diff --git a/internal/services/library_service.go b/internal/services/library_service.go
index 0ad61dd..1619606 100644
--- a/internal/services/library_service.go
+++ b/internal/services/library_service.go
@@ -4,6 +4,7 @@ import (
 	"bookhoard/internal/database"
 	"context"
 	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -286,6 +287,19 @@ func (s *LibraryService) BrowseDirectories(ctx context.Context, path string) ([]
 	return dirs, cleanPath, parentPath, nil
 }
 
+// SyncAllowedExtensions syncs the Go AllowedExtensions map into the database.
+// This ensures library_types.allowed_extensions stays in sync with the Go source of truth.
+func (s *LibraryService) SyncAllowedExtensions(ctx context.Context) {
+	for typeName, exts := range AllowedExtensions {
+		if err := s.db.SyncLibraryTypeExtensions(ctx, database.SyncLibraryTypeExtensionsParams{
+			Name:              typeName,
+			AllowedExtensions: exts,
+		}); err != nil {
+			log.Printf("Warning: failed to sync allowed extensions for library type %s: %v", typeName, err)
+		}
+	}
+}
+
 func (s *LibraryService) ResolveMediaPath(ctx context.Context, libraryID pgtype.UUID, relativePath string) (string, error) {
 	// Get library folders for this library
 	folders, err := s.db.GetLibraryFolders(ctx, libraryID)