = m.ContentType,
-					Url = m.Base64Preview,
-					Blob = m.Blob
-				}).ToList(),
-				Title = messageForm.Title,
-				User = new MessageUser
-				{
-					UserId = CascadingState.User.Id,
-					UserName = CascadingState.User.UserName,
-					DisplayName = CascadingState.User.DisplayName,
-					PictureUrl = CascadingState.User.PictureUrl,
-					ProfileUrl = CascadingState.User.ProfileUrl,
-					BackgroundUrl = CascadingState.User.BackgroundUrl
-				},
-			});
-	}
-
-	async Task OnMessageReply(MessageForm messageForm)
-	{
-		await Task.Run(() =>
-		{
-		});
-		var replyMessage = await MessagesService.SubmitMessage(messageForm);
-		Messages.Insert(0, new()
-			{
-				RootMessageId = messageForm.RootMessageId,
-				MessageId = Guid.NewGuid().ToString(),
-				Content = messageForm.Content?.ParseContent(messageForm.ContentType),
-				CreatedAt = DateTime.UtcNow,
-				MessageType = messageForm.MessageType,
-				Medias = messageForm.Media.Select(m => new Media
-				{
-					FileName = m.FileName,
-					AltText = m.AltText,
-					ContentType = m.ContentType,
-					Url = m.Base64Preview,
-					Blob = m.Blob
-				}).ToList(),
-				Title = messageForm.Title,
-				User = new MessageUser
-				{
-					UserId = CascadingState.User.Id,
-					UserName = CascadingState.User.UserName,
-					DisplayName = CascadingState.User.DisplayName,
-					PictureUrl = CascadingState.User.PictureUrl,
-					ProfileUrl = CascadingState.User.ProfileUrl,
-					BackgroundUrl = CascadingState.User.BackgroundUrl
-				}
-			});
-	}
-
-	async ValueTask OnMessageBoost(Message message)
-	{
-		var boostedMessageTemp = await MessagesService.BoostUnboostMessage(message);
-		message.BoostsCounter = message.IsBoostedByCurrentUser ? message.BoostsCounter - 1 : message.BoostsCounter + 1;
-		message.IsBoostedByCurrentUser = !message.IsBoostedByCurrentUser;
-		if (message.IsBoostedByCurrentUser)
-		{
-			var boostedMessage = new Message
-				{
-					BoostingUser = new()
-					{
-						UserId = CascadingState.User.Id,
-						DisplayName = CascadingState.User.DisplayName,
-						PictureUrl = CascadingState.User.PictureUrl,
-						ProfileUrl = CascadingState.User.ProfileUrl,
-						UserName = CascadingState.User.UserName
-					},
-					BoostsCounter = message.BoostsCounter,
-					Content = message.Content,
-					CreatedAt = message.CreatedAt,
-					IsBoostedByCurrentUser = true,
-					IsFavourite = message.IsFavourite,
-					Medias = message.Medias,
-					MessageId = message.MessageId,
-					MessageType = message.MessageType,
-					RootMessageId = message.RootMessageId,
-					Title = message.Title,
-					User = message.User
-				};
-			Messages.Insert(0, boostedMessage);
+			Toast.AddResponseError(result);
+			return;
 		}
-		else
+
+		Messages.Insert(0, result.Data as Message);
+	}
+
+	async Task OnMessageBoost(Message message)
+	{
+		var result = await MessagesService.BoostUnboostMessage(message);
+		if (result.IsInvalid)
 		{
-			Messages.RemoveAll(m => m.MessageId == message.MessageId && m.BoostingUser != null && m.BoostingUser.UserId == CascadingState.User.Id);
+			Toast.AddResponseError(result);
+			return;
 		}
+
+		if (!message.IsBoostedByCurrentUser)
+		{
+			Messages.RemoveAll(m => m.MessageId == message.MessageId && m.BoostingUser?.UserId == CascadingState.User.Id);
+			return;
+		}
+
+		// The feed shows a boost as a copy of the message carrying the booster.
+		Messages.Insert(0, new()
+		{
+			BoostingUser = CascadingState.User.ToBoostingUser(),
+			BoostsCounter = message.BoostsCounter,
+			Content = message.Content,
+			CreatedAt = message.CreatedAt,
+			IsBoostedByCurrentUser = true,
+			IsFavourite = message.IsFavourite,
+			Medias = message.Medias,
+			MessageId = message.MessageId,
+			MessageType = message.MessageType,
+			RootMessageId = message.RootMessageId,
+			Title = message.Title,
+			User = message.User
+		});
 	}
 
-	async ValueTask OnMessageFavourite(Message message)
+	async Task OnMessageFavourite(Message message)
 	{
-		message.IsFavourite = !message.IsFavourite;
-		var favouriteMessage = await MessagesService.FavouriteUnfavouriteMessage(message);
+		var result = await MessagesService.FavouriteUnfavouriteMessage(message);
+		if (result.IsInvalid)
+			Toast.AddResponseError(result);
 	}
 
-	async ValueTask OnMessageDelete(Message message)
+	async Task OnMessageDelete(Message message)
 	{
+		var result = await MessagesService.DeleteMessage(message);
+		if (result.IsInvalid)
+		{
+			Toast.AddResponseError(result);
+			return;
+		}
+
 		Messages.Remove(message);
-		var deleteResult = await MessagesService.DeleteMessage(message);
+		Toast.AddResponseSuccess(Localizer["Message deleted."]);
 	}
 
-	async ValueTask OnMessageMediaDownload(Media media)
+	async Task OnMessageMediaDownload(Media media)
 	{
-		await Task.Run(() =>
-		{
-		});
 		await BlazorDownloadFileService.DownloadFileAsync(media.FileName, media.Blob, media.ContentType);
 	}
 
-	async ValueTask OnUserBlock(MessageUser messageUser)
+	async Task OnUserBlock(MessageUser messageUser)
 	{
-		var blockResult = await MessagesService.BlockUserFromMessage(messageUser);
+		var result = await MessagesService.BlockUserFromMessage(messageUser);
+		if (result.IsInvalid)
+		{
+			Toast.AddResponseError(result);
+			return;
+		}
+
+		Toast.AddResponseSuccess(Localizer["{0} blocked.", messageUser.DisplayName]);
 	}
 
-	async ValueTask OnUserDirectMessage(Message message)
+	async Task OnUserDirectMessage(Message message)
 	{
-		var directMessage = await MessagesService.ReplyMessage(message, MessageType.Direct);
+		var result = await MessagesService.ReplyMessage(message, MessageType.Direct);
+		if (result.IsInvalid)
+			Toast.AddResponseError(result);
 	}
 
-	async ValueTask OnUserSilence(MessageUser messageUser)
+	async Task OnUserSilence(MessageUser messageUser)
 	{
-		var silenceResult = await MessagesService.SilenceUserFromMessage(messageUser);
-	}
+		var result = await MessagesService.SilenceUserFromMessage(messageUser);
+		if (result.IsInvalid)
+		{
+			Toast.AddResponseError(result);
+			return;
+		}
 
-}
+		Toast.AddResponseSuccess(Localizer["{0} muted.", messageUser.DisplayName]);
+	}
+}