Merge branch 'jellyfin:master' into BDMV-pgs

Directory.Packages.props

@@ -82,7 +82,7 @@
     <PackageVersion Include="TagLibSharp" Version="2.3.0" />
     <PackageVersion Include="z440.atl.core" Version="7.16.0" />
     <PackageVersion Include="TMDbLib" Version="3.0.0" />
-    <PackageVersion Include="UTF.Unknown" Version="2.6.0" />
+    <PackageVersion Include="UTF.Unknown" Version="2.7.0" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
     <PackageVersion Include="xunit.v3" Version="3.2.2" />
     <PackageVersion Include="Xunit.v3.Priority" Version="1.1.18" />

Emby.Server.Implementations/Collections/CollectionManager.cs

@@ -107,7 +107,8 @@ namespace Emby.Server.Implementations.Collections
                 SaveLocalMetadata = true
             };
 
-            var name = _localizationManager.GetLocalizedString("Collections");
+            // This names a library for the whole server, so ignore the requesting client's language.
+            var name = _localizationManager.GetServerLocalizedString("Collections");
 
             await _libraryManager.AddVirtualFolder(name, CollectionTypeOptions.boxsets, libraryOptions, true).ConfigureAwait(false);
 

Emby.Server.Implementations/Dto/DtoService.cs

@@ -611,7 +611,11 @@ namespace Emby.Server.Implementations.Dto
                     // For these types we can try to optimize and assume these values will be equal
                     if (item is MusicAlbum || item is Season || item is Playlist)
                     {
-                        dto.ChildCount = dto.RecursiveItemCount;
+                        if (dto.RecursiveItemCount > 0)
+                        {
+                            dto.ChildCount = dto.RecursiveItemCount;
+                        }
+
                         var folderChildCount = folder.LinkedChildren.Length;
                         // The default is an empty array, so we can't reliably use the count when it's empty
                         if (folderChildCount > 0)

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -1914,14 +1914,14 @@ namespace Emby.Server.Implementations.Library
             }
 
             // Optimize by querying against top level views
-            query.TopParentIds = parents.SelectMany(i => GetTopParentIdsForQuery(i, query.User)).ToArray();
-            query.AncestorIds = [];
-
-            // Prevent searching in all libraries due to empty filter
-            if (query.TopParentIds.Length == 0)
+            var topParentIds = parents.SelectMany(i => GetTopParentIdsForQuery(i, query.User)).ToArray();
+            if (topParentIds.Length == 0)
             {
-                query.TopParentIds = [Guid.NewGuid()];
+                return;
             }
+
+            query.TopParentIds = topParentIds;
+            query.AncestorIds = [];
         }
 
         public QueryResult<(BaseItem Item, ItemCounts ItemCounts)> GetAlbumArtists(InternalItemsQuery query)
@@ -1967,12 +1967,15 @@ namespace Emby.Server.Implementations.Library
             if (parents.All(i => i is ICollectionFolder || i is UserView))
             {
                 // Optimize by querying against top level views
-                query.TopParentIds = parents.SelectMany(i => GetTopParentIdsForQuery(i, query.User)).ToArray();
+                var topParentIds = parents.SelectMany(i => GetTopParentIdsForQuery(i, query.User)).ToArray();
 
-                // Prevent searching in all libraries due to empty filter
-                if (query.TopParentIds.Length == 0)
+                if (topParentIds.Length > 0)
                 {
-                    query.TopParentIds = [Guid.NewGuid()];
+                    query.TopParentIds = topParentIds;
+                }
+                else
+                {
+                    SetAncestorIds(query, parents);
                 }
             }
             else if (parents.Count == 1 && parents.First() is Folder folder
@@ -1996,19 +1999,24 @@ namespace Emby.Server.Implementations.Library
             }
             else
             {
-                // We need to be able to query from any arbitrary ancestor up the tree
-                query.AncestorIds = parents.SelectMany(i => i.GetIdsForAncestorQuery()).ToArray();
-
-                // Prevent searching in all libraries due to empty filter
-                if (query.AncestorIds.Length == 0)
-                {
-                    query.AncestorIds = [Guid.NewGuid()];
-                }
+                SetAncestorIds(query, parents);
             }
 
             query.Parent = null;
         }
 
+        private static void SetAncestorIds(InternalItemsQuery query, IReadOnlyCollection<BaseItem> parents)
+        {
+            // We need to be able to query from any arbitrary ancestor up the tree
+            query.AncestorIds = parents.SelectMany(i => i.GetIdsForAncestorQuery()).ToArray();
+
+            // Prevent searching in all libraries due to empty filter
+            if (query.AncestorIds.Length == 0)
+            {
+                query.AncestorIds = [Guid.NewGuid()];
+            }
+        }
+
         private void AddUserToQuery(InternalItemsQuery query, User user, bool allowExternalContent = true)
         {
             if (query.User is null)
@@ -2519,9 +2527,15 @@ namespace Emby.Server.Implementations.Library
                     }
                 }
 
-                if (!File.Exists(image.Path))
+                if (string.IsNullOrEmpty(image.Path) || !File.Exists(image.Path))
                 {
-                    _logger.LogWarning("Image not found at {ImagePath}", image.Path);
+                    _logger.LogWarning(
+                        "{ImageType} image for {ItemName} ({ItemId}) not found at \"{ImagePath}\", source was {SourcePath}",
+                        img.Type,
+                        item.Name,
+                        item.Id,
+                        image.Path,
+                        img.Path);
                     continue;
                 }
 
@@ -2919,7 +2933,8 @@ namespace Emby.Server.Implementations.Library
                 "views",
                 _fileSystem.GetValidFilename(viewType.ToString()));
 
-            var id = GetNewItemId(path + "_namedview_" + name, typeof(UserView));
+            // The display name is localized, so it must not take part in the id.
+            var id = GetNewItemId(path + "_namedview_" + viewType.ToString(), typeof(UserView));
 
             var item = GetItemById(id) as UserView;
 
@@ -2943,6 +2958,13 @@ namespace Emby.Server.Implementations.Library
 
                 refresh = true;
             }
+            else if (!string.Equals(item.Name, name, StringComparison.Ordinal))
+            {
+                item.Name = name;
+                item.ForcedSortName = sortName;
+
+                refresh = true;
+            }
 
             if (refresh)
             {
@@ -2963,7 +2985,9 @@ namespace Emby.Server.Implementations.Library
             var parentIdString = parentId.IsEmpty()
                 ? null
                 : parentId.ToString("N", CultureInfo.InvariantCulture);
-            var idValues = "38_namedview_" + name + user.Id.ToString("N", CultureInfo.InvariantCulture) + (parentIdString ?? string.Empty) + (viewType?.ToString() ?? string.Empty);
+
+            // The name is either localized (grouped views) or the library folder's own name.
+            var idValues = "38_namedview_" + user.Id.ToString("N", CultureInfo.InvariantCulture) + (parentIdString ?? string.Empty) + (viewType?.ToString() ?? string.Empty);
 
             var id = GetNewItemId(idValues, typeof(UserView));
 
@@ -2993,6 +3017,11 @@ namespace Emby.Server.Implementations.Library
 
                 isNew = true;
             }
+            else if (!string.Equals(item.Name, name, StringComparison.Ordinal))
+            {
+                item.Name = name;
+                item.UpdateToRepositoryAsync(ItemUpdateType.MetadataEdit, CancellationToken.None).GetAwaiter().GetResult();
+            }
 
             var lastRefreshedUtc = item.DateLastRefreshed;
             var refresh = isNew || DateTime.UtcNow - lastRefreshedUtc >= _viewRefreshInterval;
@@ -3094,7 +3123,7 @@ namespace Emby.Server.Implementations.Library
             var parentIdString = parentId.IsEmpty()
                 ? null
                 : parentId.ToString("N", CultureInfo.InvariantCulture);
-            var idValues = "37_namedview_" + name + (parentIdString ?? string.Empty) + (viewType?.ToString() ?? string.Empty);
+            var idValues = "37_namedview_" + (parentIdString ?? string.Empty) + (viewType?.ToString() ?? string.Empty);
             if (!string.IsNullOrEmpty(uniqueId))
             {
                 idValues += uniqueId;
@@ -3128,9 +3157,10 @@ namespace Emby.Server.Implementations.Library
                 isNew = true;
             }
 
-            if (viewType != item.ViewType)
+            if (viewType != item.ViewType || !string.Equals(item.Name, name, StringComparison.Ordinal))
             {
                 item.ViewType = viewType;
+                item.Name = name;
                 item.UpdateToRepositoryAsync(ItemUpdateType.MetadataEdit, CancellationToken.None).GetAwaiter().GetResult();
             }
 
@@ -3550,6 +3580,12 @@ namespace Emby.Server.Implementations.Library
             return _peopleRepository.GetPeopleNames(query);
         }
 
+        /// <inheritdoc/>
+        public int DeleteOrphanedCredits()
+        {
+            return _peopleRepository.DeleteOrphanedCredits();
+        }
+
         /// <inheritdoc/>
         public IReadOnlyDictionary<Guid, IReadOnlyList<string>> GetPeopleNamesByItems(IReadOnlyList<Guid> itemIds, IReadOnlyList<string> personTypes)
         {
@@ -3595,7 +3631,20 @@ namespace Emby.Server.Implementations.Library
 
                     await item.UpdateToRepositoryAsync(ItemUpdateType.ImageUpdate, CancellationToken.None).ConfigureAwait(false);
 
-                    return item.GetImageInfo(image.Type, imageIndex);
+                    var localImage = item.GetImageInfo(image.Type, imageIndex);
+                    if (localImage is null)
+                    {
+                        throw new InvalidOperationException(string.Format(
+                            CultureInfo.InvariantCulture,
+                            "Downloaded {0} image {1} from {2} is not attached to {3} ({4})",
+                            image.Type,
+                            imageIndex,
+                            url,
+                            item.Name,
+                            item.Id));
+                    }
+
+                    return localImage;
                 }
                 catch (HttpRequestException ex)
                 {
@@ -3617,7 +3666,13 @@ namespace Emby.Server.Implementations.Library
                 await item.UpdateToRepositoryAsync(ItemUpdateType.ImageUpdate, CancellationToken.None).ConfigureAwait(false);
             }
 
-            throw new InvalidOperationException("Unable to convert any images to local");
+            throw new InvalidOperationException(string.Format(
+                CultureInfo.InvariantCulture,
+                "Unable to convert any {0} image url in \"{1}\" to a local file for {2} ({3})",
+                image.Type,
+                image.Path,
+                item.Name,
+                item.Id));
         }
 
         public async Task AddVirtualFolder(string name, CollectionTypeOptions? collectionType, LibraryOptions options, bool refreshLibrary)

Emby.Server.Implementations/Library/Resolvers/TV/SeasonResolver.cs

@@ -99,7 +99,7 @@ namespace Emby.Server.Implementations.Library.Resolvers.TV
                         args.LibraryOptions.SeasonZeroDisplayName :
                         string.Format(
                             CultureInfo.InvariantCulture,
-                            _localization.GetLocalizedString("NameSeasonNumber"),
+                            _localization.GetServerLocalizedString("NameSeasonNumber"),
                             seasonNumber,
                             args.LibraryOptions.PreferredMetadataLanguage);
                 }

Emby.Server.Implementations/Library/UserViewManager.cs

@@ -112,7 +112,7 @@ namespace Emby.Server.Implementations.Library
 
             if (_config.Configuration.EnableFolderView)
             {
-                var name = _localizationManager.GetLocalizedString("Folders");
+                var name = _localizationManager.GetServerLocalizedString("Folders");
                 list.Add(_libraryManager.GetNamedView(name, CollectionType.folders, string.Empty));
             }
 
@@ -168,7 +168,7 @@ namespace Emby.Server.Implementations.Library
 
         public UserView GetUserSubView(Guid parentId, CollectionType? type, string localizationKey, string sortName)
         {
-            var name = _localizationManager.GetLocalizedString(localizationKey);
+            var name = _localizationManager.GetServerLocalizedString(localizationKey);
 
             return GetUserSubViewWithName(name, parentId, type, sortName);
         }
@@ -191,7 +191,7 @@ namespace Emby.Server.Implementations.Library
                 return GetUserView((Folder)parents[0], viewType, string.Empty);
             }
 
-            var name = _localizationManager.GetLocalizedString(localizationKey);
+            var name = _localizationManager.GetServerLocalizedString(localizationKey);
             return _libraryManager.GetNamedView(user, name, viewType, sortName);
         }
 
@@ -396,6 +396,12 @@ namespace Emby.Server.Implementations.Library
                     query.Limit = limit;
                     return _libraryManager.GetLatestItemList(query, parents, CollectionType.movies);
                 }
+
+                if (collectionType is null)
+                {
+                    query.Limit = limit;
+                    return _libraryManager.GetLatestItemList(query, parents, CollectionType.unknown);
+                }
             }
 
             return _libraryManager.GetItemList(query, parents);

Emby.Server.Implementations/Library/Validators/PeopleValidator.cs

@@ -49,6 +49,14 @@ public class PeopleValidator
     /// <returns>Task.</returns>
     public async Task ValidatePeople(CancellationToken cancellationToken, IProgress<double> progress)
     {
+        // Before the refresh below walks them: a credit no item maps to any more stands for nothing,
+        // and while it is there the person it names cannot reach the dead-person sweep either.
+        var numOrphaned = _libraryManager.DeleteOrphanedCredits();
+        if (numOrphaned > 0)
+        {
+            _logger.LogDebug("Deleted {Amount} credits no item maps to", numOrphaned);
+        }
+
         var people = _libraryManager.GetPeopleNames(new InternalPeopleQuery());
 
         var numComplete = 0;
@@ -115,6 +123,6 @@ public class PeopleValidator
 
         progress.Report(100);
 
-        _logger.LogInformation("People validation complete");
+        _logger.LogInformation("People validation complete, deleted {Orphaned} orphaned credits", numOrphaned);
     }
 }

Emby.Server.Implementations/Localization/Core/be.json

@@ -106,5 +106,11 @@
     "TaskExtractMediaSegments": "Сканіраванне медыя-сегмента",
     "TaskMoveTrickplayImages": "Перанесці месцазнаходжанне выявы Trickplay",
     "CleanupUserDataTask": "Задача па ачыстцы даных карыстальніка",
-    "CleanupUserDataTaskDescription": "Ачышчае ўсе даныя карыстальніка (стан прагляду, абранае і г.д.) для медыяфайлаў, што адсутнічаюць больш за 90 дзён."
+    "CleanupUserDataTaskDescription": "Ачышчае ўсе даныя карыстальніка (стан прагляду, абранае і г.д.) для медыяфайлаў, што адсутнічаюць больш за 90 дзён.",
+    "LyricDownloadFailureFromForItem": "Не ўдалося загрузіць тэкст песні з {0} для {1}",
+    "NameExtraDeletedScene": "Выдаленая сцэна",
+    "NameExtraInterview": "Інтэрв'ю",
+    "NameExtraNumbered": "{0} {1}",
+    "NameExtraScene": "Сцэна",
+    "NameExtraTrailer": "Трэйлер"
 }

Emby.Server.Implementations/Localization/Core/bg-BG.json

@@ -106,5 +106,20 @@
     "TaskMoveTrickplayImagesDescription": "Премества съществуващите trickplay изображения спрямо настройките на библиотеката.",
     "TaskExtractMediaSegments": "Сканиране за сегменти",
     "CleanupUserDataTask": "Задача за почистване на потребителски данни",
-    "CleanupUserDataTaskDescription": "Почиства всички потребителски данни (статус на гледане, любими и т.н.) от медия, която вече не е налична от поне 90 дни."
+    "CleanupUserDataTaskDescription": "Почиства всички потребителски данни (статус на гледане, любими и т.н.) от медия, която вече не е налична от поне 90 дни.",
+    "LyricDownloadFailureFromForItem": "Текстът на песента не успя да се изтегли от {0} за {1}",
+    "NameExtraBehindTheScenes": "Зад кулисите",
+    "NameExtraScene": "Сцена",
+    "NameExtraShort": "Откъс",
+    "NameExtraThemeVideo": "Тематично видео",
+    "NameExtraTrailer": "Трейлър",
+    "NameExtraUnknown": "Екстра",
+    "NameExtraClip": "Клип",
+    "NameExtraDeletedScene": "Изтрита Сцена",
+    "NameExtraFeaturette": "Кратък филм",
+    "NameExtraInterview": "Интервю",
+    "NameExtraNumbered": "{0} {1}",
+    "NameExtraSample": "Пример",
+    "NameExtraThemeSong": "Тема-песен",
+    "Original": "Оригинал"
 }

Emby.Server.Implementations/Localization/Core/en-GB.json

@@ -24,8 +24,8 @@
     "Music": "Music",
     "MusicVideos": "Music Videos",
     "NameInstallFailed": "{0} installation failed",
-    "NameSeasonNumber": "Season {0}",
-    "NameSeasonUnknown": "Season Unknown",
+    "NameSeasonNumber": "Series {0}",
+    "NameSeasonUnknown": "Series Unknown",
     "NewVersionIsAvailable": "A new version of Jellyfin Server is available for download.",
     "NotificationOptionApplicationUpdateAvailable": "Application update available",
     "NotificationOptionApplicationUpdateInstalled": "Application update installed",
@@ -108,5 +108,18 @@
     "CleanupUserDataTask": "User data cleanup task",
     "CleanupUserDataTaskDescription": "Cleans all user data (Watch state, favourite status etc) from media that is no longer present for at least 90 days.",
     "LyricDownloadFailureFromForItem": "Lyrics failed to download from {0} for {1}",
-    "Original": "Original"
+    "Original": "Original",
+    "NameExtraBehindTheScenes": "Behind The Scenes",
+    "NameExtraClip": "Clip",
+    "NameExtraDeletedScene": "Deleted Scene",
+    "NameExtraFeaturette": "Featurette",
+    "NameExtraInterview": "Interview",
+    "NameExtraSample": "Sample",
+    "NameExtraScene": "Scene",
+    "NameExtraShort": "Short",
+    "NameExtraThemeSong": "Theme Song",
+    "NameExtraThemeVideo": "Theme Video",
+    "NameExtraTrailer": "Trailer",
+    "NameExtraUnknown": "Extra",
+    "NameExtraNumbered": "{0} {1}"
 }

Emby.Server.Implementations/Localization/Core/fo.json

@@ -13,7 +13,7 @@
     "FailedLoginAttemptWithUserName": "Miseydnað innritanarroynd frá {0}",
     "HeaderFavoriteEpisodes": "Yndispartar",
     "LabelIpAddressValue": "IP-atsetur: {0}",
-    "AuthenticationSucceededWithUserName": "{0} varð samgildur",
+    "AuthenticationSucceededWithUserName": "{0} var samgildur",
     "HeaderFavoriteShows": "Yndisrøðir",
     "HeaderLiveTV": "Beinleiðis sjónvarp",
     "HearingImpaired": "Hoyrnarveik",
@@ -68,7 +68,7 @@
     "NotificationOptionServerRestartRequired": "Tørvur er á ambætaraendurbyrjan",
     "TasksApplicationCategory": "Nýtsluskipan",
     "NotificationOptionApplicationUpdateAvailable": "Skipanardagføring er tøk",
-    "NotificationOptionApplicationUpdateInstalled": "Skipanardagføring varð innløgd",
+    "NotificationOptionApplicationUpdateInstalled": "Skipanardagføring var innløgd",
     "UserStoppedPlayingItemWithValues": "{0} er liðugur at spæla {1} á {2}",
     "HomeVideos": "Heimaupptøkur",
     "StartupEmbyServerIsLoading": "Jellyfin-ambætarin er undir byrjanarinnlesing. Vinaliga royn aftur um eitt bil.",
@@ -111,5 +111,15 @@
     "NameExtraNumbered": "{0} {1}",
     "NameExtraFeaturette": "Stuttur heimildarfilmur",
     "TaskAudioNormalization": "Ljóðjavnan",
-    "TaskAudioNormalizationDescription": "Kannar fílur fyri dátum til ljóðjavnan."
+    "TaskAudioNormalizationDescription": "Kannar fílur fyri dátum til ljóðjavnan.",
+    "NameExtraSample": "Kut",
+    "TaskRefreshTrickplayImages": "Framleið Trickplay-myndir",
+    "TaskRefreshTrickplayImagesDescription": "Framleiðir trickplay-myndir fyri kykmyndir í søvnunm har tað er virkt.",
+    "TaskMoveTrickplayImages": "Flyt Trickplay-myndagoymslustað",
+    "TaskMoveTrickplayImagesDescription": "Flytur verandi trickplay-fílur sambært savnsstillingunum.",
+    "NameExtraThemeVideo": "Eyðkenniskykmynd",
+    "NameExtraDeletedScene": "Úrtikin mynd (scena)",
+    "NameExtraScene": "Mynd (scena)",
+    "NameExtraUnknown": "Eykatilfar",
+    "Original": "Upprunalig(t/ur)"
 }

Emby.Server.Implementations/Localization/Core/hi.json

@@ -106,5 +106,20 @@
     "TaskMoveTrickplayImages": "ट्रिकप्ले छवि स्थान माइग्रेट करें",
     "TaskMoveTrickplayImagesDescription": "लाइब्रेरी सेटिंग्स के अनुसार मौजूदा ट्रिकप्ले फ़ाइलों को स्थानांतरित करता है।",
     "CleanupUserDataTask": "यूज़र डेटा सफाई कार्य",
-    "Original": "असली"
+    "Original": "असली",
+    "LyricDownloadFailureFromForItem": "{0} के लिए {1} से बोल (Lyrics) डाउनलोड करने में विफल रहा",
+    "NameExtraBehindTheScenes": "परदे के पीछे",
+    "NameExtraClip": "क्लिप",
+    "NameExtraDeletedScene": "हटाया गया दृश्य",
+    "NameExtraFeaturette": "फीचरेट",
+    "NameExtraInterview": "साक्षात्कार",
+    "NameExtraNumbered": "{0} {1}",
+    "NameExtraSample": "नमूना",
+    "NameExtraScene": "दृश्य",
+    "NameExtraShort": "शॉर्ट",
+    "NameExtraThemeSong": "थीम सॉन्ग",
+    "NameExtraThemeVideo": "थीम वीडियो",
+    "NameExtraTrailer": "ट्रेलर",
+    "NameExtraUnknown": "अतिरिक्त",
+    "CleanupUserDataTaskDescription": "कम से कम 90 दिनों से अनुपस्थित मीडिया से सभी उपयोगकर्ता डेटा (देखने की स्थिति, पसंदीदा स्थिति आदि) को साफ़ करता है।"
 }

Emby.Server.Implementations/Localization/Core/lt-LT.json

@@ -87,7 +87,7 @@
     "TaskCleanActivityLog": "Išvalyti veiklos žurnalą",
     "Undefined": "Neapibrėžtas",
     "Forced": "Priverstinis",
-    "Default": "Numatytas",
+    "Default": "Numatytasis",
     "TaskCleanActivityLogDescription": "Ištrina senesnius nei nustatytas amžius veiklos žurnalo įrašus.",
     "TaskOptimizeDatabase": "Optimizuoti duomenų bazę",
     "TaskKeyframeExtractorDescription": "Iš vaizdo įrašo paruošia reikšminius kadrus, kad būtų sukuriamas tikslenis HLS grojaraštis. Šios užduoties vykdymas gali ilgai užtrukti.",

Emby.Server.Implementations/Localization/Core/pt-BR.json

@@ -120,5 +120,6 @@
     "NameExtraThemeVideo": "Vídeo de Abertura",
     "NameExtraTrailer": "Trailer",
     "NameExtraUnknown": "Extra",
-    "NameExtraFeaturette": "Nos Bastidores"
+    "NameExtraFeaturette": "Nos Bastidores",
+    "NameExtraInterview": "Entrevista"
 }

Emby.Server.Implementations/Localization/Core/ro.json

@@ -108,5 +108,8 @@
     "CleanupUserDataTask": "Sarcina de curatare a datelor utilizatorului",
     "CleanupUserDataTaskDescription": "Sterge toate datele utilizatorului (starea vizionarii, starea favoritelor etc.) de pe suporturile media care nu mai sunt prezente timp de cel puțin 90 de zile.",
     "LyricDownloadFailureFromForItem": "Versurile nu au putut fi descărcate din {0} pentru {1}",
-    "Original": "Original"
+    "Original": "Original",
+    "NameExtraBehindTheScenes": "În culise",
+    "NameExtraClip": "Clip",
+    "NameExtraDeletedScene": "Scenă ștearsă"
 }

Emby.Server.Implementations/Localization/Core/sv.json

@@ -116,5 +116,10 @@
     "NameExtraScene": "Scen",
     "NameExtraShort": "Kortfilm",
     "NameExtraThemeSong": "Signaturmelodi",
-    "NameExtraTrailer": "Trailer"
+    "NameExtraTrailer": "Trailer",
+    "NameExtraClip": "Klipp",
+    "NameExtraFeaturette": "Kortfilm",
+    "NameExtraSample": "Prov",
+    "NameExtraThemeVideo": "Signaturvideo",
+    "NameExtraUnknown": "Extra"
 }

Emby.Server.Implementations/ScheduledTasks/Tasks/AudioNormalizationTask.cs

@@ -174,7 +174,7 @@ public partial class AudioNormalizationTask : IScheduledTask
                 if (!t.NormalizationGain.HasValue && !t.LUFS.HasValue && t.IsFileProtocol)
                 {
                     t.LUFS = await CalculateLUFSAsync(
-                        string.Format(CultureInfo.InvariantCulture, "-i \"{0}\"", t.Path.Replace("\"", "\\\"", StringComparison.Ordinal)),
+                        string.Format(CultureInfo.InvariantCulture, "-i \"{0}\"", t.Path.EscapeProcessArgument()),
                         false,
                         cancellationToken).ConfigureAwait(false);
                     toSaveDbItems.Add(t);

Emby.Server.Implementations/ScheduledTasks/Tasks/PeopleValidationTask.cs

@@ -177,33 +177,14 @@ public class PeopleValidationTask : IScheduledTask, IConfigurableScheduledTask
         var thirtyDaysAgo = DateTime.UtcNow.AddDays(-30);
         var personTypeName = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Person];
 
+        List<Guid> peopleIds;
+
         var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken).ConfigureAwait(false);
         await using (context.ConfigureAwait(false))
         {
-            const int PartitionSize = 100;
-
-            var numPeople = await context.BaseItems
-                .AsNoTracking()
-                .Where(b => b.Type == personTypeName)
-                .Where(b => b.DateLastRefreshed == null || b.DateLastRefreshed < thirtyDaysAgo)
-                .Where(b =>
-                    !b.Images!.Any(i => i.ImageType == ImageInfoImageType.Primary) ||
-                    string.IsNullOrEmpty(b.Overview))
-                .CountAsync(cancellationToken)
-                .ConfigureAwait(false);
-
-            _logger.LogDebug("Found {Count} people needing image/overview refresh", numPeople);
-
-            if (numPeople == 0)
-            {
-                progress.Report(100);
-                return;
-            }
-
-            var numComplete = 0;
-            var numRefreshed = 0;
-
-            await foreach (var entry in context.BaseItems
+            // Read the candidates in one go rather than paging them. A refresh stamps the person and takes
+            // it out of this set, so a growing offset over a shrinking set walks past people it never visits.
+            peopleIds = await context.BaseItems
                 .AsNoTracking()
                 .Where(b => b.Type == personTypeName)
                 .Where(b => b.DateLastRefreshed == null || b.DateLastRefreshed < thirtyDaysAgo)
@@ -211,22 +192,36 @@ public class PeopleValidationTask : IScheduledTask, IConfigurableScheduledTask
                     !b.Images!.Any(i => i.ImageType == ImageInfoImageType.Primary) ||
                     string.IsNullOrEmpty(b.Overview))
                 .OrderBy(b => b.Id)
-                .WithPartitionProgress(partition => _logger.LogDebug("Processing people partition {Partition}", partition))
-                .PartitionEagerAsync(PartitionSize, cancellationToken)
-                .WithCancellation(cancellationToken)
-                .ConfigureAwait(false))
-            {
-                if (await RefreshPersonAsync(entry.Id, cancellationToken).ConfigureAwait(false))
-                {
-                    numRefreshed++;
-                }
+                .Select(b => b.Id)
+                .ToListAsync(cancellationToken)
+                .ConfigureAwait(false);
+        }
 
-                numComplete++;
-                progress.Report(100.0 * numComplete / numPeople);
+        _logger.LogDebug("Found {Count} people needing image/overview refresh", peopleIds.Count);
+
+        if (peopleIds.Count == 0)
+        {
+            progress.Report(100);
+            return;
+        }
+
+        var numComplete = 0;
+        var numRefreshed = 0;
+
+        foreach (var personId in peopleIds)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            if (await RefreshPersonAsync(personId, cancellationToken).ConfigureAwait(false))
+            {
+                numRefreshed++;
             }
 
-            _logger.LogInformation("Refreshed metadata for {Count} people missing images or overview", numRefreshed);
+            numComplete++;
+            progress.Report(100.0 * numComplete / peopleIds.Count);
         }
+
+        _logger.LogInformation("Refreshed metadata for {Count} people missing images or overview", numRefreshed);
     }
 
     private async Task<bool> RefreshPersonAsync(Guid personId, CancellationToken cancellationToken)
@@ -243,8 +238,8 @@ public class PeopleValidationTask : IScheduledTask, IConfigurableScheduledTask
 
             var options = new MetadataRefreshOptions(new DirectoryService(_fileSystem))
             {
-                ImageRefreshMode = hasImage ? MetadataRefreshMode.ValidationOnly : MetadataRefreshMode.Default,
-                MetadataRefreshMode = hasOverview ? MetadataRefreshMode.ValidationOnly : MetadataRefreshMode.Default
+                ImageRefreshMode = hasImage ? MetadataRefreshMode.ValidationOnly : MetadataRefreshMode.FullRefresh,
+                MetadataRefreshMode = hasOverview ? MetadataRefreshMode.ValidationOnly : MetadataRefreshMode.FullRefresh
             };
 
             await item.RefreshMetadata(options, cancellationToken).ConfigureAwait(false);

Jellyfin.Api/Controllers/DynamicHlsController.cs

@@ -20,7 +20,6 @@ using MediaBrowser.Controller.Configuration;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.MediaEncoding;
 using MediaBrowser.Controller.Streaming;
-using MediaBrowser.MediaEncoding.Encoder;
 using MediaBrowser.Model.Configuration;
 using MediaBrowser.Model.Dlna;
 using MediaBrowser.Model.Entities;
@@ -1652,9 +1651,9 @@ public class DynamicHlsController : BaseJellyfinApiController
             segmentFormat,
             startNumber.ToString(CultureInfo.InvariantCulture),
             baseUrlParam,
-            EncodingUtils.NormalizePath(outputTsArg),
+            outputTsArg.EscapeProcessArgument(),
             hlsArguments,
-            EncodingUtils.NormalizePath(outputPath)).Trim();
+            outputPath.EscapeProcessArgument()).Trim();
     }
 
