Merge pull request #17044 from Shadowghost/version-model-and-handling

Fixes for multi version handling

Emby.Server.Implementations/Dto/DtoService.cs

@@ -169,9 +169,13 @@ namespace Emby.Server.Implementations.Dto
 
             // Batch-fetch user data for all items
             Dictionary<Guid, UserItemData>? userDataBatch = null;
+            IReadOnlyDictionary<Guid, VersionResumeData>? resumeDataBatch = null;
             if (user is not null && options.EnableUserData)
             {
                 userDataBatch = _userDataRepository.GetUserDataBatch(accessibleItems, user);
+
+                // For items with alternate versions, the most recently played version drives resume.
+                resumeDataBatch = _userDataRepository.GetResumeUserDataBatch(accessibleItems, user);
             }
 
             // Pre-compute collection folders once to avoid N+1 queries in CanDelete
@@ -250,7 +254,8 @@ namespace Emby.Server.Implementations.Dto
                     allCollectionFolders,
                     childCountBatch,
                     playedCountBatch,
-                    artistsBatch);
+                    artistsBatch,
+                    resumeDataBatch?.GetValueOrDefault(item.Id));
 
                 if (item is LiveTvChannel tvChannel)
                 {
@@ -311,7 +316,8 @@ namespace Emby.Server.Implementations.Dto
             List<Folder>? allCollectionFolders = null,
             Dictionary<Guid, int>? childCountBatch = null,
             Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null,
-            IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null)
+            IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null,
+            VersionResumeData? resumeData = null)
         {
             var dto = new BaseItemDto
             {
@@ -355,7 +361,8 @@ namespace Emby.Server.Implementations.Dto
                     options,
                     userData,
                     childCountBatch,
-                    playedCountBatch);
+                    playedCountBatch,
+                    resumeData);
             }
 
             if (item is IHasMediaSources
@@ -371,7 +378,7 @@ namespace Emby.Server.Implementations.Dto
                 AttachStudios(dto, item);
             }
 
-            AttachBasicFields(dto, item, owner, options, artistsBatch);
+            AttachBasicFields(dto, item, owner, options, artistsBatch, user);
 
             if (options.ContainsField(ItemFields.CanDelete))
             {
@@ -540,7 +547,8 @@ namespace Emby.Server.Implementations.Dto
             DtoOptions options,
             UserItemData? userData = null,
             Dictionary<Guid, int>? childCountBatch = null,
-            Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null)
+            Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null,
+            VersionResumeData? resumeData = null)
         {
             if (item.IsFolder)
             {
@@ -602,6 +610,9 @@ namespace Emby.Server.Implementations.Dto
                         // Use pre-fetched user data
                         dto.UserData = GetUserItemDataDto(userData, item.Id);
                         item.FillUserDataDtoValues(dto.UserData, userData, dto, user, options);
+
+                        // For items with alternate versions, the most recently played version drives resume.
+                        resumeData?.ApplyTo(dto.UserData);
                     }
                     else
                     {
@@ -945,7 +956,8 @@ namespace Emby.Server.Implementations.Dto
         /// <param name="owner">The owner.</param>
         /// <param name="options">The options.</param>
         /// <param name="artistsBatch">Optional pre-fetched artist lookup shared across a batch of items.</param>
-        private void AttachBasicFields(BaseItemDto dto, BaseItem item, BaseItem? owner, DtoOptions options, IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null)
+        /// <param name="user">The user, for per-user values such as the accessible media source count.</param>
+        private void AttachBasicFields(BaseItemDto dto, BaseItem item, BaseItem? owner, DtoOptions options, IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null, User? user = null)
         {
             if (options.ContainsField(ItemFields.DateCreated))
             {
@@ -1259,7 +1271,12 @@ namespace Emby.Server.Implementations.Dto
 
                 if (options.ContainsField(ItemFields.MediaSourceCount))
                 {
-                    var mediaSourceCount = video.MediaSourceCount;
+                    // Match the per-user filtering of the media sources: versions the user cannot
+                    // access are not selectable, so they must not count towards the badge either.
+                    var mediaSourceCount = user is null
+                        || (!video.PrimaryVersionId.HasValue && video.LinkedAlternateVersions.Length == 0 && !video.HasLocalAlternateVersions)
+                            ? video.MediaSourceCount
+                            : video.GetAllVersions().Count(v => v.Id.Equals(video.Id) || v.IsVisibleStandalone(user));
                     if (mediaSourceCount != 1)
                     {
                         dto.MediaSourceCount = mediaSourceCount;

Emby.Server.Implementations/Library/MediaSourceManager.cs

@@ -229,7 +229,11 @@ namespace Emby.Server.Implementations.Library
                 list.Add(source);
             }
 
-            return SortMediaSources(list, item.Id).ToArray();
+            var preferredId = mediaSources.Count > 0 && Guid.TryParse(mediaSources[0].Id, out var topSourceId)
+                ? topSourceId
+                : item.Id;
+
+            return SortMediaSources(list, preferredId).ToArray();
         }
 
         /// <inheritdoc />>
@@ -406,6 +410,69 @@ namespace Emby.Server.Implementations.Library
                         source.SupportsDirectStream = user.HasPermission(PermissionKind.EnablePlaybackRemuxing);
                     }
                 }
+
+                sources = SetAlternateVersionResumeStates(item, sources, user);
+            }
+
+            return sources;
+        }
+
+        /// <summary>
+        /// Populates each source's own playback position for the user and, when the queried item is a
+        /// primary, moves the most recently played version to the front so that resuming without an
+        /// explicit source selection plays the version that was last watched. A directly queried
+        /// alternate version keeps its own source first.
+        /// </summary>
+        /// <param name="item">The queried item.</param>
+        /// <param name="sources">The item's media sources.</param>
+        /// <param name="user">The user.</param>
+        /// <returns>The media sources, reordered when a version drives resume.</returns>
+        private IReadOnlyList<MediaSourceInfo> SetAlternateVersionResumeStates(BaseItem item, IReadOnlyList<MediaSourceInfo> sources, User user)
+        {
+            // For a video, multiple sources means alternate versions.
+            if (item is not Video video || sources.Count < 2)
+            {
+                return sources;
+            }
+
+            var versions = video.GetAllVersions();
+            if (versions.Count < 2)
+            {
+                return sources;
+            }
+
+            var userDataByVersion = _userDataManager.GetUserDataBatch(versions, user);
+            var dataBySourceId = new Dictionary<string, UserItemData>(versions.Count, StringComparer.OrdinalIgnoreCase);
+            foreach (var version in versions)
+            {
+                if (userDataByVersion.TryGetValue(version.Id, out var data))
+                {
+                    dataBySourceId[version.Id.ToString("N", CultureInfo.InvariantCulture)] = data;
+                }
+            }
+
+            foreach (var source in sources)
+            {
+                if (source.Id is not null
+                    && dataBySourceId.TryGetValue(source.Id, out var data)
+                    && data.PlaybackPositionTicks > 0)
+                {
+                    source.PlaybackPositionTicks = data.PlaybackPositionTicks;
+                }
+            }
+
+            // Reorder only for a resumable (in-progress) version;
+            // a completed version has no position to resume, so it must not be pulled to the front here.
+            var resumeSource = VersionPlaybackSelector.SelectMostRecentlyPlayed(
+                sources,
+                source => source.Id is not null ? dataBySourceId.GetValueOrDefault(source.Id) : null,
+                data => data.PlaybackPositionTicks > 0);
+
+            if (resumeSource is not null && !video.PrimaryVersionId.HasValue && !ReferenceEquals(sources[0], resumeSource))
+            {
+                var reordered = new List<MediaSourceInfo>(sources.Count) { resumeSource };
+                reordered.AddRange(sources.Where(s => !ReferenceEquals(s, resumeSource)));
+                return reordered;
             }
 
             return sources;

Emby.Server.Implementations/Library/UserDataManager.cs

@@ -247,6 +247,103 @@ namespace Emby.Server.Implementations.Library
             return result;
         }
 
+        /// <inheritdoc />
+        public VersionResumeData? GetResumeUserData(User user, BaseItem item)
+        {
+            return GetResumeUserDataBatch([item], user).GetValueOrDefault(item.Id);
+        }
+
+        /// <inheritdoc />
+        public IReadOnlyDictionary<Guid, VersionResumeData> GetResumeUserDataBatch(IReadOnlyList<BaseItem> items, User user)
+        {
+            ArgumentNullException.ThrowIfNull(user);
+
+            var result = new Dictionary<Guid, VersionResumeData>();
+
+            // Candidate primaries: a directly queried version (PrimaryVersionId set) keeps its own data.
+            // Linked alternates are already known in memory; only the local-alternate existence check
+            // would otherwise hit the database (one query per item via Video.HasLocalAlternateVersions),
+            // so collect those ids and resolve them all in a single query below.
+            List<Video>? candidates = null;
+            List<Guid>? localProbeIds = null;
+            foreach (var item in items)
+            {
+                if (item is not Video video || video.PrimaryVersionId.HasValue)
+                {
+                    continue;
+                }
+
+                (candidates ??= []).Add(video);
+
+                if (video.LinkedAlternateVersions.Length == 0)
+                {
+                    (localProbeIds ??= []).Add(video.Id);
+                }
+            }
+
+            if (candidates is null)
+            {
+                return result;
+            }
+
+            HashSet<Guid>? withLocalAlternates = null;
+            if (localProbeIds is not null)
+            {
+                using var dbContext = _repository.CreateDbContext();
+                withLocalAlternates = dbContext.LinkedChildren
+                    .Where(lc => lc.ChildType == Jellyfin.Database.Implementations.Entities.LinkedChildType.LocalAlternateVersion
+                        && localProbeIds.Contains(lc.ParentId))
+                    .Select(lc => lc.ParentId)
+                    .Distinct()
+                    .ToHashSet();
+            }
+
+            List<(Guid PrimaryId, IReadOnlyList<Video> Versions)>? versionGroups = null;
+            List<BaseItem>? allVersions = null;
+
+            foreach (var video in candidates)
+            {
+                // Only items that actually have alternate versions aggregate over them.
+                if (video.LinkedAlternateVersions.Length == 0
+                    && (withLocalAlternates is null || !withLocalAlternates.Contains(video.Id)))
+                {
+                    continue;
+                }
+
+                var versions = video.GetAllVersions();
+                if (versions.Count < 2)
+                {
+                    continue;
+                }
+
+                (versionGroups ??= []).Add((video.Id, versions));
+                (allVersions ??= []).AddRange(versions);
+            }
+
+            if (versionGroups is null)
+            {
+                return result;
+            }
+
+            var userDataByVersion = GetUserDataBatch(allVersions!.DistinctBy(i => i.Id).ToList(), user);
+
+            foreach (var (primaryId, versions) in versionGroups)
+            {
+                // Consider both in-progress and completed versions so a finished alternate still marks the primary as played.
+                var resumeVersion = VersionPlaybackSelector.SelectMostRecentlyPlayed(
+                    versions,
+                    version => userDataByVersion.GetValueOrDefault(version.Id),
+                    data => data.PlaybackPositionTicks > 0 || data.Played);
+
+                if (resumeVersion is not null)
+                {
+                    result[primaryId] = new VersionResumeData(resumeVersion.Id, userDataByVersion[resumeVersion.Id]);
+                }
+            }
+
+            return result;
+        }
+
         /// <summary>
         /// Gets the internal key.
         /// </summary>
@@ -281,6 +378,10 @@ namespace Emby.Server.Implementations.Library
             var dto = GetUserItemDataDto(userData, item.Id);
 
             item.FillUserDataDtoValues(dto, userData, itemDto, user, options);
+
+            // For an item with alternate versions, surface the most recently played version's resume point.
+            GetResumeUserData(user, item)?.ApplyTo(dto);
+
             return dto;
         }
 
@@ -385,5 +486,41 @@ namespace Emby.Server.Implementations.Library
 
             return playedToCompletion;
         }
+
+        /// <inheritdoc />
+        public void ResetPlaybackStreamSelections(User user, BaseItem item)
+        {
+            ArgumentNullException.ThrowIfNull(user);
+            ArgumentNullException.ThrowIfNull(item);
+
+            using var dbContext = _repository.CreateDbContext();
+            var rows = dbContext.UserData
+                .Where(e => e.ItemId == item.Id && e.UserId == user.Id
+                            && (e.AudioStreamIndex != null || e.SubtitleStreamIndex != null))
+                .ToList();
+
+            if (rows.Count == 0)
+            {
+                return;
+            }
+
+            foreach (var row in rows)
+            {
+                row.AudioStreamIndex = null;
+                row.SubtitleStreamIndex = null;
+            }
+
+            dbContext.SaveChanges();
+
+            var cacheKey = GetCacheKey(user.InternalId, item.Id);
+            if (_cache.TryGet(cacheKey, out var cached))
+            {
+                cached.AudioStreamIndex = null;
+                cached.SubtitleStreamIndex = null;
+                _cache.AddOrUpdate(cacheKey, cached);
+            }
+
+            item.UserData = dbContext.UserData.Where(e => e.ItemId == item.Id).AsNoTracking().ToArray();
+        }
     }
 }

Emby.Server.Implementations/Session/SessionManager.cs

@@ -729,6 +729,31 @@ namespace Emby.Server.Implementations.Session
             return item;
         }
 
