Also share sub setbox

Jellyfin.Plugin.ShareLinks/Services/ItemTagService.cs

@@ -8,6 +8,7 @@ using MediaBrowser.Controller.Entities.TV;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Model.Entities;
 using Microsoft.Extensions.Logging;
+using MediaBrowser.Controller.Entities.Movies;
 
 namespace Jellyfin.Plugin.ShareLinks.Services;
 
@@ -147,13 +148,38 @@ public sealed class ItemTagService
     private static List<BaseItem> BuildTagTreeTargets(BaseItem item)
     {
         var targets = new List<BaseItem> { item };
-
+        CollectDescendants(item, targets, new HashSet<Guid> { item.Id });
-        if (item is Folder folder)
+        return targets;
-        {
-            targets.AddRange(folder.GetRecursiveChildren());
     }
 
-        return targets;
+    private static void CollectDescendants(BaseItem item, List<BaseItem> targets, HashSet<Guid> seen)
+    {
+        IEnumerable<BaseItem> children = item switch
+        {
+            // A BoxSet's members are logical links, not real ParentId children -
+            // GetRecursiveChildren() does not follow LinkedChildren of a nested
+            // BoxSet, so each level has to be resolved and recursed into by hand.
+            BoxSet boxSet => boxSet.GetLinkedChildren(),
+            Folder folder => folder.GetRecursiveChildren(),
+            _ => Enumerable.Empty<BaseItem>()
+        };
+
+        foreach (var child in children)
+        {
+            if (!seen.Add(child.Id))
+            {
+                continue;
+            }
+
+            targets.Add(child);
+
+            // GetRecursiveChildren() already walks a physical folder tree fully,
+            // so only a BoxSet child (nested collection) needs an extra pass.
+            if (child is BoxSet)
+            {
+                CollectDescendants(child, targets, seen);
+            }
+        }
     }
 
     /// <summary>