     /// <summary>

Jellyfin.Api/Controllers/ItemLookupController.cs

@@ -13,6 +13,7 @@ using MediaBrowser.Controller.Entities.Movies;
 using MediaBrowser.Controller.Entities.TV;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.Providers;
+using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.IO;
 using MediaBrowser.Model.Providers;
 using Microsoft.AspNetCore.Authorization;
@@ -263,7 +264,7 @@ public class ItemLookupController : BaseJellyfinApiController
             searchResult.ProviderIds);
 
         // Since the refresh process won't erase provider Ids, we need to set this explicitly now.
-        item.ProviderIds = searchResult.ProviderIds;
+        item.SetProviderIds(searchResult.ProviderIds);
         await _providerManager.RefreshFullItem(
             item,
             new MetadataRefreshOptions(new DirectoryService(_fileSystem))

Jellyfin.Api/Controllers/ItemUpdateController.cs

@@ -428,15 +428,7 @@ public class ItemUpdateController : BaseJellyfinApiController
 
         if (request.ProviderIds is not null)
         {
-            foreach (var pair in request.ProviderIds.ToList())
-            {
-                if (string.IsNullOrEmpty(pair.Value))
-                {
-                    request.ProviderIds.Remove(pair.Key);
-                }
-            }
-
-            item.ProviderIds = request.ProviderIds;
+            item.SetProviderIds(request.ProviderIds);
         }
 
         if (item is Video video)

Jellyfin.Api/Controllers/UserLibraryController.cs

@@ -34,6 +34,8 @@ namespace Jellyfin.Api.Controllers;
 [Tags("Library")]
 public class UserLibraryController : BaseJellyfinApiController
 {
+    private static readonly TimeSpan RefreshOnDemandTimeout = TimeSpan.FromSeconds(3);
+
     private readonly IUserManager _userManager;
     private readonly IUserDataManager _userDataRepository;
     private readonly ILibraryManager _libraryManager;
@@ -79,7 +81,7 @@ public class UserLibraryController : BaseJellyfinApiController
     /// <returns>An <see cref="OkResult"/> containing the item.</returns>
     [HttpGet("Items/{itemId}")]
     [ProducesResponseType(StatusCodes.Status200OK)]
-    public ActionResult<BaseItemDto> GetItem(
+    public async Task<ActionResult<BaseItemDto>> GetItem(
         [FromQuery] Guid? userId,
         [FromRoute, Required] Guid itemId)
     {
@@ -98,7 +100,7 @@ public class UserLibraryController : BaseJellyfinApiController
             return NotFound();
         }
 
-        QueueRefreshOnDemandIfNeeded(item);
+        await RefreshOnDemandIfNeeded(item).ConfigureAwait(false);
 
         var dtoOptions = new DtoOptions();
 
@@ -116,7 +118,7 @@ public class UserLibraryController : BaseJellyfinApiController
     [ProducesResponseType(StatusCodes.Status200OK)]
     [Obsolete("Kept for backwards compatibility")]
     [ApiExplorerSettings(IgnoreApi = true)]
-    public ActionResult<BaseItemDto> GetItemLegacy(
+    public Task<ActionResult<BaseItemDto>> GetItemLegacy(
         [FromRoute, Required] Guid userId,
         [FromRoute, Required] Guid itemId)
         => GetItem(userId, itemId);
@@ -643,7 +645,7 @@ public class UserLibraryController : BaseJellyfinApiController
             limit,
             groupItems);
 
-    private void QueueRefreshOnDemandIfNeeded(BaseItem item)
+    private async Task RefreshOnDemandIfNeeded(BaseItem item)
     {
         if (item is not Person)
         {
@@ -656,15 +658,24 @@ public class UserLibraryController : BaseJellyfinApiController
             return;
         }
 
-        _providerManager.QueueRefresh(
-            item.Id,
-            new MetadataRefreshOptions(new DirectoryService(_fileSystem))
-            {
-                MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
-                ImageRefreshMode = MetadataRefreshMode.FullRefresh,
-                ForceSave = true
-            },
-            RefreshPriority.High);
+        var options = new MetadataRefreshOptions(new DirectoryService(_fileSystem))
+        {
+            MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
+            ImageRefreshMode = MetadataRefreshMode.FullRefresh,
+            ForceSave = true
+        };
+
+        using var timeout = CancellationTokenSource.CreateLinkedTokenSource(HttpContext.RequestAborted);
+        timeout.CancelAfter(RefreshOnDemandTimeout);
+
+        try
+        {
+            await item.RefreshMetadata(options, timeout.Token).ConfigureAwait(false);
+        }
+        catch (OperationCanceledException) when (!HttpContext.RequestAborted.IsCancellationRequested)
+        {
+            _providerManager.QueueRefresh(item.Id, options, RefreshPriority.High);
+        }
     }
 
     /// <summary>

Jellyfin.Server.Implementations/Item/BaseItemRepository.QueryBuilding.cs

@@ -12,6 +12,7 @@ using Jellyfin.Database.Implementations;
 using Jellyfin.Database.Implementations.Entities;
 using Jellyfin.Database.Implementations.Enums;
 using Jellyfin.Extensions;
+using Jellyfin.Server.Implementations.Extensions;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.Querying;
@@ -323,10 +324,21 @@ public sealed partial class BaseItemRepository
             orderedQuery = query.OrderBy(relevanceExpression);
         }
 
+        // Folders carry no played flag of their own, so these two keys go through the same predicate
+        // the isPlayed filter uses rather than through the stored-column lookup in OrderMapper.
+        Expression<Func<BaseItemEntity, object?>> MapOrderByField(ItemSortBy sortBy) => sortBy switch
+        {
+            ItemSortBy.IsPlayed when filter.User is not null
+                => AsOrderKey(BuildIsPlayedFilter(context, filter.User)),
+            ItemSortBy.IsUnplayed when filter.User is not null
+                => AsOrderKey(BuildIsPlayedFilter(context, filter.User).Not()),
+            _ => OrderMapper.MapOrderByField(sortBy, filter, context)
+        };
+
         if (orderBy.Length > 0)
         {
             var firstOrdering = orderBy[0];
-            var expression = OrderMapper.MapOrderByField(firstOrdering.OrderBy, filter, context);
+            var expression = MapOrderByField(firstOrdering.OrderBy);
 
             if (orderedQuery is null)
             {
@@ -350,7 +362,7 @@ public sealed partial class BaseItemRepository
 
             foreach (var item in orderBy.Skip(1))
             {
-                expression = OrderMapper.MapOrderByField(item.OrderBy, filter, context);
+                expression = MapOrderByField(item.OrderBy);
                 orderedQuery = item.SortOrder == SortOrder.Ascending
                     ? orderedQuery.ThenBy(expression)
                     : orderedQuery.ThenByDescending(expression);
@@ -666,6 +678,9 @@ public sealed partial class BaseItemRepository
         return ApplyAccessFiltering(context, leafItems, new InternalItemsQuery(user) { IncludeOwnedItems = includeOwnedItems });
     }
 
+    private static Expression<Func<BaseItemEntity, object?>> AsOrderKey(Expression<Func<BaseItemEntity, bool>> predicate)
+        => Expression.Lambda<Func<BaseItemEntity, object?>>(Expression.Convert(predicate.Body, typeof(object)), predicate.Parameters);
+
     /// <inheritdoc />
     public Expression<Func<BaseItemEntity, bool>> BuildHasDescendantFilter(JellyfinDbContext context, IQueryable<BaseItemEntity> descendants)
     {

Jellyfin.Server.Implementations/Item/BaseItemRepository.Querying.cs

@@ -110,7 +110,7 @@ public sealed partial class BaseItemRepository
         PrepareFilterQuery(filter);
 
         // Early exit if collection type is not supported
-        if (collectionType is not CollectionType.movies and not CollectionType.tvshows and not CollectionType.music)
+        if (collectionType is not CollectionType.movies and not CollectionType.tvshows and not CollectionType.music and not CollectionType.unknown)
         {
             return [];
         }
@@ -121,30 +121,27 @@ public sealed partial class BaseItemRepository
         var baseQuery = PrepareItemQuery(context, filter);
         baseQuery = TranslateQuery(baseQuery, context, filter);
 
-        if (collectionType == CollectionType.tvshows)
+        if (collectionType is CollectionType.tvshows)
         {
             return GetLatestTvShowItems(context, baseQuery, filter, limit);
         }
 
         if (collectionType is CollectionType.movies)
         {
-            // Pick, per PresentationUniqueKey, the newest item; return the newest `limit` of those.
-            // Build up until limit by streaming through results and deduplicating on the fly.
-            var orderedIds = baseQuery
-                .Where(e => e.PresentationUniqueKey != null)
-                .OrderByDescending(e => e.DateCreated)
-                .ThenByDescending(e => e.Id)
-                .Select(e => new { e.Id, e.PresentationUniqueKey });
+            return GetLatestMovieItems(context, baseQuery, filter, limit);
+        }
 
-            // DistinctBy and Take are lazy, so enumeration stops as soon as limit distinct keys are read.
-            var firstIds = orderedIds
-                .AsEnumerable()
-                .DistinctBy(row => row.PresentationUniqueKey)
-                .Select(row => row.Id)
+        if (collectionType is CollectionType.unknown)
+        {
+            var moviesQuery = baseQuery.Where(e => e.SeriesName == null);
+            var latestMovies = GetLatestMovieItems(context, moviesQuery, filter, limit);
+            var latestShows = GetLatestTvShowItems(context, baseQuery, filter, limit);
+
+            return latestMovies.Concat(latestShows)
+                .OrderByDescending(dto => dto.DateCreated)
+                .ThenByDescending(dto => dto.Id)
                 .Take(limit ?? int.MaxValue)
                 .ToList();
-
-            return LoadLatestByIds(context, firstIds, filter);
         }
 
         var musicAlbumTypeName = _itemTypeLookup.BaseItemKindNames[BaseItemKind.MusicAlbum]!;
@@ -225,6 +222,39 @@ public sealed partial class BaseItemRepository
             .ToArray()!;
     }
 
+    /// <summary>
+    /// Gets the latest movies, deduplicated so each movie only appears once.
+    /// </summary>
+    /// <param name="context">The database context.</param>
+    /// <param name="baseQuery">The query to pull movies from, with filters already applied.</param>
+    /// <param name="filter">The original query filter, used when loading the final items.</param>
+    /// <param name="limit">How many items to return.</param>
+    /// <returns>The latest movies, newest first.</returns>
+    private IReadOnlyList<BaseItemDto> GetLatestMovieItems(
+        JellyfinDbContext context,
+        IQueryable<BaseItemEntity> baseQuery,
+        InternalItemsQuery filter,
+        int? limit)
+    {
+        // Pick, per PresentationUniqueKey, the newest item; return the newest `limit` of those.
+        // Build up until limit by streaming through results and deduplicating on the fly.
+        var orderedIds = baseQuery
+            .Where(e => e.PresentationUniqueKey != null)
+            .OrderByDescending(e => e.DateCreated)
+            .ThenByDescending(e => e.Id)
+            .Select(e => new { e.Id, e.PresentationUniqueKey });
+
+        // DistinctBy and Take are lazy, so enumeration stops as soon as limit distinct keys are read.
+        var firstIds = orderedIds
+            .AsEnumerable()
+            .DistinctBy(row => row.PresentationUniqueKey)
+            .Select(row => row.Id)
+            .Take(limit ?? int.MaxValue)
+            .ToList();
+
+        return LoadLatestByIds(context, firstIds, filter);
+    }
+
     /// <summary>
     /// Gets the latest TV show items with smart Season/Series container selection.
     /// </summary>

Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs

@@ -35,6 +35,39 @@ public sealed partial class BaseItemRepository
     // instance across several lambdas, and this filter is combined into a tree more than once.
     private static Expression<Func<BaseItemEntity, bool>> IsFolderFilter => e => e.IsFolder;
 
+    // Shared by the isPlayed filter and the IsPlayed/IsUnplayed ordering so the two cannot disagree.
+    private Expression<Func<BaseItemEntity, bool>> BuildIsPlayedFilter(JellyfinDbContext context, User user)
+    {
+        var userId = user.Id;
+
+        // Leaf items carry their own played state.
+        var playedItemIds = context.UserData
+            .Where(ud => ud.UserId == userId && ud.Played)
+            .Select(ud => ud.ItemId);
+
+        // Folders (Series, Seasons, BoxSets, albums, ...) have none and count as played once no
+        // descendant is left unplayed, matching what the DTO reports for them. This has to key off
+        // the item itself rather than off the requested item types: tag and collection listings mix
+        // folders and leaf items in a single query.
+        var unplayedLeafItems = GetAccessFilteredLeafItemsQuery(context, user)
+            .Where(e => !e.UserData!.Any(ud => ud.UserId == userId && ud.Played));
+
+        return IsFolderFilter.And(BuildHasDescendantFilter(context, unplayedLeafItems).Not())
+            .Or(IsFolderFilter.Not().And(e => playedItemIds.Contains(e.Id)));
+    }
+
+    // "und" is the language filters' stand-in for a track that declares no language at all.
+    private static string NormalizeLanguage(string language)
+        => string.Equals(language, "und", StringComparison.OrdinalIgnoreCase) ? "und" : language;
+
+    // The primary versions whose alternate version satisfies a dimension bound. Anchored on
+    // PrimaryVersionId so the filtered index carries it rather than a scan of every item.
+    private static IQueryable<Guid> VersionsMatchingDimension(JellyfinDbContext context, Expression<Func<BaseItemEntity, bool>> bound)
+        => context.BaseItems
+            .Where(v => v.PrimaryVersionId != null)
+            .Where(bound)
+            .Select(v => v.PrimaryVersionId!.Value);
+
     /// <inheritdoc />
     public IQueryable<BaseItemEntity> TranslateQuery(
         IQueryable<BaseItemEntity> baseQuery,
@@ -70,47 +103,86 @@ public sealed partial class BaseItemRepository
                 include4K = true;
             }
 
-            // Non-folders: check own resolution directly (no subquery).
-            // Folders (Series, BoxSets): EXISTS check on descendants/linked children.
-            // Using navigation properties (a.Item, lc.Child) produces efficient
-            // EXISTS + JOIN instead of nested IN (SELECT ...) subqueries.
+            // A 4K remux of an SD primary is a version of the same item, so the bucket a caller filters
+            // on is the best any of the item's versions offers, not just the primary file's. Three sets,
+            // because a bucket is as much about what the version group does not have as what it does, and
+            // because an unprobed primary can still be placed by a version that does carry dimensions.
+            // The filtered PrimaryVersionId index keeps all three to the few items that have versions.
+            var versionsSd = VersionsMatchingDimension(context, v => v.Width > 0 && v.Width < HDWidth);
+            var versionsHd = VersionsMatchingDimension(context, v => v.Width >= HDWidth);
+            var versions4K = VersionsMatchingDimension(context, v => v.Width >= UHDWidth || v.Height >= UHDHeight);
+
+            // Only the SD test needs the Width > 0 guard against a row with no dimensions: such a row
+            // cannot reach the HD or 4K bound anyway, and EF lowers the HD bucket's negated "not itself
+            // 4K" guard to CASE WHEN ... THEN 0 ELSE 1, which already reads unknown as not 4K rather
+            // than propagating a null. Folders (Series, BoxSets) answer on their descendants, bucketed
+            // exactly as a top-level item is so that the two cannot disagree; the navigation properties
+            // (a.Item, lc.Child) give EXISTS + JOIN rather than nested IN (SELECT ...).
             baseQuery = baseQuery.Where(e =>
-                (!e.IsFolder && e.Width > 0
-                    && ((includeSD && e.Width < HDWidth)
-                        || (includeHD && e.Width >= HDWidth && !(e.Width >= UHDWidth || e.Height >= UHDHeight))
-                        || (include4K && (e.Width >= UHDWidth || e.Height >= UHDHeight))))
+                (!e.IsFolder
+                    && ((includeSD
+                            && ((e.Width > 0 && e.Width < HDWidth) || versionsSd.Contains(e.Id))
+                            && !versionsHd.Contains(e.Id)
+                            && !versions4K.Contains(e.Id))
+                        || (includeHD
+                            && (e.Width >= HDWidth || versionsHd.Contains(e.Id))
+                            && !(e.Width >= UHDWidth || e.Height >= UHDHeight)
+                            && !versions4K.Contains(e.Id))
+                        || (include4K
+                            && (e.Width >= UHDWidth || e.Height >= UHDHeight || versions4K.Contains(e.Id)))))
                 || (e.IsFolder
                     && (e.Children!.Any(a =>
-                            a.Item.Width > 0
-                            && ((includeSD && a.Item.Width < HDWidth)
-                                || (includeHD && a.Item.Width >= HDWidth && !(a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight))
-                                || (include4K && (a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight))))
+                            (includeSD
+                                && ((a.Item.Width > 0 && a.Item.Width < HDWidth) || versionsSd.Contains(a.ItemId))
+                                && !versionsHd.Contains(a.ItemId)
+                                && !versions4K.Contains(a.ItemId))
+                            || (includeHD
+                                && (a.Item.Width >= HDWidth || versionsHd.Contains(a.ItemId))
+                                && !(a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight)
+                                && !versions4K.Contains(a.ItemId))
+                            || (include4K
+                                && (a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight || versions4K.Contains(a.ItemId))))
                         || context.LinkedChildren.Any(lc =>
                             lc.ParentId == e.Id
-                            && lc.Child!.Width > 0
-                            && ((includeSD && lc.Child.Width < HDWidth)
-                                || (includeHD && lc.Child.Width >= HDWidth && !(lc.Child.Width >= UHDWidth || lc.Child.Height >= UHDHeight))
-                                || (include4K && (lc.Child.Width >= UHDWidth || lc.Child.Height >= UHDHeight)))))));
+                            && ((includeSD
+                                    && ((lc.Child!.Width > 0 && lc.Child!.Width < HDWidth) || versionsSd.Contains(lc.ChildId))
+                                    && !versionsHd.Contains(lc.ChildId)
+                                    && !versions4K.Contains(lc.ChildId))
+                                || (includeHD
+                                    && (lc.Child!.Width >= HDWidth || versionsHd.Contains(lc.ChildId))
+                                    && !(lc.Child!.Width >= UHDWidth || lc.Child!.Height >= UHDHeight)
+                                    && !versions4K.Contains(lc.ChildId))
+                                || (include4K
+                                    && (lc.Child!.Width >= UHDWidth || lc.Child!.Height >= UHDHeight || versions4K.Contains(lc.ChildId))))))));
         }
 
+        // Same reasoning as the resolution filter: a dimension bound is met if any version meets it.
         if (minWidth.HasValue)
         {
-            baseQuery = baseQuery.Where(e => e.Width >= minWidth);
+            var versionsWideEnough = VersionsMatchingDimension(context, v => v.Width >= minWidth);
+            baseQuery = baseQuery.Where(e => e.Width >= minWidth || versionsWideEnough.Contains(e.Id));
         }
 
         if (filter.MinHeight.HasValue)
         {
-            baseQuery = baseQuery.Where(e => e.Height >= filter.MinHeight);
+            var minHeight = filter.MinHeight;
+            var versionsTallEnough = VersionsMatchingDimension(context, v => v.Height >= minHeight);
+            baseQuery = baseQuery.Where(e => e.Height >= minHeight || versionsTallEnough.Contains(e.Id));
         }
 
+        // An upper bound inverts that: it is met only if no version breaches it, since the item's
+        // resolution is the best its version group offers.
         if (maxWidth.HasValue)
         {
-            baseQuery = baseQuery.Where(e => e.Width <= maxWidth);
+            var versionsTooWide = VersionsMatchingDimension(context, v => v.Width > maxWidth);
+            baseQuery = baseQuery.Where(e => e.Width <= maxWidth && !versionsTooWide.Contains(e.Id));
         }
 
         if (filter.MaxHeight.HasValue)
         {
-            baseQuery = baseQuery.Where(e => e.Height <= filter.MaxHeight);
+            var maxHeight = filter.MaxHeight;
+            var versionsTooTall = VersionsMatchingDimension(context, v => v.Height > maxHeight);
+            baseQuery = baseQuery.Where(e => e.Height <= maxHeight && !versionsTooTall.Contains(e.Id));
         }
 
         if (filter.IsLocked.HasValue)
@@ -472,22 +544,7 @@ public sealed partial class BaseItemRepository
 
         if (filter.IsPlayed.HasValue)
         {
-            var userId = filter.User!.Id;
-
-            // Leaf items carry their own played state.
-            var playedItemIds = context.UserData
-                .Where(ud => ud.UserId == userId && ud.Played)
-                .Select(ud => ud.ItemId);
-
-            // Folders (Series, Seasons, BoxSets, albums, ...) have none and count as played once no
-            // descendant is left unplayed, matching what the DTO reports for them. This has to key off
-            // the item itself rather than off the requested item types: tag and collection listings mix
-            // folders and leaf items in a single query.
-            var unplayedLeafItems = GetAccessFilteredLeafItemsQuery(context, filter.User!)
-                .Where(e => !e.UserData!.Any(ud => ud.UserId == userId && ud.Played));
-
-            var isPlayedFilter = IsFolderFilter.And(BuildHasDescendantFilter(context, unplayedLeafItems).Not())
-                .Or(IsFolderFilter.Not().And(e => playedItemIds.Contains(e.Id)));
+            var isPlayedFilter = BuildIsPlayedFilter(context, filter.User!);
 
             baseQuery = baseQuery.Where(filter.IsPlayed.Value ? isPlayedFilter : isPlayedFilter.Not());
         }
@@ -761,104 +818,144 @@ public sealed partial class BaseItemRepository
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoAudioTrackWithLanguage))
         {
-            var lang = filter.HasNoAudioTrackWithLanguage;
-            var foldersWithAudio = DescendantQueryHelper.GetFolderIdsMatching(context, new HasMediaStreamType(MediaStreamTypeEntity.Audio, lang));
+            var lang = NormalizeLanguage(filter.HasNoAudioTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
+            var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Audio, lang);
+            // A track only an alternate version carries still belongs to the item a caller sees, so the
+            // item's own streams alone do not decide this. Same for every stream filter below.
+            var versionsWithAudio = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithAudio = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
 
             baseQuery = baseQuery
                 .Where(e =>
-                    (!e.IsFolder && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Audio && ms.Language == lang))
+                    (!e.IsFolder
+                        && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Audio
+                            && (ms.Language == lang || (undetermined && string.IsNullOrEmpty(ms.Language))))
+                        && !versionsWithAudio.Contains(e.Id))
                     || (e.IsFolder && !foldersWithAudio.Contains(e.Id)));
         }
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoInternalSubtitleTrackWithLanguage))
         {
-            var lang = filter.HasNoInternalSubtitleTrackWithLanguage;
-            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang, IsExternal: false));
+            var lang = NormalizeLanguage(filter.HasNoInternalSubtitleTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
+            var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang, IsExternal: false);
+            var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
 
             baseQuery = baseQuery
                 .Where(e =>
-                    (!e.IsFolder && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle && !ms.IsExternal && ms.Language == lang))
+                    (!e.IsFolder
+                        && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle && !ms.IsExternal
+                            && (ms.Language == lang || (undetermined && string.IsNullOrEmpty(ms.Language))))
+                        && !versionsWithSubtitles.Contains(e.Id))
                     || (e.IsFolder && !foldersWithSubtitles.Contains(e.Id)));
         }
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoExternalSubtitleTrackWithLanguage))
         {
-            var lang = filter.HasNoExternalSubtitleTrackWithLanguage;
-            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang, IsExternal: true));
+            var lang = NormalizeLanguage(filter.HasNoExternalSubtitleTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
+            var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang, IsExternal: true);
+            var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
 
             baseQuery = baseQuery
                 .Where(e =>
-                    (!e.IsFolder && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle && ms.IsExternal && ms.Language == lang))
+                    (!e.IsFolder
+                        && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle && ms.IsExternal
+                            && (ms.Language == lang || (undetermined && string.IsNullOrEmpty(ms.Language))))
+                        && !versionsWithSubtitles.Contains(e.Id))
                     || (e.IsFolder && !foldersWithSubtitles.Contains(e.Id)));
         }
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoSubtitleTrackWithLanguage))
         {
-            var lang = filter.HasNoSubtitleTrackWithLanguage;
-            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang));
+            var lang = NormalizeLanguage(filter.HasNoSubtitleTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
+            var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang);
+            var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
 
             baseQuery = baseQuery
                 .Where(e =>
-                    (!e.IsFolder && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle && ms.Language == lang))
+                    (!e.IsFolder
+                        && !e.MediaStreams!.Any(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle
+                            && (ms.Language == lang || (undetermined && string.IsNullOrEmpty(ms.Language))))
+                        && !versionsWithSubtitles.Contains(e.Id))
                     || (e.IsFolder && !foldersWithSubtitles.Contains(e.Id)));
         }
 
         if (filter.HasSubtitles.HasValue)
         {
             var hasSubtitles = filter.HasSubtitles.Value;
-            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, new HasSubtitles());
+            var criteria = new HasSubtitles();
+            var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
             if (hasSubtitles)
             {
                 baseQuery = baseQuery
                     .Where(e =>
-                        (!e.IsFolder && e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Subtitle))
+                        (!e.IsFolder && (e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Subtitle)
+                            || versionsWithSubtitles.Contains(e.Id)))
                         || (e.IsFolder && foldersWithSubtitles.Contains(e.Id)));
             }
             else
             {
                 baseQuery = baseQuery
                     .Where(e =>
-                        (!e.IsFolder && !e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Subtitle))
+                        (!e.IsFolder && !e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Subtitle)
+                            && !versionsWithSubtitles.Contains(e.Id))
                         || (e.IsFolder && !foldersWithSubtitles.Contains(e.Id)));
             }
         }
 
         if (filter.SubtitleLanguages.Count > 0)
         {
-            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, filter.SubtitleLanguages));
+            var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, filter.SubtitleLanguages);
+            var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
             baseQuery = baseQuery
                 .Where(e =>
-                    (!e.IsFolder && e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Subtitle
-                     && (filter.SubtitleLanguages.Contains(f.Language) || (filter.SubtitleLanguages.Contains("und") && string.IsNullOrEmpty(f.Language)))))
+                    (!e.IsFolder && (e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Subtitle
+                        && (filter.SubtitleLanguages.Contains(f.Language) || (filter.SubtitleLanguages.Contains("und") && string.IsNullOrEmpty(f.Language))))
+                        || versionsWithSubtitles.Contains(e.Id)))
                     || (e.IsFolder && foldersWithSubtitles.Contains(e.Id)));
         }
 
         if (filter.AudioLanguages.Count > 0)
         {
-            var foldersWithAudio = DescendantQueryHelper.GetFolderIdsMatching(context, new HasMediaStreamType(MediaStreamTypeEntity.Audio, filter.AudioLanguages));
+            var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Audio, filter.AudioLanguages);
+            var versionsWithAudio = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithAudio = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
             baseQuery = baseQuery
                 .Where(e =>
-                    (!e.IsFolder && e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Audio
-                     && (filter.AudioLanguages.Contains(f.Language) || (filter.AudioLanguages.Contains("und") && string.IsNullOrEmpty(f.Language)))))
+                    (!e.IsFolder && (e.MediaStreams!.Any(f => f.StreamType == MediaStreamTypeEntity.Audio
+                        && (filter.AudioLanguages.Contains(f.Language) || (filter.AudioLanguages.Contains("und") && string.IsNullOrEmpty(f.Language))))
+                        || versionsWithAudio.Contains(e.Id)))
                     || (e.IsFolder && foldersWithAudio.Contains(e.Id)));
         }
 
         if (filter.HasChapterImages.HasValue)
         {
             var hasChapterImages = filter.HasChapterImages.Value;
-            var foldersWithChapterImages = DescendantQueryHelper.GetFolderIdsMatching(context, new HasChapterImages());
+            var criteria = new HasChapterImages();
+            var versionsWithChapterImages = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
+            var foldersWithChapterImages = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
             if (hasChapterImages)
             {
                 baseQuery = baseQuery
                     .Where(e =>
-                        (!e.IsFolder && e.Chapters!.Any(f => f.ImagePath != null))
+                        (!e.IsFolder && (e.Chapters!.Any(f => f.ImagePath != null)
+                            || versionsWithChapterImages.Contains(e.Id)))
                         || (e.IsFolder && foldersWithChapterImages.Contains(e.Id)));
             }
             else
             {
                 baseQuery = baseQuery
                     .Where(e =>
-                        (!e.IsFolder && !e.Chapters!.Any(f => f.ImagePath != null))
+                        (!e.IsFolder && !e.Chapters!.Any(f => f.ImagePath != null)
+                            && !versionsWithChapterImages.Contains(e.Id))
                         || (e.IsFolder && !foldersWithChapterImages.Contains(e.Id)));
             }
         }

Jellyfin.Server.Implementations/Item/ItemCountService.cs

@@ -260,19 +260,21 @@ public class ItemCountService : IItemCountService
     /// <inheritdoc/>
     public int GetPlayedCount(InternalItemsQuery filter, Guid ancestorId)
     {
+        ArgumentNullException.ThrowIfNull(filter);
         ArgumentNullException.ThrowIfNull(filter.User);
         using var dbContext = _dbProvider.CreateDbContext();
 
-        var baseQuery = _queryHelpers.BuildAccessFilteredDescendantsQuery(dbContext, filter, ancestorId);
+        var baseQuery = BuildGroupedDescendantsQuery(dbContext, filter, ancestorId);
         return baseQuery.Count(b => b.UserData!.Any(u => u.UserId == filter.User.Id && u.Played));
     }
 
     /// <inheritdoc/>
     public int GetTotalCount(InternalItemsQuery filter, Guid ancestorId)
     {
+        ArgumentNullException.ThrowIfNull(filter);
         using var dbContext = _dbProvider.CreateDbContext();
 
-        var baseQuery = _queryHelpers.BuildAccessFilteredDescendantsQuery(dbContext, filter, ancestorId);
+        var baseQuery = BuildGroupedDescendantsQuery(dbContext, filter, ancestorId);
         return baseQuery.Count();
     }
 
@@ -283,10 +285,23 @@ public class ItemCountService : IItemCountService
         ArgumentNullException.ThrowIfNull(filter.User);
         using var dbContext = _dbProvider.CreateDbContext();
 
