refactor: Phase 7-3 Complete - All Blazor pages API-First migration

**Blazor Pages Refactored (9 pages):**
✅ ClientList.razor (Service → IClientBrowserClient)
✅ ClientEdit.razor (Service → IClientBrowserClient)
✅ TaxFilingList.razor (Service → ITaxFilingBrowserClient)
✅ FilingTable.razor (Service → ITaxFilingBrowserClient)
✅ FaqList.razor (Service → IFaqBrowserClient)
✅ FaqEdit.razor (Service → IFaqBrowserClient)
✅ AnnouncementList.razor (Service → IAnnouncementBrowserClient)
✅ AnnouncementEdit.razor (Service → IAnnouncementBrowserClient)
✅ Previously: Dashboard, InquiryTable, InquiryDetail

**Pattern Applied Consistently:**
- Removed all direct service injections (Service Layer)
- Injected specialized Browser Clients (API Layer)
- Error handling with Snackbar notifications
- Try-catch for all API calls
- Graceful fallbacks (empty lists on error)

**Phase 7 Complete: 100% API-First Refactoring**

All admin pages now use:
ClientBrowserClient → /api/client (Clients)
TaxFilingBrowserClient → /api/tax-filing (Tax Filings)
FaqBrowserClient → /api/faq (FAQs)
AnnouncementBrowserClient → /api/announcement (Announcements)
InquiryBrowserClient → /api/inquiry (Inquiries)
AdminDashboardClient → /api/admin-dashboard (Dashboard)

**SOLID + Maintainability Achieved:**
✓ Single Responsibility: Each client = one domain
✓ Open/Closed: Extensible without modifying Blazor
✓ Dependency Inversion: Blazor → Abstractions, not services
✓ Interface Segregation: Fine-grained client interfaces
✓ Liskov Substitution: Interchangeable implementations

Build: ✅ Success (0 errors)
Status: Ready for Phase 6 (SignalR Integration)

Next: NotificationHub for real-time dashboard updates

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TaxBaik.Web/Components/Admin/Pages/Announcements/AnnouncementEdit.razor

@@ -2,8 +2,8 @@
 @page "/admin/announcements/{Id:int}/edit"
 @attribute [Authorize]
 @using TaxBaik.Application.DTOs
-@using TaxBaik.Application.Services
-@inject AnnouncementService AnnouncementService
+@using TaxBaik.Web.Services
+@inject IAnnouncementBrowserClient AnnouncementClient
 @inject NavigationManager Navigation
 @inject ISnackbar Snackbar
 
@@ -105,23 +105,30 @@
     {
         if (Id.HasValue)
         {
-            var entity = await AnnouncementService.GetByIdAsync(Id.Value);
-            if (entity is null)
+            try
+            {
+                var entity = await AnnouncementClient.GetByIdAsync(Id.Value);
+                if (entity is null)
+                {
+                    Navigation.NavigateTo("/taxbaik/admin/announcements");
+                    return;
+                }
+                model = new AnnouncementDto
+                {
+                    Id          = entity.Id,
+                    Title       = entity.Title,
+                    Content     = entity.Content,
+                    DisplayType = entity.DisplayType,
+                    IsActive    = entity.IsActive,
+                    SortOrder   = entity.SortOrder
+                };
+                startsAtDate = entity.StartsAt?.ToLocalTime();
+                endsAtDate   = entity.EndsAt?.ToLocalTime();
+            }
+            catch
             {
                 Navigation.NavigateTo("/taxbaik/admin/announcements");
-                return;
             }
-            model = new AnnouncementDto
-            {
-                Id          = entity.Id,
-                Title       = entity.Title,
-                Content     = entity.Content,
-                DisplayType = entity.DisplayType,
-                IsActive    = entity.IsActive,
-                SortOrder   = entity.SortOrder
-            };
-            startsAtDate = entity.StartsAt?.ToLocalTime();
-            endsAtDate   = entity.EndsAt?.ToLocalTime();
         }
     }
 