+        /// <summary>
+        /// Resolves the item whose user data (playback position, played status) should be updated
+        /// for a playback report. When an alternate version is played the client reports the displayed
+        /// item as <c>ItemId</c> and the played version as <c>MediaSourceId</c>.
+        /// </summary>
+        /// <param name="libraryItem">The now playing (displayed) item.</param>
+        /// <param name="mediaSourceId">The reported media source id.</param>
+        /// <returns>The item to track progress against.</returns>
+        private BaseItem GetProgressItem(BaseItem libraryItem, string mediaSourceId)
+        {
+            if (libraryItem is Video libraryVideo
+                && !string.IsNullOrEmpty(mediaSourceId)
+                && Guid.TryParse(mediaSourceId, out var mediaSourceItemId)
+                && !mediaSourceItemId.Equals(libraryVideo.Id))
+            {
+                var versionItem = libraryVideo.GetAlternateVersion(mediaSourceItemId);
+                if (versionItem is not null)
+                {
+                    return versionItem;
+                }
+            }
+
+            return libraryItem;
+        }
+
         /// <summary>
         /// Used to report that playback has started for an item.
         /// </summary>
@@ -760,9 +785,10 @@ namespace Emby.Server.Implementations.Session
 
             if (libraryItem is not null)
             {
+                var progressItem = GetProgressItem(libraryItem, info.MediaSourceId);
                 foreach (var user in users)
                 {
-                    OnPlaybackStart(user, libraryItem);
+                    OnPlaybackStart(user, progressItem);
                 }
             }
 
@@ -894,9 +920,10 @@ namespace Emby.Server.Implementations.Session
             // only update saved user data on actual check-ins, not automated ones
             if (libraryItem is not null && !isAutomated)
             {
+                var progressItem = GetProgressItem(libraryItem, info.MediaSourceId);
                 foreach (var user in users)
                 {
-                    OnPlaybackProgress(user, libraryItem, info);
+                    OnPlaybackProgress(user, progressItem, info);
                 }
             }
 
@@ -956,6 +983,20 @@ namespace Emby.Server.Implementations.Session
             if (changed)
             {
                 _userDataManager.SaveUserData(user, item, data, UserDataSaveReason.PlaybackProgress, CancellationToken.None);
+
+                // A completed version marks every alternate version played and clears their resume points, so the
+                // whole movie leaves Continue Watching and reads as watched everywhere. (Per-version resume positions
+                // only persist while nothing has been completed yet.)
+                if (data.Played == true && item is Video playedVideo)
+                {
+                    playedVideo.PropagatePlayedState(user, true);
+                }
+            }
+
+            if ((!user.RememberAudioSelections && info.AudioStreamIndex.HasValue)
+                || (!user.RememberSubtitleSelections && info.SubtitleStreamIndex.HasValue))
+            {
+                _userDataManager.ResetPlaybackStreamSelections(user, item);
             }
         }
 
@@ -1087,9 +1128,10 @@ namespace Emby.Server.Implementations.Session
 
             if (libraryItem is not null)
             {
+                var progressItem = GetProgressItem(libraryItem, info.MediaSourceId);
                 foreach (var user in users)
                 {
-                    playedToCompletion = OnPlaybackStopped(user, libraryItem, info.PositionTicks, info.Failed);
+                    playedToCompletion = OnPlaybackStopped(user, progressItem, info.PositionTicks, info.Failed);
                 }
             }
 
@@ -1142,6 +1184,14 @@ namespace Emby.Server.Implementations.Session
 
             _userDataManager.SaveUserData(user, item, data, UserDataSaveReason.PlaybackFinished, CancellationToken.None);
 
+            // A completed version marks every alternate version played and clears their resume points, so the
+            // whole movie leaves Continue Watching and reads as watched everywhere. (Per-version resume positions
+            // only persist while nothing has been completed yet.)
+            if (data.Played == true && item is Video playedVideo)
+            {
+                playedVideo.PropagatePlayedState(user, true);
+            }
+
             return playedToCompletion;
         }
 

Emby.Server.Implementations/TV/TVSeriesManager.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using Jellyfin.Data;
 using Jellyfin.Data.Enums;
@@ -136,11 +137,15 @@ namespace Emby.Server.Implementations.TV
 
                 if (nextEpisode is not null)
                 {
+                    // The last played date and the version that was actually played live on the version item's user data
+                    // The played state propagated to the sibling versions carries no date
+                    var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(result.LastWatched, user);
+                    nextEpisode = GetPreferredVersion(nextEpisode, result.LastWatched, playedVersion);
+
                     DateTime lastWatchedDate = DateTime.MinValue;
                     if (result.LastWatched is not null)
                     {
-                        var userData = _userDataManager.GetUserData(user, result.LastWatched);
-                        lastWatchedDate = userData?.LastPlayedDate ?? DateTime.MinValue.AddDays(1);
+                        lastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
                     }
 
                     nextUpList.Add((lastWatchedDate, nextEpisode));
@@ -152,11 +157,13 @@ namespace Emby.Server.Implementations.TV
 
                     if (nextPlayedEpisode is not null)
                     {
+                        var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(result.LastWatchedForRewatching, user);
+                        nextPlayedEpisode = GetPreferredVersion(nextPlayedEpisode, result.LastWatchedForRewatching, playedVersion);
+
                         DateTime rewatchLastWatchedDate = DateTime.MinValue;
                         if (result.LastWatchedForRewatching is not null)
                         {
-                            var userData = _userDataManager.GetUserData(user, result.LastWatchedForRewatching);
-                            rewatchLastWatchedDate = userData?.LastPlayedDate ?? DateTime.MinValue.AddDays(1);
+                            rewatchLastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
                         }
 
                         nextUpList.Add((rewatchLastWatchedDate, nextPlayedEpisode));
@@ -219,10 +226,13 @@ namespace Emby.Server.Implementations.TV
 
             if (nextEpisode is not null && !includeResumable)
             {
-                var userData = _userDataManager.GetUserData(user, nextEpisode);
-                if (userData?.PlaybackPositionTicks > 0)
+                // The resume progress may live on an alternate version
+                foreach (var version in nextEpisode.GetAllVersions())
                 {
-                    return null;
+                    if (_userDataManager.GetUserData(user, version)?.PlaybackPositionTicks > 0)
+                    {
+                        return null;
+                    }
                 }
             }
 
@@ -237,6 +247,74 @@ namespace Emby.Server.Implementations.TV
             return DetermineNextEpisode(result, user, includeSpecials, includeResumable: false, includePlayed: true);
         }
 
+        /// <summary>
+        /// Gets the version of the last watched episode that was actually played, together with its last played date.
+        /// The version that was played carries the most recent LastPlayedDate.
+        /// dates.
+        /// </summary>
+        /// <param name="lastWatched">The last watched episode (any version).</param>
+        /// <param name="user">The user.</param>
+        /// <returns>The played version and its last played date.</returns>
+        private (Video? PlayedVersion, DateTime? LastPlayedDate) GetMostRecentlyPlayedVersion(BaseItem? lastWatched, User user)
+        {
+            if (lastWatched is not Video lastWatchedVideo)
+            {
+                return (null, null);
+            }
+
+            var versions = lastWatchedVideo.GetAllVersions();
+            var userDataByVersion = _userDataManager.GetUserDataBatch(versions, user);
+
+            var playedVersion = VersionPlaybackSelector.SelectMostRecentlyPlayed(
+                versions,
+                version => userDataByVersion.GetValueOrDefault(version.Id),
+                data => data.LastPlayedDate.HasValue);
+
+            return (playedVersion, playedVersion is null ? null : userDataByVersion[playedVersion.Id].LastPlayedDate);
+        }
+
+        /// <summary>
+        /// When the last watched episode was played as an alternate version, prefer the next episode's version with the matching name,
+        /// so Next Up continues in the version the user has been watching instead of falling back to the primary.
+        /// </summary>
+        /// <param name="nextEpisode">The determined next episode (a primary).</param>
+        /// <param name="lastWatched">The last watched episode.</param>
+        /// <param name="playedVersion">The version of the last watched episode that was played.</param>
+        /// <returns>The matching version of the next episode, or the episode itself.</returns>
+        private Episode GetPreferredVersion(Episode nextEpisode, BaseItem? lastWatched, Video? playedVersion)
+        {
+            // No version preference, or the primary was played
+            if (lastWatched is not Video lastWatchedVideo
+                || playedVersion is null
+                || !playedVersion.PrimaryVersionId.HasValue)
+            {
+                return nextEpisode;
+            }
+
+            // Match by version name
+            var playedVersionId = playedVersion.Id.ToString("N", CultureInfo.InvariantCulture);
+            var playedVersionName = lastWatchedVideo.GetMediaSources(false)
+                .FirstOrDefault(source => string.Equals(source.Id, playedVersionId, StringComparison.OrdinalIgnoreCase))?.Name;
+
+            if (string.IsNullOrEmpty(playedVersionName))
+            {
+                return nextEpisode;
+            }
+
+            var matchingSource = nextEpisode.GetMediaSources(false)
+                .FirstOrDefault(source => string.Equals(source.Name, playedVersionName, StringComparison.OrdinalIgnoreCase));
+
+            if (matchingSource is not null
+                && Guid.TryParse(matchingSource.Id, out var matchingId)
+                && !matchingId.Equals(nextEpisode.Id)
+                && _libraryManager.GetItemById<Episode>(matchingId) is { } matchingVersion)
+            {
+                return matchingVersion;
+            }
+
+            return nextEpisode;
+        }
+
         private static string GetUniqueSeriesKey(Series series)
         {
             return series.GetPresentationUniqueKey();

Jellyfin.Api/Controllers/ItemsController.cs

@@ -965,9 +965,15 @@ public class ItemsController : BaseJellyfinApiController
         var excludeItemIds = Array.Empty<Guid>();
         if (excludeActiveSessions)
         {
+            // NowPlayingItem.Id is the displayed/primary id, but resume queries surface the actually-played
+            // alternate version's own id. Expand each active session to every version id so an in-progress
+            // alternate is excluded too, instead of leaking back into the resume list.
             excludeItemIds = _sessionManager.Sessions
                 .Where(s => s.UserId.Equals(requestUserId) && s.NowPlayingItem is not null)
-                .Select(s => s.NowPlayingItem.Id)
+                .SelectMany(s => _libraryManager.GetItemById(s.NowPlayingItem.Id) is Video video
+                    ? video.GetAllVersions().Select(v => v.Id)
+                    : [s.NowPlayingItem.Id])
+                .Distinct()
                 .ToArray();
         }
 

Jellyfin.Api/Controllers/TvShowsController.cs

@@ -277,8 +277,15 @@ public class TvShowsController : BaseJellyfinApiController
 
         if (startItemId.HasValue)
         {
+            // The start item may be an alternate version, which is not part of the episode listing; start from its primary episode instead.
+            var startId = startItemId.Value;
+            if (_libraryManager.GetItemById<Video>(startId)?.PrimaryVersionId is { } primaryVersionId)
+            {
+                startId = primaryVersionId;
+            }
+
             episodes = episodes
-                .SkipWhile(i => !startItemId.Value.Equals(i.Id))
+                .SkipWhile(i => !startId.Equals(i.Id))
                 .ToList();
         }
 

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

@@ -62,18 +62,21 @@ public sealed partial class BaseItemRepository
 
     private IQueryable<BaseItemEntity> ApplyGroupingFilter(JellyfinDbContext context, IQueryable<BaseItemEntity> dbQuery, InternalItemsQuery filter)
     {
-        // Collapse duplicates sharing a presentation key (e.g. alternate versions) by picking
-        // the min Id per group. Keep the grouped ids as an IQueryable sub-select; materializing
+        // Collapse duplicates sharing a presentation key (e.g. alternate versions), preferring the
+        // primary version (PrimaryVersionId is null) so detail pages and actions target it instead
+        // of an arbitrary alternate. Keep the grouped ids as an IQueryable sub-select; materializing
         // to a List would inline one bound parameter per id and hit SQLite's variable cap.
         var enableGroupByPresentationUniqueKey = EnableGroupByPresentationUniqueKey(filter);
         if (enableGroupByPresentationUniqueKey && filter.GroupBySeriesPresentationUniqueKey)
         {
-            var groupedIds = dbQuery.GroupBy(e => new { e.PresentationUniqueKey, e.SeriesPresentationUniqueKey }).Select(e => e.Min(x => x.Id));
+            var groupedIds = dbQuery.GroupBy(e => new { e.PresentationUniqueKey, e.SeriesPresentationUniqueKey })
+                .Select(g => g.Where(e => e.PrimaryVersionId == null).Min(e => (Guid?)e.Id) ?? g.Min(e => (Guid?)e.Id));
             dbQuery = context.BaseItems.AsNoTracking().Where(e => groupedIds.Contains(e.Id));
         }
         else if (enableGroupByPresentationUniqueKey)
         {
-            var groupedIds = dbQuery.GroupBy(e => e.PresentationUniqueKey).Select(e => e.Min(x => x.Id));
+            var groupedIds = dbQuery.GroupBy(e => e.PresentationUniqueKey)
+                .Select(g => g.Where(e => e.PrimaryVersionId == null).Min(e => (Guid?)e.Id) ?? g.Min(e => (Guid?)e.Id));
             dbQuery = context.BaseItems.AsNoTracking().Where(e => groupedIds.Contains(e.Id));
         }
         else if (filter.GroupBySeriesPresentationUniqueKey)