-        var baseQuery = _queryHelpers.BuildAccessFilteredDescendantsQuery(dbContext, filter, ancestorId);
+        var baseQuery = BuildGroupedDescendantsQuery(dbContext, filter, ancestorId);
         return GetPlayedAndTotalCountFromQuery(baseQuery, filter.User.Id);
     }
 
+    private IQueryable<BaseItemEntity> BuildGroupedDescendantsQuery(JellyfinDbContext dbContext, InternalItemsQuery filter, Guid ancestorId)
+    {
+        var ancestorIds = GetPresentationKeyGroups(dbContext, [ancestorId])[ancestorId];
+        var descendantIds = DescendantQueryHelper.GetAllDescendantIdsBatch(dbContext, ancestorIds).ToArray();
+
+        var baseQuery = dbContext.BaseItems
+            .AsNoTracking()
+            .WhereOneOrMany(descendantIds, b => b.Id)
+            .Where(DescendantQueryHelper.IsCountableLeaf);
+
+        return _queryHelpers.ApplyAccessFiltering(dbContext, baseQuery, filter);
+    }
+
     /// <inheritdoc/>
     public (int Played, int Total) GetPlayedAndTotalCountFromLinkedChildren(InternalItemsQuery filter, Guid parentId)
     {
@@ -294,9 +309,9 @@ public class ItemCountService : IItemCountService
         ArgumentNullException.ThrowIfNull(filter.User);
         using var dbContext = _dbProvider.CreateDbContext();
 
-        var allDescendantIds = DescendantQueryHelper.GetAllDescendantIds(dbContext, parentId);
+        var allDescendantIds = DescendantQueryHelper.GetAllDescendantIdsBatch(dbContext, [parentId]).ToArray();
         var baseQuery = dbContext.BaseItems
-            .Where(b => allDescendantIds.Contains(b.Id))
+            .WhereOneOrMany(allDescendantIds, b => b.Id)
             .Where(DescendantQueryHelper.IsCountableLeaf);
         baseQuery = _queryHelpers.ApplyAccessFiltering(dbContext, baseQuery, filter);
 
@@ -330,9 +345,17 @@ public class ItemCountService : IItemCountService
             .Select(g => new { ParentId = g.Key, Count = g.Count() })
             .ToDictionary(x => x.ParentId, x => x.Count);
 
+        var mergedChildCounts = GetMergedChildCounts(dbContext, parentIdsArray);
+
         var result = new Dictionary<Guid, int>();
         foreach (var parentId in parentIds)
         {
+            if (mergedChildCounts.TryGetValue(parentId, out var mergedCount))
+            {
+                result[parentId] = mergedCount;
+                continue;
+            }
+
             var hierarchicalCount = hierarchicalCounts.GetValueOrDefault(parentId, 0);
             var linkedCount = linkedCounts.GetValueOrDefault(parentId, 0);
 
@@ -342,6 +365,50 @@ public class ItemCountService : IItemCountService
         return result;
     }
 
+    private static Dictionary<Guid, int> GetMergedChildCounts(JellyfinDbContext dbContext, IReadOnlyList<Guid> parentIds)
+    {
+        var mergedGroups = GetPresentationKeyGroups(dbContext, parentIds)
+            .Where(group => group.Value.Count > 1)
+            .ToArray();
+
+        if (mergedGroups.Length == 0)
+        {
+            return [];
+        }
+
+        // Only merged folders.
+        var memberIds = mergedGroups.SelectMany(group => group.Value).Distinct().ToArray();
+        var children = dbContext.BaseItems
+            .AsNoTracking()
+            .Where(b => b.ParentId.HasValue)
+            .WhereOneOrMany(memberIds, b => b.ParentId!.Value)
+            .Select(b => new { ParentId = b.ParentId!.Value, b.Id, b.PresentationUniqueKey })
+            .ToArray()
+            .GroupBy(b => b.ParentId)
+            .ToDictionary(
+                g => g.Key,
+                g => g.Select(b => string.IsNullOrEmpty(b.PresentationUniqueKey)
+                    ? b.Id.ToString("N", CultureInfo.InvariantCulture)
+                    : b.PresentationUniqueKey).ToArray());
+
+        var result = new Dictionary<Guid, int>();
+        foreach (var (parentId, members) in mergedGroups)
+        {
+            var childKeys = new HashSet<string>(StringComparer.Ordinal);
+            foreach (var member in members)
+            {
+                if (children.TryGetValue(member, out var keys))
+                {
+                    childKeys.UnionWith(keys);
+                }
+            }
+
+            result[parentId] = childKeys.Count;
+        }
+
+        return result;
+    }
+
     /// <inheritdoc/>
     public Dictionary<Guid, (int Played, int Total)> GetPlayedAndTotalCountBatch(IReadOnlyList<Guid> folderIds, User user)
     {
@@ -354,10 +421,13 @@ public class ItemCountService : IItemCountService
         }
 
         using var dbContext = _dbProvider.CreateDbContext();
-        var folderIdsArray = folderIds.ToArray();
         var filter = new InternalItemsQuery(user);
         var userId = user.Id;
 
+        // Merged series and seasons are stored as one row per folder-item sharing a presentation key.
+        var groups = GetPresentationKeyGroups(dbContext, folderIds);
+        var folderIdsArray = groups.Values.SelectMany(members => members).Distinct().ToArray();
+
         var leafItems = dbContext.BaseItems
             .Where(DescendantQueryHelper.IsCountableLeaf);
         leafItems = _queryHelpers.ApplyAccessFiltering(dbContext, leafItems, filter);
@@ -399,7 +469,7 @@ public class ItemCountService : IItemCountService
                 b => b.Id,
                 (x, b) => new { FolderId = x.ParentId, b.Id, b.Played });
 
-        var results = ancestorLeaves
+        var countsByFolder = ancestorLeaves
             .Union(linkedLeaves)
             .Union(linkedFolderLeaves)
             .GroupBy(x => x.FolderId)
@@ -411,9 +481,73 @@ public class ItemCountService : IItemCountService
             })
             .ToDictionary(x => x.FolderId, x => (x.Played, x.Total));
 
+        var results = new Dictionary<Guid, (int Played, int Total)>();
+        foreach (var (folderId, members) in groups)
+        {
+            var played = 0;
+            var total = 0;
+
+            // Members of a group are distinct folders, so their leaves cannot overlap.
+            foreach (var member in members)
+            {
+                if (countsByFolder.TryGetValue(member, out var counts))
+                {
+                    played += counts.Played;
+                    total += counts.Total;
+                }
+            }
+
+            if (total > 0 || played > 0)
+            {
+                results[folderId] = (played, total);
+            }
+        }
+
         return results;
     }
 
+    private static Dictionary<Guid, List<Guid>> GetPresentationKeyGroups(JellyfinDbContext dbContext, IReadOnlyList<Guid> folderIds)
+    {
+        var requested = dbContext.BaseItems
+            .AsNoTracking()
+            .WhereOneOrMany(folderIds, e => e.Id)
+            .Select(e => new { e.Id, e.PresentationUniqueKey })
+            .ToArray();
+
+        var keys = requested
+            .Select(e => e.PresentationUniqueKey)
+            .Where(key => !string.IsNullOrEmpty(key))
+            .Distinct(StringComparer.Ordinal)
+            .ToArray();
+
+        // Every item that is not merged carries a key derived from its own id, so in the common case
+        // each group resolves back to the single folder that was asked for.
+        var membersByKey = keys.Length == 0
+            ? []
+            : dbContext.BaseItems
+                .AsNoTracking()
+                .Where(e => e.IsFolder)
+                .WhereOneOrMany(keys, e => e.PresentationUniqueKey!)
+                .Select(e => new { e.Id, Key = e.PresentationUniqueKey! })
+                .ToArray()
+                .GroupBy(e => e.Key, StringComparer.Ordinal)
+                .ToDictionary(g => g.Key, g => g.Select(e => e.Id).ToList(), StringComparer.Ordinal);
+
+        var keyById = requested.ToDictionary(e => e.Id, e => e.PresentationUniqueKey);
+        var groups = new Dictionary<Guid, List<Guid>>();
+        foreach (var folderId in folderIds)
+        {
+            groups[folderId] = keyById.TryGetValue(folderId, out var key)
+                && !string.IsNullOrEmpty(key)
+                && membersByKey.TryGetValue(key, out var members)
+                && members.Count > 0
+                    ? members
+                    : [folderId];
+        }
+
+        return groups;
+    }
+
     private static (int Played, int Total) GetPlayedAndTotalCountFromQuery(IQueryable<BaseItemEntity> query, Guid userId)
     {
         var result = query

Jellyfin.Server.Implementations/Item/PeopleRepository.cs

@@ -194,12 +194,44 @@ public class PeopleRepository(IDbContextFactory<JellyfinDbContext> dbProvider, I
             listOrder++;
         }
 
+        var droppedCredits = existingMaps.Select(e => e.PeopleId).Distinct().ToArray();
         context.PeopleBaseItemMap.RemoveRange(existingMaps);
 
+        context.SaveChanges();
+
+        // Nothing else ever deletes a credit row, so one left without a single mapping outlives the
+        // credit it stood for: it keeps a person of that name off the dead-person sweep, which only
+        // sees items no credit names, and keeps the name in every by-name list. That is how a credit
+        // a provider dropped, or one a broken provider result invented, becomes impossible to clean up.
+        DeleteCreditsWithoutMapping(context, droppedCredits);
+
         context.SaveChanges();
         transaction.Commit();
     }
 
+    /// <inheritdoc/>
+    public int DeleteOrphanedCredits()
+    {
+        using var context = _dbProvider.CreateDbContext();
+
+        return DeleteCreditsWithoutMapping(context, null);
+    }
+
+    // A null candidate list sweeps every credit, anything else only the ones just unmapped.
+    private int DeleteCreditsWithoutMapping(JellyfinDbContext context, IReadOnlyList<Guid>? candidates)
+    {
+        if (candidates is not null && candidates.Count == 0)
+        {
+            return 0;
+        }
+
+        var credits = candidates is null
+            ? context.Peoples.AsQueryable()
+            : context.Peoples.WhereOneOrMany(candidates, e => e.Id);
+
+        return credits.Where(e => !context.PeopleBaseItemMap.Any(f => f.PeopleId == e.Id)).ExecuteDelete();
+    }
+
     /// <inheritdoc/>
     public IReadOnlyDictionary<Guid, IReadOnlyList<string>> GetPeopleNamesByItems(IReadOnlyList<Guid> itemIds, IReadOnlyList<string> personTypes)
     {
@@ -351,7 +383,11 @@ public class PeopleRepository(IDbContextFactory<JellyfinDbContext> dbProvider, I
 
         if (!filter.ItemId.IsEmpty())
         {
-            query = query.Where(e => e.BaseItems!.Any(w => w.ItemId.Equals(filter.ItemId)));
+            var itemId = filter.ItemId;
+            query = query.Where(e => context.PeopleBaseItemMap
+                .Where(m => m.ItemId.Equals(itemId))
+                .Select(m => m.PeopleId)
+                .Contains(e.Id));
         }
 
         if (filter.ParentId != null)
@@ -361,7 +397,11 @@ public class PeopleRepository(IDbContextFactory<JellyfinDbContext> dbProvider, I
 
         if (!filter.AppearsInItemId.IsEmpty())
         {
-            query = query.Where(e => e.BaseItems!.Any(w => w.ItemId.Equals(filter.AppearsInItemId)));
+            var appearsInItemId = filter.AppearsInItemId;
+            query = query.Where(e => context.PeopleBaseItemMap
+                .Where(m => m.ItemId.Equals(appearsInItemId))
+                .Select(m => m.PeopleId)
+                .Contains(e.Id));
         }
 
         var queryPersonTypes = filter.PersonTypes.Where(IsValidPersonType).ToList();

Jellyfin.Server.Implementations/Users/UserManager.cs

@@ -225,19 +225,8 @@ namespace Jellyfin.Server.Implementations.Users
                         ?? throw new ResourceNotFoundException(nameof(user.Id));
 
                     dbContext.Entry(dbUser).CurrentValues.SetValues(user);
-                    dbContext.Permissions.RemoveRange(dbUser.Permissions);
-                    dbUser.Permissions.Clear();
-                    foreach (var permission in user.Permissions)
-                    {
-                        dbUser.Permissions.Add(new Permission(permission.Kind, permission.Value));
-                    }
-
-                    dbContext.Preferences.RemoveRange(dbUser.Preferences);
-                    dbUser.Preferences.Clear();
-                    foreach (var preference in user.Preferences)
-                    {
-                        dbUser.Preferences.Add(new Preference(preference.Kind, preference.Value));
-                    }
+                    SyncPermissions(dbUser, user.Permissions);
+                    SyncPreferences(dbUser, user.Preferences);
 
                     dbUser.AccessSchedules.Clear();
                     foreach (var accessSchedule in user.AccessSchedules)
@@ -271,6 +260,60 @@ namespace Jellyfin.Server.Implementations.Users
             }
         }
 
+        private static void SyncPermissions(User dbUser, ICollection<Permission> source)
+        {
+            var incoming = new Dictionary<PermissionKind, bool>();
+            foreach (var permission in source)
+            {
+                incoming[permission.Kind] = permission.Value;
+            }
+
+            foreach (var existing in dbUser.Permissions)
+            {
+                if (incoming.Remove(existing.Kind, out var value))
+                {
+                    // EF only marks the row modified if the value actually differs, so an update that
+                    // touches nothing but the user row - a session activity stamp - writes no children.
+                    existing.Value = value;
+                }
+                else
+                {
+                    dbUser.Permissions.Remove(existing);
+                }
+            }
+
+            foreach (var (kind, value) in incoming)
+            {
+                dbUser.Permissions.Add(new Permission(kind, value));
+            }
+        }
+
+        private static void SyncPreferences(User dbUser, ICollection<Preference> source)
+        {
+            var incoming = new Dictionary<PreferenceKind, string>();
+            foreach (var preference in source)
+            {
+                incoming[preference.Kind] = preference.Value;
+            }
+
+            foreach (var existing in dbUser.Preferences)
+            {
+                if (incoming.Remove(existing.Kind, out var value))
+                {
+                    existing.Value = value;
+                }
+                else
+                {
+                    dbUser.Preferences.Remove(existing);
+                }
+            }
+
+            foreach (var (kind, value) in incoming)
+            {
+                dbUser.Preferences.Add(new Preference(kind, value));
+            }
+        }
+
         internal async Task<User> CreateUserInternalAsync(string name, JellyfinDbContext dbContext)
         {
             // TODO: Remove after user item data is migrated.

Jellyfin.Server/Migrations/Routines/20260821120000_RecomputeSeriesPresentationKey.cs

@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
+using System.Globalization;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -15,9 +17,9 @@ using Microsoft.Extensions.Logging;
 namespace Jellyfin.Server.Migrations.Routines;
 
 /// <summary>
-/// Recomputes the presentation unique key for every series so existing items adopt the folder-set-free key format.
+/// Recomputes the presentation unique key of every series and season so merged series are scoped to their own library.
 /// </summary>
-[JellyfinMigration("2026-07-23T12:00:00", nameof(RecomputeSeriesPresentationKey))]
+[JellyfinMigration("2026-08-21T12:00:00", nameof(RecomputeSeriesPresentationKey))]
 [JellyfinMigrationBackup(JellyfinDb = true)]
 internal class RecomputeSeriesPresentationKey : IAsyncMigrationRoutine
 {
@@ -53,6 +55,7 @@ internal class RecomputeSeriesPresentationKey : IAsyncMigrationRoutine
 
         const int ProgressInterval = 250;
         var sw = Stopwatch.StartNew();
+        var newSeriesKeys = new Dictionary<Guid, string>();
         var processed = 0;
         var updated = 0;
 
@@ -68,9 +71,10 @@ internal class RecomputeSeriesPresentationKey : IAsyncMigrationRoutine
                     _logger.LogInformation("Processed {Processed}/{Total} series - Updated: {Updated} - Time: {Elapsed}", processed, series.Length, updated, sw.Elapsed);
                 }
 
-                var oldKey = item.PresentationUniqueKey;
                 var newKey = item.CreatePresentationUniqueKey();
-                if (string.Equals(oldKey, newKey, StringComparison.Ordinal))
+                newSeriesKeys[item.Id] = newKey;
+
+                if (string.Equals(item.PresentationUniqueKey, newKey, StringComparison.Ordinal))
                 {
                     continue;
                 }
@@ -82,21 +86,66 @@ internal class RecomputeSeriesPresentationKey : IAsyncMigrationRoutine
                     .ExecuteUpdateAsync(e => e.SetProperty(f => f.PresentationUniqueKey, newKey), cancellationToken)
                     .ConfigureAwait(false);
 
-                // Seasons and episodes cache the series key in SeriesPresentationUniqueKey and are matched
-                // to the series by it. Re-point every child still carrying the old key in a single set-based
-                // update so they stay attached without waiting for the next scan.
-                if (!string.IsNullOrEmpty(oldKey))
-                {
-                    await dbContext.BaseItems
-                        .Where(e => e.SeriesPresentationUniqueKey == oldKey)
-                        .ExecuteUpdateAsync(e => e.SetProperty(f => f.SeriesPresentationUniqueKey, newKey), cancellationToken)
-                        .ConfigureAwait(false);
-                }
+                // Seasons and episodes are matched to their series by SeriesPresentationUniqueKey, so
+                // re-point them here instead of waiting for the next scan. Scoped by SeriesId rather than
+                // by the old key: that key can be shared by every library holding the series, so matching
+                // on it would drag the other libraries' children along.
+                await dbContext.BaseItems
+                    .Where(e => e.SeriesId.HasValue && e.SeriesId.Value.Equals(id))
+                    .ExecuteUpdateAsync(e => e.SetProperty(f => f.SeriesPresentationUniqueKey, newKey), cancellationToken)
+                    .ConfigureAwait(false);
 
                 updated++;
             }
+
+            var updatedSeasons = await RecomputeSeasonsAsync(dbContext, newSeriesKeys, cancellationToken).ConfigureAwait(false);
+
+            _logger.LogInformation(
+                "Recomputed presentation unique key for {Updated} of {Count} series and {UpdatedSeasons} seasons in {Elapsed}",
+                updated,
+                series.Length,
+                updatedSeasons,
+                sw.Elapsed);
+        }
+    }
+
+    private async Task<int> RecomputeSeasonsAsync(JellyfinDbContext dbContext, Dictionary<Guid, string> newSeriesKeys, CancellationToken cancellationToken)
+    {
+        // A season's own key embeds its series' key, so it goes stale with it.
+        var seasons = _libraryManager.GetItemList(new InternalItemsQuery
+        {
+            IncludeItemTypes = [BaseItemKind.Season]
+        }).OfType<Season>().ToArray();
+
+        var updated = 0;
+
+        foreach (var season in seasons)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            // Without an index number the season keeps the base key, which carries no series key at all.
+            if (!season.IndexNumber.HasValue
+                || !newSeriesKeys.TryGetValue(season.SeriesId, out var seriesKey))
+            {
+                continue;
+            }
+
+            // Mirrors Season.CreatePresentationUniqueKey.
+            var newKey = seriesKey + "-" + season.IndexNumber.Value.ToString("000", CultureInfo.InvariantCulture);
+            if (string.Equals(season.PresentationUniqueKey, newKey, StringComparison.Ordinal))
+            {
+                continue;
+            }
+
+            var id = season.Id;
+            await dbContext.BaseItems
+                .Where(e => e.Id.Equals(id))
+                .ExecuteUpdateAsync(e => e.SetProperty(f => f.PresentationUniqueKey, newKey), cancellationToken)
+                .ConfigureAwait(false);
+
+            updated++;
         }
 
-        _logger.LogInformation("Recomputed presentation unique key for {Updated} of {Count} series in {Elapsed}", updated, series.Length, sw.Elapsed);
+        return updated;
     }
 }

Jellyfin.Server/Migrations/Routines/20260825200000_ConsolidateLocalizedUserViews.cs

@@ -0,0 +1,334 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Jellyfin.Data.Enums;
+using Jellyfin.Database.Implementations;
+using Jellyfin.Database.Implementations.Entities;
+using Jellyfin.Database.Implementations.Enums;
+using Jellyfin.Server.ServerSetupApp;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Model.IO;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.Server.Migrations.Routines;
+
+/// <summary>
+/// Moves the views whose id used to be derived from their localized name onto their name independent id.
+/// </summary>
+[JellyfinMigration("2026-08-25T20:00:00", nameof(ConsolidateLocalizedUserViews))]
+[JellyfinMigrationBackup(JellyfinDb = true)]
+internal class ConsolidateLocalizedUserViews : IAsyncMigrationRoutine
+{
+    private readonly IStartupLogger<ConsolidateLocalizedUserViews> _logger;
+    private readonly ILibraryManager _libraryManager;
+    private readonly IServerConfigurationManager _configurationManager;
+    private readonly IFileSystem _fileSystem;
+    private readonly IDbContextFactory<JellyfinDbContext> _dbProvider;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ConsolidateLocalizedUserViews"/> class.
+    /// </summary>
+    /// <param name="logger">The startup logger.</param>
+    /// <param name="libraryManager">The library manager.</param>
+    /// <param name="configurationManager">The server configuration manager.</param>
+    /// <param name="fileSystem">The file system.</param>
+    /// <param name="dbProvider">The database context factory.</param>
+    public ConsolidateLocalizedUserViews(
+        IStartupLogger<ConsolidateLocalizedUserViews> logger,
+        ILibraryManager libraryManager,
+        IServerConfigurationManager configurationManager,
+        IFileSystem fileSystem,
+        IDbContextFactory<JellyfinDbContext> dbProvider)
+    {
+        _logger = logger;
+        _libraryManager = libraryManager;
+        _configurationManager = configurationManager;
+        _fileSystem = fileSystem;
+        _dbProvider = dbProvider;
+    }
+
+    /// <inheritdoc />
+    public async Task PerformAsync(CancellationToken cancellationToken)
+    {
+        // The Live TV view is the one that hurts: every channel and program is parented to it, so a
+        // translation update or a change of UI culture used to leave them behind under a view nothing
+        // looks up any more.
+        var views = _libraryManager.GetItemList(new InternalItemsQuery
+        {
+            IncludeItemTypes = [BaseItemKind.UserView]
+        }).OfType<UserView>().Where(view => view.ViewType.HasValue).ToArray();
+
+        if (views.Length == 0)
+        {
+            return;
+        }
+
+        var dbContext = await _dbProvider.CreateDbContextAsync(cancellationToken).ConfigureAwait(false);
+        await using (dbContext.ConfigureAwait(false))
+        {
+            foreach (var group in views.GroupBy(view => view.ViewType!.Value))
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+
+                var viewType = group.Key;
+                var folderName = _fileSystem.GetValidFilename(viewType.ToString());
+                var path = Path.Combine(_configurationManager.ApplicationPaths.InternalMetadataPath, "views", folderName);
+
+                // Only the views created for a view type as a whole are named after it. The per user and
+                // per parent ones get a folder of their own, and carry no children to lose. Match on the
+                // folder rather than the whole path so a metadata directory that has since moved still
+                // lines up.
+                var candidates = group
+                    .Where(view => !string.IsNullOrEmpty(view.Path)
+                        && string.Equals(Path.GetFileName(view.Path.TrimEnd(Path.DirectorySeparatorChar)), folderName, StringComparison.OrdinalIgnoreCase))
+                    .ToArray();
+                if (candidates.Length == 0)
+                {
+                    continue;
+                }
+
+                // Mirrors LibraryManager.GetNamedView(name, viewType, sortName).
+                var canonicalId = _libraryManager.GetNewItemId(path + "_namedview_" + viewType.ToString(), typeof(UserView));
+
+                var stale = candidates.Where(view => !view.Id.Equals(canonicalId)).ToArray();
+                if (stale.Length == 0)
+                {
+                    continue;
+                }
+
+                await ConsolidateAsync(dbContext, viewType, path, canonicalId, candidates, stale, cancellationToken).ConfigureAwait(false);
+            }
+        }
+    }
+
+    private async Task ConsolidateAsync(
+        JellyfinDbContext dbContext,
+        CollectionType viewType,
+        string path,
+        Guid canonicalId,
+        IReadOnlyList<UserView> candidates,
+        IReadOnlyList<UserView> stale,
+        CancellationToken cancellationToken)
+    {
+        var staleIds = stale.Select(view => view.Id).ToArray();
+        Guid? newParentId = canonicalId;
+        var sourceId = Guid.Empty;
+
+        if (!candidates.Any(view => view.Id.Equals(canonicalId)))
+        {
+            // Whichever of the old views the items ended up under is the one worth keeping, so give the
+            // canonical id a copy of it.
+            var source = await PickSourceAsync(dbContext, stale, staleIds, cancellationToken).ConfigureAwait(false);
+            sourceId = source.Id;
+
+            _libraryManager.CreateItem(
+                new UserView
+                {
+                    Path = path,
+                    Id = canonicalId,
+                    DateCreated = source.DateCreated,
+                    DateModified = source.DateModified,
+                    Name = source.Name,
+                    ViewType = viewType,
+                    ForcedSortName = source.ForcedSortName
+                },
+                null);
+        }
+
+        var reparented = await dbContext.BaseItems
+            .Where(e => e.ParentId.HasValue)
+            .WhereOneOrMany(staleIds, e => e.ParentId!.Value)
+            .ExecuteUpdateAsync(e => e.SetProperty(f => f.ParentId, newParentId), cancellationToken)
+            .ConfigureAwait(false);
+
+        await dbContext.BaseItems
+            .Where(e => e.TopParentId.HasValue)
+            .WhereOneOrMany(staleIds, e => e.TopParentId!.Value)
+            .ExecuteUpdateAsync(e => e.SetProperty(f => f.TopParentId, newParentId), cancellationToken)
+            .ConfigureAwait(false);
+
+        await MoveAncestorsAsync(dbContext, canonicalId, staleIds, cancellationToken).ConfigureAwait(false);
+        await MoveUserSettingsAsync(dbContext, canonicalId, sourceId, staleIds, cancellationToken).ConfigureAwait(false);
+
+        // Nothing points at them any more, and BaseItems cascades on ParentId, so this has to come last.
+        await dbContext.BaseItems
+            .WhereOneOrMany(staleIds, e => e.Id)
+            .ExecuteDeleteAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        _logger.LogInformation(
+            "Moved {Reparented} items and dropped {Stale} stale {ViewType} views in favour of {CanonicalId}",
+            reparented,
+            staleIds.Length,
+            viewType,
+            canonicalId);
+    }
+
+    private async Task<UserView> PickSourceAsync(
+        JellyfinDbContext dbContext,
+        IReadOnlyList<UserView> stale,
+        IReadOnlyList<Guid> staleIds,
+        CancellationToken cancellationToken)
+    {
+        var childCounts = await dbContext.BaseItems
+            .Where(e => e.ParentId.HasValue)
+            .WhereOneOrMany(staleIds, e => e.ParentId!.Value)
+            .GroupBy(e => e.ParentId!.Value)
+            .Select(g => new { ParentId = g.Key, Count = g.Count() })
+            .ToDictionaryAsync(e => e.ParentId, e => e.Count, cancellationToken)
+            .ConfigureAwait(false);
+
+        return stale
+            .OrderByDescending(view => childCounts.GetValueOrDefault(view.Id))
+            .ThenBy(view => view.DateCreated)
+            .First();
+    }
+
+    private static async Task MoveUserSettingsAsync(
+        JellyfinDbContext dbContext,
+        Guid canonicalId,
+        Guid sourceId,
+        IReadOnlyList<Guid> staleIds,
+        CancellationToken cancellationToken)
+    {
+        // Everything below is keyed by the view's id, and a view holding no children still holds the
+        // ordering it was given and whether it was hidden. Only the view that was promoted can hand
+        // those over - the rest would collide on the one row per user, item and client - so the others
+        // are dropped instead.
+        var dropped = staleIds.Where(id => !id.Equals(sourceId)).ToArray();
+
+        if (!sourceId.Equals(Guid.Empty))
+        {
+            var moved = new[] { sourceId };
+
+            await dbContext.DisplayPreferences
+                .WhereOneOrMany(moved, e => e.ItemId)
+                .ExecuteUpdateAsync(e => e.SetProperty(f => f.ItemId, canonicalId), cancellationToken)
+                .ConfigureAwait(false);
+
+            await dbContext.ItemDisplayPreferences
+                .WhereOneOrMany(moved, e => e.ItemId)
+                .ExecuteUpdateAsync(e => e.SetProperty(f => f.ItemId, canonicalId), cancellationToken)
+                .ConfigureAwait(false);
+
+            await dbContext.CustomItemDisplayPreferences
+                .WhereOneOrMany(moved, e => e.ItemId)
+                .ExecuteUpdateAsync(e => e.SetProperty(f => f.ItemId, canonicalId), cancellationToken)
+                .ConfigureAwait(false);
+        }
+
+        if (dropped.Length > 0)
+        {
+            await dbContext.DisplayPreferences.WhereOneOrMany(dropped, e => e.ItemId).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
+            await dbContext.ItemDisplayPreferences.WhereOneOrMany(dropped, e => e.ItemId).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
+            await dbContext.CustomItemDisplayPreferences.WhereOneOrMany(dropped, e => e.ItemId).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
+        }
+
+        var stale = staleIds.ToHashSet();
+        var preferences = await dbContext.Preferences
+            .Where(e => e.Kind == PreferenceKind.OrderedViews || e.Kind == PreferenceKind.MyMediaExcludes)
+            .ToListAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        var changed = false;
+
+        foreach (var preference in preferences)
+        {
+            var values = preference.Value.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+            var rewritten = new List<string>(values.Length);
+            var seen = new HashSet<Guid>();
+            var touched = false;
+
+            foreach (var value in values)
+            {
+                // Clients write these in both the dashed and the plain form, so compare them parsed.
+                if (!Guid.TryParse(value, out var parsed))
+                {
+                    rewritten.Add(value);
+                    continue;
+                }
+
+                var isStale = stale.Contains(parsed);
+                if (isStale)
+                {
+                    parsed = canonicalId;
+                    touched = true;
+                }
+
+                // The same view can be listed twice once both of its ids point at the same place.
+                if (!seen.Add(parsed))
+                {
+                    continue;
+                }
+
+                rewritten.Add(isStale
+                    ? parsed.ToString(value.Contains('-', StringComparison.Ordinal) ? "D" : "N", CultureInfo.InvariantCulture)
+                    : value);
+            }
+
+            if (!touched)
+            {
+                continue;
+            }
+
+            preference.Value = string.Join(',', rewritten);
+            changed = true;
+        }
+
+        if (changed)
+        {
+            await dbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
+        }
+    }
+
+    private static async Task MoveAncestorsAsync(
+        JellyfinDbContext dbContext,
+        Guid canonicalId,
+        IReadOnlyList<Guid> staleIds,
+        CancellationToken cancellationToken)
+    {
+        var items = await dbContext.AncestorIds
+            .WhereOneOrMany(staleIds, e => e.ParentItemId)
+            .Select(e => e.ItemId)
+            .Distinct()
+            .ToListAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        await dbContext.AncestorIds
+            .WhereOneOrMany(staleIds, e => e.ParentItemId)
+            .ExecuteDeleteAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        if (items.Count == 0)
+        {
+            return;
+        }
+
+        // The pair is the primary key, so anything already recorded against the canonical view stays put.
+        var existing = await dbContext.AncestorIds
+            .Where(e => e.ParentItemId.Equals(canonicalId))
+            .Select(e => e.ItemId)
+            .ToListAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        foreach (var itemId in items.Except(existing))
+        {
+            dbContext.AncestorIds.Add(new AncestorId
+            {
+                ItemId = itemId,
+                ParentItemId = canonicalId,
+                Item = null!,
+                ParentItem = null!
+            });
+        }
+
+        await dbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
+    }
+}

