fix: 오류 수정

Author: ImGdevel

ProjectVG.Application/ApplicationServiceCollectionExtensions.cs

@@ -2,6 +2,7 @@
 using ProjectVG.Application.Services.Auth;
 using ProjectVG.Application.Services.Character;
 using ProjectVG.Application.Services.Chat;
+using ProjectVG.Application.Services.Chat.CostTracking;
 using ProjectVG.Application.Services.Conversation;
 using ProjectVG.Application.Services.Session;
 using ProjectVG.Application.Services.Users;
@@ -15,7 +16,7 @@ public static IServiceCollection AddApplicationServices(this IServiceCollection
         {
             // Auth Services
             services.AddScoped<IAuthService, AuthService>();
-            services.AddScoped<IOAuth2Service, OAuth2Service>();
+            services.AddSingleton<IOAuth2Service, OAuth2Service>();
             services.AddScoped<IOAuth2ProviderFactory, OAuth2ProviderFactory>();
 
             // User Services
@@ -27,7 +28,6 @@ public static IServiceCollection AddApplicationServices(this IServiceCollection
             // Chat Services
             services.AddScoped<IChatService, ChatService>();
             services.AddScoped<IChatMetricsService, ChatMetricsService>();
-            services.AddScoped<ICostTrackingDecoratorFactory, CostTrackingDecoratorFactory>();
 
             // Conversation Services
             services.AddScoped<IConversationService, ConversationService>();

ProjectVG.Application/Services/Auth/OAuth2Service.cs

@@ -203,17 +203,27 @@ public async Task<OAuth2UserInfo> GetUserInfoAsync(string accessToken, string pr
 
         public async Task<OAuth2AuthRequest> StoreOAuth2RequestAsync(string state, OAuth2AuthRequest request)
         {
-            _oauth2Requests[state] = JsonSerializer.Serialize(request);
-            await Task.CompletedTask;
-            return request;
+            try
+            {
+                _oauth2Requests[state] = JsonSerializer.Serialize(request);
+                await Task.CompletedTask;
+                return request;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "OAuth2 요청 저장 실패: State={State}", state);
+                throw;
+            }
         }
 
         public async Task<OAuth2AuthRequest?> GetOAuth2RequestAsync(string state)
-        {
+        {            
             if (_oauth2Requests.TryGetValue(state, out var json)) {
+                var request = JsonSerializer.Deserialize<OAuth2AuthRequest>(json);
                 await Task.CompletedTask;
-                return JsonSerializer.Deserialize<OAuth2AuthRequest>(json);
+                return request;
             }
+            
             await Task.CompletedTask;
             return null;
         }

ProjectVG.Application/Services/Chat/CostTracking/CostTrackingDecoratorFactory.cs

@@ -1,6 +1,4 @@
 using Microsoft.Extensions.DependencyInjection;
-using ProjectVG.Application.Models.Chat;
-using ProjectVG.Application.Services.Chat.CostTracking;
 
 namespace ProjectVG.Application.Services.Chat.CostTracking
 {