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

@@ -513,13 +513,17 @@ public sealed partial class BaseItemRepository
         if (filter.IsResumable.HasValue)
         {
             var hasSeries = filter.IncludeItemTypes.Contains(BaseItemKind.Series);
+            var userId = filter.User!.Id;
+            var isResumable = filter.IsResumable.Value;
+            var seriesTypeName = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Series];
 
+            // In-progress user data rows; alternate versions track their own progress.
+            var inProgress = context.UserData
+                .Where(ud => ud.UserId == userId && ud.PlaybackPositionTicks > 0);
+
+            IQueryable<Guid>? resumableSeriesIds = null;
             if (hasSeries)
             {
-                var userId = filter.User!.Id;
-                var seriesTypeName = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Series];
-                var isResumable = filter.IsResumable.Value;
-
                 // Aggregate per series in a single GROUP BY pass, instead of three full scans.
                 var seriesEpisodeStats = context.BaseItems
                     .AsNoTracking()
@@ -535,26 +539,44 @@ public sealed partial class BaseItemRepository
 
                 // A series is resumable if it has an in-progress episode,
                 // or if it has both played and unplayed episodes (partially watched).
-                var resumableSeriesIds = seriesEpisodeStats
+                resumableSeriesIds = seriesEpisodeStats
                     .Where(s => s.HasInProgress || (s.HasPlayed && s.HasUnplayed))
                     .Select(s => s.SeriesId);
+            }
 
-                // Non-series items: resumable if PlaybackPositionTicks > 0
-                var resumableItemIds = context.UserData
-                    .Where(ud => ud.UserId == userId && ud.PlaybackPositionTicks > 0)
-                    .Select(ud => ud.ItemId);
+            if (isResumable)
+            {
+                // Resume queries surface the version that was actually played, which may be an alternate.
+                // Match each version on its own progress rather than coalescing onto the primary.
+                var inProgressIds = inProgress.Select(ud => ud.ItemId);
 
-                baseQuery = baseQuery.Where(e =>
-                    (e.Type == seriesTypeName && resumableSeriesIds.Contains(e.Id) == isResumable)
-                    || (e.Type != seriesTypeName && resumableItemIds.Contains(e.Id) == isResumable));
+                baseQuery = hasSeries
+                    ? baseQuery.Where(e =>
+                        (e.Type == seriesTypeName && resumableSeriesIds!.Contains(e.Id))
+                        || (e.Type != seriesTypeName && inProgressIds.Contains(e.Id)))
+                    : baseQuery.Where(e => inProgressIds.Contains(e.Id));
+
+                // When several versions of the same item are in progress, keep only the most recently played one, use id as tiebreaker.
+                baseQuery = baseQuery.Where(e => e.Type == seriesTypeName || !context.BaseItems
+                    .Where(s => s.Id != e.Id && (s.PrimaryVersionId ?? s.Id) == (e.PrimaryVersionId ?? e.Id))
+                    .Any(s =>
+                        inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                            > inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                        || (inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                                == inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                            && s.Id.CompareTo(e.Id) < 0)));
             }
             else
             {
-                var resumableItemIds = context.UserData
-                    .Where(ud => ud.UserId == filter.User!.Id && ud.PlaybackPositionTicks > 0)
-                    .Select(ud => ud.ItemId);
-                var isResumable = filter.IsResumable.Value;
-                baseQuery = baseQuery.Where(e => resumableItemIds.Contains(e.Id) == isResumable);
+                // Not-resumable queries operate on primaries only.
+                var resumableMovieIds = inProgress
+                    .Join(context.BaseItems, ud => ud.ItemId, bi => bi.Id, (ud, bi) => bi.PrimaryVersionId ?? bi.Id);
+
+                baseQuery = hasSeries
+                    ? baseQuery.Where(e =>
+                        (e.Type == seriesTypeName && !resumableSeriesIds!.Contains(e.Id))
+                        || (e.Type != seriesTypeName && !resumableMovieIds.Contains(e.Id)))
+                    : baseQuery.Where(e => !resumableMovieIds.Contains(e.Id));
             }
         }
 
@@ -741,10 +763,13 @@ public sealed partial class BaseItemRepository
         }
         else if (filter.OwnerIds.Length == 0 && filter.ExtraTypes.Length == 0 && !filter.IncludeOwnedItems)
         {
-            // Exclude alternate versions and owned non-extra items from general queries.
-            // Alternate versions have PrimaryVersionId set (pointing to their primary).
+            // Exclude owned non-extra items from general queries.
             // Extras (trailers, etc.) have OwnerId set but also have ExtraType set - keep those.
-            baseQuery = baseQuery.Where(e => e.PrimaryVersionId == null && (e.OwnerId == null || e.ExtraType != null));
+            // Alternate versions (PrimaryVersionId set) are normally excluded too, but resume queries
+            // keep them so the actually-played version can surface instead of collapsing onto the primary.
+            baseQuery = filter.IsResumable == true
+                ? baseQuery.Where(e => e.OwnerId == null || e.ExtraType != null)
+                : baseQuery.Where(e => e.PrimaryVersionId == null && (e.OwnerId == null || e.ExtraType != null));
         }
 
         if (filter.OwnerIds.Length > 0)

Jellyfin.Server.Implementations/Item/BaseItemRepository.cs

@@ -167,6 +167,14 @@ public sealed partial class BaseItemRepository
             return false;
         }
 
+        // Resume queries surface the actually-played version (which may be an alternate sharing the
+        // primary's presentation key). The resumable filter already keeps one version per group, so
+        // presentation-key grouping must not collapse the surfaced version back onto the primary.
+        if (query.IsResumable == true)
+        {
+            return false;
+        }
+
         if (query.GroupBySeriesPresentationUniqueKey)
         {
             return false;

Jellyfin.Server.Implementations/Item/OrderMapper.cs

@@ -34,7 +34,14 @@ public static class OrderMapper
             (ItemSortBy.AirTime, _) => e => e.SortName,
             (ItemSortBy.Runtime, _) => e => e.RunTimeTicks,
             (ItemSortBy.Random, _) => e => EF.Functions.Random(),
-            (ItemSortBy.DatePlayed, _) => e => e.UserData!.Where(f => f.UserId.Equals(query.User!.Id)).OrderBy(f => f.CustomDataKey).FirstOrDefault()!.LastPlayedDate,
+            (ItemSortBy.DatePlayed, not null) => e =>
+                jellyfinDbContext.UserData
+                    .Where(w => w.UserId == query.User.Id && (w.ItemId == e.Id || w.Item!.PrimaryVersionId == e.Id))
+                    .Max(f => f.LastPlayedDate),
+            (ItemSortBy.DatePlayed, null) => e =>
+                jellyfinDbContext.UserData
+                    .Where(w => w.ItemId == e.Id || w.Item!.PrimaryVersionId == e.Id)
+                    .Max(f => f.LastPlayedDate),
             (ItemSortBy.PlayCount, _) => e => e.UserData!.Where(f => f.UserId.Equals(query.User!.Id)).OrderBy(f => f.CustomDataKey).FirstOrDefault()!.PlayCount,
             (ItemSortBy.IsFavoriteOrLiked, _) => e => e.UserData!.Where(f => f.UserId.Equals(query.User!.Id)).OrderBy(f => f.CustomDataKey).Select(f => (bool?)f.IsFavorite).FirstOrDefault() ?? false,
             (ItemSortBy.IsFolder, _) => e => e.IsFolder,

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -87,6 +87,8 @@ namespace MediaBrowser.Controller.Entities
             Model.Entities.ExtraType.Short
         };
 
+        private static readonly char[] VersionDelimiters = ['-', '_', '.'];
+
         private string _sortName;
 
         private string _forcedSortName;
@@ -1099,8 +1101,9 @@ namespace MediaBrowser.Controller.Entities
                 }
             }
 
-            var list = GetAllItemsForMediaSources();
-            var result = list.Select(i => GetVersionInfo(enablePathSubstitution, i.Item, i.MediaSourceType)).ToList();
+            var list = GetAllItemsForMediaSources().ToList();
+            var commonPrefix = GetCommonNamePrefix(list);
+            var result = list.Select(i => GetVersionInfo(enablePathSubstitution, i.Item, i.MediaSourceType, commonPrefix)).ToList();
 
             if (IsActiveRecording())
             {
@@ -1110,17 +1113,15 @@ namespace MediaBrowser.Controller.Entities
                 }
             }
 
-            return result.OrderBy(i =>
-            {
-                if (i.VideoType == VideoType.VideoFile)
-                {
-                    return 0;
-                }
+            // The source belonging to the item being queried sorts first so it is the default the client plays.
+            var selfId = Id.ToString("N", CultureInfo.InvariantCulture);
 
-                return 1;
-            }).ThenBy(i => i.Video3DFormat.HasValue ? 1 : 0)
-            .ThenByDescending(i => i, new MediaSourceWidthComparator())
-            .ToArray();
+            return result
+                .OrderByDescending(i => string.Equals(i.Id, selfId, StringComparison.OrdinalIgnoreCase))
+                .ThenBy(i => i.VideoType == VideoType.VideoFile ? 0 : 1)
+                .ThenBy(i => i.Video3DFormat.HasValue ? 1 : 0)
+                .ThenByDescending(i => i, new MediaSourceWidthComparator())
+                .ToArray();
         }
 
         protected virtual IEnumerable<(BaseItem Item, MediaSourceType MediaSourceType)> GetAllItemsForMediaSources()
@@ -1128,7 +1129,7 @@ namespace MediaBrowser.Controller.Entities
             return Enumerable.Empty<(BaseItem, MediaSourceType)>();
         }
 
-        private MediaSourceInfo GetVersionInfo(bool enablePathSubstitution, BaseItem item, MediaSourceType type)
+        private MediaSourceInfo GetVersionInfo(bool enablePathSubstitution, BaseItem item, MediaSourceType type, string commonPrefix = null)
         {
             ArgumentNullException.ThrowIfNull(item);
 
@@ -1141,7 +1142,7 @@ namespace MediaBrowser.Controller.Entities
                 Protocol = protocol ?? MediaProtocol.File,
                 MediaStreams = MediaSourceManager.GetMediaStreams(item.Id),
                 MediaAttachments = MediaSourceManager.GetMediaAttachments(item.Id),
-                Name = GetMediaSourceName(item),
+                Name = GetMediaSourceName(item, commonPrefix),
                 Path = enablePathSubstitution ? GetMappedPath(item, itemPath, protocol) : itemPath,
                 RunTimeTicks = item.RunTimeTicks,
                 Container = item.Container,
@@ -1220,7 +1221,7 @@ namespace MediaBrowser.Controller.Entities
             return info;
         }
 
-        internal string GetMediaSourceName(BaseItem item)
+        internal string GetMediaSourceName(BaseItem item, string commonPrefix = null)
         {
             var terms = new List<string>();
 
@@ -1228,12 +1229,31 @@ namespace MediaBrowser.Controller.Entities
             if (item.IsFileProtocol && !string.IsNullOrEmpty(path))
             {
                 var displayName = System.IO.Path.GetFileNameWithoutExtension(path);
-                if (HasLocalAlternateVersions)
+
+                // Prefer the suffix that differs from the other versions: strip the prefix shared by
+                // all sibling files. This works regardless of folder layout, so it also labels episode
+                // versions that share a season folder (e.g. "Greyscale" instead of the full
+                // "Show - S01E02 - Title - Greyscale"). The prefix is already retreated to a delimiter
+                // boundary (see GetCommonVersionPrefix).
+                if (!string.IsNullOrEmpty(commonPrefix)
+                    && displayName.Length > commonPrefix.Length
+                    && displayName.StartsWith(commonPrefix, StringComparison.OrdinalIgnoreCase))
+                {
+                    var name = displayName.AsSpan(commonPrefix.Length).TrimStart([' ', .. VersionDelimiters]);
+                    if (!name.IsWhiteSpace())
+                    {
+                        terms.Add(name.ToString());
+                    }
+                }
+
+                // Fall back to the containing folder name (the common layout for movie versions, and
+                // the path taken when no common prefix could be derived).
+                if (terms.Count == 0 && HasLocalAlternateVersions)
                 {
                     var containingFolderName = System.IO.Path.GetFileName(ContainingFolderPath);
                     if (displayName.Length > containingFolderName.Length && displayName.StartsWith(containingFolderName, StringComparison.OrdinalIgnoreCase))
                     {
-                        var name = displayName.AsSpan(containingFolderName.Length).TrimStart([' ', '-']);
+                        var name = displayName.AsSpan(containingFolderName.Length).TrimStart([' ', .. VersionDelimiters]);
                         if (!name.IsWhiteSpace())
                         {
                             terms.Add(name.ToString());
@@ -1290,6 +1310,98 @@ namespace MediaBrowser.Controller.Entities
             return string.Join('/', terms);
         }
 