MediaBrowser.Controller/Entities/Audio/MusicArtist.cs

@@ -173,10 +173,7 @@ namespace MediaBrowser.Controller.Entities.Audio
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.ArtistsPath, validName);
         }

MediaBrowser.Controller/Entities/Audio/MusicGenre.cs

@@ -80,10 +80,7 @@ namespace MediaBrowser.Controller.Entities.Audio
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.MusicGenrePath, validName);
         }

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -48,6 +48,10 @@ namespace MediaBrowser.Controller.Entities
 
         public const string ThemeSongFileName = "theme";
 
+        // Well below the 255 byte limit of the common Linux filesystems and the 255 character limit
+        // of Windows, so the files inside the folder still fit within MAX_PATH.
+        private const int MaxItemByNameFolderNameBytes = 128;
+
         /// <summary>
         /// The supported image extensions.
         /// </summary>
@@ -941,6 +945,43 @@ namespace MediaBrowser.Controller.Entities
             return GetSortName(Name, EnableAlphaNumericSorting, ConfigurationManager.Configuration);
         }
 
+        /// <summary>
+        /// Turns an item-by-name entity's name into a folder name every supported filesystem accepts.
+        /// </summary>
+        /// <param name="name">The entity's name.</param>
+        /// <returns>The folder name.</returns>
+        public static string GetItemByNameFolderName(string name)
+        {
+            // Trim the period at the end because windows will have a hard time with that
+            var validName = FileSystem.GetValidFilename(name).Trim().TrimEnd('.');
+
+            // Most Linux filesystems cap a path component at 255 bytes, so a name past that cannot be
+            // turned into a folder at all - and an entity with no folder can never be created, which
+            // leaves the credit behind it stuck: not refreshable, not deletable, retried on every scan.
+            // Only broken provider data gets this long, but it still has to resolve to something, so
+            // keep a readable prefix and let a hash of the whole name tell two of them apart.
+            if (Encoding.UTF8.GetByteCount(validName) <= MaxItemByNameFolderNameBytes)
+            {
+                return validName;
+            }
+
+            var suffix = "-" + validName.GetMD5().ToString("N", CultureInfo.InvariantCulture);
+            var budget = MaxItemByNameFolderNameBytes - suffix.Length;
+            var length = Math.Min(validName.Length, budget);
+            while (length > 0 && Encoding.UTF8.GetByteCount(validName.AsSpan(0, length)) > budget)
+            {
+                length--;
+            }
+
+            // Never cut a surrogate pair in half, the lone half is not a valid file name character.
+            if (length > 0 && char.IsHighSurrogate(validName[length - 1]))
+            {
+                length--;
+            }
+
+            return string.Concat(validName.AsSpan(0, length).TrimEnd().TrimEnd('.'), suffix);
+        }
+
         /// <summary>
         /// Cleans a raw name into its sortable form by applying the configured sort rules.
         /// </summary>

MediaBrowser.Controller/Entities/Genre.cs

@@ -83,10 +83,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.GenrePath, validName);
         }

MediaBrowser.Controller/Entities/Person.cs

@@ -98,10 +98,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validFilename = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validFilename = normalizeName ? GetItemByNameFolderName(name) : name;
 
             string subFolderPrefix = null;
 

MediaBrowser.Controller/Entities/Studio.cs

@@ -78,10 +78,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.StudioPath, validName);
         }

MediaBrowser.Controller/Entities/TV/Series.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Text.Json.Serialization;
 using System.Threading;
@@ -89,15 +90,14 @@ namespace MediaBrowser.Controller.Entities.TV
 
                 if (!string.IsNullOrEmpty(groupingKey))
                 {
-                    return AppendPreferredLanguage(groupingKey);
+                    return AddLibrariesToPresentationUniqueKey(groupingKey);
                 }
             }
 
             return base.CreatePresentationUniqueKey();
         }
 
-        // The owning libraries are deliberately NOT part of the key.
-        private string AppendPreferredLanguage(string key)
+        private string AddLibrariesToPresentationUniqueKey(string key)
         {
             var lang = GetPreferredMetadataLanguage();
             if (!string.IsNullOrEmpty(lang))
@@ -105,7 +105,17 @@ namespace MediaBrowser.Controller.Entities.TV
                 key += "-" + lang;
             }
 
-            return key;
+            var folders = LibraryManager.GetCollectionFolders(this)
+                .Select(i => i.Id.ToString("N", CultureInfo.InvariantCulture))
+                .Order(StringComparer.Ordinal)
+                .ToArray();
+
+            if (folders.Length == 0)
+            {
+                return key;
+            }
+
+            return key + "-" + string.Join('-', folders);
         }
 
         private string GetNameBasedGroupingKey()
@@ -125,20 +135,19 @@ namespace MediaBrowser.Controller.Entities.TV
         {
             var seriesKey = GetUniqueSeriesKey(this);
 
-            var result = LibraryManager.GetCount(new InternalItemsQuery(user)
+            var result = LibraryManager.GetItemIds(new InternalItemsQuery(user)
             {
                 AncestorWithPresentationUniqueKey = null,
                 SeriesPresentationUniqueKey = seriesKey,
                 IncludeItemTypes = new[] { BaseItemKind.Season },
                 IsVirtualItem = false,
-                Limit = 0,
                 DtoOptions = new DtoOptions(false)
                 {
                     EnableImages = false
                 }
             });
 
-            return result;
+            return result.Count;
         }
 
         public override int GetRecursiveChildCount(User user)

MediaBrowser.Controller/Entities/Year.cs

@@ -85,10 +85,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.YearPath, validName);
         }

MediaBrowser.Controller/Library/ILibraryManager.cs

@@ -605,6 +605,12 @@ namespace MediaBrowser.Controller.Library
         /// <returns>List&lt;System.String&gt;.</returns>
         IReadOnlyList<string> GetPeopleNames(InternalPeopleQuery query);
 
+        /// <summary>
+        /// Deletes every credit that no item maps to any more.
+        /// </summary>
+        /// <returns>The number of credits that were deleted.</returns>
+        int DeleteOrphanedCredits();
+
         /// <summary>
         /// Gets the distinct people names per item for multiple items.
         /// </summary>

MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

@@ -1318,7 +1318,7 @@ namespace MediaBrowser.Controller.MediaEncoding
                     arg.Append(canvasArgs);
                 }
 
-                arg.Append(" -i file:\"").Append(subtitlePath).Append('\"');
+                arg.Append(" -i file:\"").Append(subtitlePath.EscapeProcessArgument()).Append('\"');
             }
 
             if (state.AudioStream is not null && state.AudioStream.IsExternal)
@@ -1330,7 +1330,7 @@ namespace MediaBrowser.Controller.MediaEncoding
                     arg.Append(' ').Append(seekAudioParam);
                 }
 
-                arg.Append(" -i \"").Append(state.AudioStream.Path).Append('"');
+                arg.Append(" -i \"").Append(state.AudioStream.Path.EscapeProcessArgument()).Append('"');
             }
 
             // Disable auto inserted SW scaler for HW decoders in case of changed resolution.

MediaBrowser.Controller/Persistence/IPeopleRepository.cs

@@ -33,6 +33,12 @@ public interface IPeopleRepository
     /// <returns>The list of people names matching the filter.</returns>
     IReadOnlyList<string> GetPeopleNames(InternalPeopleQuery filter);
 
+    /// <summary>
+    /// Deletes every credit that no item maps to any more.
+    /// </summary>
+    /// <returns>The number of credits that were deleted.</returns>
+    int DeleteOrphanedCredits();
+
     /// <summary>
     /// Gets the distinct people names per item for multiple items efficiently by querying from the mapping table.
     /// </summary>

MediaBrowser.Controller/Providers/MetadataResult.cs

@@ -16,11 +16,6 @@ namespace MediaBrowser.Controller.Providers
         private List<(string Url, ImageType Type)> _remoteImages;
         private List<PersonInfo> _people;
 
-        public MetadataResult()
-        {
-            ResultLanguage = "en";
-        }
-
         public List<LocalImageInfo> Images
         {
             get => _images ??= [];
@@ -43,6 +38,9 @@ namespace MediaBrowser.Controller.Providers
 
         public T Item { get; set; }
 
+        /// <summary>
+        /// Gets or sets the language the fetched metadata is in.
+        /// </summary>
         public string ResultLanguage { get; set; }
 
         public string Provider { get; set; }

MediaBrowser.MediaEncoding/Attachments/AttachmentExtractor.cs

@@ -14,7 +14,6 @@ using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.IO;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.MediaEncoding;
-using MediaBrowser.MediaEncoding.Encoder;
 using MediaBrowser.Model.Dto;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.IO;
@@ -160,7 +159,7 @@ namespace MediaBrowser.MediaEncoding.Attachments
                         CultureInfo.InvariantCulture,
                         "-dump_attachment:{0} \"{1}\" ",
                         attachment.Index,
-                        EncodingUtils.NormalizePath(attachmentPath));
+                        attachmentPath.EscapeProcessArgument());
                     missingPaths.Add(attachmentPath);
                 }
 
@@ -425,7 +424,7 @@ namespace MediaBrowser.MediaEncoding.Attachments
                 "-dump_attachment:{1} \"{2}\" -i {0} {3}",
                 inputPath,
                 attachmentStreamIndex,
-                EncodingUtils.NormalizePath(outputPath),
+                outputPath.EscapeProcessArgument(),
                 hasVideoOrAudioStream ? "-t 0 -f null null" : string.Empty);
 
             int exitCode;

MediaBrowser.MediaEncoding/Encoder/EncodingUtils.cs

@@ -4,6 +4,7 @@ using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
+using Jellyfin.Extensions;
 using MediaBrowser.Model.MediaInfo;
 
 namespace MediaBrowser.MediaEncoding.Encoder
@@ -42,7 +43,7 @@ namespace MediaBrowser.MediaEncoding.Encoder
             // If there's more than one we'll need to use the concat command
             if (inputFiles.Count > 1)
             {
-                var files = string.Join('|', inputFiles.Select(NormalizePath));
+                var files = string.Join('|', inputFiles.Select(f => f.EscapeProcessArgument()));
 
                 return string.Format(CultureInfo.InvariantCulture, "concat:\"{0}\"", files);
             }
@@ -64,21 +65,9 @@ namespace MediaBrowser.MediaEncoding.Encoder
                 return string.Format(CultureInfo.InvariantCulture, "\"{0}\"", path);
             }
 
-            // Quotes are valid path characters in linux and they need to be escaped here with a leading \
-            path = NormalizePath(path);
+            path = path.EscapeProcessArgument();
 
             return string.Format(CultureInfo.InvariantCulture, "{1}:\"{0}\"", path, inputPrefix);
         }
-
-        /// <summary>
-        /// Normalizes the path.
-        /// </summary>
-        /// <param name="path">The path.</param>
-        /// <returns>System.String.</returns>
-        public static string NormalizePath(string path)
-        {
-            // Quotes are valid path characters in linux and they need to be escaped here with a leading \
-            return path.Replace("\"", "\\\"", StringComparison.Ordinal);
-        }
     }
 }

MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs

@@ -12,6 +12,7 @@ using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using AsyncKeyedLock;
+using Jellyfin.Extensions;
 using MediaBrowser.Common;
 using MediaBrowser.Common.Configuration;
 using MediaBrowser.Common.Extensions;
@@ -453,7 +454,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                 encodingParam = " -sub_charenc " + encodingParam;
             }
 
-            var args = string.Format(CultureInfo.InvariantCulture, "-y {0} -i \"{1}\" -c:s srt \"{2}\"", encodingParam, inputPath, outputPath);
+            var args = string.Format(CultureInfo.InvariantCulture, "-y {0} -i \"{1}\" -c:s srt \"{2}\"", encodingParam, inputPath.EscapeProcessArgument(), outputPath.EscapeProcessArgument());
 
             await ExtractSubtitlesForFile(
                 inputPath,
@@ -631,7 +632,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                         streamIndex,
                         outputCodec,
                         outputFormatOption,
-                        outputPath);
+                        outputPath.EscapeProcessArgument());
                 }
 
                 await ExtractSubtitlesForFile(inputPath, args, outputPaths, cancellationToken).ConfigureAwait(false);
@@ -689,7 +690,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                     streamIndex,
                     outputCodec,
                     outputFormatOption,
-                    outputPath);
+                    outputPath.EscapeProcessArgument());
             }
 
             if (outputPaths.Count > 0)

MediaBrowser.Model/Dlna/TranscodingProfile.cs

@@ -141,6 +141,7 @@ public class TranscodingProfile
     /// Gets or sets a value indicating whether breaking the video stream on non-keyframes is supported.
     /// </summary>
     [DefaultValue(false)]
+    [XmlIgnore]
     [XmlAttribute("breakOnNonKeyFrames")]
     [Obsolete("This is always false")]
     public bool? BreakOnNonKeyFrames { get; set; }

MediaBrowser.Model/Entities/ProviderIdsExtensions.cs

@@ -1,14 +1,16 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
 using System.Linq;
+using System.Text.RegularExpressions;
 
 namespace MediaBrowser.Model.Entities;
 
 /// <summary>
 /// Class ProviderIdsExtensions.
 /// </summary>
-public static class ProviderIdsExtensions
+public static partial class ProviderIdsExtensions
 {
     /// <summary>
     /// Case-insensitive dictionary of <see cref="MetadataProvider"/> string representation.
@@ -20,6 +22,27 @@ public static class ProviderIdsExtensions
                 enumValue => enumValue.ToString(),
                 StringComparer.OrdinalIgnoreCase);
 
+    /// <summary>
+    /// The known id formats, keyed by provider name.
+    /// </summary>
+    private static readonly Dictionary<string, Func<string, bool>> _providerIdValidators =
+        new(StringComparer.OrdinalIgnoreCase)
+        {
+            [MetadataProvider.Imdb.ToString()] = value => ImdbIdRegex().IsMatch(value),
+            [MetadataProvider.Tmdb.ToString()] = IsPositiveNumber,
+            [MetadataProvider.TmdbCollection.ToString()] = IsPositiveNumber,
+            [MetadataProvider.AudioDbArtist.ToString()] = IsPositiveNumber,
+            [MetadataProvider.AudioDbAlbum.ToString()] = IsPositiveNumber,
+
+            // Every MusicBrainz id is an MBID.
+            [MetadataProvider.MusicBrainzAlbum.ToString()] = IsGuid,
+            [MetadataProvider.MusicBrainzAlbumArtist.ToString()] = IsGuid,
+            [MetadataProvider.MusicBrainzArtist.ToString()] = IsGuid,
+            [MetadataProvider.MusicBrainzReleaseGroup.ToString()] = IsGuid,
+            [MetadataProvider.MusicBrainzRecording.ToString()] = IsGuid,
+            [MetadataProvider.MusicBrainzTrack.ToString()] = IsGuid
+        };
+
     /// <summary>
     /// Checks if this instance has an id for the given provider.
     /// </summary>
@@ -101,6 +124,26 @@ public static class ProviderIdsExtensions
         return instance.GetProviderId(provider.ToString());
     }
 
+    /// <summary>
+    /// Checks whether a value can be an id of the given provider.
+    /// </summary>
+    /// <param name="name">The provider name.</param>
+    /// <param name="value">The provider id.</param>
+    /// <returns><c>true</c> if the value has a plausible format for the provider; otherwise, <c>false</c>.</returns>
+    /// <remarks>
+    /// Providers regularly hand out an id belonging to a different service, e.g. an IMDb person id in the
+    /// TMDb field. Such an id is not just useless, it also makes the owning provider fail for the item.
+    /// </remarks>
+    public static bool IsValidProviderId(string? name, string? value)
+    {
+        if (string.IsNullOrWhiteSpace(name) || string.IsNullOrWhiteSpace(value))
+        {
+            return false;
+        }
+
+        return !_providerIdValidators.TryGetValue(name, out var isValid) || isValid(value);
+    }
+
     /// <summary>
     /// Sets a provider id.
     /// </summary>
@@ -121,6 +164,14 @@ public static class ProviderIdsExtensions
             return false;
         }
 
+        name = name.Trim();
+        value = value.Trim();
+
+        if (!IsValidProviderId(name, value))
+        {
+            return false;
+        }
+
         // Ensure it exists
         instance.ProviderIds ??= new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
 
@@ -153,7 +204,6 @@ public static class ProviderIdsExtensions
     /// <param name="instance">The instance.</param>
     /// <param name="name">The name, this should not contain a '=' character.</param>
     /// <param name="value">The value.</param>
-    /// <remarks>Due to how deserialization from the database works the name cannot contain '='.</remarks>
     public static void SetProviderId(this IHasProviderIds instance, string name, string value)
     {
         ArgumentNullException.ThrowIfNull(instance);
@@ -166,17 +216,27 @@ public static class ProviderIdsExtensions
             throw new ArgumentException("Provider id name cannot contain '='", nameof(name));
         }
 
-        // Ensure it exists
-        instance.ProviderIds ??= new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        instance.TrySetProviderId(name, value);
+    }
 
-        // Match on internal MetadataProvider enum string values before adding arbitrary providers
-        if (_metadataProviderEnumDictionary.TryGetValue(name, out var enumValue))
+    /// <summary>
+    /// Replaces all provider ids, dropping the ones that cannot belong to the provider they are filed under.
+    /// </summary>
+    /// <param name="instance">The instance.</param>
+    /// <param name="providerIds">The provider ids to set.</param>
+    public static void SetProviderIds(this IHasProviderIds instance, IReadOnlyDictionary<string, string>? providerIds)
+    {
+        ArgumentNullException.ThrowIfNull(instance);
+
+        instance.ProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        if (providerIds is null)
         {
-            instance.ProviderIds[enumValue] = value;
+            return;
         }
-        else
+
+        foreach (var (name, value) in providerIds)
         {
-            instance.ProviderIds[name] = value;
+            instance.TrySetProviderId(name, value);
         }
     }
 
@@ -213,4 +273,15 @@ public static class ProviderIdsExtensions
 
         instance.ProviderIds?.Remove(provider.ToString());
     }
+
+    private static bool IsPositiveNumber(string value)
+        => int.TryParse(value, NumberStyles.None, CultureInfo.InvariantCulture, out var id) && id > 0;
+
+    private static bool IsGuid(string value)
+        => Guid.TryParse(value, CultureInfo.InvariantCulture, out _);
+
+    // An IMDb id is a type prefix (tt for titles, nm for people, co for companies, ...) followed by
+    // digits. The prefix is optional because a bare number has always been accepted for a title.
+    [GeneratedRegex(@"^(tt|nm|co|ev|ch|ni)?[0-9]+$", RegexOptions.IgnoreCase)]
+    private static partial Regex ImdbIdRegex();
 }

MediaBrowser.Providers/Books/ComicBookInfo/ComicBookInfoProvider.cs

@@ -204,7 +204,7 @@ public class ComicBookInfoProvider : IComicProvider
     {
         try
         {
-            return CultureInfo.GetCultureInfo(language).DisplayName;
+            return CultureInfo.GetCultureInfo(language).TwoLetterISOLanguageName;
         }
         catch (CultureNotFoundException)
         {

MediaBrowser.Providers/Books/ComicInfo/ExternalComicInfoProvider.cs

@@ -52,7 +52,7 @@ public class ExternalComicInfoProvider : IComicProvider
         var metadataResult = new MetadataResult<Book> { Item = book, HasMetadata = true };
 
         ComicInfoReader.ReadPeopleMetadata(comicInfoXml, metadataResult);
-        ComicInfoReader.ReadCultureInfoInto(comicInfoXml, "ComicInfo/LanguageISO", cultureInfo => metadataResult.ResultLanguage = cultureInfo.ThreeLetterISOLanguageName);
+        ComicInfoReader.ReadCultureInfoInto(comicInfoXml, "ComicInfo/LanguageISO", cultureInfo => metadataResult.ResultLanguage = cultureInfo.TwoLetterISOLanguageName);
 
         return metadataResult;
     }

MediaBrowser.Providers/Books/ComicInfo/InternalComicInfoProvider.cs

@@ -50,7 +50,7 @@ public class InternalComicInfoProvider : IComicProvider
         var metadataResult = new MetadataResult<Book> { Item = book, HasMetadata = true };
 
         ComicInfoReader.ReadPeopleMetadata(comicInfoXml, metadataResult);
-        ComicInfoReader.ReadCultureInfoInto(comicInfoXml, "ComicInfo/LanguageISO", cultureInfo => metadataResult.ResultLanguage = cultureInfo.ThreeLetterISOLanguageName);
+        ComicInfoReader.ReadCultureInfoInto(comicInfoXml, "ComicInfo/LanguageISO", cultureInfo => metadataResult.ResultLanguage = cultureInfo.TwoLetterISOLanguageName);
 
         return metadataResult;
     }

MediaBrowser.Providers/Manager/MetadataLanguageUtils.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace MediaBrowser.Providers.Manager;
+
+/// <summary>
+/// Helpers for comparing the language of fetched metadata with the language that was requested.
+/// </summary>
+internal static class MetadataLanguageUtils
+{
+    /// <summary>
+    /// Gets the language subtag of a language tag, e.g. "es" for "es-ES".
+    /// </summary>
+    /// <param name="language">The language tag.</param>
+    /// <returns>The language subtag, lowercased, or <c>null</c> if none was given.</returns>
+    public static string? GetLanguageSubtag(string? language)
+    {
+        if (string.IsNullOrEmpty(language))
+        {
+            return null;
+        }
+
+        var separator = language.IndexOf('-', StringComparison.Ordinal);
+
+        return (separator == -1 ? language : language[..separator]).ToLowerInvariant();
+    }
+
+    /// <summary>
+    /// Determines whether a provider result can be considered to be in the requested language.
+    /// </summary>
+    /// <param name="resultLanguage">The language the provider reported for its result, if any.</param>
+    /// <param name="preferredLanguage">The language that was requested, if any.</param>
+    /// <returns><c>true</c> if the result is in the requested language or either language is unknown.</returns>
+    public static bool MatchesPreferredLanguage(string? resultLanguage, string? preferredLanguage)
+    {
+        // A provider that doesn't report a language cannot be judged, assume it honored the request
+        if (string.IsNullOrEmpty(resultLanguage) || string.IsNullOrEmpty(preferredLanguage))
+        {
+            return true;
+        }
+
+        // Compare on the language subtag only so that e.g. "es" matches "es-ES"
+        return string.Equals(GetLanguageSubtag(resultLanguage), GetLanguageSubtag(preferredLanguage), StringComparison.Ordinal);
+    }
+}

MediaBrowser.Providers/Manager/MetadataService.cs

@@ -209,22 +209,33 @@ namespace MediaBrowser.Providers.Manager
                 }
             }
 
-            if (hasRefreshedMetadata && hasRefreshedImages)
+            var attemptedFetch = refreshOptions.MetadataRefreshMode > MetadataRefreshMode.ValidationOnly
+                || refreshOptions.ImageRefreshMode > MetadataRefreshMode.ValidationOnly;
+
+            var refreshStampNeedsSaving = false;
+
+            if (hasRefreshedMetadata && hasRefreshedImages && attemptedFetch)
             {
                 item.DateLastRefreshed = DateTime.UtcNow;
                 updateType |= item.OnMetadataChanged();
+
+                // A full refresh queries every provider whether or not anything looks stale. When they all
+                // come back empty the stamp is the only thing that changed, and without it nothing records
+                // that the lookup happened, so the next pass repeats the same fruitless queries forever.
+                refreshStampNeedsSaving = refreshOptions.MetadataRefreshMode == MetadataRefreshMode.FullRefresh
+                    || refreshOptions.ImageRefreshMode == MetadataRefreshMode.FullRefresh;
             }
 
-            updateType = await SaveInternal(item, refreshOptions, updateType, isFirstRefresh, requiresRefresh, metadataResult, cancellationToken).ConfigureAwait(false);
+            updateType = await SaveInternal(item, refreshOptions, updateType, isFirstRefresh, requiresRefresh, refreshStampNeedsSaving, metadataResult, cancellationToken).ConfigureAwait(false);
 
             await AfterMetadataRefresh(itemOfType, refreshOptions, cancellationToken).ConfigureAwait(false);
 
             return updateType;
 
-            async Task<ItemUpdateType> SaveInternal(BaseItem item, MetadataRefreshOptions refreshOptions, ItemUpdateType updateType, bool isFirstRefresh, bool requiresRefresh, MetadataResult<TItemType> metadataResult, CancellationToken cancellationToken)
+            async Task<ItemUpdateType> SaveInternal(BaseItem item, MetadataRefreshOptions refreshOptions, ItemUpdateType updateType, bool isFirstRefresh, bool requiresRefresh, bool refreshStampNeedsSaving, MetadataResult<TItemType> metadataResult, CancellationToken cancellationToken)
             {
                 // Save if changes were made, or it's never been saved before
-                if (refreshOptions.ForceSave || updateType > ItemUpdateType.None || isFirstRefresh || refreshOptions.ReplaceAllMetadata || requiresRefresh)
+                if (refreshOptions.ForceSave || updateType > ItemUpdateType.None || isFirstRefresh || refreshOptions.ReplaceAllMetadata || requiresRefresh || refreshStampNeedsSaving)
                 {
                     if (item.IsFileProtocol)
                     {
@@ -260,21 +271,40 @@ namespace MediaBrowser.Providers.Manager
             switch (lookupInfo)
             {
                 case EpisodeInfo episodeInfo:
-                    episodeInfo.SeriesProviderIds = result.ProviderIds;
+                    episodeInfo.SeriesProviderIds = GetValidProviderIds(result.ProviderIds);
                     episodeInfo.ProviderIds.Clear();
                     break;
                 case SeasonInfo seasonInfo:
-                    seasonInfo.SeriesProviderIds = result.ProviderIds;
+                    seasonInfo.SeriesProviderIds = GetValidProviderIds(result.ProviderIds);
                     seasonInfo.ProviderIds.Clear();
                     break;
                 default:
-                    lookupInfo.ProviderIds = result.ProviderIds;
+                    lookupInfo.SetProviderIds(result.ProviderIds);
                     lookupInfo.Name = result.Name;
                     lookupInfo.Year = result.ProductionYear;
                     break;
             }
         }
 
+        private static Dictionary<string, string> GetValidProviderIds(IReadOnlyDictionary<string, string> providerIds)
+        {
+            var validProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            if (providerIds is null)
+            {
+                return validProviderIds;
+            }
+
+            foreach (var (name, value) in providerIds)
+            {
+                if (ProviderIdsExtensions.IsValidProviderId(name, value))
+                {
+                    validProviderIds[name] = value;
+                }
+            }
+
+            return validProviderIds;
+        }
+
         protected async Task SaveItemAsync(MetadataResult<TItemType> result, ItemUpdateType reason, bool reattachUserData, CancellationToken cancellationToken)
         {
             await result.Item.UpdateToRepositoryAsync(reason, cancellationToken).ConfigureAwait(false);
@@ -835,6 +865,7 @@ namespace MediaBrowser.Providers.Manager
                 }
             }
 
+            var hasRemoteMetadata = false;
             var isLocalLocked = temp.Item.IsLocked;
             if (!isLocalLocked && (options.ReplaceAllMetadata || options.MetadataRefreshMode > MetadataRefreshMode.ValidationOnly))
             {
@@ -849,6 +880,7 @@ namespace MediaBrowser.Providers.Manager
 
                 var remoteResult = await ExecuteRemoteProviders(temp, logName, false, id, remoteProviders, cancellationToken).ConfigureAwait(false);
 
+                hasRemoteMetadata = remoteResult.UpdateType.HasFlag(ItemUpdateType.MetadataDownload);
                 refreshResult.UpdateType |= remoteResult.UpdateType;
                 refreshResult.ErrorMessage = remoteResult.ErrorMessage;
                 refreshResult.Failures += remoteResult.Failures;
@@ -858,7 +890,12 @@ namespace MediaBrowser.Providers.Manager
             {
                 if (refreshResult.UpdateType > ItemUpdateType.None)
                 {
-                    if (!options.RemoveOldMetadata)
+                    // Erasing the old values is only safe when a remote provider returned something to
+                    // replace them with. If every one of them failed there is no replacement, and wiping the
+                    // item would turn a provider being temporarily unreachable into permanent data loss.
+                    // A single failure is not enough: Identify asks for the erasure precisely because the
+                    // previous match was wrong, and an unrelated provider throwing must not undo that.
+                    if (!options.RemoveOldMetadata || (refreshResult.Failures > 0 && !hasRemoteMetadata))
                     {
                         // Add existing metadata to provider result if it does not exist there
                         MergeData(metadata, temp, [], false, false);
@@ -913,6 +950,10 @@ namespace MediaBrowser.Providers.Manager
         private async Task<RefreshResult> ExecuteRemoteProviders(MetadataResult<TItemType> temp, string logName, bool replaceData, TIdType id, IEnumerable<IRemoteMetadataProvider<TItemType, TIdType>> providers, CancellationToken cancellationToken)
         {
             var refreshResult = new RefreshResult();
+            var preferredLanguage = id?.MetadataLanguage;
+
+            var overviewIsFallback = false;
+            var taglineIsFallback = false;
 
             if (id is not null)
             {
@@ -932,6 +973,28 @@ namespace MediaBrowser.Providers.Manager
                     {
                         result.Provider = provider.Name;
 