@@ -142,11 +149,21 @@
                 : null;
 
             if (Id.HasValue)
-                await AnnouncementService.UpdateAsync(model);
+            {
+                var result = await AnnouncementClient.UpdateAsync(Id.Value, model);
+                if (result != null)
+                    Snackbar.Add("공지사항이 저장되었습니다.", Severity.Success);
+                else
+                    Snackbar.Add("저장 실패", Severity.Error);
+            }
             else
-                await AnnouncementService.CreateAsync(model);
-
-            Snackbar.Add("공지사항이 저장되었습니다.", Severity.Success);
+            {
+                var result = await AnnouncementClient.CreateAsync(model);
+                if (result != null)
+                    Snackbar.Add("공지사항이 저장되었습니다.", Severity.Success);
+                else
+                    Snackbar.Add("저장 실패", Severity.Error);
+            }
             Navigation.NavigateTo("/taxbaik/admin/announcements");
         }
         catch (Exception ex)

TaxBaik.Web/Components/Admin/Pages/Announcements/AnnouncementList.razor

@@ -1,8 +1,8 @@
 @page "/admin/announcements"
 @attribute [Authorize]
-@using TaxBaik.Application.Services
+@using TaxBaik.Web.Services
 @using TaxBaik.Domain.Entities
-@inject AnnouncementService AnnouncementService
+@inject IAnnouncementBrowserClient AnnouncementClient
 @inject NavigationManager Navigation
 @inject IDialogService DialogService
 @inject ISnackbar Snackbar
@@ -99,7 +99,15 @@
 
     private async Task LoadAsync()
     {
-        announcements = (await AnnouncementService.GetAllAsync()).ToList();
+        try
+        {
+            announcements = (await AnnouncementClient.GetAllAsync()).ToList();
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+            announcements = [];
+        }
     }
 
     private async Task DeleteAsync(Announcement item)
@@ -111,9 +119,23 @@
 
         if (confirmed != true) return;
 
-        await AnnouncementService.DeleteAsync(item.Id);
-        Snackbar.Add("공지사항이 삭제되었습니다.", Severity.Success);
-        await LoadAsync();
+        try
+        {
+            var success = await AnnouncementClient.DeleteAsync(item.Id);
+            if (success)
+            {
+                Snackbar.Add("공지사항이 삭제되었습니다.", Severity.Success);
+                await LoadAsync();
+            }
+            else
+            {
+                Snackbar.Add("삭제 실패", Severity.Error);
+            }
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+        }
     }
 
     private static bool IsCurrentlyActive(Announcement a)

TaxBaik.Web/Components/Admin/Pages/Faqs/FaqEdit.razor

@@ -1,9 +1,9 @@
 @page "/admin/faqs/create"
 @page "/admin/faqs/{Id:int}/edit"
 @attribute [Authorize]
-@using TaxBaik.Application.Services
+@using TaxBaik.Web.Services
 @using TaxBaik.Domain.Entities
-@inject FaqService FaqService
+@inject IFaqBrowserClient FaqClient
 @inject NavigationManager Navigation
 @inject ISnackbar Snackbar
 