+        /// <summary>
+        /// Derives the prefix shared by the supplied media source items' file names, used to strip the
+        /// common part and surface a short version label per source. Returns null when there are fewer
+        /// than two file-based sources, since there is nothing to differentiate.
+        /// </summary>
+        /// <param name="items">The media source items.</param>
+        /// <returns>The shared prefix, or null when no useful prefix exists.</returns>
+        private static string GetCommonNamePrefix(IReadOnlyList<(BaseItem Item, MediaSourceType MediaSourceType)> items)
+        {
+            var fileNames = new List<string>();
+            foreach (var (item, _) in items)
+            {
+                if (item.IsFileProtocol && !string.IsNullOrEmpty(item.Path))
+                {
+                    fileNames.Add(System.IO.Path.GetFileNameWithoutExtension(item.Path));
+                }
+            }
+
+            if (fileNames.Count < 2)
+            {
+                return null;
+            }
+
+            var prefix = GetCommonVersionPrefix(fileNames);
+            return string.IsNullOrEmpty(prefix) ? null : prefix;
+        }
+
+        /// <summary>
+        /// Computes the case-insensitive longest common prefix of the supplied version file names,
+        /// retreated to the last delimiter boundary. Retreating keeps the differing suffix intact:
+        /// it avoids slicing through a word every version shares (e.g. "Grey" in "Greyscale" and
+        /// "Greyish") while still trimming the common part when every version is suffixed (e.g.
+        /// "- Greyscale" / "- Colorized"). It prefers a structural delimiter ('-', '_', '.') so a
+        /// token shared by the descriptors but separated only by spaces (e.g. a common "2160p ") is
+        /// kept in the label, falling back to a space only when no structural delimiter is shared. The
+        /// separators mirror the version delimiters recognised by the naming layer (Emby.Naming
+        /// VideoFlagDelimiters).
+        /// </summary>
+        /// <param name="fileNames">The version file names without extension; must contain at least one entry.</param>
+        /// <returns>The shared prefix retreated to a separator boundary, or an empty string when none is shared.</returns>
+        internal static string GetCommonVersionPrefix(IReadOnlyList<string> fileNames)
+        {
+            var prefix = fileNames[0];
+            for (var i = 1; i < fileNames.Count && prefix.Length > 0; i++)
+            {
+                var name = fileNames[i];
+                var length = Math.Min(prefix.Length, name.Length);
+                var common = 0;
+                while (common < length && char.ToUpperInvariant(prefix[common]) == char.ToUpperInvariant(name[common]))
+                {
+                    common++;
+                }
+
+                prefix = prefix[..common];
+            }
+
+            // If the common prefix is itself a whole file name then one version is unlabelled (the
+            // base name); the boundary already sits at the end of that name, so don't retreat into it.
+            var prefixIsWholeName = false;
+            for (var i = 0; i < fileNames.Count; i++)
+            {
+                if (fileNames[i].Length == prefix.Length)
+                {
+                    prefixIsWholeName = true;
+                    break;
+                }
+            }
+
+            if (!prefixIsWholeName)
+            {
+                // Retreat to the last structural delimiter ('-', '_', '.').
+                var cut = prefix.Length;
+                while (cut > 0 && Array.IndexOf(VersionDelimiters, prefix[cut - 1]) < 0)
+                {
+                    cut--;
+                }
+
+                if (cut == 0)
+                {
+                    cut = prefix.Length;
+                    while (cut > 0 && prefix[cut - 1] != ' ')
+                    {
+                        cut--;
+                    }
+                }
+
+                prefix = prefix[..cut];
+            }
+
+            return prefix;
+        }
+
         public Task RefreshMetadata(CancellationToken cancellationToken)
         {
             return RefreshMetadata(new MetadataRefreshOptions(new DirectoryService(FileSystem)), cancellationToken);
@@ -2011,12 +2123,23 @@ namespace MediaBrowser.Controller.Entities
             // I think it is okay to do this here.
             // if this is only called when a user is manually forcing something to un-played
             // then it probably is what we want to do...
+            ResetPlayedState(data);
+
+            UserDataManager.SaveUserData(user, this, data, UserDataSaveReason.TogglePlayed, CancellationToken.None);
+        }
+
+        /// <summary>
+        /// Clears the played state on the supplied user data.
+        /// </summary>
+        /// <param name="data">The user data to reset.</param>
+        protected static void ResetPlayedState(UserItemData data)
+        {
+            ArgumentNullException.ThrowIfNull(data);
+
             data.PlayCount = 0;
             data.PlaybackPositionTicks = 0;
             data.LastPlayedDate = null;
             data.Played = false;
-
-            UserDataManager.SaveUserData(user, this, data, UserDataSaveReason.TogglePlayed, CancellationToken.None);
         }
 
         /// <summary>
@@ -2731,6 +2854,15 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.Sort(GetExtras(user).Where(e => e.ExtraType == Model.Entities.ExtraType.ThemeVideo), user, orderBy).ToArray();
         }
 
+        /// <summary>
+        /// Gets the ids of the items whose owned extras belong to this item.
+        /// </summary>
+        /// <returns>An array containing the owner ids.</returns>
+        protected virtual Guid[] GetExtraOwnerIds()
+        {
+            return [Id];
+        }
+
         /// <summary>
         /// Get all extras associated with this item, sorted by <see cref="SortName"/>.
         /// </summary>
@@ -2740,7 +2872,7 @@ namespace MediaBrowser.Controller.Entities
         {
             return LibraryManager.GetItemList(new InternalItemsQuery(user)
             {
-                OwnerIds = [Id],
+                OwnerIds = GetExtraOwnerIds(),
                 OrderBy = [(ItemSortBy.SortName, SortOrder.Ascending)]
             });
         }
@@ -2755,7 +2887,7 @@ namespace MediaBrowser.Controller.Entities
         {
             return LibraryManager.GetItemList(new InternalItemsQuery(user)
             {
-                OwnerIds = [Id],
+                OwnerIds = GetExtraOwnerIds(),
                 ExtraTypes = extraTypes.ToArray(),
                 OrderBy = [(ItemSortBy.SortName, SortOrder.Ascending)]
             });

MediaBrowser.Controller/Entities/Video.cs

@@ -34,11 +34,11 @@ namespace MediaBrowser.Controller.Entities
     {
         public Video()
         {
-            AdditionalParts = Array.Empty<string>();
-            LocalAlternateVersions = Array.Empty<string>();
-            SubtitleFiles = Array.Empty<string>();
-            AudioFiles = Array.Empty<string>();
-            LinkedAlternateVersions = Array.Empty<LinkedChild>();
+            AdditionalParts = [];
+            LocalAlternateVersions = [];
+            SubtitleFiles = [];
+            AudioFiles = [];
+            LinkedAlternateVersions = [];
         }
 
         [JsonIgnore]
@@ -254,7 +254,7 @@ namespace MediaBrowser.Controller.Entities
 
         private int GetMediaSourceCount(HashSet<Guid> callstack = null)
         {
-            callstack ??= new();
+            callstack ??= [];
             if (PrimaryVersionId.HasValue)
             {
                 var item = LibraryManager.GetItemById(PrimaryVersionId.Value);
@@ -335,6 +335,102 @@ namespace MediaBrowser.Controller.Entities
             PresentationUniqueKey = CreatePresentationUniqueKey();
         }
 
+        /// <summary>
+        /// Marks the played status of this video and propagates it to its alternate versions.
+        /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="datePlayed">The date played.</param>
+        /// <param name="resetPosition">if set to <c>true</c> [reset position].</param>
+        public override void MarkPlayed(User user, DateTime? datePlayed, bool resetPosition)
+        {
+            base.MarkPlayed(user, datePlayed, resetPosition);
+            PropagatePlayedState(user, true, resetPosition);
+        }
+
+        /// <summary>
+        /// Marks this video unplayed and propagates the change to its alternate versions.
+        /// </summary>
+        /// <param name="user">The user.</param>
+        public override void MarkUnplayed(User user)
+        {
+            base.MarkUnplayed(user);
+
+            // MarkUnplayed always clears the position on this video, so reset the versions too.
+            PropagatePlayedState(user, false, true);
+        }
+
+        /// <summary>
+        /// Propagates the played status to every alternate version of this video.
+        /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="played">The played status to apply to the alternate versions.</param>
+        /// <param name="resetPosition">When marking played, controls whether each version's resume point
+        /// is also reset (<c>true</c>) or left untouched (<c>false</c>). Ignored when marking unplayed,
+        /// which always fully resets every version.</param>
+        public void PropagatePlayedState(User user, bool played, bool resetPosition = true)
+        {
+            ArgumentNullException.ThrowIfNull(user);
+
+            if (!PrimaryVersionId.HasValue && LinkedAlternateVersions.Length == 0 && !HasLocalAlternateVersions)
+            {
+                return;
+            }
+
+            foreach (var (item, _) in GetAllItemsForMediaSources())
+            {
+                if (item.Id.Equals(Id) || item is not Video)
+                {
+                    continue;
+                }
+
+                if (played)
+                {
+                    var dto = new UpdateUserItemDataDto { Played = true };
+                    if (resetPosition)
+                    {
+                        dto.PlaybackPositionTicks = 0;
+                    }
+
+                    // SaveUserData only writes the fields set on the DTO, so play count and other state are preserved.
+                    UserDataManager.SaveUserData(user, item, dto, UserDataSaveReason.TogglePlayed);
+                }
+                else
+                {
+                    var data = UserDataManager.GetUserData(user, item);
+                    if (data is null)
+                    {
+                        continue;
+                    }
+
+                    ResetPlayedState(data);
+                    UserDataManager.SaveUserData(user, item, data, UserDataSaveReason.TogglePlayed, CancellationToken.None);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Gets this video together with all of its alternate versions (local and linked and, when this
+        /// is itself an alternate, the primary and the primary's other versions), deduplicated.
+        /// </summary>
+        /// <returns>This video and every alternate version of it.</returns>
+        public IReadOnlyList<Video> GetAllVersions()
+        {
+            return GetAllItemsForMediaSources()
+                .Select(i => i.Item)
+                .OfType<Video>()
+                .ToList();
+        }
+
+        /// <summary>
+        /// Gets the alternate version of this video that matches the supplied item id.
+        /// </summary>
+        /// <param name="itemId">The version item id (the playback media source id).</param>
+        /// <returns>The matching version, or <c>null</c> when the id is not a version of this video.</returns>
+        public Video GetAlternateVersion(Guid itemId)
+        {
+            return GetAllVersions().FirstOrDefault(i => i.Id.Equals(itemId));
+        }
+
         public override string CreatePresentationUniqueKey()
         {
             if (PrimaryVersionId.HasValue)
@@ -642,39 +738,58 @@ namespace MediaBrowser.Controller.Entities
             }).FirstOrDefault();
         }
 
+        /// <summary>
+        /// Gets the ids of the items whose owned extras belong to this item.
+        /// Extras are linked to a single version but need tp be surfaced for all versions.
+        /// </summary>
+        /// <returns>An array containing the owner ids.</returns>
+        protected override Guid[] GetExtraOwnerIds()
+        {
+            return GetAllItemsForMediaSources()
+                .Select(i => i.Item.Id)
+                .Distinct()
+                .ToArray();
+        }
+
         protected override IEnumerable<(BaseItem Item, MediaSourceType MediaSourceType)> GetAllItemsForMediaSources()
         {
-            var list = new List<(BaseItem, MediaSourceType)>
-            {
-                (this, MediaSourceType.Default)
-            };
+            var primary = PrimaryVersionId.HasValue
+                ? LibraryManager.GetItemById(PrimaryVersionId.Value) as Video
+                : null;
 
-            list.AddRange(
-                LibraryManager.GetLinkedAlternateVersions(this)
-                    .Select(i => ((BaseItem)i, MediaSourceType.Grouping)));
+            var primaryLinked = primary is null
+                ? []
+                : LibraryManager.GetLinkedAlternateVersions(primary).ToList();
 
-            if (PrimaryVersionId.HasValue)
-            {
-                if (LibraryManager.GetItemById(PrimaryVersionId.Value) is Video primary)
-                {
-                    var existingIds = list.Select(i => i.Item1.Id).ToList();
-                    list.Add((primary, MediaSourceType.Grouping));
-                    list.AddRange(LibraryManager.GetLinkedAlternateVersions(primary).Where(i => !existingIds.Contains(i.Id)).Select(i => ((BaseItem)i, MediaSourceType.Grouping)));
-                }
-            }
+            // Grouping marks user-merged (splittable) sources. The primary is only such a source when
+            // this video is linked onto it; for local (file-based) alternates the primary is just
+            // another default source.
+            var primaryType = primaryLinked.Any(i => i.Id.Equals(Id))
+                ? MediaSourceType.Grouping
+                : MediaSourceType.Default;
 
-            var localAlternates = list
-                .SelectMany(i =>
-                {
-                    return i.Item1 is Video video ? LibraryManager.GetLocalAlternateVersionIds(video) : Enumerable.Empty<Guid>();
-                })
-                .Select(LibraryManager.GetItemById)
-                .Where(i => i is not null)
+            // This video and its linked alternates, when this is itself an alternate, the primary and the primary's linked alternates.
+            var grouped = new[] { ((BaseItem)this, MediaSourceType.Default) }
+                .Concat(LibraryManager.GetLinkedAlternateVersions(this).Select(i => ((BaseItem)i, MediaSourceType.Grouping)))
+                .Concat(primary is null
+                    ? []
+                    : primaryLinked.Select(i => ((BaseItem)i, MediaSourceType.Grouping)).Prepend(((BaseItem)primary, primaryType)))
                 .ToList();
 