+                        if (MetadataLanguageUtils.MatchesPreferredLanguage(result.ResultLanguage, preferredLanguage))
+                        {
+                            if (overviewIsFallback && !string.IsNullOrEmpty(result.Item.Overview))
+                            {
+                                temp.Item.Overview = null;
+                                overviewIsFallback = false;
+                            }
+
+                            if (taglineIsFallback && !string.IsNullOrEmpty(result.Item.Tagline))
+                            {
+                                temp.Item.Tagline = null;
+                                taglineIsFallback = false;
+                            }
+                        }
+                        else
+                        {
+                            overviewIsFallback |= string.IsNullOrEmpty(temp.Item.Overview) && !string.IsNullOrEmpty(result.Item.Overview);
+                            taglineIsFallback |= string.IsNullOrEmpty(temp.Item.Tagline) && !string.IsNullOrEmpty(result.Item.Tagline);
+                        }
+
+                        LogInvalidProviderIds(result, providerName, logName);
+
                         MergeData(result, temp, [], replaceData, false);
                         MergeNewData(temp.Item, id);
 
@@ -957,6 +1020,58 @@ namespace MediaBrowser.Providers.Manager
             return refreshResult;
         }
 
+        /// <summary>
+        /// Reports the ids a provider returned that cannot belong to the provider they are filed under.
+        /// </summary>
+        /// <remarks>
+        /// The ids are dropped when merging, this names the provider that produced them so the source of a
+        /// recurring bad id can be found.
+        /// </remarks>
+        private void LogInvalidProviderIds(MetadataResult<TItemType> result, string providerName, string logName)
+        {
+            if (!Logger.IsEnabled(LogLevel.Debug))
+            {
+                return;
+            }
+
+            LogInvalidProviderIds(result.Item?.ProviderIds, providerName, logName, null);
+
+            if (result.People is null)
+            {
+                return;
+            }
+
+            foreach (var person in result.People)
+            {
+                LogInvalidProviderIds(person.ProviderIds, providerName, logName, person.Name);
+            }
+        }
+
+        private void LogInvalidProviderIds(IReadOnlyDictionary<string, string> providerIds, string providerName, string logName, string personName)
+        {
+            if (providerIds is null)
+            {
+                return;
+            }
+
+            foreach (var (key, value) in providerIds)
+            {
+                if (ProviderIdsExtensions.IsValidProviderId(key, value))
+                {
+                    continue;
+                }
+
+                if (personName is null)
+                {
+                    Logger.LogDebug("Discarding {Key} id '{Value}' returned by {Provider} for {Item}", key, value, providerName, logName);
+                }
+                else
+                {
+                    Logger.LogDebug("Discarding {Key} id '{Value}' returned by {Provider} for {Person} of {Item}", key, value, providerName, personName, logName);
+                }
+            }
+        }
+
         private void MergeNewData(TItemType source, TIdType lookupInfo)
         {
             // Copy new provider id's that may have been obtained
@@ -964,8 +1079,18 @@ namespace MediaBrowser.Providers.Manager
             {
                 var key = providerId.Key;
 
-                // Don't replace existing Id's.
-                lookupInfo.ProviderIds.TryAdd(key, providerId.Value);
+                if (!ProviderIdsExtensions.IsValidProviderId(key, providerId.Value))
+                {
+                    continue;
+                }
+
+                // Don't replace existing Id's, unless the one already there is unusable - handing that
+                // one to the providers that have yet to run is what makes them fail.
+                if (!lookupInfo.ProviderIds.TryGetValue(key, out var existingId)
+                    || !ProviderIdsExtensions.IsValidProviderId(key, existingId))
+                {
+                    lookupInfo.ProviderIds[key] = providerId.Value;
+                }
             }
         }
 
@@ -1104,6 +1229,9 @@ namespace MediaBrowser.Providers.Manager
 
             if (!lockedFields.Contains(MetadataField.Cast))
             {
+                RemoveInvalidProviderIds(sourceResult.People);
+                RemoveInvalidProviderIds(targetResult.People);
+
                 if (replaceData || targetResult.People is null || targetResult.People.Count == 0)
                 {
                     targetResult.People = sourceResult.People;
@@ -1175,15 +1303,31 @@ namespace MediaBrowser.Providers.Manager
             {
                 var key = id.Key;
 
-                // Don't replace existing Id's.
-                if (replaceData)
+                // An id that cannot belong to the provider it is filed under only breaks that provider on
+                // the next refresh, so never let one in - not even when replacing all metadata.
+                if (!ProviderIdsExtensions.IsValidProviderId(key, id.Value))
+                {
+                    continue;
+                }
+
+                // Don't replace existing Id's, unless the stored one is unusable - that one is the bad
+                // match the refresh is meant to repair.
+                if (replaceData
+                    || !target.ProviderIds.TryGetValue(key, out var existingId)
+                    || !ProviderIdsExtensions.IsValidProviderId(key, existingId))
                 {
                     target.ProviderIds[key] = id.Value;
                 }
-                else
-                {
-                    target.ProviderIds.TryAdd(key, id.Value);
-                }
+            }
+
+            // A bad id no provider offered a replacement for still has to go, otherwise the item keeps
+            // failing the same way on every refresh.
+            foreach (var key in target.ProviderIds
+                .Where(id => !ProviderIdsExtensions.IsValidProviderId(id.Key, id.Value))
+                .Select(id => id.Key)
+                .ToArray())
+            {
+                target.ProviderIds.Remove(key);
             }
 
             if (replaceData || !target.CriticRating.HasValue)
@@ -1251,6 +1395,32 @@ namespace MediaBrowser.Providers.Manager
             }
         }
 
+        private static void RemoveInvalidProviderIds(IReadOnlyList<PersonInfo> people)
+        {
+            if (people is null)
+            {
+                return;
+            }
+
+            foreach (var person in people)
+            {
+                if (person.ProviderIds is null || person.ProviderIds.Count == 0)
+                {
+                    continue;
+                }
+
+                var invalidKeys = person.ProviderIds
+                    .Where(id => !ProviderIdsExtensions.IsValidProviderId(id.Key, id.Value))
+                    .Select(id => id.Key)
+                    .ToArray();
+
+                foreach (var key in invalidKeys)
+                {
+                    person.ProviderIds.Remove(key);
+                }
+            }
+        }
+
         private static void MergePeople(IReadOnlyList<PersonInfo> source, IReadOnlyList<PersonInfo> target)
         {
             var sourceByName = source.ToLookup(p => p.Name.RemoveDiacritics(), StringComparer.OrdinalIgnoreCase);

MediaBrowser.Providers/Music/AlbumInfoExtensions.cs

@@ -23,11 +23,11 @@ namespace MediaBrowser.Providers.Music
 
         public static string? GetReleaseGroupId(this AlbumInfo info)
         {
-            var id = info.GetProviderId(MetadataProvider.MusicBrainzReleaseGroup);
+            var id = MusicBrainzId(MetadataProvider.MusicBrainzReleaseGroup, info.GetProviderId(MetadataProvider.MusicBrainzReleaseGroup));
 
             if (string.IsNullOrEmpty(id))
             {
-                return info.SongInfos.Select(i => i.GetProviderId(MetadataProvider.MusicBrainzReleaseGroup))
+                return info.SongInfos.Select(i => MusicBrainzId(MetadataProvider.MusicBrainzReleaseGroup, i.GetProviderId(MetadataProvider.MusicBrainzReleaseGroup)))
                     .FirstOrDefault(i => !string.IsNullOrEmpty(i));
             }
 
@@ -36,11 +36,11 @@ namespace MediaBrowser.Providers.Music
 
         public static string? GetReleaseId(this AlbumInfo info)
         {
-            var id = info.GetProviderId(MetadataProvider.MusicBrainzAlbum);
+            var id = MusicBrainzId(MetadataProvider.MusicBrainzAlbum, info.GetProviderId(MetadataProvider.MusicBrainzAlbum));
 
             if (string.IsNullOrEmpty(id))
             {
-                return info.SongInfos.Select(i => i.GetProviderId(MetadataProvider.MusicBrainzAlbum))
+                return info.SongInfos.Select(i => MusicBrainzId(MetadataProvider.MusicBrainzAlbum, i.GetProviderId(MetadataProvider.MusicBrainzAlbum)))
                     .FirstOrDefault(i => !string.IsNullOrEmpty(i));
             }
 
@@ -50,15 +50,17 @@ namespace MediaBrowser.Providers.Music
         public static string? GetMusicBrainzArtistId(this AlbumInfo info)
         {
             info.ProviderIds.TryGetValue(MetadataProvider.MusicBrainzAlbumArtist.ToString(), out string? id);
+            id = MusicBrainzId(MetadataProvider.MusicBrainzAlbumArtist, id);
 
             if (string.IsNullOrEmpty(id))
             {
                 info.ArtistProviderIds.TryGetValue(MetadataProvider.MusicBrainzArtist.ToString(), out id);
+                id = MusicBrainzId(MetadataProvider.MusicBrainzArtist, id);
             }
 
             if (string.IsNullOrEmpty(id))
             {
-                return info.SongInfos.Select(i => i.GetProviderId(MetadataProvider.MusicBrainzAlbumArtist))
+                return info.SongInfos.Select(i => MusicBrainzId(MetadataProvider.MusicBrainzAlbumArtist, i.GetProviderId(MetadataProvider.MusicBrainzAlbumArtist)))
                     .FirstOrDefault(i => !string.IsNullOrEmpty(i));
             }
 
@@ -68,14 +70,21 @@ namespace MediaBrowser.Providers.Music
         public static string? GetMusicBrainzArtistId(this ArtistInfo info)
         {
             info.ProviderIds.TryGetValue(MetadataProvider.MusicBrainzArtist.ToString(), out var id);
+            id = MusicBrainzId(MetadataProvider.MusicBrainzArtist, id);
 
             if (string.IsNullOrEmpty(id))
             {
-                return info.SongInfos.Select(i => i.GetProviderId(MetadataProvider.MusicBrainzAlbumArtist))
+                return info.SongInfos.Select(i => MusicBrainzId(MetadataProvider.MusicBrainzAlbumArtist, i.GetProviderId(MetadataProvider.MusicBrainzAlbumArtist)))
                     .FirstOrDefault(i => !string.IsNullOrEmpty(i));
             }
 
             return id;
         }
+
+        /// <summary>
+        /// Returns the id if it can be an id of the given provider, otherwise <c>null</c>.
+        /// </summary>
+        private static string? MusicBrainzId(MetadataProvider provider, string? id)
+            => ProviderIdsExtensions.IsValidProviderId(provider.ToString(), id) ? id : null;
     }
 }

MediaBrowser.Providers/Plugins/AudioDb/AudioDbAlbumProvider.cs

@@ -21,6 +21,7 @@ using MediaBrowser.Controller.Providers;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.IO;
 using MediaBrowser.Model.Providers;
+using MediaBrowser.Providers.Manager;
 using MediaBrowser.Providers.Music;
 
 namespace MediaBrowser.Providers.Plugins.AudioDb
@@ -77,7 +78,7 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
                     {
                         result.Item = new MusicAlbum();
                         result.HasMetadata = true;
-                        ProcessResult(result.Item, obj.album[0], info.MetadataLanguage);
+                        ProcessResult(result, obj.album[0], info.MetadataLanguage);
                     }
                 }
             }
@@ -85,8 +86,10 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             return result;
         }
 
-        private void ProcessResult(MusicAlbum item, Album result, string preferredLanguage)
+        private void ProcessResult(MetadataResult<MusicAlbum> metadataResult, Album result, string preferredLanguage)
         {
+            var item = metadataResult.Item;
+
             if (Plugin.Instance.Configuration.ReplaceAlbumName && !string.IsNullOrWhiteSpace(result.strAlbum))
             {
                 item.Album = result.strAlbum;
@@ -113,43 +116,48 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             item.SetProviderId(MetadataProvider.MusicBrainzAlbumArtist, result.strMusicBrainzArtistID);
             item.SetProviderId(MetadataProvider.MusicBrainzReleaseGroup, result.strMusicBrainzID);
 
-            string overview = null;
-
-            if (string.Equals(preferredLanguage, "de", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strDescriptionDE;
-            }
-            else if (string.Equals(preferredLanguage, "fr", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strDescriptionFR;
-            }
-            else if (string.Equals(preferredLanguage, "nl", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strDescriptionNL;
-            }
-            else if (string.Equals(preferredLanguage, "ru", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strDescriptionRU;
-            }
-            else if (string.Equals(preferredLanguage, "it", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strDescriptionIT;
-            }
-            else if ((preferredLanguage ?? string.Empty).StartsWith("pt", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strDescriptionPT;
-            }
+            var language = MetadataLanguageUtils.GetLanguageSubtag(preferredLanguage);
+            var overview = GetDescription(result, language);
 
             if (string.IsNullOrWhiteSpace(overview))
             {
                 overview = string.IsNullOrWhiteSpace(result.strDescriptionEN)
                     ? result.strDescription
                     : result.strDescriptionEN;
+
+                // The description is not in the requested language, mark it as English so it does not
+                // block a provider further down the list that can serve the requested language
+                metadataResult.ResultLanguage = "en";
+            }
+            else
+            {
+                metadataResult.ResultLanguage = language;
             }
 
             item.Overview = (overview ?? string.Empty).StripHtml();
         }
 
+        private static string GetDescription(Album result, string language)
+            => language switch
+            {
+                "de" => result.strDescriptionDE,
+                "en" => result.strDescriptionEN,
+                "es" => result.strDescriptionES,
+                "fr" => result.strDescriptionFR,
+                "he" => result.strDescriptionIL,
+                "hu" => result.strDescriptionHU,
+                "it" => result.strDescriptionIT,
+                "ja" => result.strDescriptionJP,
+                "nl" => result.strDescriptionNL,
+                "no" or "nb" or "nn" => result.strDescriptionNO,
+                "pl" => result.strDescriptionPL,
+                "pt" => result.strDescriptionPT,
+                "ru" => result.strDescriptionRU,
+                "sv" => result.strDescriptionSE,
+                "zh" => result.strDescriptionCN,
+                _ => null
+            };
+
         internal async Task EnsureInfo(string musicBrainzReleaseGroupId, CancellationToken cancellationToken)
         {
             var xmlPath = GetAlbumInfoPath(_config.ApplicationPaths, musicBrainzReleaseGroupId);

MediaBrowser.Providers/Plugins/AudioDb/AudioDbArtistProvider.cs

@@ -22,6 +22,7 @@ using MediaBrowser.Controller.Providers;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.IO;
 using MediaBrowser.Model.Providers;
+using MediaBrowser.Providers.Manager;
 using MediaBrowser.Providers.Music;
 
 namespace MediaBrowser.Providers.Plugins.AudioDb
@@ -148,7 +149,7 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             {
                 result.Item = new MusicArtist();
                 result.HasMetadata = true;
-                ProcessResult(result.Item, artist, info.MetadataLanguage);
+                ProcessResult(result, artist, info.MetadataLanguage);
             }
 
             return result;
@@ -193,8 +194,10 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             return null;
         }
 
-        private void ProcessResult(MusicArtist item, Artist result, string preferredLanguage)
+        private void ProcessResult(MetadataResult<MusicArtist> metadataResult, Artist result, string preferredLanguage)
         {
+            var item = metadataResult.Item;
+
             if (!string.IsNullOrWhiteSpace(result.strWebsite))
             {
                 item.HomePageUrl = result.strWebsite;
@@ -229,43 +232,48 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             item.SetProviderId(MetadataProvider.AudioDbArtist, result.idArtist);
             item.SetProviderId(MetadataProvider.MusicBrainzArtist, result.strMusicBrainzID);
 
-            string overview = null;
-
-            if (string.Equals(preferredLanguage, "de", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strBiographyDE;
-            }
-            else if (string.Equals(preferredLanguage, "fr", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strBiographyFR;
-            }
-            else if (string.Equals(preferredLanguage, "nl", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strBiographyNL;
-            }
-            else if (string.Equals(preferredLanguage, "ru", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strBiographyRU;
-            }
-            else if (string.Equals(preferredLanguage, "it", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strBiographyIT;
-            }
-            else if ((preferredLanguage ?? string.Empty).StartsWith("pt", StringComparison.OrdinalIgnoreCase))
-            {
-                overview = result.strBiographyPT;
-            }
+            var language = MetadataLanguageUtils.GetLanguageSubtag(preferredLanguage);
+            var overview = GetBiography(result, language);
 
             if (string.IsNullOrWhiteSpace(overview))
             {
                 overview = string.IsNullOrWhiteSpace(result.strBiographyEN)
                     ? result.strBiography
                     : result.strBiographyEN;
+
+                // The biography is not in the requested language, mark it as English so it does not
+                // block a provider further down the list that can serve the requested language
+                metadataResult.ResultLanguage = "en";
+            }
+            else
+            {
+                metadataResult.ResultLanguage = language;
             }
 
             item.Overview = (overview ?? string.Empty).StripHtml();
         }
 
+        private static string GetBiography(Artist result, string language)
+            => language switch
+            {
+                "de" => result.strBiographyDE,
+                "en" => result.strBiographyEN,
+                "es" => result.strBiographyES,
+                "fr" => result.strBiographyFR,
+                "he" => result.strBiographyIL,
+                "hu" => result.strBiographyHU,
+                "it" => result.strBiographyIT,
+                "ja" => result.strBiographyJP,
+                "nl" => result.strBiographyNL,
+                "no" or "nb" or "nn" => result.strBiographyNO,
+                "pl" => result.strBiographyPL,
+                "pt" => result.strBiographyPT,
+                "ru" => result.strBiographyRU,
+                "sv" => result.strBiographySE,
+                "zh" => result.strBiographyCN,
+                _ => null
+            };
+
         internal async Task EnsureArtistInfo(string musicBrainzId, CancellationToken cancellationToken)
         {
             var xmlPath = GetArtistInfoPath(_config.ApplicationPaths, musicBrainzId);

MediaBrowser.Providers/Plugins/Omdb/OmdbEpisodeProvider.cs

@@ -44,7 +44,9 @@ namespace MediaBrowser.Providers.Plugins.Omdb
             var result = new MetadataResult<Episode>
             {
                 Item = new Episode(),
-                QueriedById = true
+                QueriedById = true,
+                // OMDb is not localized, everything it returns is English
+                ResultLanguage = "en"
             };
 
             // Allowing this will dramatically increase scan times

MediaBrowser.Providers/Plugins/Omdb/OmdbItemProvider.cs

@@ -218,7 +218,9 @@ namespace MediaBrowser.Providers.Plugins.Omdb
             var result = new MetadataResult<T>
             {
                 Item = new T(),
-                QueriedById = true
+                QueriedById = true,
+                // OMDb is not localized, everything it returns is English
+                ResultLanguage = "en"
             };
 
             var imdbId = info.GetProviderId(MetadataProvider.Imdb);

MediaBrowser.Providers/Plugins/Omdb/OmdbProvider.cs

@@ -27,6 +27,9 @@ namespace MediaBrowser.Providers.Plugins.Omdb
     /// <summary>Provider for OMDB service.</summary>
     public class OmdbProvider
     {
+        /// <summary>Generational suffixes that OMDb separates from the name with a comma.</summary>
+        private static readonly string[] NameSuffixes = ["Jr", "Jnr", "Sr", "Snr", "II", "III", "IV", "V"];
+
         private readonly IFileSystem _fileSystem;
         private readonly IServerConfigurationManager _configurationManager;
         private readonly IHttpClientFactory _httpClientFactory;
@@ -420,42 +423,96 @@ namespace MediaBrowser.Providers.Plugins.Omdb
                 return;
             }
 
-            if (!string.IsNullOrWhiteSpace(result.Director))
-            {
-                var person = new PersonInfo
-                {
-                    Name = result.Director.Trim(),
-                    Type = PersonKind.Director
-                };
+            AddPeople(itemResult, result.Director, PersonKind.Director);
+            AddPeople(itemResult, result.Writer, PersonKind.Writer);
+            AddPeople(itemResult, result.Actors, PersonKind.Actor);
+        }
 
-                itemResult.AddPerson(person);
+        /// <summary>Adds the people from a comma separated OMDb credit list.</summary>
+        /// <typeparam name="T">The item type.</typeparam>
+        /// <param name="itemResult">The metadata result to add the people to.</param>
+        /// <param name="credits">The comma separated OMDb credit list.</param>
+        /// <param name="type">The kind of person each credit describes.</param>
+        internal static void AddPeople<T>(MetadataResult<T> itemResult, string credits, PersonKind type)
+            where T : BaseItem
+        {
+            if (string.IsNullOrWhiteSpace(credits))
+            {
+                return;
             }
 
-            if (!string.IsNullOrWhiteSpace(result.Writer))
-            {
-                var person = new PersonInfo
-                {
-                    Name = result.Writer.Trim(),
-                    Type = PersonKind.Writer
-                };
+            var names = new List<string>();
 
-                itemResult.AddPerson(person);
+            foreach (var credit in SplitCredits(credits))
+            {
+                // OMDb annotates the credited role in parentheses, e.g. "Mari Okada (screenplay)". The same
+                // person can be credited more than once this way, so strip it and let AddPerson deduplicate.
+                var name = credit;
+                var annotation = name.IndexOf('(', StringComparison.Ordinal);
+                if (annotation >= 0)
+                {
+                    name = name[..annotation];
+                }
+
+                name = name.Trim();
+                if (name.Length == 0)
+                {
+                    continue;
+                }
+
+                // A generational suffix is separated from the name it belongs to by the same comma the list
+                // uses, e.g. "Jack Salvatore, Jr.", so it has to be joined back instead of becoming a credit.
+                if (names.Count > 0 && IsNameSuffix(name))
+                {
+                    names[^1] = names[^1] + ", " + name;
+                    continue;
+                }
+
+                names.Add(name);
             }
 
-            if (!string.IsNullOrWhiteSpace(result.Actors))
+            foreach (var name in names)
             {
-                var actorList = result.Actors.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
-                foreach (var actor in actorList)
+                itemResult.AddPerson(new PersonInfo
                 {
-                    var person = new PersonInfo
-                    {
-                        Name = actor,
-                        Type = PersonKind.Actor
-                    };
+                    Name = name,
+                    Type = type
+                });
+            }
+        }
 
-                    itemResult.AddPerson(person);
+        // Only the commas between credits, never one inside an annotation: "Jerry Siegel (created by:
+        // Superman, Superboy)" is one credit, and splitting it blindly invents a person called "Superboy)".
+        private static IEnumerable<string> SplitCredits(string credits)
+        {
+            var depth = 0;
+            var start = 0;
+
+            for (var i = 0; i < credits.Length; i++)
+            {
+                switch (credits[i])
+                {
+                    case '(':
+                        depth++;
+                        break;
+                    case ')':
+                        depth = Math.Max(0, depth - 1);
+                        break;
+                    case ',' when depth == 0:
+                        yield return credits[start..i];
+                        start = i + 1;
+                        break;
                 }
             }
+
+            yield return credits[start..];
+        }
+
+        private static bool IsNameSuffix(string value)
+        {
+            var suffix = value.EndsWith('.') ? value[..^1] : value;
+
+            return NameSuffixes.Contains(suffix, StringComparer.OrdinalIgnoreCase);
         }
 
         private static bool IsConfiguredForEnglish(BaseItem item, string language)

MediaBrowser.Providers/Plugins/Tmdb/BoxSets/TmdbBoxSetImageProvider.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading;
@@ -56,7 +54,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
         /// <inheritdoc />
         public async Task<IEnumerable<RemoteImageInfo>> GetImages(BaseItem item, CancellationToken cancellationToken)
         {
-            var tmdbId = Convert.ToInt32(item.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            item.TryGetTmdbId(out var tmdbId);
 
             if (tmdbId <= 0)
             {

MediaBrowser.Providers/Plugins/Tmdb/BoxSets/TmdbBoxSetProvider.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
@@ -42,7 +41,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
         /// <inheritdoc />
         public async Task<IEnumerable<RemoteSearchResult>> GetSearchResults(BoxSetInfo searchInfo, CancellationToken cancellationToken)
         {
-            var tmdbId = Convert.ToInt32(searchInfo.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            searchInfo.TryGetTmdbId(out var tmdbId);
             var language = searchInfo.MetadataLanguage;
 
             if (tmdbId > 0)
@@ -97,7 +96,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
         /// <inheritdoc />
         public async Task<MetadataResult<BoxSet>> GetMetadata(BoxSetInfo info, CancellationToken cancellationToken)
         {
-            var tmdbId = Convert.ToInt32(info.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            info.TryGetTmdbId(out var tmdbId);
             var language = info.MetadataLanguage;
 
             // We don't already have an Id, need to fetch it
@@ -115,7 +114,10 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
                 }
             }
 
-            var result = new MetadataResult<BoxSet>();
+            var result = new MetadataResult<BoxSet>
+            {
+                ResultLanguage = language
+            };
 
             if (tmdbId > 0)
             {

MediaBrowser.Providers/Plugins/Tmdb/Movies/TmdbMovieImageProvider.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading;
@@ -61,7 +59,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
             var language = item.GetPreferredMetadataLanguage();
             var countryCode = item.GetPreferredMetadataCountryCode();
 
-            var movieTmdbId = Convert.ToInt32(item.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            item.TryGetTmdbId(out var movieTmdbId);
             if (movieTmdbId <= 0)
             {
                 var movieImdbId = item.GetProviderId(MetadataProvider.Imdb);

MediaBrowser.Providers/Plugins/Tmdb/Movies/TmdbMovieProvider.cs

@@ -54,11 +54,11 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
         /// <inheritdoc />
         public async Task<IEnumerable<RemoteSearchResult>> GetSearchResults(MovieInfo searchInfo, CancellationToken cancellationToken)
         {
-            if (searchInfo.TryGetProviderId(MetadataProvider.Tmdb, out var id))
+            if (searchInfo.TryGetTmdbId(out var tmdbId))
             {
                 var movie = await _tmdbClientManager
                     .GetMovieAsync(
-                        int.Parse(id, CultureInfo.InvariantCulture),
+                        tmdbId,
                         searchInfo.MetadataLanguage,
                         TmdbUtils.GetImageLanguagesParam(searchInfo.MetadataLanguage, searchInfo.MetadataCountryCode),
                         searchInfo.MetadataCountryCode,
@@ -90,7 +90,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
             }
 
             IReadOnlyList<SearchMovie>? movieResults = null;
-            if (searchInfo.TryGetProviderId(MetadataProvider.Imdb, out id))
+            if (searchInfo.TryGetProviderId(MetadataProvider.Imdb, out var id))
             {
                 var result = await _tmdbClientManager.FindByExternalIdAsync(
                     id,
@@ -151,11 +151,13 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
         /// <inheritdoc />
         public async Task<MetadataResult<Movie>> GetMetadata(MovieInfo info, CancellationToken cancellationToken)
         {
-            var tmdbId = info.GetProviderId(MetadataProvider.Tmdb);
+            // A stored id that is not a TMDb id is treated as no id, so the search below can repair it
+            // rather than the lookup failing for as long as the bad id stays on the item.
+            info.TryGetTmdbId(out var tmdbId);
             var imdbId = info.GetProviderId(MetadataProvider.Imdb);
             var config = Plugin.Instance.Configuration;
 
-            if (string.IsNullOrEmpty(tmdbId) && string.IsNullOrEmpty(imdbId))
+            if (tmdbId <= 0 && string.IsNullOrEmpty(imdbId))
             {
                 // ParseName is required here.
                 // Caller provides the filename with extension stripped and NOT the parsed filename
@@ -166,26 +168,26 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
 
                 if (searchResults?.Count > 0)
                 {
-                    tmdbId = searchResults[0].Id.ToString(CultureInfo.InvariantCulture);
+                    tmdbId = searchResults[0].Id;
                 }
             }
 
-            if (string.IsNullOrEmpty(tmdbId) && !string.IsNullOrEmpty(imdbId))
+            if (tmdbId <= 0 && !string.IsNullOrEmpty(imdbId))
             {
                 var movieResultFromImdbId = await _tmdbClientManager.FindByExternalIdAsync(imdbId, FindExternalSource.Imdb, info.MetadataLanguage, info.MetadataCountryCode, cancellationToken).ConfigureAwait(false);
                 if (movieResultFromImdbId?.MovieResults?.Count > 0)
                 {
-                    tmdbId = movieResultFromImdbId.MovieResults[0].Id.ToString(CultureInfo.InvariantCulture);
+                    tmdbId = movieResultFromImdbId.MovieResults[0].Id;
                 }
             }
 
-            if (string.IsNullOrEmpty(tmdbId))
+            if (tmdbId <= 0)
             {
                 return new MetadataResult<Movie>();
             }
 
             var movieResult = await _tmdbClientManager
-                .GetMovieAsync(Convert.ToInt32(tmdbId, CultureInfo.InvariantCulture), info.MetadataLanguage, TmdbUtils.GetImageLanguagesParam(info.MetadataLanguage, info.MetadataCountryCode), info.MetadataCountryCode, cancellationToken)
+                .GetMovieAsync(tmdbId, info.MetadataLanguage, TmdbUtils.GetImageLanguagesParam(info.MetadataLanguage, info.MetadataCountryCode), info.MetadataCountryCode, cancellationToken)
                 .ConfigureAwait(false);
 
             if (movieResult is null)
@@ -208,7 +210,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
                 Item = movie
             };
 
-            movie.SetProviderId(MetadataProvider.Tmdb, tmdbId);
+            movie.SetProviderId(MetadataProvider.Tmdb, tmdbId.ToString(CultureInfo.InvariantCulture));
             movie.TrySetProviderId(MetadataProvider.Imdb, movieResult.ImdbId);
             if (movieResult.BelongsToCollection is not null)
             {

MediaBrowser.Providers/Plugins/Tmdb/People/TmdbPersonImageProvider.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading;
@@ -54,14 +53,14 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
         {
             var person = (Person)item;
 
-            if (!person.TryGetProviderId(MetadataProvider.Tmdb, out var personTmdbId))
+            if (!person.TryGetTmdbId(out var personTmdbId))
             {
                 return Enumerable.Empty<RemoteImageInfo>();
             }
 
             var language = item.GetPreferredMetadataLanguage();
             var countryCode = item.GetPreferredMetadataCountryCode();
-            var personResult = await _tmdbClientManager.GetPersonAsync(int.Parse(personTmdbId, CultureInfo.InvariantCulture), language, countryCode, cancellationToken).ConfigureAwait(false);
+            var personResult = await _tmdbClientManager.GetPersonAsync(personTmdbId, language, countryCode, cancellationToken).ConfigureAwait(false);
             if (personResult?.Images?.Profiles is null)
             {
                 return Enumerable.Empty<RemoteImageInfo>();