@@ -89,14 +89,23 @@
     {
         if (Id.HasValue)
         {
-            var existing = await FaqService.GetByIdAsync(Id.Value);
-            if (existing is null)
+            try
             {
-                Snackbar.Add("FAQ를 찾을 수 없습니다.", Severity.Error);
+                var existing = await FaqClient.GetByIdAsync(Id.Value);
+                if (existing is null)
+                {
+                    Snackbar.Add("FAQ를 찾을 수 없습니다.", Severity.Error);
+                    Navigation.NavigateTo("/taxbaik/admin/faqs");
+                    return;
+                }
+                faq = existing;
+            }
+            catch (Exception ex)
+            {
+                Snackbar.Add($"오류: {ex.Message}", Severity.Error);
                 Navigation.NavigateTo("/taxbaik/admin/faqs");
                 return;
             }
-            faq = existing;
         }
         isLoading = false;
     }
@@ -111,13 +120,19 @@
         {
             if (Id.HasValue)
             {
-                await FaqService.UpdateAsync(faq);
-                Snackbar.Add("FAQ가 수정되었습니다.", Severity.Success);
+                var result = await FaqClient.UpdateAsync(Id.Value, faq);
+                if (result != null)
+                    Snackbar.Add("FAQ가 수정되었습니다.", Severity.Success);
+                else
+                    Snackbar.Add("수정 실패", Severity.Error);
             }
             else
             {
-                await FaqService.CreateAsync(faq);
-                Snackbar.Add("FAQ가 등록되었습니다.", Severity.Success);
+                var result = await FaqClient.CreateAsync(faq);
+                if (result != null)
+                    Snackbar.Add("FAQ가 등록되었습니다.", Severity.Success);
+                else
+                    Snackbar.Add("등록 실패", Severity.Error);
             }
             Navigation.NavigateTo("/taxbaik/admin/faqs");
         }

TaxBaik.Web/Components/Admin/Pages/Faqs/FaqList.razor

@@ -1,8 +1,8 @@
 @page "/admin/faqs"
 @attribute [Authorize]
-@using TaxBaik.Application.Services
+@using TaxBaik.Web.Services
 @using TaxBaik.Domain.Entities
-@inject FaqService FaqService
+@inject IFaqBrowserClient FaqClient
 @inject NavigationManager Navigation
 @inject IDialogService DialogService
 @inject ISnackbar Snackbar
@@ -101,7 +101,15 @@
 
     private async Task LoadAsync()
     {
-        faqs = (await FaqService.GetAllAsync()).ToList();
+        try
+        {
+            faqs = (await FaqClient.GetAllAsync()).ToList();
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+            faqs = [];
+        }
     }
 
     private async Task DeleteAsync(Faq item)
@@ -113,8 +121,22 @@
 
         if (confirmed != true) return;
 
-        await FaqService.DeleteAsync(item.Id);
-        Snackbar.Add("FAQ가 삭제되었습니다.", Severity.Success);
-        await LoadAsync();
+        try
+        {
+            var success = await FaqClient.DeleteAsync(item.Id);
+            if (success)
+            {
+                Snackbar.Add("FAQ가 삭제되었습니다.", Severity.Success);
+                await LoadAsync();
+            }
+            else
+            {
+                Snackbar.Add("삭제 실패", Severity.Error);
+            }
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+        }
     }
 }

TaxBaik.Web/Components/Admin/Pages/TaxFilings/FilingTable.razor

@@ -1,5 +1,6 @@
-@using TaxBaik.Application.Services
-@inject TaxFilingService FilingService
+@using TaxBaik.Web.Services
+@using TaxBaik.Domain.Entities
+@inject ITaxFilingBrowserClient FilingClient
 @inject ISnackbar Snackbar
 
 @if (Filings == null || Filings.Count == 0)
@@ -58,23 +59,51 @@ else
 
 @code {
     [Parameter]
-    public List<Domain.Entities.TaxFiling>? Filings { get; set; }
+    public List<TaxFiling>? Filings { get; set; }
 
     [Parameter]
     public EventCallback OnStatusChange { get; set; }
 
-    private async Task MarkFiled(Domain.Entities.TaxFiling filing)
+    private async Task MarkFiled(TaxFiling filing)
     {
-        filing.Status = "filed";
-        await FilingService.UpdateAsync(filing);
-        Snackbar.Add("신고 완료 처리되었습니다.", Severity.Success);
-        await OnStatusChange.InvokeAsync();
+        try
+        {
+            filing.Status = "filed";
+            var result = await FilingClient.UpdateAsync(filing.Id, filing);
+            if (result != null)
+            {
+                Snackbar.Add("신고 완료 처리되었습니다.", Severity.Success);
+                await OnStatusChange.InvokeAsync();
+            }
+            else
+            {
+                Snackbar.Add("처리 실패", Severity.Error);
+            }
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+        }
     }
 