-            list.AddRange(localAlternates.Select(i => (i, MediaSourceType.Default)));
+            // The local (file-based) alternate versions of every grouped item.
+            var localAlternates = grouped
+                .Select(i => i.Item1)
+                .OfType<Video>()
+                .SelectMany(LibraryManager.GetLocalAlternateVersionIds)
+                .Select(LibraryManager.GetItemById)
+                .Where(i => i is not null)
+                .Select(i => (i, MediaSourceType.Default));
 
-            return list;
+            // Deduplicate
+            return grouped
+                .Concat(localAlternates)
+                .DistinctBy(i => i.Item1.Id)
+                .ToList();
         }
     }
 }

MediaBrowser.Controller/Library/IUserDataManager.cs

@@ -62,6 +62,24 @@ namespace MediaBrowser.Controller.Library
         /// <returns>A dictionary mapping item IDs to their user data.</returns>
         Dictionary<Guid, UserItemData> GetUserDataBatch(IReadOnlyList<BaseItem> items, User user);
 
+        /// <summary>
+        /// Gets the user data that should drive resume for a multi-version item: the data of the most
+        /// recently played alternate version (including the item itself) that has a resume point.
+        /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="item">The item.</param>
+        /// <returns>The resume version's data, or <c>null</c> when the item has no versions or none has a resume point.</returns>
+        VersionResumeData? GetResumeUserData(User user, BaseItem item);
+
+        /// <summary>
+        /// Gets the resume-driving user data for multiple items in a single batch operation.
+        /// See <see cref="GetResumeUserData(User, BaseItem)"/>.
+        /// </summary>
+        /// <param name="items">The items to get resume data for.</param>
+        /// <param name="user">The user.</param>
+        /// <returns>A dictionary mapping item ids to their resume version's data; items without one are omitted.</returns>
+        IReadOnlyDictionary<Guid, VersionResumeData> GetResumeUserDataBatch(IReadOnlyList<BaseItem> items, User user);
+
         /// <summary>
         /// Gets the user data dto.
         /// </summary>
@@ -80,5 +98,13 @@ namespace MediaBrowser.Controller.Library
         /// <param name="reportedPositionTicks">New playstate.</param>
         /// <returns>True if playstate was updated.</returns>
         bool UpdatePlayState(BaseItem item, UserItemData data, long? reportedPositionTicks);
+
+        /// <summary>
+        /// Clears any stored audio and subtitle stream selections for the given user/item pair.
+        /// Used when the user has opted out of remembering selections.
+        /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="item">The item.</param>
+        void ResetPlaybackStreamSelections(User user, BaseItem item);
     }
 }

MediaBrowser.Controller/Library/VersionPlaybackSelector.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using MediaBrowser.Controller.Entities;
+
+namespace MediaBrowser.Controller.Library
+{
+    /// <summary>
+    /// Single definition of "which alternate version was most recently played" shared by the resume tile
+    /// (<see cref="IUserDataManager.GetResumeUserData"/>), the media-source default ordering and Next Up.
+    /// Each call site declares its own eligibility rule so the intentional differences (resumable-only vs.
+    /// resumable-or-completed) are visible in one place instead of being re-implemented divergently.
+    /// The SQL resume query keeps its own translation of the same rule.
+    /// </summary>
+    public static class VersionPlaybackSelector
+    {
+        /// <summary>
+        /// Selects the entry whose user data has the greatest <see cref="UserItemData.LastPlayedDate"/>,
+        /// considering only entries that satisfy <paramref name="isEligible"/>. On an exact tie the first
+        /// encountered entry wins.
+        /// </summary>
+        /// <typeparam name="T">The candidate type (e.g. a version item or a media source).</typeparam>
+        /// <param name="items">The candidates to choose from.</param>
+        /// <param name="dataSelector">Resolves the user data for a candidate, or <c>null</c> when it has none.</param>
+        /// <param name="isEligible">Whether a candidate's user data makes it a valid winner.</param>
+        /// <returns>The most recently played eligible candidate, or <c>default</c> when none qualify.</returns>
+        public static T? SelectMostRecentlyPlayed<T>(
+            IEnumerable<T> items,
+            Func<T, UserItemData?> dataSelector,
+            Func<UserItemData, bool> isEligible)
+        {
+            ArgumentNullException.ThrowIfNull(items);
+            ArgumentNullException.ThrowIfNull(dataSelector);
+            ArgumentNullException.ThrowIfNull(isEligible);
+
+            T? winner = default;
+            var winnerDate = DateTime.MinValue;
+            var hasWinner = false;
+
+            foreach (var item in items)
+            {
+                var data = dataSelector(item);
+                if (data is null || !isEligible(data))
+                {
+                    continue;
+                }
+
+                var date = data.LastPlayedDate ?? DateTime.MinValue;
+                if (!hasWinner || date > winnerDate)
+                {
+                    winner = item;
+                    winnerDate = date;
+                    hasWinner = true;
+                }
+            }
+
+            return winner;
+        }
+    }
+}

MediaBrowser.Controller/Library/VersionResumeData.cs

@@ -0,0 +1,41 @@
+using System;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Model.Dto;
+
+namespace MediaBrowser.Controller.Library
+{
+    /// <summary>
+    /// The user data of the most recently played alternate version that should drive the completion state of a multi-version item.
+    /// </summary>
+    /// <param name="VersionId">The id of the version that owns <paramref name="UserData"/>.</param>
+    /// <param name="UserData">The resume version's user data.</param>
+    public record VersionResumeData(Guid VersionId, UserItemData UserData)
+    {
+        /// <summary>
+        /// Merges the most recently played version's completion state into the supplied user data dto.
+        /// Completion (played) propagates to the primary. An in-progress resume position stays on the version
+        /// that owns it, which is surfaced directly (e.g. in resume queries) so that playback always targets
+        /// the correct version rather than resuming the primary at another version's offset. When the movie was
+        /// finished on a different version, the primary's own stale resume position is cleared so it does not
+        /// render as "watched and resumable" at the same time.
+        /// </summary>
+        /// <param name="dto">The user data dto to update.</param>
+        public void ApplyTo(UserItemDataDto dto)
+        {
+            dto.Played = dto.Played || UserData.Played;
+
+            if ((UserData.LastPlayedDate ?? DateTime.MinValue) > (dto.LastPlayedDate ?? DateTime.MinValue))
+            {
+                dto.LastPlayedDate = UserData.LastPlayedDate;
+            }
+
+            // A different version was finished (played, no resume position of its own) and is the most
+            // recently played: the whole movie is watched.
+            if (!VersionId.Equals(dto.ItemId) && UserData.Played && UserData.PlaybackPositionTicks <= 0)
+            {
+                dto.PlaybackPositionTicks = 0;
+                dto.PlayedPercentage = null;
+            }
+        }
+    }
+}

MediaBrowser.Model/Dto/MediaSourceInfo.cs

@@ -55,6 +55,11 @@ namespace MediaBrowser.Model.Dto
 
         public long? RunTimeTicks { get; set; }
 
+        /// <summary>
+        /// Gets or sets the playback position for this specific source.
+        /// </summary>
+        public long? PlaybackPositionTicks { get; set; }
+
         public bool ReadAtNativeFramerate { get; set; }
 
         public bool IgnoreDts { get; set; }

MediaBrowser.Providers/TV/SeriesMetadataService.cs

@@ -78,11 +78,73 @@ public class SeriesMetadataService : MetadataService<Series, SeriesInfo>
     {
         await base.AfterMetadataRefresh(item, refreshOptions, cancellationToken).ConfigureAwait(false);
 
+        // Note that this only updates the children's SeriesPresentationUniqueKey and SeasonId, not the ParentIndexNumber
+        if (LibraryManager.GetLibraryOptions(item).EnableAutomaticSeriesGrouping)
+        {
+            await UpdateSeriesChildrenInfoAsync(item, cancellationToken).ConfigureAwait(false);
+        }
+
         RemoveObsoleteEpisodes(item);
         RemoveObsoleteSeasons(item);
         await CreateSeasonsAsync(item, cancellationToken).ConfigureAwait(false);
     }
 
+    /// <summary>
+    /// Reconciles seasons and episodes with the series' finalized state.
+    /// </summary>
+    /// <remarks>
+    /// The series' presentation unique key can change during a refresh once provider ids become
+    /// available - notably with <c>EnableAutomaticSeriesGrouping</c>, where the key is derived from
+    /// the provider id and the owning libraries instead of the (immutable) item id. Seasons and
+    /// episodes cache this value in <see cref="IHasSeries.SeriesPresentationUniqueKey"/> and are
+    /// matched to (and displayed under) the series by it, so any child left with a stale key - or an
+    /// episode not yet linked to a freshly created season - stays hidden until a later scan. Syncing
+    /// them against the series here lets everything appear within a single scan.
+    /// </remarks>
+    /// <param name="series">The series.</param>
+    /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>The async task.</returns>
+    private async Task UpdateSeriesChildrenInfoAsync(Series series, CancellationToken cancellationToken)
+    {
+        // Reload children so episode numbers / seasons persisted earlier in the refresh are seen.
+        series.Children = null;
+        var seriesKey = series.GetPresentationUniqueKey();
+        var children = series.GetRecursiveChildren(i => i is Season || i is Episode);
+        var seasons = children.OfType<Season>().ToList();
+
+        foreach (var child in children)
+        {
+            var updateType = ItemUpdateType.None;
+
+            if (child is IHasSeries hasSeries
+                && !string.Equals(hasSeries.SeriesPresentationUniqueKey, seriesKey, StringComparison.Ordinal))
+            {
+                hasSeries.SeriesPresentationUniqueKey = seriesKey;
+                updateType |= ItemUpdateType.MetadataImport;
+            }
+
+            if (child is Episode episode)
+            {
+                var seasonId = episode.FindSeasonId();
+                if (seasonId.IsEmpty() && episode.ParentIndexNumber.HasValue)
+                {
+                    seasonId = seasons.Find(s => s.IndexNumber == episode.ParentIndexNumber)?.Id ?? Guid.Empty;
+                }
+
+                if (!seasonId.IsEmpty() && !episode.SeasonId.Equals(seasonId))
+                {
+                    episode.SeasonId = seasonId;
+                    updateType |= ItemUpdateType.MetadataImport;
+                }
+            }
+
+            if (updateType > ItemUpdateType.None)
+            {
+                await child.UpdateToRepositoryAsync(updateType, cancellationToken).ConfigureAwait(false);
+            }
+        }
+    }
+
     /// <inheritdoc />
     protected override void MergeData(MetadataResult<Series> source, MetadataResult<Series> target, MetadataField[] lockedFields, bool replaceData, bool mergeMetadataSettings)
     {
@@ -235,6 +297,28 @@ public class SeriesMetadataService : MetadataService<Series, SeriesInfo>
     private async Task CreateSeasonsAsync(Series series, CancellationToken cancellationToken)
     {
         var seriesChildren = series.GetRecursiveChildren(i => i is Episode || i is Season);
+
+        // CreateSeasonsAsync can run before the episodes themselves have been refreshed during an
+        // initial scan, so their ParentIndexNumber may still be unset. Resolve the season number
+        // from the path first to avoid creating a premature "Season Unknown" instead of the real
+        // season for episodes that live directly in a flat series folder.
+        foreach (var episode in seriesChildren.OfType<Episode>())
+        {
+            if (episode.ParentIndexNumber.HasValue)
+            {
+                continue;
+            }
+
+            try
+            {
+                LibraryManager.FillMissingEpisodeNumbersFromPath(episode, false);
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError(ex, "Error resolving season number from path for {Path}", episode.Path);
+            }
+        }
+
         var seasons = seriesChildren.OfType<Season>().ToList();
         var episodes = seriesChildren.OfType<Episode>().ToList();
 

