Refactor Telegram bot configuration and deep link handling

- Removed the `BotUsername` property from `TelegramOptions` and updated the `.env.example` to reflect this change, as the bot's username is now dynamically retrieved via the Bot API.
- Introduced `ITelegramBotInfo` to cache the bot's username, improving the handling of deep links in `TelegramEndpoints`.
- Updated API documentation to clarify that the deep link is now dependent on the bot's token and its availability through the Bot API, enhancing clarity for developers.

backend/src/PnvPanel.Api/Endpoints/TelegramEndpoints.cs

@@ -1,10 +1,9 @@
-using Microsoft.Extensions.Options;
 using PnvPanel.Api.Common;
 using PnvPanel.Application.Auth;
+using PnvPanel.Application.Common.Interfaces;
 using PnvPanel.Application.Common.Messaging;
 using PnvPanel.Application.Telegram;
 using PnvPanel.Domain.Telegram;
-using PnvPanel.Infrastructure.Telegram;
 
 namespace PnvPanel.Api.Endpoints;
 
@@ -25,16 +24,14 @@ public static class TelegramEndpoints
     }
 
     private static async Task<IResult> CreateLinkToken(
-        ISender sender, IOptions<TelegramOptions> options, CancellationToken cancellationToken)
+        ISender sender, ITelegramBotInfo botInfo, CancellationToken cancellationToken)
     {
         var result = await sender.Send(new CreateLinkTokenCommand(), cancellationToken);
         if (!result.IsSuccess)
             return result.ToHttpResult();
 
-        var botUsername = options.Value.BotUsername;
-        var deepLink = string.IsNullOrWhiteSpace(botUsername)
-            ? null
-            : $"https://t.me/{botUsername}?start=link_{result.Value.Token}";
+        var botUsername = await botInfo.GetUsernameAsync(cancellationToken);
+        var deepLink = botUsername is null ? null : $"https://t.me/{botUsername}?start=link_{result.Value.Token}";
 
         return Results.Ok(new LinkTokenResponseDto(deepLink, result.Value.ExpiresAt));
     }
@@ -46,17 +43,15 @@ public static class TelegramEndpoints
     }
 
     private static async Task<IResult> CreateLoginRequest(
-        HttpRequest request, ISender sender, IOptions<TelegramOptions> options, CancellationToken cancellationToken)
+        HttpRequest request, ISender sender, ITelegramBotInfo botInfo, CancellationToken cancellationToken)
     {
         var context = request.HttpContext.Connection.RemoteIpAddress?.ToString();
         var result = await sender.Send(new CreateLoginRequestCommand(context), cancellationToken);
         if (!result.IsSuccess)
             return result.ToHttpResult();
 
-        var botUsername = options.Value.BotUsername;
-        var deepLink = string.IsNullOrWhiteSpace(botUsername)
-            ? null
-            : $"https://t.me/{botUsername}?start=login_{result.Value.RequestId}";
+        var botUsername = await botInfo.GetUsernameAsync(cancellationToken);
+        var deepLink = botUsername is null ? null : $"https://t.me/{botUsername}?start=login_{result.Value.RequestId}";
 
         return Results.Ok(new TelegramLoginRequestResponseDto(result.Value.RequestId, deepLink, result.Value.ExpiresAt));
     }

backend/src/PnvPanel.Api/Program.cs

@@ -85,6 +85,8 @@ builder.Services.AddSingleton<ITelegramBotClient>(sp =>
 });
 // Scoped — зависит от IIdentityService (scoped), не Singleton.
 builder.Services.AddScoped<ITelegramNotifier, TelegramNotifier>();
+// Singleton — кэширует username бота (getMe) на весь процесс, не из ручного env (см. TelegramBotInfo).
+builder.Services.AddSingleton<ITelegramBotInfo, TelegramBotInfo>();
 builder.Services.AddSingleton<PnvBotUpdateHandler>();
 builder.Services.AddHostedService<TelegramBotHostedService>();
 

backend/src/PnvPanel.Api/Telegram/TelegramBotInfo.cs

@@ -0,0 +1,42 @@
+using Microsoft.Extensions.Options;
+using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Infrastructure.Telegram;
+using Telegram.Bot;
+
+namespace PnvPanel.Api.Telegram;
+
+/// <summary>Кэширует username бота на время жизни процесса (getMe не меняется, повторный запрос не нужен).</summary>
+internal sealed class TelegramBotInfo(ITelegramBotClient botClient, IOptions<TelegramOptions> options) : ITelegramBotInfo
+{
+    private readonly SemaphoreSlim _lock = new(1, 1);
+    private string? _cachedUsername;
+
+    public async Task<string?> GetUsernameAsync(CancellationToken cancellationToken)
+    {
+        if (_cachedUsername is not null)
+            return _cachedUsername;
+
+        if (string.IsNullOrWhiteSpace(options.Value.BotToken))
+            return null;
+
+        await _lock.WaitAsync(cancellationToken);
+        try
+        {
+            if (_cachedUsername is not null)
+                return _cachedUsername;
+
+            var me = await botClient.GetMe(cancellationToken);
+            _cachedUsername = me.Username;
+            return _cachedUsername;
+        }
+        catch
+        {
+            // Telegram недоступен/бот не отвечает — деплинк просто не покажем вызывающей стороне.
+            return null;
+        }
+        finally
+        {
+            _lock.Release();
+        }
+    }
+}

backend/src/PnvPanel.Application/Common/Interfaces/ITelegramBotInfo.cs

@@ -0,0 +1,15 @@
+namespace PnvPanel.Application.Common.Interfaces;
+
+/// <summary>
+/// Метаданные самого бота (не пользователя). Реализация — в Api (нужен ITelegramBotClient),
+/// аналогично ITelegramNotifier.
+/// </summary>
+public interface ITelegramBotInfo
+{
+    /// <summary>
+    /// Username бота для диплинков (https://t.me/{username}?start=...), получен через Bot API
+    /// (getMe), не из ручной конфигурации — так деплинк не сломается из-за опечатки/пробела в env.
+    /// Null, если BotToken не задан или Telegram недоступен.
+    /// </summary>
+    Task<string?> GetUsernameAsync(CancellationToken cancellationToken);
+}

backend/src/PnvPanel.Infrastructure/Telegram/TelegramOptions.cs

@@ -5,7 +5,6 @@ public sealed class TelegramOptions
     public const string SectionName = "Telegram";
 
     public string? BotToken { get; init; }
-    public string? BotUsername { get; init; }
     public string PublicSiteUrl { get; init; } = string.Empty;
 
     /// <summary>Прокси для запросов к Bot API (обычно socks5://[user:pass@]host:port). Пусто — без прокси.</summary>