Keep folder extras with the item that owns the folder

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -771,6 +771,17 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         protected virtual bool SupportsOwnedItems => !ParentId.IsEmpty() && IsFileProtocol;
 
+        /// <summary>
+        /// Gets a value indicating whether this item searches the folder it lives in for its own extras.
+        /// </summary>
+        [JsonIgnore]
+        protected virtual bool SearchesContainingFolderForExtras =>
+            IsFileProtocol
+            && SupportsOwnedItems
+            && !IsInMixedFolder
+            && this is not (ICollectionFolder or UserRootFolder or AggregateFolder)
+            && GetType() != typeof(Folder);
+
         [JsonIgnore]
         public virtual bool SupportsPeople => false;
 
@@ -1528,7 +1539,14 @@ namespace MediaBrowser.Controller.Entities
         /// <returns><c>true</c> if any items have changed, else <c>false</c>.</returns>
         protected virtual async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, IReadOnlyList<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
-            if (!IsFileProtocol || !SupportsOwnedItems || IsInMixedFolder || this is ICollectionFolder or UserRootFolder or AggregateFolder || this.GetType() == typeof(Folder))
+            if (!SearchesContainingFolderForExtras)
+            {
+                return false;
+            }
+
+            if (GetParent() is Folder container
+                && container.SearchesContainingFolderForExtras
+                && string.Equals(container.Path, ContainingFolderPath, StringComparison.OrdinalIgnoreCase))
             {
                 return false;
             }

MediaBrowser.Controller/Entities/TV/Episode.cs

@@ -47,7 +47,7 @@ namespace MediaBrowser.Controller.Entities.TV
         public int? IndexNumberEnd { get; set; }
 
         [JsonIgnore]
-        protected override bool SupportsOwnedItems => IsStacked || MediaSourceCount > 1;
+        protected override bool SupportsOwnedItems => IsStacked || LocalAlternateVersions.Length > 0 || MediaSourceCount > 1;
 
         [JsonIgnore]
         public override bool SupportsInheritedParentImages => true;

MediaBrowser.Controller/Entities/Video.cs

@@ -527,7 +527,13 @@ namespace MediaBrowser.Controller.Entities
 
         protected override async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, IReadOnlyList<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
-            var hasChanges = await base.RefreshedOwnedItems(options, fileSystemChildren, cancellationToken).ConfigureAwait(false);
+            var hasChanges = false;
+
+            // The extras of a version group are maintained by its primary.
+            if (!PrimaryVersionId.HasValue)
+            {
+                hasChanges = await base.RefreshedOwnedItems(options, fileSystemChildren, cancellationToken).ConfigureAwait(false);
+            }
 
             // Clean up LocalAlternateVersions - remove paths that no longer exist
             if (LocalAlternateVersions.Length > 0)
@@ -588,10 +594,20 @@ namespace MediaBrowser.Controller.Entities
                 {
                     altVideo.OwnerId = Id;
                     altVideo.SetPrimaryVersionId(Id);
+                    altVideo.IsInMixedFolder = IsInMixedFolder;
                     LibraryManager.CreateItem(altVideo, GetParent());
                 }
             }
 
+            // A version is resolved on its own, so it does not learn whether the folder it sits in
+            // holds other items. It has to share that with the version it belongs to, before the
+            // refresh below acts on it.
+            if (LibraryManager.GetItemById(id) is Video resolvedVersion && resolvedVersion.IsInMixedFolder != IsInMixedFolder)
+            {
+                resolvedVersion.IsInMixedFolder = IsInMixedFolder;
+                await resolvedVersion.UpdateToRepositoryAsync(ItemUpdateType.MetadataImport, cancellationToken).ConfigureAwait(false);
+            }
+
             await RefreshMetadataForOwnedVideo(options, copyTitleMetadata, path, cancellationToken).ConfigureAwait(false);
 
             // Create LinkedChild entry for this local alternate version
@@ -671,6 +687,7 @@ namespace MediaBrowser.Controller.Entities
 
                 video.Id = id;
                 video.OwnerId = Id;
+                video.IsInMixedFolder = IsInMixedFolder;
                 LibraryManager.CreateItem(video, parentFolder);
                 newOptions.ForceSave = true;
             }