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

@@ -1,6 +1,15 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Threading;
+using Jellyfin.Database.Implementations.Entities;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.LiveTv;
+using MediaBrowser.Controller.MediaSegments;
+using MediaBrowser.Model.Dto;
+using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.MediaInfo;
 using Moq;
 using Xunit;
@@ -46,4 +55,284 @@ public class BaseItemTests
         Assert.Equal(name, video.GetMediaSourceName(video));
         Assert.Equal(altName, video.GetMediaSourceName(videoAlt));
     }
+
+    [Theory]
+    // Episode versions share a season folder; the common prefix (not the folder name) yields the label.
+    // Both files carry a suffix (no bare base name), so the shared "- " must be stripped too.
+    [InlineData(
+        "Spider-Noir - S01E02 - Wo ist Flint - Greyscale",
+        "Spider-Noir - S01E02 - Wo ist Flint - Colorized",
+        "Greyscale",
+        "Colorized")]
+    // One version is the bare base name; the other is suffixed.
+    [InlineData(
+        "Spider-Noir - S01E02 - Wo ist Flint",
+        "Spider-Noir - S01E02 - Wo ist Flint - Greyscale",
+        "Spider-Noir - S01E02 - Wo ist Flint",
+        "Greyscale")]
+    // Suffixes share a leading word ("Grey"); the prefix must retreat to the separator, not split it.
+    [InlineData(
+        "Demo - S01E01 - Greyscale",
+        "Demo - S01E01 - Greyish",
+        "Greyscale",
+        "Greyish")]
+    // Underscore separator.
+    [InlineData("Movie (2020)_4K", "Movie (2020)_1080p", "4K", "1080p")]
+    // Dot separator.
+    [InlineData("Movie (2020).UHD", "Movie (2020).1080p", "UHD", "1080p")]
+    // Resolution variants that share leading digits must retreat to the separator, not yield "p"/"i".
+    [InlineData("Movie - 1080p", "Movie - 1080i", "1080p", "1080i")]
+    // A token shared by the descriptors but separated only by spaces (the resolution) must stay in the
+    // label: retreat to the '-' delimiter, not the interior space, so the resolution is kept.
+    [InlineData(
+        "movie (2020) - 2160p Extended",
+        "movie (2020) - 2160p Original",
+        "2160p Extended",
+        "2160p Original")]
+    // Bracketed version labels: the opening bracket is kept in the label.
+    [InlineData(
+        "Blade Runner (1982) [Final Cut] [1080p HEVC AAC]",
+        "Blade Runner (1982) [EE by ADM] [480p HEVC AAC]",
+        "[Final Cut] [1080p HEVC AAC]",
+        "[EE by ADM] [480p HEVC AAC]")]
+    public void GetMediaSourceName_CommonPrefix_Valid(string primaryName, string altName, string expectedPrimary, string expectedAlt)
+    {
+        var primaryPath = "/Shows/Demo/Season 01/" + primaryName + ".mkv";
+        var altPath = "/Shows/Demo/Season 01/" + altName + ".mkv";
+        var commonPrefix = BaseItem.GetCommonVersionPrefix([primaryName, altName]);
+
+        var video = new Video()
+        {
+            Path = primaryPath
+        };
+
+        var videoAlt = new Video()
+        {
+            Path = altPath,
+        };
+
+        var mediaSourceManager = new Mock<IMediaSourceManager>();
+        mediaSourceManager.Setup(x => x.GetPathProtocol(It.IsAny<string>()))
+                .Returns((string x) => MediaProtocol.File);
+        var libraryManager = new Mock<ILibraryManager>();
+        // No local alternate versions: these are linked (separate items), so the folder fallback is unavailable.
+        libraryManager.Setup(x => x.GetLocalAlternateVersionIds(It.IsAny<Video>()))
+                .Returns(Array.Empty<Guid>());
+        BaseItem.MediaSourceManager = mediaSourceManager.Object;
+        BaseItem.LibraryManager = libraryManager.Object;
+
+        Assert.Equal(expectedPrimary, video.GetMediaSourceName(video, commonPrefix));
+        Assert.Equal(expectedAlt, videoAlt.GetMediaSourceName(videoAlt, commonPrefix));
+    }
+
+    [Fact]
+    public void GetAlternateVersion_ReturnsMatchingLocalVersion()
+    {
+        var (primary, alt1, alt2) = SetupVersionGroup();
+
+        Assert.Same(alt1, primary.GetAlternateVersion(alt1.Id));
+        Assert.Same(alt2, primary.GetAlternateVersion(alt2.Id));
+        Assert.Same(primary, primary.GetAlternateVersion(primary.Id));
+        Assert.Null(primary.GetAlternateVersion(Guid.NewGuid()));
+    }
+
+    [Fact]
+    public void GetAllVersions_FromAnyVersion_ReturnsEveryVersionOnce()
+    {
+        var (primary, alt1, alt2) = SetupVersionGroup();
+
+        foreach (var source in new[] { primary, alt1, alt2 })
+        {
+            var versions = source.GetAllVersions();
+
+            Assert.Equal(3, versions.Count);
+            Assert.Contains(versions, v => v.Id.Equals(primary.Id));
+            Assert.Contains(versions, v => v.Id.Equals(alt1.Id));
+            Assert.Contains(versions, v => v.Id.Equals(alt2.Id));
+        }
+    }
+
+    [Fact]
+    public void PropagatePlayedState_MarksAlternateVersions_AndResetsPositionByDefault()
+    {
+        var (primary, alt1, alt2) = SetupVersionGroup();
+
+        var saved = CaptureSaves();
+
+        var user = new User("test", "default", "default");
+        primary.PropagatePlayedState(user, true);
+
+        // Both alternate versions are marked played, the primary (self) is not, and the position is
+        // reset so a watched version does not linger in "Continue Watching".
+        Assert.Equal(2, saved.Count);
+        Assert.DoesNotContain(saved, e => e.ItemId.Equals(primary.Id));
+        Assert.Contains(saved, e => e.ItemId.Equals(alt1.Id));
+        Assert.Contains(saved, e => e.ItemId.Equals(alt2.Id));
+        Assert.All(saved, e =>
+        {
+            Assert.True(e.Dto.Played.GetValueOrDefault());
+            Assert.Equal(0, e.Dto.PlaybackPositionTicks);
+        });
+    }
+
+    [Fact]
+    public void PropagatePlayedState_WithoutReset_LeavesPositionUntouched()
+    {
+        var (primary, _, _) = SetupVersionGroup();
+
+        var saved = CaptureSaves();
+
+        primary.PropagatePlayedState(new User("test", "default", "default"), true, resetPosition: false);
+
+        Assert.Equal(2, saved.Count);
+        Assert.All(saved, e =>
+        {
+            Assert.True(e.Dto.Played.GetValueOrDefault());
+            Assert.Null(e.Dto.PlaybackPositionTicks);
+        });
+    }
+
+    [Fact]
+    public void PropagatePlayedState_Unwatched_ClearsAllWatchedStateOnVersions()
+    {
+        var (primary, alt1, alt2) = SetupVersionGroup();
+
+        // Each alternate starts out watched, with a play count, resume point and last-played date.
+        var existing = new Dictionary<Guid, UserItemData>
+        {
+            [alt1.Id] = new UserItemData { Key = "alt1", Played = true, PlayCount = 3, PlaybackPositionTicks = 1000, LastPlayedDate = new DateTime(2020, 1, 1, 0, 0, 0, DateTimeKind.Utc) },
+            [alt2.Id] = new UserItemData { Key = "alt2", Played = true, PlayCount = 1, PlaybackPositionTicks = 500, LastPlayedDate = new DateTime(2021, 2, 2, 0, 0, 0, DateTimeKind.Utc) },
+        };
+
+        var saved = new List<UserItemData>();
+        var userDataManager = new Mock<IUserDataManager>();
+        userDataManager.Setup(x => x.GetUserData(It.IsAny<User>(), It.IsAny<BaseItem>()))
+            .Returns((User _, BaseItem item) => existing.GetValueOrDefault(item.Id));
+        userDataManager
+            .Setup(x => x.SaveUserData(It.IsAny<User>(), It.IsAny<BaseItem>(), It.IsAny<UserItemData>(), It.IsAny<UserDataSaveReason>(), It.IsAny<CancellationToken>()))
+            .Callback<User, BaseItem, UserItemData, UserDataSaveReason, CancellationToken>((_, _, data, _, _) => saved.Add(data));
+        BaseItem.UserDataManager = userDataManager.Object;
+
+        primary.PropagatePlayedState(new User("test", "default", "default"), false);
+
+        // Every alternate is fully reset to an unwatched state, mirroring MarkUnplayed: the played flag,
+        // play count, resume point and last-played date are all cleared so no watched state lingers.
+        Assert.Equal(2, saved.Count);
+        Assert.All(saved, d =>
+        {
+            Assert.False(d.Played);
+            Assert.Equal(0, d.PlayCount);
+            Assert.Equal(0, d.PlaybackPositionTicks);
+            Assert.Null(d.LastPlayedDate);
+        });
+    }
+
+    private static List<(Guid ItemId, UpdateUserItemDataDto Dto)> CaptureSaves()
+    {
+        var saved = new List<(Guid ItemId, UpdateUserItemDataDto Dto)>();
+        var userDataManager = new Mock<IUserDataManager>();
+        userDataManager
+            .Setup(x => x.SaveUserData(It.IsAny<User>(), It.IsAny<BaseItem>(), It.IsAny<UpdateUserItemDataDto>(), It.IsAny<UserDataSaveReason>()))
+            .Callback<User, BaseItem, UpdateUserItemDataDto, UserDataSaveReason>((_, item, dto, _) => saved.Add((item.Id, dto)));
+        BaseItem.UserDataManager = userDataManager.Object;
+        return saved;
+    }
+
+    [Fact]
+    public void PropagatePlayedState_SingleVersion_DoesNothing()
+    {
+        var solo = new Video { Id = Guid.NewGuid(), Path = "/Movies/Solo/Solo.mkv" };
+
+        var mediaSourceManager = new Mock<IMediaSourceManager>();
+        mediaSourceManager.Setup(x => x.GetPathProtocol(It.IsAny<string>())).Returns(MediaProtocol.File);
+        var libraryManager = new Mock<ILibraryManager>();
+        libraryManager.Setup(x => x.GetLocalAlternateVersionIds(It.IsAny<Video>())).Returns(Array.Empty<Guid>());
+        libraryManager.Setup(x => x.GetLinkedAlternateVersions(It.IsAny<Video>())).Returns(Array.Empty<Video>());
+        BaseItem.MediaSourceManager = mediaSourceManager.Object;
+        BaseItem.LibraryManager = libraryManager.Object;
+
+        var userDataManager = new Mock<IUserDataManager>();
+        BaseItem.UserDataManager = userDataManager.Object;
+
+        solo.PropagatePlayedState(new User("test", "default", "default"), true);
+
+        userDataManager.Verify(
+            x => x.SaveUserData(It.IsAny<User>(), It.IsAny<BaseItem>(), It.IsAny<UpdateUserItemDataDto>(), It.IsAny<UserDataSaveReason>()),
+            Times.Never);
+    }
+
+    private static (Video Primary, Video Alt1, Video Alt2) SetupVersionGroup()
+    {
+        var primary = new Video { Id = Guid.NewGuid(), Path = "/Movies/Movie/Movie.mkv" };
+        var alt1 = new Video { Id = Guid.NewGuid(), Path = "/Movies/Movie/Movie - 1080p.mkv", PrimaryVersionId = primary.Id };
+        var alt2 = new Video { Id = Guid.NewGuid(), Path = "/Movies/Movie/Movie - 4K.mkv", PrimaryVersionId = primary.Id };
+
+        // 2160p primary, 1080p alternates: width is only the ordering tiebreaker, set so it would place
+        // the primary first — letting the tests confirm the queried version's own source still wins.
+        var widths = new Dictionary<Guid, int> { [primary.Id] = 3840, [alt1.Id] = 1920, [alt2.Id] = 1920 };
+        var mediaSourceManager = new Mock<IMediaSourceManager>();
+        mediaSourceManager.Setup(x => x.GetPathProtocol(It.IsAny<string>())).Returns(MediaProtocol.File);
+        mediaSourceManager.Setup(x => x.GetMediaStreams(It.IsAny<Guid>()))
+            .Returns((Guid id) => new List<MediaStream> { new MediaStream { Type = MediaStreamType.Video, Width = widths.GetValueOrDefault(id) } });
+        mediaSourceManager.Setup(x => x.GetMediaAttachments(It.IsAny<Guid>())).Returns(new List<MediaAttachment>());
+
+        var segmentManager = new Mock<IMediaSegmentManager>();
+        segmentManager.Setup(x => x.IsTypeSupported(It.IsAny<BaseItem>())).Returns(false);
+        BaseItem.MediaSegmentManager = segmentManager.Object;
+
+        var libraryManager = new Mock<ILibraryManager>();
+        libraryManager.Setup(x => x.GetLinkedAlternateVersions(It.IsAny<Video>())).Returns(Array.Empty<Video>());
+        libraryManager.Setup(x => x.GetLocalAlternateVersionIds(primary)).Returns(new[] { alt1.Id, alt2.Id });
+        libraryManager.Setup(x => x.GetLocalAlternateVersionIds(alt1)).Returns(Array.Empty<Guid>());
+        libraryManager.Setup(x => x.GetLocalAlternateVersionIds(alt2)).Returns(Array.Empty<Guid>());
+        libraryManager.Setup(x => x.GetItemById(alt1.Id)).Returns(alt1);
+        libraryManager.Setup(x => x.GetItemById(alt2.Id)).Returns(alt2);
+        libraryManager.Setup(x => x.GetItemById(primary.Id)).Returns(primary);
+
+        var recordingsManager = new Mock<IRecordingsManager>();
+        recordingsManager.Setup(x => x.GetActiveRecordingInfo(It.IsAny<string>())).Returns((ActiveRecordingInfo?)null);
+        Video.RecordingsManager = recordingsManager.Object;
+
+        BaseItem.MediaSourceManager = mediaSourceManager.Object;
+        BaseItem.LibraryManager = libraryManager.Object;
+
+        return (primary, alt1, alt2);
+    }
+
+    [Fact]
+    public void GetMediaSources_DefaultsToTheQueriedVersionsOwnSource()
+    {
+        var (primary, alt1, _) = SetupVersionGroup();
+
+        // Resuming the 1080p alternate must default to the 1080p source, not the higher-resolution
+        // 2160p primary that the width ordering would otherwise place first.
+        Assert.Equal(alt1.Id.ToString("N"), alt1.GetMediaSources(false)[0].Id);
+
+        // Opening the primary still defaults to the primary's own (here highest-resolution) source.
+        Assert.Equal(primary.Id.ToString("N"), primary.GetMediaSources(false)[0].Id);
+    }
+
+    [Fact]
+    public void GetAllItemsForMediaSources_FromAnyVersion_HasNoDuplicates()
+    {
+        var (primary, alt1, alt2) = SetupVersionGroup();
+
+        var method = typeof(Video).GetMethod("GetAllItemsForMediaSources", BindingFlags.Instance | BindingFlags.NonPublic);
+        Assert.NotNull(method);
+
+        // Each version must surface exactly once, regardless of which member the list is built from.
+        // Building from an alternate previously re-added that alternate as a "local alternate" of the
+        // primary, producing a duplicate entry in the version dropdown.
+        foreach (var source in new[] { primary, alt1, alt2 })
+        {
+            var items = (IEnumerable<(BaseItem Item, MediaSourceType MediaSourceType)>)method!.Invoke(source, null)!;
+            var ids = items.Select(i => i.Item.Id).ToList();
+
+            Assert.Equal(3, ids.Count);
+            Assert.Equal(ids.Count, ids.Distinct().Count());
+            Assert.Contains(primary.Id, ids);
+            Assert.Contains(alt1.Id, ids);
+            Assert.Contains(alt2.Id, ids);
+        }
+    }
 }