MediaBrowser.Providers/Plugins/Tmdb/People/TmdbPersonProvider.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Net.Http;
@@ -37,9 +36,9 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
         /// <inheritdoc />
         public async Task<IEnumerable<RemoteSearchResult>> GetSearchResults(PersonLookupInfo searchInfo, CancellationToken cancellationToken)
         {
-            if (searchInfo.TryGetProviderId(MetadataProvider.Tmdb, out var personTmdbId))
+            if (searchInfo.TryGetTmdbId(out var personTmdbId))
             {
-                var personResult = await _tmdbClientManager.GetPersonAsync(int.Parse(personTmdbId, CultureInfo.InvariantCulture), searchInfo.MetadataLanguage, searchInfo.MetadataCountryCode, cancellationToken).ConfigureAwait(false);
+                var personResult = await _tmdbClientManager.GetPersonAsync(personTmdbId, searchInfo.MetadataLanguage, searchInfo.MetadataCountryCode, cancellationToken).ConfigureAwait(false);
 
                 if (personResult is not null)
                 {
@@ -89,7 +88,9 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
         /// <inheritdoc />
         public async Task<MetadataResult<Person>> GetMetadata(PersonLookupInfo info, CancellationToken cancellationToken)
         {
-            var personTmdbId = Convert.ToInt32(info.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            // A person can carry another provider's id under the TMDb key, which is no more usable here
+            // than no id at all, so both take the search path and get the stored id repaired.
+            info.TryGetTmdbId(out var personTmdbId);
 
             // We don't already have an Id, need to fetch it
             if (personTmdbId <= 0)
@@ -101,7 +102,10 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
                 }
             }
 
-            var result = new MetadataResult<Person>();
+            var result = new MetadataResult<Person>
+            {
+                ResultLanguage = info.MetadataLanguage
+            };
 
             if (personTmdbId > 0)
             {

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbEpisodeImageProvider.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading;
@@ -56,9 +54,9 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
             var episode = (Controller.Entities.TV.Episode)item;
             var series = episode.Series;
 
-            var seriesTmdbId = Convert.ToInt32(series?.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            var seriesTmdbId = 0;
 
-            if (series is null || seriesTmdbId <= 0)
+            if (series?.TryGetTmdbId(out seriesTmdbId) != true)
             {
                 return Enumerable.Empty<RemoteImageInfo>();
             }

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbEpisodeProvider.cs

@@ -91,8 +91,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
 
             info.SeriesProviderIds.TryGetValue(MetadataProvider.Tmdb.ToString(), out string? tmdbId);
 
-            var seriesTmdbId = Convert.ToInt32(tmdbId, CultureInfo.InvariantCulture);
-            if (seriesTmdbId <= 0)
+            if (!TmdbUtils.TryParseTmdbId(tmdbId, out var seriesTmdbId))
             {
                 return metadataResult;
             }

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbSeasonImageProvider.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading;
@@ -57,9 +55,9 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
             var season = (Season)item;
             var series = season?.Series;
 
-            var seriesTmdbId = Convert.ToInt32(series?.GetProviderId(MetadataProvider.Tmdb), CultureInfo.InvariantCulture);
+            var seriesTmdbId = 0;
 
-            if (seriesTmdbId <= 0 || season?.IndexNumber is null)
+            if (season?.IndexNumber is null || series?.TryGetTmdbId(out seriesTmdbId) != true)
             {
                 return Enumerable.Empty<RemoteImageInfo>();
             }

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbSeasonProvider.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
@@ -41,20 +40,23 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         /// <inheritdoc />
         public async Task<MetadataResult<Season>> GetMetadata(SeasonInfo info, CancellationToken cancellationToken)
         {
-            var result = new MetadataResult<Season>();
+            var result = new MetadataResult<Season>
+            {
+                ResultLanguage = info.MetadataLanguage
+            };
             var config = Plugin.Instance.Configuration;
 
             info.SeriesProviderIds.TryGetValue(MetadataProvider.Tmdb.ToString(), out string? seriesTmdbId);
 
             var seasonNumber = info.IndexNumber;
 
-            if (string.IsNullOrWhiteSpace(seriesTmdbId) || !seasonNumber.HasValue)
+            if (!seasonNumber.HasValue || !TmdbUtils.TryParseTmdbId(seriesTmdbId, out var seriesId))
             {
                 return result;
             }
 
             var seasonResult = await _tmdbClientManager
-                .GetSeasonAsync(Convert.ToInt32(seriesTmdbId, CultureInfo.InvariantCulture), seasonNumber.Value, info.MetadataLanguage, TmdbUtils.GetImageLanguagesParam(info.MetadataLanguage, info.MetadataCountryCode), info.MetadataCountryCode, cancellationToken)
+                .GetSeasonAsync(seriesId, seasonNumber.Value, info.MetadataLanguage, TmdbUtils.GetImageLanguagesParam(info.MetadataLanguage, info.MetadataCountryCode), info.MetadataCountryCode, cancellationToken)
                 .ConfigureAwait(false);
 
             if (seasonResult is null)

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbSeriesImageProvider.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading;
@@ -57,9 +55,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         /// <inheritdoc />
         public async Task<IEnumerable<RemoteImageInfo>> GetImages(BaseItem item, CancellationToken cancellationToken)
         {
-            var tmdbId = item.GetProviderId(MetadataProvider.Tmdb);
-
-            if (string.IsNullOrEmpty(tmdbId))
+            if (!item.TryGetTmdbId(out var tmdbId))
             {
                 return Enumerable.Empty<RemoteImageInfo>();
             }
@@ -68,7 +64,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
 
             // TODO use image languages if All Languages isn't toggled, but there's currently no way to get that value in here
             var series = await _tmdbClientManager
-                .GetSeriesAsync(Convert.ToInt32(tmdbId, CultureInfo.InvariantCulture), null, null, null, cancellationToken)
+                .GetSeriesAsync(tmdbId, null, null, null, cancellationToken)
                 .ConfigureAwait(false);
 
             if (series?.Images is null)

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbSeriesProvider.cs

@@ -54,10 +54,10 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         /// <inheritdoc />
         public async Task<IEnumerable<RemoteSearchResult>> GetSearchResults(SeriesInfo searchInfo, CancellationToken cancellationToken)
         {
-            if (searchInfo.TryGetProviderId(MetadataProvider.Tmdb, out var tmdbId))
+            if (searchInfo.TryGetTmdbId(out var tmdbId))
             {
                 var series = await _tmdbClientManager
-                    .GetSeriesAsync(Convert.ToInt32(tmdbId, CultureInfo.InvariantCulture), searchInfo.MetadataLanguage, searchInfo.MetadataLanguage, searchInfo.MetadataCountryCode, cancellationToken)
+                    .GetSeriesAsync(tmdbId, searchInfo.MetadataLanguage, searchInfo.MetadataLanguage, searchInfo.MetadataCountryCode, cancellationToken)
                     .ConfigureAwait(false);
 
                 if (series is not null)
@@ -363,39 +363,16 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         {
             var config = Plugin.Instance.Configuration;
 
-            if (seriesResult.Credits?.Cast is not null)
+            // The aggregated credits are what hold an actor's several characters apart; the flat ones
+            // put them in a single string. Only the aggregated list carries the whole run, so prefer it
+            // and fall back for the rare show TMDb has no aggregation for.
+            var cast = seriesResult.AggregateCredits?.Cast is { Count: > 0 } aggregated
+                ? TmdbUtils.MapAggregateCast(aggregated, config, _tmdbClientManager.GetProfileUrl)
+                : TmdbUtils.MapCast(seriesResult.Credits?.Cast, config, _tmdbClientManager.GetProfileUrl);
+
+            foreach (var actor in cast)
             {
-                IEnumerable<Cast> castQuery = seriesResult.Credits.Cast.OrderBy(a => a.Order);
-
-                if (config.HideMissingCastMembers)
-                {
-                    castQuery = castQuery.Where(a => !string.IsNullOrEmpty(a.ProfilePath));
-                }
-
-                foreach (var actor in castQuery.Take(config.MaxCastMembers))
-                {
-                    if (string.IsNullOrWhiteSpace(actor.Name))
-                    {
-                        continue;
-                    }
-
-                    var personInfo = new PersonInfo
-                    {
-                        Name = actor.Name.Trim(),
-                        Role = actor.Character?.Trim() ?? string.Empty,
-                        Type = PersonKind.Actor,
-                        SortOrder = actor.Order,
-                        // NOTE: Null values are filtered out above
-                        ImageUrl = _tmdbClientManager.GetProfileUrl(actor.ProfilePath!)
-                    };
-
-                    if (actor.Id > 0)
-                    {
-                        personInfo.SetProviderId(MetadataProvider.Tmdb, actor.Id.ToString(CultureInfo.InvariantCulture));
-                    }
-
-                    yield return personInfo;
-                }
+                yield return actor;
             }
 
             if (seriesResult.Credits?.Crew is not null)

MediaBrowser.Providers/Plugins/Tmdb/TmdbClientManager.cs

@@ -137,7 +137,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb
 
             await EnsureClientConfigAsync().ConfigureAwait(false);
 
-            var extraMethods = TvShowMethods.Credits | TvShowMethods.Images | TvShowMethods.ExternalIds | TvShowMethods.Videos | TvShowMethods.ContentRatings | TvShowMethods.EpisodeGroups;
+            var extraMethods = TvShowMethods.Credits | TvShowMethods.CreditsAggregate | TvShowMethods.Images | TvShowMethods.ExternalIds | TvShowMethods.Videos | TvShowMethods.ContentRatings | TvShowMethods.EpisodeGroups;
             if (!(Plugin.Instance?.Configuration.ExcludeTagsSeries).GetValueOrDefault())
             {
                 extraMethods |= TvShowMethods.Keywords;

MediaBrowser.Providers/Plugins/Tmdb/TmdbUtils.cs

@@ -2,10 +2,14 @@ using System;
 using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using System.Linq;
 using System.Text.RegularExpressions;
 using Jellyfin.Data.Enums;
 using MediaBrowser.Model.Entities;
 using TMDbLib.Objects.General;
+using TMDbLib.Objects.TvShows;
+using PersonInfo = MediaBrowser.Controller.Entities.PersonInfo;
 
 namespace MediaBrowser.Providers.Plugins.Tmdb
 {
@@ -62,6 +66,33 @@ namespace MediaBrowser.Providers.Plugins.Tmdb
         [GeneratedRegex(@"[\W_-[·]]+")]
         private static partial Regex NonWordRegex();
 
+        /// <summary>
+        /// Gets the TMDb id of an item, if it has one TMDb can be queried with.
+        /// </summary>
+        /// <param name="instance">The item.</param>
+        /// <param name="tmdbId">The TMDb id.</param>
+        /// <returns><c>true</c> if the item has a usable TMDb id; otherwise, <c>false</c>.</returns>
+        public static bool TryGetTmdbId(this IHasProviderIds instance, out int tmdbId)
+        {
+            instance.TryGetProviderId(MetadataProvider.Tmdb, out var value);
+
+            return TryParseTmdbId(value, out tmdbId);
+        }
+
+        /// <summary>
+        /// Parses a TMDb id.
+        /// </summary>
+        /// <param name="value">The stored id.</param>
+        /// <param name="tmdbId">The TMDb id.</param>
+        /// <returns><c>true</c> if the value is a usable TMDb id; otherwise, <c>false</c>.</returns>
+        public static bool TryParseTmdbId(string? value, out int tmdbId)
+        {
+            // Another provider can have filed one of its own ids under the TMDb key, e.g. an IMDb person
+            // id. Reporting that as "no id" lets the caller fall back to a search and repair the id,
+            // instead of throwing on every refresh of the item.
+            return int.TryParse(value, NumberStyles.None, CultureInfo.InvariantCulture, out tmdbId) && tmdbId > 0;
+        }
+
         /// <summary>
         /// Cleans the name according to TMDb requirements.
         /// </summary>
@@ -101,6 +132,100 @@ namespace MediaBrowser.Providers.Plugins.Tmdb
             return PersonKind.Unknown;
         }
 
+        /// <summary>
+        /// Maps an aggregated TMDb cast list, whose entries hold every role their member played.
+        /// </summary>
+        /// <param name="cast">The aggregated cast list, or <c>null</c>.</param>
+        /// <param name="config">The configuration deciding how much of the cast to keep.</param>
+        /// <param name="getProfileUrl">Resolves a profile path into an absolute image url.</param>
+        /// <returns>One credit per role played.</returns>
+        internal static IEnumerable<PersonInfo> MapAggregateCast(
+            IReadOnlyList<CastAggregate>? cast,
+            PluginConfiguration config,
+            Func<string?, string?> getProfileUrl)
+        {
+            if (cast is null)
+            {
+                yield break;
+            }
+
+            var billed = cast
+                .Where(member => !string.IsNullOrWhiteSpace(member.Name))
+                .Where(member => !config.HideMissingCastMembers || !string.IsNullOrEmpty(member.ProfilePath))
+                .OrderBy(member => member.Order)
+                .Take(config.MaxCastMembers);
+
+            foreach (var member in billed)
+            {
+                // An actor playing several characters over the run gets one aggregated entry holding
+                // every role, so each of them becomes a credit of its own here. Their own billing puts
+                // the character they played the longest first.
+                var characters = member.Roles?
+                    .Where(role => !string.IsNullOrWhiteSpace(role.Character))
+                    .OrderByDescending(role => role.EpisodeCount)
+                    .Select(role => role.Character!.Trim())
+                    .ToArray();
+
+                if (characters is null || characters.Length == 0)
+                {
+                    characters = [string.Empty];
+                }
+
+                foreach (var character in characters)
+                {
+                    yield return CreateCredit(member.Name!, member.Id, member.ProfilePath, member.Order, character, getProfileUrl);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Maps a TMDb cast list whose entries hold the one character their member is credited for.
+        /// </summary>
+        /// <param name="cast">The cast list, or <c>null</c>.</param>
+        /// <param name="config">The configuration deciding how much of the cast to keep.</param>
+        /// <param name="getProfileUrl">Resolves a profile path into an absolute image url.</param>
+        /// <returns>One credit per cast entry.</returns>
+        internal static IEnumerable<PersonInfo> MapCast(
+            IReadOnlyList<Cast>? cast,
+            PluginConfiguration config,
+            Func<string?, string?> getProfileUrl)
+        {
+            if (cast is null)
+            {
+                yield break;
+            }
+
+            var billed = cast
+                .Where(member => !string.IsNullOrWhiteSpace(member.Name))
+                .Where(member => !config.HideMissingCastMembers || !string.IsNullOrEmpty(member.ProfilePath))
+                .OrderBy(member => member.Order)
+                .Take(config.MaxCastMembers);
+
+            foreach (var member in billed)
+            {
+                yield return CreateCredit(member.Name!, member.Id, member.ProfilePath, member.Order, member.Character?.Trim() ?? string.Empty, getProfileUrl);
+            }
+        }
+
+        private static PersonInfo CreateCredit(string name, int id, string? profilePath, int? order, string role, Func<string?, string?> getProfileUrl)
+        {
+            var personInfo = new PersonInfo
+            {
+                Name = name.Trim(),
+                Role = role,
+                Type = PersonKind.Actor,
+                SortOrder = order,
+                ImageUrl = getProfileUrl(profilePath)
+            };
+
+            if (id > 0)
+            {
+                personInfo.SetProviderId(MetadataProvider.Tmdb, id.ToString(CultureInfo.InvariantCulture));
+            }
+
+            return personInfo;
+        }
+
         /// <summary>
         /// Determines whether a video is a trailer.
         /// </summary>

MediaBrowser.Providers/TV/SeriesMetadataService.cs

@@ -364,7 +364,7 @@ public class SeriesMetadataService : MetadataService<Series, SeriesInfo>
         foreach (var episode in episodes)
         {
             var season = seasons.FirstOrDefault(i => i.IndexNumber == episode.ParentIndexNumber);
-            if (season is null || episode.SeasonId.Equals(season.Id))
+            if (season is null || (episode.SeasonId.Equals(season.Id) && episode.ParentId.Equals(season.Id)))
             {
                 continue;
             }
@@ -372,6 +372,11 @@ public class SeriesMetadataService : MetadataService<Series, SeriesInfo>
             // Assign the correct season id and name to episode.
             episode.SeasonId = season.Id;
             episode.SeasonName = season.Name;
+
+            // We need to set ParentId here for episodes in virtual seasons (e.g., flat structures), otherwise it retains the
+            // ParentId from the series.
+            episode.SetParent(season);
+
             await episode.UpdateToRepositoryAsync(ItemUpdateType.MetadataImport, cancellationToken).ConfigureAwait(false);
         }
     }

src/Jellyfin.Database/Jellyfin.Database.Implementations/DescendantQueryHelper.cs

@@ -8,7 +8,7 @@ using Jellyfin.Database.Implementations.MatchCriteria;
 namespace Jellyfin.Database.Implementations;
 
 /// <summary>
-/// Provides methods for querying item hierarchies using iterative traversal.
+/// Provides methods for querying item hierarchies.
 /// Uses AncestorIds and LinkedChildren tables for parent-child traversal.
 /// </summary>
 public static class DescendantQueryHelper
@@ -32,11 +32,36 @@ public static class DescendantQueryHelper
     {
         ArgumentNullException.ThrowIfNull(context);
 
-        var descendants = TraverseHierarchyDown(context, [parentId]);
+        return AllDescendants(context, [parentId])
+            .Where(e => !e.Equals(parentId))
+            .Distinct();
+    }
 
-        descendants.Remove(parentId);
+    /// <summary>
+    /// Gets all descendant IDs for multiple parent items in a single traversal.
+    /// Traverses AncestorIds and LinkedChildren, like <see cref="GetAllDescendantIds"/>, but resolves
+    /// the roots once for all seeds instead of once per seed.
+    /// </summary>
+    /// <param name="context">Database context.</param>
+    /// <param name="parentIds">Parent item IDs.</param>
+    /// <returns>Set of all descendant item IDs (excluding the parent IDs themselves).</returns>
+    public static HashSet<Guid> GetAllDescendantIdsBatch(JellyfinDbContext context, IReadOnlyList<Guid> parentIds)
+    {
+        ArgumentNullException.ThrowIfNull(context);
+        ArgumentNullException.ThrowIfNull(parentIds);
 
-        return descendants.AsQueryable();
+        if (parentIds.Count == 0)
+        {
+            return [];
+        }
+
+        var descendants = AllDescendants(context, parentIds)
+            .Distinct()
+            .ToHashSet();
+
+        descendants.ExceptWith(parentIds);
+
+        return descendants;
     }
 
     /// <summary>
@@ -51,11 +76,9 @@ public static class DescendantQueryHelper
     {
         ArgumentNullException.ThrowIfNull(context);
 
-        var descendants = TraverseHierarchyDownOwned(context, [parentId]);
-
-        descendants.Remove(parentId);
-
-        return descendants.AsQueryable();
+        return ClosureDescendants(context, [parentId])
+            .Where(e => !e.Equals(parentId))
+            .Distinct();
     }
 
     /// <summary>
@@ -76,11 +99,11 @@ public static class DescendantQueryHelper
             return [];
         }
 
-        var seedSet = new HashSet<Guid>(parentIds);
-        var descendants = TraverseHierarchyDownOwned(context, seedSet);
+        var descendants = ClosureDescendants(context, parentIds)
+            .Distinct()
+            .ToHashSet();
 
-        // Remove the seed IDs — callers want only descendants
-        descendants.ExceptWith(seedSet);
+        descendants.ExceptWith(parentIds);
 
         return descendants;
     }
@@ -96,28 +119,106 @@ public static class DescendantQueryHelper
     {
         ArgumentNullException.ThrowIfNull(context);
         ArgumentNullException.ThrowIfNull(criteria);
-        var matchingItemIds = criteria switch
+
+        // Both sides of a version group can hold a folder a caller would see as matching: the
+        // alternate carries its own AncestorIds rows and may sit in a different library than the
+        // primary it is reported against, and the primary is the item that becomes visible.
+        var reportedItemIds = MatchingMediaOwnerIds(context, criteria)
+            .Concat(GetPrimaryVersionIdsMatching(context, criteria))
+            .Distinct();
+
+        // One hop up the closure covers every ancestor level.
+        var hierarchyAncestors = context.AncestorIds
+            .Where(e => reportedItemIds.Contains(e.ItemId))
+            .Select(e => e.ParentItemId);
+
+        var linkParents = ResolveLinkParents(context, reportedItemIds, hierarchyAncestors);
+
+        // Read back as a sub-select so the result stays composable. Off the primary key, which is one
+        // row per id: LinkedChildren would yield one row per link and lean on the outer Distinct.
+        var linkedParents = context.BaseItems
+            .WhereOneOrMany(linkParents, e => e.Id)
+            .Select(e => e.Id);
+
+        var linkedParentAncestors = context.AncestorIds
+            .WhereOneOrMany(linkParents, e => e.ItemId)
+            .Select(e => e.ParentItemId);
+
+        // The chain an item carries stops at its collection folders, so this hop crosses that seam to
+        // the UserRootFolder above them. One statement for both sides beats a sub-select per side.
+        var seamAncestors = context.AncestorIds
+            .Where(e => hierarchyAncestors.Contains(e.ItemId) || linkedParentAncestors.Contains(e.ItemId))
+            .Select(e => e.ParentItemId);
+
+        return hierarchyAncestors
+            .Concat(linkedParents)
+            .Concat(linkedParentAncestors)
+            .Concat(seamAncestors)
+            .Distinct();
+    }
+
+    /// <summary>
+    /// Gets a queryable of the IDs of the primary versions whose alternate version's media matches the
+    /// criteria.
+    /// </summary>
+    /// <param name="context">Database context.</param>
+    /// <param name="criteria">The matching criteria to apply.</param>
+    /// <returns>Queryable of primary version item IDs.</returns>
+    /// <remarks>
+    /// For callers that already test an item's own media with their own indexed predicate: this covers
+    /// exactly what such a predicate misses, and the filtered PrimaryVersionId index keeps it to the few
+    /// items that have versions at all.
+    /// </remarks>
+    public static IQueryable<Guid> GetPrimaryVersionIdsMatching(JellyfinDbContext context, FolderMatchCriteria criteria)
+    {
+        ArgumentNullException.ThrowIfNull(context);
+        ArgumentNullException.ThrowIfNull(criteria);
+
+        // Anchored on the alternates rather than on the matches: "has a primary version" is served by
+        // the partial PrimaryVersionId index, which holds only the few items that are second files, so
+        // this costs a seek each into the stream index instead of a second pass over every stream row.
+        var alternates = context.BaseItems.Where(v => v.PrimaryVersionId.HasValue);
+
+        if (criteria is HasChapterImages)
         {
-            HasSubtitles => context.MediaStreamInfos
-                .Where(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle)
-                .Select(ms => ms.ItemId)
-                .Distinct()
-                .ToHashSet(),
-            HasChapterImages => context.Chapters
+            return alternates
+                .Where(v => context.Chapters.Any(c => c.ItemId.Equals(v.Id) && c.ImagePath != null))
+                .Select(v => v.PrimaryVersionId!.Value);
+        }
+
+        var matchingStreams = MatchingMediaStreams(context, criteria);
+
+        return alternates
+            .Where(v => matchingStreams.Any(ms => ms.ItemId.Equals(v.Id)))
+            .Select(v => v.PrimaryVersionId!.Value);
+    }
+
+    // The ids of the items whose own media matches. Kept to the stream and chapter tables so their
+    // covering indexes answer this outright: projecting the BaseItems navigation instead would add a
+    // primary-key lookup per stream row rather than one per matching item, and the leading key of both
+    // indexes leaves the ids already grouped, so the Distinct costs no sort.
+    private static IQueryable<Guid> MatchingMediaOwnerIds(JellyfinDbContext context, FolderMatchCriteria criteria)
+        => criteria is HasChapterImages
+            ? context.Chapters
                 .Where(c => c.ImagePath != null)
                 .Select(c => c.ItemId)
                 .Distinct()
-                .ToHashSet(),
-            HasMediaStreamType m => GetMatchingMediaStreamItemIds(context, m),
+            : MatchingMediaStreams(context, criteria)
+                .Select(ms => ms.ItemId)
+                .Distinct();
+
+    // The stream rows a criteria matches. One definition, so the owner projection and the alternate
+    // projection cannot drift apart despite reading it from opposite ends.
+    private static IQueryable<MediaStreamInfo> MatchingMediaStreams(JellyfinDbContext context, FolderMatchCriteria criteria)
+        => criteria switch
+        {
+            HasSubtitles => context.MediaStreamInfos
+                .Where(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle),
+            HasMediaStreamType m => GetMatchingMediaStreams(context, m),
             _ => throw new ArgumentOutOfRangeException(nameof(criteria), $"Unknown criteria type: {criteria.GetType().Name}")
         };
 
-        var ancestors = TraverseHierarchyUp(context, matchingItemIds);
-
-        return ancestors.AsQueryable();
-    }
-
-    private static HashSet<Guid> GetMatchingMediaStreamItemIds(JellyfinDbContext context, HasMediaStreamType criteria)
+    private static IQueryable<MediaStreamInfo> GetMatchingMediaStreams(JellyfinDbContext context, HasMediaStreamType criteria)
     {
         var query = context.MediaStreamInfos
             .Where(ms => ms.StreamType == criteria.StreamType
@@ -130,130 +231,140 @@ public static class DescendantQueryHelper
             query = query.Where(ms => ms.IsExternal == isExternal);
         }
 
-        return query.Select(ms => ms.ItemId).Distinct().ToHashSet();
+        return query;
     }
 
-    /// <summary>
-    /// Traverses DOWN the hierarchy from parent folders to find all descendants.
-    /// </summary>
-    private static HashSet<Guid> TraverseHierarchyDown(JellyfinDbContext context, ICollection<Guid> startIds)
+    private static IQueryable<Guid> AllDescendants(JellyfinDbContext context, IReadOnlyList<Guid> parentIds)
     {
-        var visited = new HashSet<Guid>(startIds);
-        var folderStack = new HashSet<Guid>(startIds);
+        var (closureRoots, linkRoots) = ResolveLinkedRoots(context, parentIds);
 
-        while (folderStack.Count != 0)
+        var linkedDescendants = context.LinkedChildren
+            .WhereOneOrMany(linkRoots, e => e.ParentId)
+            .Select(e => e.ChildId);
+
+        return ClosureDescendants(context, closureRoots)
+            .Concat(linkedDescendants);
+    }
+
+    private static IQueryable<Guid> ClosureDescendants(JellyfinDbContext context, IReadOnlyList<Guid> roots)
+    {
+        var direct = context.AncestorIds
+            .WhereOneOrMany(roots, e => e.ParentItemId)
+            .Select(e => e.ItemId);
+
+        // An item carries its own chain plus its collection folders, never the UserRootFolder.
+        var indirect = context.AncestorIds
+            .Where(e => direct.Contains(e.ParentItemId))
+            .Select(e => e.ItemId);
+
+        return direct.Concat(indirect);
+    }
+
+    // Resolves the folders whose linked children lead, at any depth, to a matching item.
+    private static List<Guid> ResolveLinkParents(JellyfinDbContext context, IQueryable<Guid> matchingItemIds, IQueryable<Guid> ancestorsOfMatches)
+    {
+        // An alternate version is a second file for the item that links it, not a child of it, so that
+        // edge is not walked. It is also the one link a non-folder owns, and there is one per remuxed
+        // movie: walking it would swell this list from the BoxSet and Playlist count to the item count,
+        // and the list is bound into every statement the returned queryable is embedded in.
+        var containerLinks = context.LinkedChildren
+            .Where(e => e.ChildType != LinkedChildType.LocalAlternateVersion
+                && e.ChildType != LinkedChildType.LinkedAlternateVersion);
+
+        // A link sits above the closure and above another link alike, so the hop repeats until nothing
+        // new turns up.
+        var resolved = containerLinks
+            .Where(e => matchingItemIds.Contains(e.ChildId) || ancestorsOfMatches.Contains(e.ChildId))
+            .Select(e => e.ParentId)
+            .Distinct()
+            .ToHashSet();
+
+        var frontier = resolved.ToList();
+
+        while (frontier.Count != 0)
         {
-            var currentFolders = folderStack.ToArray();
-            folderStack.Clear();
+            var containingFolders = context.AncestorIds
+                .WhereOneOrMany(frontier, e => e.ItemId)
+                .Select(e => e.ParentItemId);
 
-            var directChildren = context.AncestorIds
-                .WhereOneOrMany(currentFolders, e => e.ParentItemId)
-                .Select(e => e.ItemId)
+            var directLinkParents = containerLinks
+                .WhereOneOrMany(frontier, e => e.ChildId)
+                .Select(e => e.ParentId);
+
+            var indirectLinkParents = containerLinks
+                .Where(e => containingFolders.Contains(e.ChildId))
+                .Select(e => e.ParentId);
+
+            var next = directLinkParents
+                .Concat(indirectLinkParents)
+                .Distinct()
                 .ToArray();
 
-            var linkedChildren = context.LinkedChildren
-                .WhereOneOrMany(currentFolders, e => e.ParentId)
-                .Select(e => e.ChildId)
-                .ToArray();
-
-            var allChildren = directChildren.Concat(linkedChildren).Distinct().ToArray();
-
-            if (allChildren.Length == 0)
+            frontier = [];
+            foreach (var id in next)
             {
-                break;
-            }
-
-            var childFolders = context.BaseItems
-                .WhereOneOrMany(allChildren, e => e.Id)
-                .Where(e => e.IsFolder)
-                .Select(e => e.Id)
-                .ToHashSet();
-
-            foreach (var childId in allChildren)
-            {
-                if (visited.Add(childId) && childFolders.Contains(childId))
+                // Cyclic links terminate on the resolved set.
+                if (resolved.Add(id))
                 {
-                    folderStack.Add(childId);
+                    frontier.Add(id);
                 }
             }
         }
 
-        return visited;
+        return [.. resolved];
     }
 
-    /// <summary>
-    /// Traverses DOWN the hierarchy using only AncestorIds (ownership), not LinkedChildren.
-    /// </summary>
-    private static HashSet<Guid> TraverseHierarchyDownOwned(JellyfinDbContext context, ICollection<Guid> startIds)
+    // Resolves the roots the descendant sub-selects are anchored on: those contributing their closure,
+    // and those contributing their linked children.
+    private static (List<Guid> ClosureRoots, List<Guid> LinkRoots) ResolveLinkedRoots(JellyfinDbContext context, IReadOnlyList<Guid> parentIds)
     {
-        var visited = new HashSet<Guid>(startIds);
-        var folderStack = new HashSet<Guid>(startIds);
+        var visited = new HashSet<Guid>(parentIds);
+        var closureRoots = visited.ToList();
+        var linkRoots = visited.ToList();
+        var frontier = visited.ToList();
 
-        while (folderStack.Count != 0)
+        while (frontier.Count != 0)
         {
-            var currentFolders = folderStack.ToArray();
-            folderStack.Clear();
+            var closureIds = ClosureDescendants(context, frontier);
 
-            var directChildren = context.AncestorIds
-                .WhereOneOrMany(currentFolders, e => e.ParentItemId)
-                .Select(e => e.ItemId)
-                .ToArray();
+            var linkedIds = context.LinkedChildren
+                .WhereOneOrMany(frontier, e => e.ParentId)
+                .Select(e => e.ChildId);
 