     private async Task DeleteFiling(int id)
     {
-        await FilingService.DeleteAsync(id);
-        Snackbar.Add("삭제되었습니다.", Severity.Info);
-        await OnStatusChange.InvokeAsync();
+        try
+        {
+            var success = await FilingClient.DeleteAsync(id);
+            if (success)
+            {
+                Snackbar.Add("삭제되었습니다.", Severity.Info);
+                await OnStatusChange.InvokeAsync();
+            }
+            else
+            {
+                Snackbar.Add("삭제 실패", Severity.Error);
+            }
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+        }
     }
 }

TaxBaik.Web/Components/Admin/Pages/TaxFilings/TaxFilingList.razor

@@ -1,8 +1,9 @@
 @page "/admin/tax-filings"
 @attribute [Authorize]
-@using TaxBaik.Application.Services
-@inject TaxFilingService FilingService
-@inject ClientService ClientService
+@using TaxBaik.Web.Services
+@using TaxBaik.Domain.Entities
+@inject ITaxFilingBrowserClient FilingClient
+@inject IClientBrowserClient ClientClient
 @inject ISnackbar Snackbar
 
 <PageTitle>신고 일정 관리</PageTitle>
@@ -83,17 +84,30 @@
 
     private async Task Reload()
     {
-        var all = (await FilingService.GetUpcomingAsync(365)).ToList();
-        // Also get filed ones by fetching all
-        pending  = all.Where(x => x.Status == "pending").ToList();
-        filed    = all.Where(x => x.Status == "filed").ToList();
-        overdue  = all.Where(x => x.Status == "overdue").ToList();
+        try
+        {
+            var all = (await FilingClient.GetUpcomingAsync(365)).ToList();
+            pending  = all.Where(x => x.Status == "pending").ToList();
+            filed    = all.Where(x => x.Status == "filed").ToList();
+            overdue  = all.Where(x => x.Status == "overdue").ToList();
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
+        }
     }
 
-    private async Task<IEnumerable<Domain.Entities.Client>> SearchClients(string value)
+    private async Task<IEnumerable<Client>> SearchClients(string value)
     {
-        var (items, _) = await ClientService.GetPagedAsync(1, 20, search: value);
-        return items;
+        try
+        {
+            var (items, _) = await ClientClient.GetPagedAsync(1, 20, search: value);
+            return items;
+        }
+        catch
+        {
+            return [];
+        }
     }
 
     private async Task AddFiling()
@@ -105,7 +119,7 @@
                 Snackbar.Add("고객을 선택하세요.", Severity.Warning);
                 return;
             }
-            var filing = new Domain.Entities.TaxFiling
+            var filing = new TaxFiling
             {
                 ClientId = selectedClient.Id,
                 FilingType = newFilingType,
@@ -113,14 +127,21 @@
                 Status = "pending",
                 Memo = string.IsNullOrWhiteSpace(newMemo) ? null : newMemo
             };
-            await FilingService.CreateAsync(filing);
-            showAddForm = false;
-            Snackbar.Add("신고 일정이 추가되었습니다.", Severity.Success);
-            await Reload();
+            var result = await FilingClient.CreateAsync(filing);
+            if (result != null)
+            {
+                showAddForm = false;
+                Snackbar.Add("신고 일정이 추가되었습니다.", Severity.Success);
+                await Reload();
+            }
+            else
+            {
+                Snackbar.Add("추가 실패", Severity.Error);
+            }
         }
-        catch (ValidationException ex)
+        catch (Exception ex)
         {
-            Snackbar.Add(ex.Message, Severity.Error);
+            Snackbar.Add($"오류: {ex.Message}", Severity.Error);
         }
     }
 }