tests/Jellyfin.Controller.Tests/Library/VersionResumeDataTests.cs

@@ -0,0 +1,89 @@
+using System;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Model.Dto;
+using Xunit;
+
+namespace Jellyfin.Controller.Tests.Library;
+
+public class VersionResumeDataTests
+{
+    [Fact]
+    public void ApplyTo_CompletedOtherVersion_PropagatesCompletionAndClearsStaleResume()
+    {
+        var lastPlayed = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc);
+        var resume = new VersionResumeData(
+            Guid.NewGuid(),
+            new UserItemData { Key = "version", PlaybackPositionTicks = 0, Played = true, LastPlayedDate = lastPlayed });
+
+        var dto = new UserItemDataDto { ItemId = Guid.NewGuid(), Key = "primary", PlaybackPositionTicks = 1, Played = false, PlayedPercentage = 50 };
+
+        resume.ApplyTo(dto);
+
+        // Completion state propagates to the primary...
+        Assert.True(dto.Played);
+        Assert.Equal(lastPlayed, dto.LastPlayedDate);
+
+        // ...and because the movie was finished on a different version, the primary's own stale resume bar is cleared.
+        Assert.Equal(0, dto.PlaybackPositionTicks);
+        Assert.Null(dto.PlayedPercentage);
+    }
+
+    [Fact]
+    public void ApplyTo_PrimaryOwnProgress_KeepsResumePosition()
+    {
+        var primaryId = Guid.NewGuid();
+        var lastPlayed = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc);
+
+        // The winning version is the primary itself (e.g. rewatching): its resume bar must survive.
+        var resume = new VersionResumeData(
+            primaryId,
+            new UserItemData { Key = "primary", PlaybackPositionTicks = 5, Played = true, LastPlayedDate = lastPlayed });
+
+        var dto = new UserItemDataDto { ItemId = primaryId, Key = "primary", PlaybackPositionTicks = 5, Played = true, PlayedPercentage = 20 };
+
+        resume.ApplyTo(dto);
+
+        Assert.True(dto.Played);
+        Assert.Equal(5, dto.PlaybackPositionTicks);
+        Assert.Equal(20, dto.PlayedPercentage);
+    }
+
+    [Fact]
+    public void ApplyTo_InProgressOtherVersion_KeepsPrimaryResumePosition()
+    {
+        var lastPlayed = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc);
+
+        // A different version that is in-progress (not finished) must not clear the primary's position.
+        var resume = new VersionResumeData(
+            Guid.NewGuid(),
+            new UserItemData { Key = "version", PlaybackPositionTicks = 25, Played = false, LastPlayedDate = lastPlayed });
+
+        var dto = new UserItemDataDto { ItemId = Guid.NewGuid(), Key = "primary", PlaybackPositionTicks = 1, Played = false, PlayedPercentage = 50 };
+
+        resume.ApplyTo(dto);
+
+        Assert.False(dto.Played);
+        Assert.Equal(1, dto.PlaybackPositionTicks);
+        Assert.Equal(50, dto.PlayedPercentage);
+    }
+
+    [Fact]
+    public void ApplyTo_DoesNotUnsetExistingPlayedOrRegressLastPlayed()
+    {
+        var primaryLastPlayed = new DateTime(2026, 1, 5, 0, 0, 0, DateTimeKind.Utc);
+        var versionLastPlayed = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc);
+        var resume = new VersionResumeData(
+            Guid.NewGuid(),
+            new UserItemData { Key = "version", Played = false, LastPlayedDate = versionLastPlayed });
+
+        var dto = new UserItemDataDto { ItemId = Guid.NewGuid(), Key = "primary", Played = true, LastPlayedDate = primaryLastPlayed };
+
+        resume.ApplyTo(dto);
+
+        // A not-yet-completed version must not clear the primary's own completion, and the more recent
+        // LastPlayedDate is kept.
+        Assert.True(dto.Played);
+        Assert.Equal(primaryLastPlayed, dto.LastPlayedDate);
+    }
+}

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

@@ -0,0 +1,233 @@
+#pragma warning disable RS0030 // Do not use banned APIs: Guid == is required inside EF expression trees to mirror the production query shapes.
+
+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;
+
+/// <summary>
+/// Verifies that the alternate-version-aware query shapes used by the resume filter
+/// (BaseItemRepository.TranslateQuery) and the DatePlayed ordering (OrderMapper) translate
+/// and evaluate correctly on the SQLite provider.
+/// </summary>
+public sealed class AlternateVersionQueryTranslationTests : IDisposable
+{
+    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]
+    public void ResumeFilter_VersionProgress_SurfacesPlayedVersion()
+    {
+        Guid userId, primaryId, versionId, otherId;
+
+        using (var ctx = CreateDbContext())
+        {
+            (userId, primaryId, versionId, otherId) = Seed(ctx);
+        }
+
+        using (var ctx = CreateDbContext())
+        {
+            var inProgress = ctx.UserData
+                .Where(ud => ud.UserId == userId && ud.PlaybackPositionTicks > 0);
+
+            // Scope to the seeded items; EnsureCreated also seeds a placeholder row.
+            var seededIds = new[] { primaryId, versionId, otherId };
+
+            // Mirrors the resumable=true filter in BaseItemRepository.TranslateQuery.
+            var inProgressIds = inProgress.Select(ud => ud.ItemId);
+            var resumable = ctx.BaseItems
+                .Where(e => seededIds.Contains(e.Id))
+                .Where(e => inProgressIds.Contains(e.Id))
+                .Where(e => !ctx.BaseItems
+                    .Where(s => s.Id != e.Id && (s.PrimaryVersionId ?? s.Id) == (e.PrimaryVersionId ?? e.Id))
+                    .Any(s =>
+                        inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                            > inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                        || (inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                                == inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                            && s.Id.CompareTo(e.Id) < 0)))
+                .Select(e => e.Id)
+                .ToList();
+
+            Assert.Equal([versionId], resumable);
+
+            // The not-resumable direction keeps primaries only.
+            var resumableMovieIds = inProgress
+                .Join(ctx.BaseItems, ud => ud.ItemId, bi => bi.Id, (ud, bi) => bi.PrimaryVersionId ?? bi.Id);
+            var notResumable = ctx.BaseItems
+                .Where(e => seededIds.Contains(e.Id) && e.PrimaryVersionId == null)
+                .Where(e => !resumableMovieIds.Contains(e.Id))
+                .Select(e => e.Id)
+                .ToList();
+
+            Assert.Equal([otherId], notResumable);
+        }
+    }
+
+    [Fact]
+    public void ResumeFilter_TiedLastPlayedDate_KeepsSingleVersion()
+    {
+        Guid userId, primaryId, versionAId, versionBId;
+
+        using (var ctx = CreateDbContext())
+        {
+            (userId, primaryId, versionAId, versionBId) = SeedTiedVersions(ctx);
+        }
+
+        using (var ctx = CreateDbContext())
+        {
+            var inProgress = ctx.UserData
+                .Where(ud => ud.UserId == userId && ud.PlaybackPositionTicks > 0);
+
+            var seededIds = new[] { primaryId, versionAId, versionBId };
+            var inProgressIds = inProgress.Select(ud => ud.ItemId);
+
+            // The exact production dedup, including the Guid.CompareTo tie-break. This asserts the
+            // expression translates on SQLite and that two versions sharing an identical LastPlayedDate
+            // collapse to a single row instead of double-listing the item in Continue Watching.
+            var resumable = ctx.BaseItems
+                .Where(e => seededIds.Contains(e.Id))
+                .Where(e => inProgressIds.Contains(e.Id))
+                .Where(e => !ctx.BaseItems
+                    .Where(s => s.Id != e.Id && (s.PrimaryVersionId ?? s.Id) == (e.PrimaryVersionId ?? e.Id))
+                    .Any(s =>
+                        inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                            > inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                        || (inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                                == inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                            && s.Id.CompareTo(e.Id) < 0)))
+                .Select(e => e.Id)
+                .ToList();
+
+            var survivor = Assert.Single(resumable);
+            Assert.Contains(survivor, new[] { versionAId, versionBId });
+        }
+    }
+
+    [Fact]
+    public void DatePlayedOrdering_VersionProgress_SortsPrimaryByVersionDate()
+    {
+        Guid userId, primaryId, otherId;
+
+        using (var ctx = CreateDbContext())
+        {
+            (userId, primaryId, _, otherId) = Seed(ctx);
+        }
+
+        using (var ctx = CreateDbContext())
+        {
+            // Scope to the seeded items; EnsureCreated also seeds a placeholder row.
+            var seededIds = new[] { primaryId, otherId };
+
+            // Mirrors the DatePlayed mapping in OrderMapper.
+            var ordered = ctx.BaseItems
+                .Where(e => seededIds.Contains(e.Id) && e.PrimaryVersionId == null)
+                .OrderByDescending(e => ctx.UserData
+                    .Where(w => w.UserId == userId && (w.ItemId == e.Id || w.Item!.PrimaryVersionId == e.Id))
+                    .Max(f => f.LastPlayedDate))
+                .Select(e => e.Id)
+                .ToList();
+
+            // The movie whose only progress is on its alternate version sorts before the unplayed one.
+            Assert.Equal([primaryId, otherId], ordered);
+        }
+    }
+
+    private static (Guid UserId, Guid PrimaryId, Guid VersionId, Guid OtherId) Seed(JellyfinDbContext ctx)
+    {
+        var user = new User("test", "auth-provider", "reset-provider");
+        ctx.Users.Add(user);
+
+        var primary = new BaseItemEntity { Id = Guid.NewGuid(), Type = "MediaBrowser.Controller.Entities.Movies.Movie" };
+        var version = new BaseItemEntity { Id = Guid.NewGuid(), Type = "MediaBrowser.Controller.Entities.Movies.Movie", PrimaryVersionId = primary.Id };
+        var other = new BaseItemEntity { Id = Guid.NewGuid(), Type = "MediaBrowser.Controller.Entities.Movies.Movie" };
+        ctx.BaseItems.AddRange(primary, version, other);
+
+        // Progress only on the alternate version.
+        ctx.UserData.Add(new UserData
+        {
+            ItemId = version.Id,
+            Item = version,
+            UserId = user.Id,
+            User = user,
+            CustomDataKey = version.Id.ToString("N"),
+            PlaybackPositionTicks = 1000,
+            LastPlayedDate = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc)
+        });
+
+        ctx.SaveChanges();
+        return (user.Id, primary.Id, version.Id, other.Id);
+    }
+
+    private static (Guid UserId, Guid PrimaryId, Guid VersionAId, Guid VersionBId) SeedTiedVersions(JellyfinDbContext ctx)
+    {
+        var user = new User("test", "auth-provider", "reset-provider");
+        ctx.Users.Add(user);
+
+        var primary = new BaseItemEntity { Id = Guid.NewGuid(), Type = "MediaBrowser.Controller.Entities.Movies.Movie" };
+        var versionA = new BaseItemEntity { Id = Guid.NewGuid(), Type = "MediaBrowser.Controller.Entities.Movies.Movie", PrimaryVersionId = primary.Id };
+        var versionB = new BaseItemEntity { Id = Guid.NewGuid(), Type = "MediaBrowser.Controller.Entities.Movies.Movie", PrimaryVersionId = primary.Id };
+        ctx.BaseItems.AddRange(primary, versionA, versionB);
+
+        // Both versions in progress with the exact same LastPlayedDate - the tie that a strict '>' cannot break.
+        var tied = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc);
+        ctx.UserData.Add(new UserData
+        {
+            ItemId = versionA.Id,
+            Item = versionA,
+            UserId = user.Id,
+            User = user,
+            CustomDataKey = versionA.Id.ToString("N"),
+            PlaybackPositionTicks = 1000,
+            LastPlayedDate = tied
+        });
+        ctx.UserData.Add(new UserData
+        {
+            ItemId = versionB.Id,
+            Item = versionB,
+            UserId = user.Id,
+            User = user,
+            CustomDataKey = versionB.Id.ToString("N"),
+            PlaybackPositionTicks = 2000,
+            LastPlayedDate = tied
+        });
+
+        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();
+    }
+}

