diff --git a/AIStudyApp/AIStudyApp/Features/Library/LibraryViewModel.swift b/AIStudyApp/AIStudyApp/Features/Library/LibraryViewModel.swift
index c107a35..2c26b0c 100644
--- a/AIStudyApp/AIStudyApp/Features/Library/LibraryViewModel.swift
+++ b/AIStudyApp/AIStudyApp/Features/Library/LibraryViewModel.swift
@@ -64,14 +64,11 @@ class LibraryViewModel: ObservableObject {
 
     func togglePin(id: String) async {
         do {
-            let _ = try await api.post("/knowledge-bases/\(id)/pin")
-            // reload after pin toggle
+            let _: GenericSuccessResponse? = try? await APIClient.shared.request("/knowledge-bases/\(id)/pin", method: "POST")
             await loadKnowledgeBases()
         } catch {}
     }
 
-    private var api: APIClient { APIClient.shared }
-
     private func fetchKBs(page: Int) async throws -> [KnowledgeBase] {
         switch currentFilter {
         case .all: return try await KnowledgeBaseService.shared.list(page: page, limit: pageSize)