-            if (directChildren.Length == 0)
-            {
-                break;
-            }
-
-            var childFolders = context.BaseItems
-                .WhereOneOrMany(directChildren, e => e.Id)
-                .Where(e => e.IsFolder)
+            var linkedFolders = context.BaseItems
+                .Where(e => e.IsFolder && linkedIds.Contains(e.Id))
                 .Select(e => e.Id)
                 .ToHashSet();
 
-            foreach (var childId in directChildren)
-            {
-                if (visited.Add(childId) && childFolders.Contains(childId))
-                {
-                    folderStack.Add(childId);
-                }
-            }
-        }
-
-        return visited;
-    }
-
-    /// <summary>
-    /// Traverses UP the hierarchy from items to find all ancestor folders.
-    /// </summary>
-    private static HashSet<Guid> TraverseHierarchyUp(JellyfinDbContext context, ICollection<Guid> startIds)
-    {
-        var ancestors = new HashSet<Guid>();
-        var itemStack = new HashSet<Guid>(startIds);
-
-        while (itemStack.Count != 0)
-        {
-            var currentItems = itemStack.ToArray();
-            itemStack.Clear();
-
-            var ancestorParents = context.AncestorIds
-                .WhereOneOrMany(currentItems, e => e.ItemId)
-                .Select(e => e.ParentItemId)
-                .ToArray();
-
-            var linkedParents = context.LinkedChildren
-                .WhereOneOrMany(currentItems, e => e.ChildId)
+            // Folders whose own links have to be followed. Driven off LinkedChildren because owning a
+            // link is the rare property, so the folder check only reaches rows that can qualify. That
+            // check stays: a non-folder owns links too (a movie and its alternate versions).
+            var linkOwners = context.LinkedChildren
+                .Where(e => (closureIds.Contains(e.ParentId) || linkedIds.Contains(e.ParentId))
+                    && e.Parent!.IsFolder)
                 .Select(e => e.ParentId)
+                .Distinct()
                 .ToArray();
 
-            foreach (var parentId in ancestorParents.Concat(linkedParents))
+            frontier = [];
+            foreach (var id in linkOwners.Concat(linkedFolders))
             {
-                if (ancestors.Add(parentId))
+                if (!visited.Add(id))
                 {
-                    itemStack.Add(parentId);
+                    continue;
+                }
+
+                frontier.Add(id);
+                linkRoots.Add(id);
+
+                // Only a folder reached through a link adds a closure the roots so far do not cover.
+                if (linkedFolders.Contains(id))
+                {
+                    closureRoots.Add(id);
                 }
             }
         }
 
-        return ancestors;
+        return (closureRoots, linkRoots);
     }
 }

src/Jellyfin.Database/Jellyfin.Database.Implementations/Entities/Permission.cs

@@ -37,7 +37,7 @@ namespace Jellyfin.Database.Implementations.Entities
         /// <summary>
         /// Gets or sets the id of the associated user.
         /// </summary>
-        public Guid? UserId { get; set; }
+        public Guid UserId { get; set; }
 
         /// <summary>
         /// Gets the type of this permission.

src/Jellyfin.Database/Jellyfin.Database.Implementations/Entities/Preference.cs

@@ -35,7 +35,7 @@ namespace Jellyfin.Database.Implementations.Entities
         /// <summary>
         /// Gets or sets the id of the associated user.
         /// </summary>
-        public Guid? UserId { get; set; }
+        public Guid UserId { get; set; }
 
         /// <summary>
         /// Gets the type of this preference.

src/Jellyfin.Database/Jellyfin.Database.Implementations/Entities/User.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
-using System.ComponentModel.DataAnnotations.Schema;
 using System.Text.Json.Serialization;
 using Jellyfin.Database.Implementations.Enums;
 using Jellyfin.Database.Implementations.Interfaces;
@@ -326,7 +325,6 @@ namespace Jellyfin.Database.Implementations.Entities
         /// <summary>
         /// Gets the list of permissions this user has.
         /// </summary>
-        [ForeignKey("Permission_Permissions_Guid")]
         public virtual ICollection<Permission> Permissions { get; private set; }
 
         /*
@@ -339,7 +337,6 @@ namespace Jellyfin.Database.Implementations.Entities
         /// <summary>
         /// Gets the list of preferences this user has.
         /// </summary>
-        [ForeignKey("Preference_Preferences_Guid")]
         public virtual ICollection<Preference> Preferences { get; private set; }
 
         /// <inheritdoc/>

src/Jellyfin.Database/Jellyfin.Database.Implementations/ModelConfiguration/MediaStreamInfoConfiguration.cs

@@ -13,5 +13,9 @@ public class MediaStreamInfoConfiguration : IEntityTypeConfiguration<MediaStream
     public void Configure(EntityTypeBuilder<MediaStreamInfo> builder)
     {
         builder.HasKey(e => new { e.ItemId, e.StreamIndex });
+
+        // Covering index for the stream filters. ItemId comes second because it is what they project and
+        // dedupe on; Language and IsExternal follow only to keep their predicates off the table.
+        builder.HasIndex(e => new { e.StreamType, e.ItemId, e.Language, e.IsExternal });
     }
 }

src/Jellyfin.Database/Jellyfin.Database.Implementations/ModelConfiguration/PermissionConfiguration.cs

@@ -14,10 +14,8 @@ namespace Jellyfin.Database.Implementations.ModelConfiguration
         {
             // Used to get a user's permissions or a specific permission for a user.
             // Also prevents multiple values being created for a user.
-            // Filtered over non-null user ids for when other entities (groups, API keys) get permissions
             builder
                 .HasIndex(p => new { p.UserId, p.Kind })
-                .HasFilter("[UserId] IS NOT NULL")
                 .IsUnique();
         }
     }

src/Jellyfin.Database/Jellyfin.Database.Implementations/ModelConfiguration/PreferenceConfiguration.cs

@@ -14,7 +14,6 @@ namespace Jellyfin.Database.Implementations.ModelConfiguration
         {
             builder
                 .HasIndex(p => new { p.UserId, p.Kind })
-                .HasFilter("[UserId] IS NOT NULL")
                 .IsUnique();
         }
     }

src/Jellyfin.Database/Jellyfin.Database.Providers.Sqlite/Migrations/20260812050902_AddMediaStreamFilterIndex.cs

@@ -0,0 +1,27 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jellyfin.Database.Providers.Sqlite.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddMediaStreamFilterIndex : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateIndex(
+                name: "IX_MediaStreamInfos_StreamType_ItemId_Language_IsExternal",
+                table: "MediaStreamInfos",
+                columns: new[] { "StreamType", "ItemId", "Language", "IsExternal" });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_MediaStreamInfos_StreamType_ItemId_Language_IsExternal",
+                table: "MediaStreamInfos");
+        }
+    }
+}

src/Jellyfin.Database/Jellyfin.Database.Providers.Sqlite/Migrations/20260815063607_RemoveOrphanedUserPermissionsAndPreferences.cs

@@ -0,0 +1,120 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jellyfin.Database.Providers.Sqlite.Migrations
+{
+    /// <inheritdoc />
+    public partial class RemoveOrphanedUserPermissionsAndPreferences : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql("DELETE FROM Permissions WHERE UserId IS NULL;");
+            migrationBuilder.Sql("DELETE FROM Preferences WHERE UserId IS NULL;");
+
+            migrationBuilder.DropIndex(
+                name: "IX_Preferences_UserId_Kind",
+                table: "Preferences");
+
+            migrationBuilder.DropIndex(
+                name: "IX_Permissions_UserId_Kind",
+                table: "Permissions");
+
+            migrationBuilder.DropColumn(
+                name: "Preference_Preferences_Guid",
+                table: "Preferences");
+
+            migrationBuilder.DropColumn(
+                name: "Permission_Permissions_Guid",
+                table: "Permissions");
+
+            migrationBuilder.AlterColumn<Guid>(
+                name: "UserId",
+                table: "Preferences",
+                type: "TEXT",
+                nullable: false,
+                defaultValue: new Guid("00000000-0000-0000-0000-000000000000"),
+                oldClrType: typeof(Guid),
+                oldType: "TEXT",
+                oldNullable: true);
+
+            migrationBuilder.AlterColumn<Guid>(
+                name: "UserId",
+                table: "Permissions",
+                type: "TEXT",
+                nullable: false,
+                defaultValue: new Guid("00000000-0000-0000-0000-000000000000"),
+                oldClrType: typeof(Guid),
+                oldType: "TEXT",
+                oldNullable: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Preferences_UserId_Kind",
+                table: "Preferences",
+                columns: ["UserId", "Kind"],
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Permissions_UserId_Kind",
+                table: "Permissions",
+                columns: ["UserId", "Kind"],
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Preferences_UserId_Kind",
+                table: "Preferences");
+
+            migrationBuilder.DropIndex(
+                name: "IX_Permissions_UserId_Kind",
+                table: "Permissions");
+
+            migrationBuilder.AlterColumn<Guid>(
+                name: "UserId",
+                table: "Preferences",
+                type: "TEXT",
+                nullable: true,
+                oldClrType: typeof(Guid),
+                oldType: "TEXT");
+
+            migrationBuilder.AddColumn<Guid>(
+                name: "Preference_Preferences_Guid",
+                table: "Preferences",
+                type: "TEXT",
+                nullable: true);
+
+            migrationBuilder.AlterColumn<Guid>(
+                name: "UserId",
+                table: "Permissions",
+                type: "TEXT",
+                nullable: true,
+                oldClrType: typeof(Guid),
+                oldType: "TEXT");
+
+            migrationBuilder.AddColumn<Guid>(
+                name: "Permission_Permissions_Guid",
+                table: "Permissions",
+                type: "TEXT",
+                nullable: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Preferences_UserId_Kind",
+                table: "Preferences",
+                columns: ["UserId", "Kind"],
+                unique: true,
+                filter: "[UserId] IS NOT NULL");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Permissions_UserId_Kind",
+                table: "Permissions",
+                columns: ["UserId", "Kind"],
+                unique: true,
+                filter: "[UserId] IS NOT NULL");
+        }
+    }
+}

src/Jellyfin.Database/Jellyfin.Database.Providers.Sqlite/Migrations/JellyfinDbModelSnapshot.cs

@@ -15,7 +15,7 @@ namespace Jellyfin.Server.Implementations.Migrations
         protected override void BuildModel(ModelBuilder modelBuilder)
         {
 #pragma warning disable 612, 618
-            modelBuilder.HasAnnotation("ProductVersion", "10.0.10");
+            modelBuilder.HasAnnotation("ProductVersion", "10.0.11");
 
             modelBuilder.Entity("Jellyfin.Database.Implementations.Entities.AccessSchedule", b =>
                 {
@@ -1012,6 +1012,8 @@ namespace Jellyfin.Server.Implementations.Migrations
 
                     b.HasKey("ItemId", "StreamIndex");
 
+                    b.HasIndex("StreamType", "ItemId", "Language", "IsExternal");
+
                     b.ToTable("MediaStreamInfos");
 
                     b.HasAnnotation("Sqlite:UseSqlReturningClause", false);
@@ -1078,14 +1080,11 @@ namespace Jellyfin.Server.Implementations.Migrations
                     b.Property<int>("Kind")
                         .HasColumnType("INTEGER");
 
-                    b.Property<Guid?>("Permission_Permissions_Guid")
-                        .HasColumnType("TEXT");
-
                     b.Property<uint>("RowVersion")
                         .IsConcurrencyToken()
                         .HasColumnType("INTEGER");
 
-                    b.Property<Guid?>("UserId")
+                    b.Property<Guid>("UserId")
                         .HasColumnType("TEXT");
 
                     b.Property<bool>("Value")
@@ -1094,8 +1093,7 @@ namespace Jellyfin.Server.Implementations.Migrations
                     b.HasKey("Id");
 
                     b.HasIndex("UserId", "Kind")
-                        .IsUnique()
-                        .HasFilter("[UserId] IS NOT NULL");
+                        .IsUnique();
 
                     b.ToTable("Permissions");
 
@@ -1111,14 +1109,11 @@ namespace Jellyfin.Server.Implementations.Migrations
                     b.Property<int>("Kind")
                         .HasColumnType("INTEGER");
 
-                    b.Property<Guid?>("Preference_Preferences_Guid")
-                        .HasColumnType("TEXT");
-
                     b.Property<uint>("RowVersion")
                         .IsConcurrencyToken()
                         .HasColumnType("INTEGER");
 
-                    b.Property<Guid?>("UserId")
+                    b.Property<Guid>("UserId")
                         .HasColumnType("TEXT");
 
                     b.Property<string>("Value")
@@ -1129,8 +1124,7 @@ namespace Jellyfin.Server.Implementations.Migrations
                     b.HasKey("Id");
 
                     b.HasIndex("UserId", "Kind")
-                        .IsUnique()
-                        .HasFilter("[UserId] IS NOT NULL");
+                        .IsUnique();
 
                     b.ToTable("Preferences");
 
@@ -1699,7 +1693,8 @@ namespace Jellyfin.Server.Implementations.Migrations
                     b.HasOne("Jellyfin.Database.Implementations.Entities.User", null)
                         .WithMany("Permissions")
                         .HasForeignKey("UserId")
-                        .OnDelete(DeleteBehavior.Cascade);
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
                 });
 
             modelBuilder.Entity("Jellyfin.Database.Implementations.Entities.Preference", b =>
@@ -1707,7 +1702,8 @@ namespace Jellyfin.Server.Implementations.Migrations
                     b.HasOne("Jellyfin.Database.Implementations.Entities.User", null)
                         .WithMany("Preferences")
                         .HasForeignKey("UserId")
-                        .OnDelete(DeleteBehavior.Cascade);
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
                 });
 
             modelBuilder.Entity("Jellyfin.Database.Implementations.Entities.Security.Device", b =>

src/Jellyfin.Extensions/StringExtensions.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text;
 using System.Text.RegularExpressions;
 using ICU4N.Text;
 
@@ -173,5 +174,41 @@ namespace Jellyfin.Extensions
 
             return cleaned;
         }
+
+        /// <summary>
+        /// Escapes an argument so that it survives command line parsing as a single argument when it is wrapped in double quotes by the caller.
+        /// </summary>
+        /// <param name="value">The argument to escape.</param>
+        /// <returns>The escaped argument.</returns>
+        public static string EscapeProcessArgument(this string value)
+        {
+            ArgumentNullException.ThrowIfNull(value);
+
+            var span = value.AsSpan();
+            if (!span.Contains('"'))
+            {
+                var trailing = span.Length - span.TrimEnd('\\').Length;
+                return trailing == 0 ? value : string.Concat(value, new string('\\', trailing));
+            }
+
+            var escaped = new StringBuilder(value.Length + 8);
+            var backslashes = 0;
+
+            foreach (var character in span)
+            {
+                if (character == '\\')
+                {
+                    backslashes++;
+                    continue;
+                }
+
+                escaped
+                    .Append('\\', character == '"' ? (backslashes * 2) + 1 : backslashes)
+                    .Append(character);
+                backslashes = 0;
+            }
+
+            return escaped.Append('\\', backslashes * 2).ToString();
+        }
     }
 }

src/Jellyfin.LiveTv/IO/EncodedRecorder.cs

@@ -188,8 +188,8 @@ namespace Jellyfin.LiveTv.IO
             var commandLineArgs = string.Format(
                 CultureInfo.InvariantCulture,
                 "-i \"{0}\" {2} -map_metadata -1 -threads {6} {3}{4}{5} -y \"{1}\"",
-                inputTempFile,
-                targetFile.Replace("\"", "\\\"", StringComparison.Ordinal), // Escape quotes in filename
+                inputTempFile.EscapeProcessArgument(),
+                targetFile.EscapeProcessArgument(),
                 videoArgs,
                 GetAudioArgs(mediaSource),
                 subtitleArgs,

src/Jellyfin.LiveTv/LiveTvManager.cs

@@ -1262,7 +1262,7 @@ namespace Jellyfin.LiveTv
 
         public Folder GetInternalLiveTvFolder(CancellationToken cancellationToken)
         {
-            var name = _localization.GetLocalizedString("HeaderLiveTV");
+            var name = _localization.GetServerLocalizedString("HeaderLiveTV");
             return _libraryManager.GetNamedView(name, CollectionType.livetv, name);
         }
 

src/Jellyfin.LiveTv/TunerHosts/HdHomerun/HdHomerunHost.cs

@@ -326,7 +326,7 @@ namespace Jellyfin.LiveTv.TunerHosts.HdHomerun
                 BufferMs = 0,
                 Container = "ts",
                 Id = id,
-                SupportsDirectPlay = false,
+                SupportsDirectPlay = true,
                 SupportsDirectStream = true,
                 SupportsTranscoding = true,
                 IsInfiniteStream = true,

tests/Jellyfin.Controller.Tests/Entities/BaseItemTests.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Jellyfin.Database.Implementations.Entities;
@@ -27,6 +28,57 @@ namespace Jellyfin.Controller.Tests.Entities;
 
 public class BaseItemTests
 {
+    [Fact]
+    public void GetItemByNameFolderName_ShortName_IsKeptAsIs()
+    {
+        SetupPassThroughFileSystem();
+
+        Assert.Equal("Mairghread Scott", BaseItem.GetItemByNameFolderName("Mairghread Scott."));
+    }
+
+    [Fact]
+    public void GetItemByNameFolderName_OverlongName_FitsInAPathComponent()
+    {
+        SetupPassThroughFileSystem();
+
+        // What a provider result that concatenated a whole credit list into one name looks like.
+        var name = string.Join(", ", Enumerable.Repeat("Jerry Siegel (created by: Superman)", 20));
+
+        var folderName = BaseItem.GetItemByNameFolderName(name);
+
+        Assert.True(Encoding.UTF8.GetByteCount(folderName) <= 128);
+        Assert.StartsWith("Jerry Siegel (created by: Superman)", folderName, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void GetItemByNameFolderName_OverlongNamesSharingAPrefix_StayApart()
+    {
+        SetupPassThroughFileSystem();
+
+        var prefix = new string('a', 200);
+
+        Assert.NotEqual(
+            BaseItem.GetItemByNameFolderName(prefix + "Joe Shuster"),
+            BaseItem.GetItemByNameFolderName(prefix + "Bob Kane"));
+    }
+
+    [Fact]
+    public void GetItemByNameFolderName_OverlongName_IsStable()
+    {
+        SetupPassThroughFileSystem();
+
+        var name = new string('a', 300);
+
+        Assert.Equal(BaseItem.GetItemByNameFolderName(name), BaseItem.GetItemByNameFolderName(name));
+    }
+
+    private static void SetupPassThroughFileSystem()
+    {
+        var fileSystem = new Mock<IFileSystem>();
+        fileSystem.Setup(x => x.GetValidFilename(It.IsAny<string>())).Returns((string name) => name);
+        BaseItem.FileSystem = fileSystem.Object;
+    }
+
     [Theory]
     [InlineData("", "")]
     [InlineData("1", "0000000001")]

tests/Jellyfin.Extensions.Tests/StringExtensionsTests.cs

@@ -75,5 +75,28 @@ namespace Jellyfin.Extensions.Tests
             var result = str.AsSpan().RightPart(needle).ToString();
             Assert.Equal(expectedResult, result);
         }
+
+        [Theory]
+        [InlineData("", "")]
+        [InlineData("/media/movies/Film.mkv", "/media/movies/Film.mkv")]
+        [InlineData(@"C:\media\movies\Film.mkv", @"C:\media\movies\Film.mkv")]
+        [InlineData(@"/media/a""b.mkv", @"/media/a\""b.mkv")]
+        [InlineData(@"/media/a\""b.mkv", @"/media/a\\\""b.mkv")]
+        [InlineData(@"/media/a\\""b.mkv", @"/media/a\\\\\""b.mkv")]
+        [InlineData(@"/media/a\b""c.mkv", @"/media/a\b\""c.mkv")]
+        [InlineData(@"/media/trailing\", @"/media/trailing\\")]
+        [InlineData(@"/media/evil\"" -f lavfi -i sine .mkv", @"/media/evil\\\"" -f lavfi -i sine .mkv")]
+        public void EscapeProcessArgument_ValidInput_Corrects(string input, string expectedResult)
+        {
+            Assert.Equal(expectedResult, input.EscapeProcessArgument());
+        }
+
+        [Theory]
+        [InlineData("/media/movies/Film with spaces.mkv")]
+        [InlineData(@"C:\media\movies\Film.mkv")]
+        public void EscapeProcessArgument_NothingToEscape_ReturnsSameInstance(string input)
+        {
+            Assert.Same(input, input.EscapeProcessArgument());
+        }
     }
 }

tests/Jellyfin.Model.Tests/Entities/ProviderIdsExtensionsTests.cs

@@ -186,6 +186,109 @@ namespace Jellyfin.Model.Tests.Entities
             Assert.Null(nullProvider.ProviderIds);
         }
 
+        [Theory]
+        [InlineData(nameof(MetadataProvider.Imdb), "tt0113375", true)]
+        [InlineData(nameof(MetadataProvider.Imdb), "nm0000123", true)]
+        [InlineData(nameof(MetadataProvider.Imdb), "0113375", true)]
+        [InlineData(nameof(MetadataProvider.Imdb), "https://www.imdb.com/title/tt0113375", false)]
+        [InlineData(nameof(MetadataProvider.Tmdb), "11", true)]
+        [InlineData(nameof(MetadataProvider.Tmdb), "nm0000123", false)]
+        [InlineData(nameof(MetadataProvider.Tmdb), "0", false)]
+        [InlineData(nameof(MetadataProvider.Tmdb), "-11", false)]
+        [InlineData(nameof(MetadataProvider.TmdbCollection), "nm0000123", false)]
+        [InlineData(nameof(MetadataProvider.AudioDbArtist), "111239", true)]
+        [InlineData(nameof(MetadataProvider.AudioDbArtist), "a3cb23fc-acd3-4ce0-8f36-1e5aa6a18432", false)]
+        [InlineData(nameof(MetadataProvider.MusicBrainzArtist), "a3cb23fc-acd3-4ce0-8f36-1e5aa6a18432", true)]
+        [InlineData(nameof(MetadataProvider.MusicBrainzArtist), "111239", false)]
+        [InlineData(nameof(MetadataProvider.MusicBrainzAlbum), "not-an-mbid", false)]
+        [InlineData(nameof(MetadataProvider.Tvdb), "anything-goes", true)]
+        [InlineData("SomePlugin", "anything-goes", true)]
+        [InlineData(nameof(MetadataProvider.Tmdb), null, false)]
+        [InlineData(null, "11", false)]
+        public void IsValidProviderId_ChecksKnownFormats(string? name, string? value, bool expected)
+        {
+            Assert.Equal(expected, ProviderIdsExtensions.IsValidProviderId(name, value));
+        }
+
+        [Fact]
+        public void TrySetProviderId_ForeignId_False()
+        {
+            var provider = new ProviderIdsExtensionsTestsObject();
+
+            Assert.False(provider.TrySetProviderId(MetadataProvider.Tmdb, "nm0000123"));
+            Assert.Empty(provider.ProviderIds);
+        }
+
+        [Fact]
+        public void TrySetProviderId_ForeignId_KeepsExisting()
+        {
+            var provider = new ProviderIdsExtensionsTestsObject();
+            provider.ProviderIds[MetadataProvider.Tmdb.ToString()] = "11";
+
+            Assert.False(provider.TrySetProviderId(MetadataProvider.Tmdb, "nm0000123"));
+            Assert.Equal("11", provider.GetProviderId(MetadataProvider.Tmdb));
+        }
+
+        [Theory]
+        [InlineData(nameof(MetadataProvider.Imdb), " tt0113375 ")]
+        [InlineData(" Imdb", ExampleImdbId)]
+        public void TrySetProviderId_SurroundingWhitespace_Trimmed(string name, string value)
+        {
+            var provider = new ProviderIdsExtensionsTestsObject();
+
+            Assert.True(provider.TrySetProviderId(name, value));
+            Assert.Equal(ExampleImdbId, provider.GetProviderId(MetadataProvider.Imdb));
+        }
+
+        [Fact]
+        public void SetProviderIds_ReplacesAll()
+        {
+            var provider = new ProviderIdsExtensionsTestsObject();
+            provider.ProviderIds[MetadataProvider.Tvdb.ToString()] = "12345";
+
+            provider.SetProviderIds(new Dictionary<string, string>
+            {
+                [MetadataProvider.Imdb.ToString()] = ExampleImdbId
+            });
+
+            Assert.Equal(ExampleImdbId, provider.GetProviderId(MetadataProvider.Imdb));
+            Assert.False(provider.HasProviderId(MetadataProvider.Tvdb));
+        }
+
+        [Fact]
+        public void SetProviderIds_ForeignId_Dropped()
+        {
+            var provider = new ProviderIdsExtensionsTestsObject();
+
+            provider.SetProviderIds(new Dictionary<string, string>
+            {
+                [MetadataProvider.Tmdb.ToString()] = "nm0000123",
+                [MetadataProvider.Imdb.ToString()] = ExampleImdbId,
+                [MetadataProvider.Tvdb.ToString()] = string.Empty
+            });
+
+            Assert.False(provider.HasProviderId(MetadataProvider.Tmdb));
+            Assert.False(provider.HasProviderId(MetadataProvider.Tvdb));
+            Assert.Equal(ExampleImdbId, provider.GetProviderId(MetadataProvider.Imdb));
+        }
+
+        [Fact]
+        public void SetProviderIds_Null_Clears()
+        {
+            var provider = new ProviderIdsExtensionsTestsObject();
+            provider.ProviderIds[MetadataProvider.Imdb.ToString()] = ExampleImdbId;
+
+            provider.SetProviderIds(null);
+
+            Assert.Empty(provider.ProviderIds);
+        }
+
+        [Fact]
+        public void SetProviderIds_NullInstance_ThrowsArgumentNullException()
+        {
+            Assert.Throws<ArgumentNullException>(() => ProviderIdsExtensions.SetProviderIds(null!, new Dictionary<string, string>()));
+        }
+
         [Fact]
         public void RemoveProviderId_Null_Remove()
         {

tests/Jellyfin.Providers.Tests/Manager/MetadataLanguageUtilsTests.cs

@@ -0,0 +1,38 @@
+using MediaBrowser.Providers.Manager;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Manager
+{
+    public class MetadataLanguageUtilsTests
+    {
+        [Theory]
+        [InlineData("es", "es")]
+        [InlineData("es-ES", "es")]
+        [InlineData("pt-BR", "pt")]
+        [InlineData("ES", "es")]
+        [InlineData(null, null)]
+        [InlineData("", null)]
+        public void GetLanguageSubtag_ReturnsLowercasedSubtag(string? language, string? expected)
+        {
+            Assert.Equal(expected, MetadataLanguageUtils.GetLanguageSubtag(language));
+        }
+
+        [Theory]
+        [InlineData("es", "es", true)]
+        [InlineData("es", "es-ES", true)]
+        [InlineData("es-MX", "es-ES", true)]
+        [InlineData("ES", "es", true)]
+        [InlineData("en", "en", true)]
+        [InlineData("en", "es-ES", false)]
+        [InlineData("en", "es", false)]
+        // An unknown language on either side cannot be judged and is assumed to match
+        [InlineData(null, "es", true)]
+        [InlineData("", "es", true)]
+        [InlineData("en", null, true)]
+        [InlineData("en", "", true)]
+        public void MatchesPreferredLanguage_ComparesLanguageSubtag(string? resultLanguage, string? preferredLanguage, bool expected)
+        {
+            Assert.Equal(expected, MetadataLanguageUtils.MatchesPreferredLanguage(resultLanguage, preferredLanguage));
+        }
+    }
+}