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

@@ -0,0 +1,144 @@
+using System;
+using System.Linq;
+using Emby.Server.Implementations.Data;
+using Jellyfin.Database.Implementations;
+using Jellyfin.Database.Implementations.Entities;
+using Jellyfin.Database.Implementations.Locking;
+using Jellyfin.Database.Providers.Sqlite;
+using Jellyfin.Server.Implementations.Item;
+using MediaBrowser.Controller;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Model.Configuration;
+using MediaBrowser.Model.Entities;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+using Xunit;
+using BaseItemKind = Jellyfin.Data.Enums.BaseItemKind;
+
+namespace Jellyfin.Server.Implementations.Tests.Item;
+
+public sealed class BaseItemRepositoryGroupingTests : IDisposable
+{
+    private readonly SqliteConnection _connection;
+    private readonly DbContextOptions<JellyfinDbContext> _dbOptions;
+    private readonly BaseItemRepository _repository;
+    private readonly string _movieTypeName;
+
+    public BaseItemRepositoryGroupingTests()
+    {
+        _connection = new SqliteConnection("Data Source=:memory:");
+        _connection.Open();
+
+        _dbOptions = new DbContextOptionsBuilder<JellyfinDbContext>()
+            .UseSqlite(_connection)
+            .Options;
+
+        using (var ctx = CreateDbContext())
+        {
+            ctx.Database.EnsureCreated();
+        }
+
+        var factory = new Mock<IDbContextFactory<JellyfinDbContext>>();
+        factory.Setup(f => f.CreateDbContext()).Returns(CreateDbContext);
+
+        var itemTypeLookup = new ItemTypeLookup();
+        _movieTypeName = itemTypeLookup.BaseItemKindNames[BaseItemKind.Movie];
+
+        var serverConfigurationManager = new Mock<IServerConfigurationManager>();
+        serverConfigurationManager.Setup(c => c.Configuration).Returns(new ServerConfiguration());
+
+        _repository = new BaseItemRepository(
+            factory.Object,
+            new Mock<IServerApplicationHost>().Object,
+            itemTypeLookup,
+            serverConfigurationManager.Object,
+            NullLogger<BaseItemRepository>.Instance);
+    }
+
+    public void Dispose()
+    {
+        _connection.Dispose();
+    }
+
+    [Fact]
+    public void GetItemList_VersionGroup_ReturnsPrimaryVersion()
+    {
+        // The alternate version sorts before the primary by id, so a plain Min(Id) per
+        // presentation key would wrongly pick the alternate as the group representative.
+        var primaryId = Guid.Parse("eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee");
+        var alternateId = Guid.Parse("11111111-1111-1111-1111-111111111111");
+        var presentationKey = primaryId.ToString("N");
+
+        using (var ctx = CreateDbContext())
+        {
+            ctx.BaseItems.Add(CreateMovieEntity(primaryId, "Movie", presentationKey, null));
+            ctx.BaseItems.Add(CreateMovieEntity(alternateId, "Movie - 1080p", presentationKey, primaryId));
+            ctx.SaveChanges();
+        }
+
+        var result = _repository.GetItemList(CreateQuery());
+
+        var item = Assert.Single(result);
+        Assert.Equal(primaryId, item.Id);
+    }
+
+    [Fact]
+    public void GetItemList_GroupWithoutPrimary_FallsBackToMinId()
+    {
+        var firstId = Guid.Parse("22222222-2222-2222-2222-222222222222");
+        var secondId = Guid.Parse("dddddddd-dddd-dddd-dddd-dddddddddddd");
+        var otherPrimaryId = Guid.Parse("cccccccc-cccc-cccc-cccc-cccccccccccc");
+        var presentationKey = otherPrimaryId.ToString("N");
+
+        using (var ctx = CreateDbContext())
+        {
+            ctx.BaseItems.Add(CreateMovieEntity(firstId, "Movie", presentationKey, otherPrimaryId));
+            ctx.BaseItems.Add(CreateMovieEntity(secondId, "Movie - 4K", presentationKey, otherPrimaryId));
+            ctx.SaveChanges();
+        }
+
+        var result = _repository.GetItemList(CreateQuery());
+
+        var item = Assert.Single(result);
+        Assert.Equal(firstId, item.Id);
+    }
+
+    private static InternalItemsQuery CreateQuery()
+    {
+        // IncludeOwnedItems keeps the alternate version rows in the query so the
+        // grouping collapse is what picks the group representative.
+        return new InternalItemsQuery(new Database.Implementations.Entities.User("test", "auth", "reset"))
+        {
+            IncludeItemTypes = [BaseItemKind.Movie],
+            IncludeOwnedItems = true
+        };
+    }
+
+    private BaseItemEntity CreateMovieEntity(Guid id, string name, string presentationKey, Guid? primaryVersionId)
+    {
+        return new BaseItemEntity
+        {
+            Id = id,
+            Type = _movieTypeName,
+            Name = name,
+            PresentationUniqueKey = presentationKey,
+            PrimaryVersionId = primaryVersionId,
+            MediaType = "Video",
+            IsMovie = true,
+            IsFolder = false,
+            IsVirtualItem = false
+        };
+    }
+
+    private JellyfinDbContext CreateDbContext()
+    {
+        return new JellyfinDbContext(
+            _dbOptions,
+            NullLogger<JellyfinDbContext>.Instance,
+            new SqliteDatabaseProvider(null!, NullLogger<SqliteDatabaseProvider>.Instance),
+            new NoLockBehavior(NullLogger<NoLockBehavior>.Instance));
+    }
+}

tests/Jellyfin.Server.Implementations.Tests/Library/MediaSourceManagerTests.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using AutoFixture;
 using AutoFixture.AutoMoq;
 using Castle.Components.DictionaryAdapter;
@@ -7,6 +9,8 @@ using Emby.Server.Implementations.Library;
 using Jellyfin.Database.Implementations.Entities;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.LiveTv;
+using MediaBrowser.Controller.MediaSegments;
 using MediaBrowser.Model.Dto;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.Globalization;
@@ -144,5 +148,111 @@ namespace Jellyfin.Server.Implementations.Tests.Library
             _mediaSourceManager.SetDefaultAudioAndSubtitleStreamIndices(_item, mediaInfo, _user);
             Assert.Equal(expectedIndex, mediaInfo.DefaultAudioStreamIndex);
         }
+
+        [Fact]
+        public void GetStaticMediaSources_PrimaryQueried_PopulatesPerVersionPositionsAndDefaultsToMostRecent()
+        {
+            var (primary, alt1, alt2) = SetupVersionGroup();
+            SetupUserDataBatch(new Dictionary<Guid, UserItemData>
+            {
+                [alt1.Id] = new UserItemData { Key = "alt1", PlaybackPositionTicks = 10, LastPlayedDate = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc) },
+                [alt2.Id] = new UserItemData { Key = "alt2", PlaybackPositionTicks = 20, LastPlayedDate = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc) }
+            });
+
+            var sources = _mediaSourceManager.GetStaticMediaSources(primary, false, _user);
+
+            // Each version carries its own resume point; the primary has none.
+            Assert.Equal((long?)10, sources.First(s => s.Id == alt1.Id.ToString("N")).PlaybackPositionTicks);
+            Assert.Equal((long?)20, sources.First(s => s.Id == alt2.Id.ToString("N")).PlaybackPositionTicks);
+            Assert.Null(sources.First(s => s.Id == primary.Id.ToString("N")).PlaybackPositionTicks);
+
+            // The most recently played version is the default source, so resuming plays the right file.
+            Assert.Equal(alt2.Id.ToString("N"), sources[0].Id);
+        }
+
+        [Fact]
+        public void GetStaticMediaSources_AlternateQueried_KeepsOwnSourceFirst()
+        {
+            var (primary, alt1, alt2) = SetupVersionGroup();
+            SetupUserDataBatch(new Dictionary<Guid, UserItemData>
+            {
+                [alt2.Id] = new UserItemData { Key = "alt2", PlaybackPositionTicks = 20, LastPlayedDate = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc) }
+            });
+
+            var sources = _mediaSourceManager.GetStaticMediaSources(alt1, false, _user);
+
+            // An explicitly opened version keeps its own source first, even when a sibling was
+            // played more recently, but the sibling's resume point is still populated.
+            Assert.Equal(alt1.Id.ToString("N"), sources[0].Id);
+            Assert.Equal((long?)20, sources.First(s => s.Id == alt2.Id.ToString("N")).PlaybackPositionTicks);
+            Assert.Equal(3, sources.Count);
+        }
+
+        [Fact]
+        public void GetStaticMediaSources_NoProgress_KeepsQueriedItemFirst()
+        {
+            var (primary, _, _) = SetupVersionGroup();
+            SetupUserDataBatch([]);
+
+            var sources = _mediaSourceManager.GetStaticMediaSources(primary, false, _user);
+
+            Assert.Equal(primary.Id.ToString("N"), sources[0].Id);
+            Assert.All(sources, s => Assert.Null(s.PlaybackPositionTicks));
+        }
+
+        [Fact]
+        public void GetStaticMediaSources_NoUser_DoesNotTouchUserData()
+        {
+            var (primary, _, _) = SetupVersionGroup();
+
+            var sources = _mediaSourceManager.GetStaticMediaSources(primary, false);
+
+            Assert.Equal(primary.Id.ToString("N"), sources[0].Id);
+            _mockUserDataManager.Verify(x => x.GetUserDataBatch(It.IsAny<IReadOnlyList<BaseItem>>(), It.IsAny<User>()), Times.Never);
+        }
+
+        private void SetupUserDataBatch(Dictionary<Guid, UserItemData> userData)
+        {
+            _mockUserDataManager
+                .Setup(x => x.GetUserDataBatch(It.IsAny<IReadOnlyList<BaseItem>>(), It.IsAny<User>()))
+                .Returns((IReadOnlyList<BaseItem> items, User _) => items
+                    .Where(i => userData.ContainsKey(i.Id))
+                    .ToDictionary(i => i.Id, i => userData[i.Id]));
+        }
+
+        private static (Video Primary, Video Alt1, Video Alt2) SetupVersionGroup()
+        {
+            var primary = new Video { Id = Guid.NewGuid(), Path = "/Movies/Movie/Movie.mkv" };
+            var alt1 = new Video { Id = Guid.NewGuid(), Path = "/Movies/Movie/Movie - 1080p.mkv", PrimaryVersionId = primary.Id };
+            var alt2 = new Video { Id = Guid.NewGuid(), Path = "/Movies/Movie/Movie - 4K.mkv", PrimaryVersionId = primary.Id };
+
+            // BaseItem.GetMediaSources runs against the static service locators.
+            var mediaSourceManager = new Mock<IMediaSourceManager>();
+            mediaSourceManager.Setup(x => x.GetPathProtocol(It.IsAny<string>())).Returns(MediaProtocol.File);
+            mediaSourceManager.Setup(x => x.GetMediaStreams(It.IsAny<Guid>())).Returns(new List<MediaStream>());
+            mediaSourceManager.Setup(x => x.GetMediaAttachments(It.IsAny<Guid>())).Returns(new List<MediaAttachment>());
+
+            var segmentManager = new Mock<IMediaSegmentManager>();
+            segmentManager.Setup(x => x.IsTypeSupported(It.IsAny<BaseItem>())).Returns(false);
+
+            var libraryManager = new Mock<ILibraryManager>();
+            libraryManager.Setup(x => x.GetLinkedAlternateVersions(It.IsAny<Video>())).Returns(Array.Empty<Video>());
+            libraryManager.Setup(x => x.GetLocalAlternateVersionIds(primary)).Returns(new[] { alt1.Id, alt2.Id });
+            libraryManager.Setup(x => x.GetLocalAlternateVersionIds(alt1)).Returns(Array.Empty<Guid>());
+            libraryManager.Setup(x => x.GetLocalAlternateVersionIds(alt2)).Returns(Array.Empty<Guid>());
+            libraryManager.Setup(x => x.GetItemById(primary.Id)).Returns(primary);
+            libraryManager.Setup(x => x.GetItemById(alt1.Id)).Returns(alt1);
+            libraryManager.Setup(x => x.GetItemById(alt2.Id)).Returns(alt2);
+
+            var recordingsManager = new Mock<IRecordingsManager>();
+            recordingsManager.Setup(x => x.GetActiveRecordingInfo(It.IsAny<string>())).Returns((ActiveRecordingInfo?)null);
+
+            BaseItem.MediaSegmentManager = segmentManager.Object;
+            BaseItem.MediaSourceManager = mediaSourceManager.Object;
+            BaseItem.LibraryManager = libraryManager.Object;
+            Video.RecordingsManager = recordingsManager.Object;
+
+            return (primary, alt1, alt2);
+        }
     }
 }