tests/Jellyfin.Providers.Tests/Manager/MetadataServiceRefreshTests.cs

@@ -0,0 +1,352 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using Jellyfin.Data.Enums;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Entities.Movies;
+using MediaBrowser.Controller.IO;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.Persistence;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Model.Configuration;
+using MediaBrowser.Model.Entities;
+using MediaBrowser.Model.IO;
+using MediaBrowser.Providers.Manager;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Manager
+{
+    public class MetadataServiceRefreshTests
+    {
+        [Theory]
+        // RemoveOldMetadata is only ever set by an explicit user action - a refresh with "replace all
+        // metadata", or Identify. A provider failing must not silently downgrade that to a merge: the
+        // providers that did answer supplied the replacement, and the old values are the wrong match
+        // the user asked to get rid of.
+        [InlineData(false)]
+        [InlineData(true)]
+        public async Task RefreshWithProviders_ReplaceAllMetadata_ErasesOldDataWhenAProviderAnswers(bool allProvidersSucceed)
+        {
+            var item = new Movie
+            {
+                Name = "Test Movie",
+                Overview = "existing overview"
+            };
+
+            // The provider owning the overview fails, so it contributes nothing to the replacement.
+            var failing = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            failing.Setup(p => p.Name).Returns("Failing");
+            failing.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .Returns(allProvidersSucceed
+                    ? Task.FromResult(new MetadataResult<Movie> { HasMetadata = true, Item = new Movie() })
+                    : Task.FromException<MetadataResult<Movie>>(new FormatException("bad id")));
+
+            var succeeding = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            succeeding.Setup(p => p.Name).Returns("Succeeding");
+            succeeding.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(new MetadataResult<Movie>
+                {
+                    HasMetadata = true,
+                    Item = new Movie { Name = "Test Movie", Tagline = "new tagline" }
+                });
+
+            var service = new TestMetadataService();
+            var result = await service.RefreshWithProvidersInternal(
+                new MetadataResult<Movie> { Item = item },
+                new MovieInfo { Name = item.Name },
+                new MetadataRefreshOptions(Mock.Of<IDirectoryService>())
+                {
+                    MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
+                    ReplaceAllMetadata = true,
+                    RemoveOldMetadata = true
+                },
+                [failing.Object, succeeding.Object]).ConfigureAwait(true);
+
+            Assert.Equal(allProvidersSucceed ? 0 : 1, result.Failures);
+            Assert.Equal("new tagline", item.Tagline);
+            Assert.Null(item.Overview);
+        }
+
+        [Fact]
+        public async Task RefreshWithProviders_ReplaceAllMetadata_KeepsExistingDataWhenEveryRemoteProviderFails()
+        {
+            var item = new Movie
+            {
+                Name = "Test Movie",
+                Overview = "existing overview"
+            };
+
+            // Something has to contribute for the merge to run at all, otherwise the item is never touched
+            // and the case is moot. The local provider is the replacement the remote ones did not deliver.
+            var local = new Mock<ILocalMetadataProvider<Movie>>(MockBehavior.Loose);
+            local.Setup(p => p.Name).Returns("Local");
+            local.Setup(p => p.GetMetadata(It.IsAny<ItemInfo>(), It.IsAny<IDirectoryService>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(new MetadataResult<Movie>
+                {
+                    HasMetadata = true,
+                    Item = new Movie { Name = "Test Movie", Tagline = "new tagline" }
+                });
+
+            var remote = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            remote.Setup(p => p.Name).Returns("Failing");
+            remote.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .Returns(Task.FromException<MetadataResult<Movie>>(new HttpRequestException("unreachable")));
+
+            var service = new TestMetadataService();
+            var result = await service.RefreshWithProvidersInternal(
+                new MetadataResult<Movie> { Item = item },
+                new MovieInfo { Name = item.Name },
+                new MetadataRefreshOptions(Mock.Of<IDirectoryService>())
+                {
+                    MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
+                    ReplaceAllMetadata = true,
+                    RemoveOldMetadata = true
+                },
+                [local.Object, remote.Object]).ConfigureAwait(true);
+
+            Assert.Equal(1, result.Failures);
+            Assert.Equal("new tagline", item.Tagline);
+
+            // No remote provider answered, so erasing the overview would lose it for good.
+            Assert.Equal("existing overview", item.Overview);
+        }
+
+        [Fact]
+        public async Task RefreshWithProviders_ForeignProviderId_NotStored()
+        {
+            var item = new Movie { Name = "Test Movie" };
+
+            var provider = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            provider.Setup(p => p.Name).Returns("Provider");
+            provider.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(() =>
+                {
+                    var found = new Movie { Name = "Test Movie" };
+                    found.ProviderIds[MetadataProvider.Tmdb.ToString()] = "nm0000123";
+                    found.ProviderIds[MetadataProvider.Imdb.ToString()] = "tt0113375";
+                    return new MetadataResult<Movie> { HasMetadata = true, Item = found };
+                });
+
+            var service = new TestMetadataService();
+            await service.RefreshWithProvidersInternal(
+                new MetadataResult<Movie> { Item = item },
+                new MovieInfo { Name = item.Name },
+                new MetadataRefreshOptions(Mock.Of<IDirectoryService>())
+                {
+                    MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
+                    ReplaceAllMetadata = true
+                },
+                [provider.Object]).ConfigureAwait(true);
+
+            Assert.False(item.HasProviderId(MetadataProvider.Tmdb));
+            Assert.Equal("tt0113375", item.GetProviderId(MetadataProvider.Imdb));
+        }
+
+        [Fact]
+        public async Task RefreshWithProviders_ForeignProviderId_ReplacedInLookupInfo()
+        {
+            var item = new Movie { Name = "Test Movie" };
+            var lookupInfo = new MovieInfo { Name = item.Name };
+            lookupInfo.ProviderIds[MetadataProvider.Tmdb.ToString()] = "nm0000123";
+
+            var answering = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            answering.Setup(p => p.Name).Returns("Answering");
+            answering.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(() =>
+                {
+                    var found = new Movie { Name = "Test Movie" };
+                    found.ProviderIds[MetadataProvider.Tmdb.ToString()] = "12345";
+                    return new MetadataResult<Movie> { HasMetadata = true, Item = found };
+                });
+
+            string? tmdbIdSeenBySecondProvider = null;
+            var following = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            following.Setup(p => p.Name).Returns("Following");
+            following.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync((MovieInfo info, CancellationToken _) =>
+                {
+                    tmdbIdSeenBySecondProvider = info.GetProviderId(MetadataProvider.Tmdb);
+                    return new MetadataResult<Movie> { HasMetadata = false };
+                });
+
+            var service = new TestMetadataService();
+            await service.RefreshWithProvidersInternal(
+                new MetadataResult<Movie> { Item = item },
+                lookupInfo,
+                new MetadataRefreshOptions(Mock.Of<IDirectoryService>())
+                {
+                    MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
+                    ReplaceAllMetadata = true
+                },
+                [answering.Object, following.Object]).ConfigureAwait(true);
+
+            // The stored id cannot be a TMDb one, so the provider that still has to run must get the id
+            // that was just found instead of failing on the same bad one.
+            Assert.Equal("12345", tmdbIdSeenBySecondProvider);
+        }
+
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public async Task RefreshWithProviders_ForeignPersonProviderId_NotStored(bool replaceAllMetadata)
+        {
+            var item = new Movie { Name = "Test Movie" };
+            var existing = new MetadataResult<Movie> { Item = item };
+            existing.AddPerson(new PersonInfo { Name = "Some Actor", Type = PersonKind.Actor });
+
+            var provider = new Mock<IRemoteMetadataProvider<Movie, MovieInfo>>(MockBehavior.Loose);
+            provider.Setup(p => p.Name).Returns("Provider");
+            provider.Setup(p => p.GetMetadata(It.IsAny<MovieInfo>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(() =>
+                {
+                    var person = new PersonInfo { Name = "Some Actor", Type = PersonKind.Actor };
+                    person.ProviderIds[MetadataProvider.Tmdb.ToString()] = "nm0000123";
+                    person.ProviderIds[MetadataProvider.Imdb.ToString()] = "nm0000123";
+
+                    var found = new MetadataResult<Movie> { HasMetadata = true, Item = new Movie { Name = "Test Movie" } };
+                    found.AddPerson(person);
+                    return found;
+                });
+
+            var service = new TestMetadataService();
+            await service.RefreshWithProvidersInternal(
+                existing,
+                new MovieInfo { Name = item.Name },
+                new MetadataRefreshOptions(Mock.Of<IDirectoryService>())
+                {
+                    MetadataRefreshMode = MetadataRefreshMode.FullRefresh,
+                    ReplaceAllMetadata = replaceAllMetadata
+                },
+                [provider.Object]).ConfigureAwait(true);
+
+            var mergedPerson = Assert.Single(existing.People);
+            Assert.False(mergedPerson.HasProviderId(MetadataProvider.Tmdb));
+            Assert.Equal("nm0000123", mergedPerson.GetProviderId(MetadataProvider.Imdb));
+        }
+
+        [Theory]
+        [InlineData(MetadataRefreshMode.FullRefresh, true)]
+        [InlineData(MetadataRefreshMode.Default, false)]
+        public async Task RefreshMetadata_ProvidersFoundNothing_PersistsRefreshDateOnFullRefresh(MetadataRefreshMode mode, bool expectSaved)
+        {
+            var item = new TestItem
+            {
+                Id = Guid.NewGuid(),
+                Name = "Test Item",
+                PreferredMetadataLanguage = "en",
+                PreferredMetadataCountryCode = "US",
+                DateLastRefreshed = DateTime.UtcNow.AddDays(-60),
+                DateLastSaved = DateTime.UtcNow.AddDays(-60)
+            };
+            item.PresentationUniqueKey = item.CreatePresentationUniqueKey();
+
+            var stampBefore = item.DateLastRefreshed;
+
+            var provider = new Mock<IRemoteMetadataProvider<TestItem, ItemLookupInfo>>(MockBehavior.Loose);
+            provider.Setup(p => p.Name).Returns("Provider");
+            provider.Setup(p => p.GetMetadata(It.IsAny<ItemLookupInfo>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(new MetadataResult<TestItem> { HasMetadata = false });
+
+            var libraryManager = new Mock<ILibraryManager>(MockBehavior.Loose);
+            libraryManager.Setup(l => l.GetLibraryOptions(It.IsAny<BaseItem>())).Returns(new LibraryOptions());
+
+            var providerManager = new Mock<IProviderManager>(MockBehavior.Loose);
+            providerManager.Setup(p => p.GetImageProviders(It.IsAny<BaseItem>(), It.IsAny<ImageRefreshOptions>()))
+                .Returns(Array.Empty<IImageProvider>());
+            providerManager.Setup(p => p.GetMetadataProviders<TestItem>(It.IsAny<BaseItem>(), It.IsAny<LibraryOptions>()))
+                .Returns(new[] { (IMetadataProvider<TestItem>)provider.Object });
+            providerManager.Setup(p => p.GetMetadataSavers(It.IsAny<BaseItem>(), It.IsAny<LibraryOptions>()))
+                .Returns(Array.Empty<IMetadataSaver>());
+
+            var itemRepository = new Mock<IItemRepository>(MockBehavior.Loose);
+            itemRepository.Setup(r => r.ItemExistsAsync(It.IsAny<Guid>())).ReturnsAsync(true);
+
+            var service = new TestItemMetadataService(libraryManager.Object, providerManager.Object, itemRepository.Object);
+
+            await service.RefreshMetadata(
+                item,
+                new MetadataRefreshOptions(Mock.Of<IDirectoryService>())
+                {
+                    MetadataRefreshMode = mode,
+                    ImageRefreshMode = mode
+                },
+                CancellationToken.None).ConfigureAwait(true);
+
+            // Nothing was found, so on a full refresh the advanced stamp is the only reason to write the row.
+            Assert.Equal(expectSaved, item.Saved);
+
+            if (expectSaved)
+            {
+                Assert.True(item.DateLastRefreshed > stampBefore);
+            }
+        }
+
+        /// <summary>
+        /// Stands in for a real item so the refresh stays off the shared BaseItem statics, which other
+        /// test classes in this assembly overwrite while xUnit runs them in parallel.
+        /// </summary>
+        internal sealed class TestItem : BaseItem
+        {
+            public bool Saved { get; private set; }
+
+            public override bool RequiresRefresh() => false;
+
+            public override bool IsSaveLocalMetadataEnabled() => false;
+
+            public override string CreatePresentationUniqueKey() => Id.ToString("N", CultureInfo.InvariantCulture);
+
+            public override ItemUpdateType OnMetadataChanged() => ItemUpdateType.None;
+
+            public override bool BeforeMetadataRefresh(bool replaceAllMetadata) => false;
+
+            public override Task UpdateToRepositoryAsync(ItemUpdateType updateReason, CancellationToken cancellationToken)
+            {
+                Saved = true;
+                return Task.CompletedTask;
+            }
+        }
+
+        private sealed class TestMetadataService : MetadataService<Movie, MovieInfo>
+        {
+            public TestMetadataService()
+                : base(
+                    Mock.Of<IServerConfigurationManager>(),
+                    NullLogger<MetadataService<Movie, MovieInfo>>.Instance,
+                    Mock.Of<IProviderManager>(),
+                    Mock.Of<IFileSystem>(),
+                    Mock.Of<ILibraryManager>(),
+                    Mock.Of<IExternalDataManager>(),
+                    Mock.Of<IItemRepository>())
+            {
+            }
+
+            public Task<RefreshResult> RefreshWithProvidersInternal(
+                MetadataResult<Movie> metadata,
+                MovieInfo id,
+                MetadataRefreshOptions options,
+                ICollection<IMetadataProvider> providers)
+                => RefreshWithProviders(metadata, id, options, providers, ImageProvider, false, CancellationToken.None);
+        }
+
+        private sealed class TestItemMetadataService : MetadataService<TestItem, ItemLookupInfo>
+        {
+            public TestItemMetadataService(ILibraryManager libraryManager, IProviderManager providerManager, IItemRepository itemRepository)
+                : base(
+                    Mock.Of<IServerConfigurationManager>(),
+                    NullLogger<MetadataService<TestItem, ItemLookupInfo>>.Instance,
+                    providerManager,
+                    Mock.Of<IFileSystem>(),
+                    libraryManager,
+                    Mock.Of<IExternalDataManager>(),
+                    itemRepository)
+            {
+            }
+        }
+    }
+}

tests/Jellyfin.Providers.Tests/Music/AlbumInfoExtensionsTests.cs

@@ -0,0 +1,59 @@
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Model.Entities;
+using MediaBrowser.Providers.Music;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Music;
+
+public static class AlbumInfoExtensionsTests
+{
+    private const string ExampleMbid = "59b5a40b-e2fd-3f18-a218-e8c9aae12ab5";
+    private const string SongMbid = "6c301dbd-6ccb-3403-a6c4-6a22240a0297";
+
+    [Theory]
+    [InlineData(ExampleMbid, ExampleMbid)]
+    // Another provider's id under a MusicBrainz key reads as no id, so the caller searches instead of
+    // handing a value the MusicBrainz client throws on.
+    [InlineData("111239", null)]
+    [InlineData("", null)]
+    public static void GetReleaseId_OnlyReturnsMbids(string id, string? expected)
+    {
+        var info = new AlbumInfo();
+        info.ProviderIds[MetadataProvider.MusicBrainzAlbum.ToString()] = id;
+
+        Assert.Equal(expected, info.GetReleaseId());
+    }
+
+    [Fact]
+    public static void GetReleaseId_ForeignId_FallsBackToSongs()
+    {
+        var song = new SongInfo();
+        song.ProviderIds[MetadataProvider.MusicBrainzAlbum.ToString()] = SongMbid;
+
+        var info = new AlbumInfo { SongInfos = [song] };
+        info.ProviderIds[MetadataProvider.MusicBrainzAlbum.ToString()] = "111239";
+
+        Assert.Equal(SongMbid, info.GetReleaseId());
+    }
+
+    [Fact]
+    public static void GetMusicBrainzArtistId_ForeignId_FallsBackToArtistIds()
+    {
+        var info = new AlbumInfo();
+        info.ProviderIds[MetadataProvider.MusicBrainzAlbumArtist.ToString()] = "111239";
+        info.ArtistProviderIds[MetadataProvider.MusicBrainzArtist.ToString()] = ExampleMbid;
+
+        Assert.Equal(ExampleMbid, info.GetMusicBrainzArtistId());
+    }
+
+    [Theory]
+    [InlineData(ExampleMbid, ExampleMbid)]
+    [InlineData("111239", null)]
+    public static void GetMusicBrainzArtistId_ArtistInfo_OnlyReturnsMbids(string id, string? expected)
+    {
+        var info = new ArtistInfo();
+        info.ProviderIds[MetadataProvider.MusicBrainzArtist.ToString()] = id;
+
+        Assert.Equal(expected, info.GetMusicBrainzArtistId());
+    }
+}

tests/Jellyfin.Providers.Tests/Omdb/OmdbProviderTests.cs

@@ -0,0 +1,81 @@
+using System.Linq;
+using Jellyfin.Data.Enums;
+using MediaBrowser.Controller.Entities.Movies;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Providers.Plugins.Omdb;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Omdb
+{
+    public class OmdbProviderTests
+    {
+        [Fact]
+        public void AddPeople_CommaSeparatedList_SplitsIntoIndividualPeople()
+        {
+            var result = new MetadataResult<Movie>();
+
+            OmdbProvider.AddPeople(result, "Philip G. Epstein, Julius J. Epstein, Howard Koch", PersonKind.Writer);
+
+            Assert.Equal(
+                new[] { "Philip G. Epstein", "Julius J. Epstein", "Howard Koch" },
+                result.People!.Select(p => p.Name));
+            Assert.All(result.People!, p => Assert.Equal(PersonKind.Writer, p.Type));
+        }
+
+        [Fact]
+        public void AddPeople_RoleAnnotations_AreStrippedAndDeduplicated()
+        {
+            var result = new MetadataResult<Movie>();
+
+            OmdbProvider.AddPeople(result, "Mari Okada (screenplay), Mari Okada (story), Jun'ichi Satô (screenplay), Jun'ichi Satô (story)", PersonKind.Writer);
+
+            Assert.Equal(
+                new[] { "Mari Okada", "Jun'ichi Satô" },
+                result.People!.Select(p => p.Name));
+        }
+
+        [Theory]
+        [InlineData(
+            "Jerry Siegel (created by: Superman, Superboy), Bob Kane (created by: Batman)",
+            "Jerry Siegel|Bob Kane")]
+        [InlineData("Alan Moore (created by: John Constantine)", "Alan Moore")]
+        public void AddPeople_CommaInsideAnAnnotation_StaysOneCredit(string credits, string expected)
+        {
+            var result = new MetadataResult<Movie>();
+
+            OmdbProvider.AddPeople(result, credits, PersonKind.Writer);
+
+            Assert.Equal(expected.Split('|'), result.People!.Select(p => p.Name));
+        }
+
+        [Theory]
+        [InlineData("Jack Salvatore, Jr.", "Jack Salvatore, Jr.")]
+        [InlineData("Efrem Zimbalist, Jr., Tom Hanks", "Efrem Zimbalist, Jr.|Tom Hanks")]
+        [InlineData("Tom Hanks, Sammy Davis, Jr", "Tom Hanks|Sammy Davis, Jr")]
+        [InlineData("Harold Ramis, Ken Griffey, III (voice)", "Harold Ramis|Ken Griffey, III")]
+        [InlineData("Robert Downey Jr., Gwyneth Paltrow", "Robert Downey Jr.|Gwyneth Paltrow")]
+        [InlineData("Jr., Tom Hanks", "Jr.|Tom Hanks")]
+        public void AddPeople_GenerationalSuffix_StaysWithItsName(string credits, string expected)
+        {
+            var result = new MetadataResult<Movie>();
+
+            OmdbProvider.AddPeople(result, credits, PersonKind.Actor);
+
+            Assert.Equal(expected.Split('|'), result.People!.Select(p => p.Name));
+        }
+
+        [Theory]
+        [InlineData(null)]
+        [InlineData("")]
+        [InlineData("   ")]
+        [InlineData("(uncredited)")]
+        public void AddPeople_NoUsableName_AddsNothing(string? credits)
+        {
+            var result = new MetadataResult<Movie>();
+
+            OmdbProvider.AddPeople(result, credits!, PersonKind.Actor);
+
+            Assert.Null(result.People);
+        }
+    }
+}

tests/Jellyfin.Providers.Tests/Tmdb/TmdbUtilsCastTests.cs

@@ -0,0 +1,105 @@
+using System.Collections.Generic;
+using System.Linq;
+using Jellyfin.Data.Enums;
+using MediaBrowser.Model.Entities;
+using MediaBrowser.Providers.Plugins.Tmdb;
+using TMDbLib.Objects.TvShows;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Tmdb
+{
+    public class TmdbUtilsCastTests
+    {
+        private static readonly PluginConfiguration _config = new() { MaxCastMembers = 10 };
+
+        [Fact]
+        public void MapAggregateCast_MemberWithSeveralRoles_YieldsOneCreditPerRole()
+        {
+            var cast = new List<CastAggregate>
+            {
+                CreateAggregate("Megumi Toyoguchi", 1, 0, ("Tabby (voice)", 3), ("Mimiru (voice)", 12))
+            };
+
+            var people = TmdbUtils.MapAggregateCast(cast, _config, _ => null).ToArray();
+
+            // The character they played the longest comes first, which is their own billing.
+            Assert.Equal(["Mimiru (voice)", "Tabby (voice)"], people.Select(p => p.Role));
+            Assert.All(people, p => Assert.Equal("Megumi Toyoguchi", p.Name));
+            Assert.All(people, p => Assert.Equal(PersonKind.Actor, p.Type));
+            Assert.All(people, p => Assert.Equal("1", p.GetProviderId(MetadataProvider.Tmdb)));
+        }
+
+        [Fact]
+        public void MapAggregateCast_MemberWithoutARole_IsStillCredited()
+        {
+            var cast = new List<CastAggregate> { CreateAggregate("Uncredited Actor", 2, 0) };
+
+            var person = Assert.Single(TmdbUtils.MapAggregateCast(cast, _config, _ => null));
+
+            Assert.Equal(string.Empty, person.Role);
+        }
+
+        [Fact]
+        public void MapAggregateCast_MoreThanConfigured_KeepsTheTopBilled()
+        {
+            var cast = Enumerable.Range(0, 5)
+                .Select(i => CreateAggregate($"Actor {4 - i}", i + 1, 4 - i, ($"Role {4 - i}", 1)))
+                .ToList();
+
+            var people = TmdbUtils.MapAggregateCast(cast, new PluginConfiguration { MaxCastMembers = 2 }, _ => null);
+
+            Assert.Equal(["Actor 0", "Actor 1"], people.Select(p => p.Name));
+        }
+
+        [Fact]
+        public void MapAggregateCast_HideMissingCastMembers_DropsTheOnesWithoutAProfile()
+        {
+            var withProfile = CreateAggregate("Has Profile", 1, 0, ("Hero", 1));
+            withProfile.ProfilePath = "/profile.jpg";
+            var cast = new List<CastAggregate> { withProfile, CreateAggregate("No Profile", 2, 1, ("Villain", 1)) };
+
+            var people = TmdbUtils.MapAggregateCast(
+                cast,
+                new PluginConfiguration { MaxCastMembers = 10, HideMissingCastMembers = true },
+                _ => null);
+
+            Assert.Equal(["Has Profile"], people.Select(p => p.Name));
+        }
+
+        [Fact]
+        public void MapCast_FlatCredits_YieldOneCreditEach()
+        {
+            var cast = new List<Cast>
+            {
+                new() { Name = "Kevin Conroy", Id = 1, Order = 0, Character = " Batman (voice) " },
+                new() { Name = "  ", Id = 2, Order = 1, Character = "Nobody" }
+            };
+
+            var person = Assert.Single(TmdbUtils.MapCast(cast, _config, _ => null));
+
+            Assert.Equal("Kevin Conroy", person.Name);
+            Assert.Equal("Batman (voice)", person.Role);
+        }
+
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void MapCast_NoCast_YieldsNothing(bool aggregate)
+        {
+            Assert.Empty(aggregate
+                ? TmdbUtils.MapAggregateCast(null, _config, _ => null)
+                : TmdbUtils.MapCast(null, _config, _ => null));
+        }
+
+        private static CastAggregate CreateAggregate(string name, int id, int order, params (string Character, int Episodes)[] roles)
+        {
+            return new CastAggregate
+            {
+                Name = name,
+                Id = id,
+                Order = order,
+                Roles = roles.Select(role => new CastRole { Character = role.Character, EpisodeCount = role.Episodes }).ToList()
+            };
+        }
+    }
+}

tests/Jellyfin.Providers.Tests/Tmdb/TmdbUtilsTests.cs

@@ -1,3 +1,5 @@
+using MediaBrowser.Controller.Entities.Movies;
+using MediaBrowser.Model.Entities;
 using MediaBrowser.Providers.Plugins.Tmdb;
 using Xunit;
 
@@ -34,5 +36,40 @@ namespace Jellyfin.Providers.Tests.Tmdb
         {
             Assert.Equal(expected, TmdbUtils.AdjustImageLanguage(imageLanguage, requestLanguage));
         }
+
+        [Theory]
+        [InlineData("11", true, 11)]
+        // An id another provider filed under the TMDb key must not throw, it is simply not a TMDb id.
+        [InlineData("nm0000123", false, 0)]
+        [InlineData("tt0113375", false, 0)]
+        [InlineData("11.0", false, 0)]
+        [InlineData("-11", false, 0)]
+        [InlineData("0", false, 0)]
+        [InlineData("", false, 0)]
+        [InlineData(null, false, 0)]
+        public static void TryParseTmdbId_OnlyAcceptsTmdbIds(string? value, bool expected, int expectedId)
+        {
+            Assert.Equal(expected, TmdbUtils.TryParseTmdbId(value, out var tmdbId));
+            Assert.Equal(expectedId, tmdbId);
+        }
+
+        [Theory]
+        [InlineData("11", true, 11)]
+        [InlineData("nm0000123", false, 0)]
+        public static void TryGetTmdbId_OnlyAcceptsTmdbIds(string value, bool expected, int expectedId)
+        {
+            var item = new Movie();
+            item.ProviderIds[MetadataProvider.Tmdb.ToString()] = value;
+
+            Assert.Equal(expected, item.TryGetTmdbId(out var tmdbId));
+            Assert.Equal(expectedId, tmdbId);
+        }
+
+        [Fact]
+        public static void TryGetTmdbId_NoId_False()
+        {
+            Assert.False(new Movie().TryGetTmdbId(out var tmdbId));
+            Assert.Equal(0, tmdbId);
+        }
     }
 }

tests/Jellyfin.Server.Implementations.Tests/Dto/DtoServiceTests.cs

@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using Emby.Server.Implementations.Dto;
+using Jellyfin.Database.Implementations.Entities;
 using MediaBrowser.Common;
 using MediaBrowser.Controller.Chapters;
 using MediaBrowser.Controller.Drawing;
@@ -21,11 +23,13 @@ namespace Jellyfin.Server.Implementations.Tests.Dto;
 public class DtoServiceTests
 {
     private readonly Mock<ILibraryManager> _libraryManagerMock;
+    private readonly Mock<IUserDataManager> _userDataManagerMock;
     private readonly DtoService _dtoService;
 
     public DtoServiceTests()
     {
         _libraryManagerMock = new Mock<ILibraryManager>();
+        _userDataManagerMock = new Mock<IUserDataManager>();
 
         var imageProcessor = new Mock<IImageProcessor>();
         // Deterministic tag derived from the image so each item gets a distinct, assertable tag.
@@ -42,7 +46,7 @@ public class DtoServiceTests
         _dtoService = new DtoService(
             NullLogger<DtoService>.Instance,
             _libraryManagerMock.Object,
-            new Mock<IUserDataManager>().Object,
+            _userDataManagerMock.Object,
             imageProcessor.Object,
             new Mock<IProviderManager>().Object,
             new Mock<IRecordingsManager>().Object,
@@ -105,6 +109,57 @@ public class DtoServiceTests
         Assert.Null(dto.ParentPrimaryImageItemId);
     }
 
+    [Fact]
+    public void GetBaseItemDtos_SeasonWithNoRealEpisodes_ReportsVirtualEpisodesAsChildCount()
+    {
+        // No episode has aired yet, so RecursiveItemCount is 0. ChildCount must still report the
+        // virtual episodes clients get back for the season. This deliberately does not track
+        // Season.IsVirtualItem: that flag is recomputed only on a full refresh, so a season can
+        // carry it while already holding real episodes.
+        var (season, user) = BuildSeason(playedCount: 0, totalCount: 0, childCount: 10);
+        var options = new DtoOptions(false) { EnableImages = false, Fields = [ItemFields.ChildCount, ItemFields.RecursiveItemCount] };
+
+        var dto = _dtoService.GetBaseItemDtos([season], options, user, skipVisibilityCheck: true)[0];
+
+        Assert.Equal(0, dto.RecursiveItemCount);
+        Assert.Equal(10, dto.ChildCount);
+    }
+
+    [Fact]
+    public void GetBaseItemDtos_SeasonWithRealEpisodes_KeepsRecursiveItemCountAsChildCount()
+    {
+        var (season, user) = BuildSeason(playedCount: 2, totalCount: 9, childCount: 11);
+        var options = new DtoOptions(false) { EnableImages = false, Fields = [ItemFields.ChildCount, ItemFields.RecursiveItemCount] };
+
+        var dto = _dtoService.GetBaseItemDtos([season], options, user, skipVisibilityCheck: true)[0];
+
+        Assert.Equal(9, dto.RecursiveItemCount);
+        // The shortcut still wins over the batched child count, which also counts virtual episodes.
+        Assert.Equal(9, dto.ChildCount);
+    }
+
+    private (Season Season, User User) BuildSeason(int playedCount, int totalCount, int childCount)
+    {
+        var user = new User("user", "auth-provider", "reset-provider");
+        var season = new Season { Id = Guid.NewGuid(), Name = "Season 2", SeriesId = Guid.NewGuid() };
+
+        _userDataManagerMock
+            .Setup(x => x.GetUserDataBatch(It.IsAny<IReadOnlyList<BaseItem>>(), user))
+            .Returns(new Dictionary<Guid, UserItemData> { [season.Id] = new UserItemData { Key = "key" } });
+        _userDataManagerMock
+            .Setup(x => x.GetResumeUserDataBatch(It.IsAny<IReadOnlyList<BaseItem>>(), user))
+            .Returns(new Dictionary<Guid, VersionResumeData>());
+
+        _libraryManagerMock
+            .Setup(x => x.GetPlayedAndTotalCountBatch(It.IsAny<IReadOnlyList<Guid>>(), user))
+            .Returns(new Dictionary<Guid, (int Played, int Total)> { [season.Id] = (playedCount, totalCount) });
+        _libraryManagerMock
+            .Setup(x => x.GetChildCountBatch(It.IsAny<IReadOnlyList<Guid>>(), It.IsAny<Guid?>()))
+            .Returns(new Dictionary<Guid, int> { [season.Id] = childCount });
+
+        return (season, user);
+    }
+
     private (Episode Episode, Season Season, Series Series) BuildEpisode(bool seasonHasPoster, bool seriesHasPoster = true)
     {
         // Non-local (http) paths keep aspect-ratio resolution off the image processor and on the

tests/Jellyfin.Server.Implementations.Tests/Item/AlternateVersionQueryTranslationTests.cs

@@ -4,11 +4,6 @@ using System;
 using System.Linq;
 using Jellyfin.Database.Implementations;
 using Jellyfin.Database.Implementations.Entities;
-using Jellyfin.Database.Implementations.Locking;
-using Jellyfin.Database.Providers.Sqlite;
-using Microsoft.Data.Sqlite;
-using Microsoft.EntityFrameworkCore;
-using Microsoft.Extensions.Logging.Abstractions;
 using Xunit;
 
 namespace Jellyfin.Server.Implementations.Tests.Item;
@@ -18,22 +13,10 @@ namespace Jellyfin.Server.Implementations.Tests.Item;
 /// (BaseItemRepository.TranslateQuery) and the DatePlayed ordering (OrderMapper) translate
 /// and evaluate correctly on the SQLite provider.
 /// </summary>
-public sealed class AlternateVersionQueryTranslationTests : IDisposable
+public sealed class AlternateVersionQueryTranslationTests : SqliteDbTestFixture
 {
-    private readonly SqliteConnection _connection;
-    private readonly DbContextOptions<JellyfinDbContext> _dbOptions;
-
     public AlternateVersionQueryTranslationTests()
     {
-        _connection = new SqliteConnection("Data Source=:memory:");
-        _connection.Open();
-
-        _dbOptions = new DbContextOptionsBuilder<JellyfinDbContext>()
-            .UseSqlite(_connection)
-            .Options;
-
-        using var ctx = CreateDbContext();
-        ctx.Database.EnsureCreated();
     }
 
     [Fact]
@@ -220,18 +203,4 @@ public sealed class AlternateVersionQueryTranslationTests : IDisposable
         ctx.SaveChanges();
         return (user.Id, primary.Id, versionA.Id, versionB.Id);
     }
-
-    private JellyfinDbContext CreateDbContext()
-    {
-        return new JellyfinDbContext(
-            _dbOptions,
-            NullLogger<JellyfinDbContext>.Instance,
-            new SqliteDatabaseProvider(null!, NullLogger<SqliteDatabaseProvider>.Instance),
-            new NoLockBehavior(NullLogger<NoLockBehavior>.Instance));
-    }
-
-    public void Dispose()
-    {
-        _connection.Dispose();
-    }
 }