Multiple fixes and improvements

Co-Authored-By: Cody Robibero <cody@robibe.ro>

3 files changed, 349 insertions, 81 deletions

diff --git a/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs b/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs
index d2f8e5060c..623c1ea0ab 100644
--- a/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs
+++ b/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs
@@ -36,8 +36,8 @@ public sealed partial class BaseItemRepository
     private static Expression<Func<BaseItemEntity, bool>> IsFolderFilter => e => e.IsFolder;
 
     // "und" is the language filters' stand-in for a track that declares no language at all.
-    private static bool IsUndetermined(string language)
-        => string.Equals(language, "und", StringComparison.OrdinalIgnoreCase);
+    private static string NormalizeLanguage(string language)
+        => string.Equals(language, "und", StringComparison.OrdinalIgnoreCase) ? "und" : language;
 
     // The primary versions whose alternate version satisfies a dimension bound. Anchored on
     // PrimaryVersionId so the filtered index carries it rather than a scan of every item.
@@ -82,40 +82,57 @@ public sealed partial class BaseItemRepository
                 include4K = true;
             }
 
-            // A 4K remux of an SD primary is a version of the same item, so the resolution a caller
-            // filters on is the best any of the item's versions offers, not just the primary file's.
-            // The filtered PrimaryVersionId index keeps this to the few items that have versions.
-            var versionsAtResolution = context.BaseItems
-                .Where(v => v.PrimaryVersionId != null
-                    && v.Width > 0
-                    && ((includeSD && v.Width < HDWidth)
-                        || (includeHD && v.Width >= HDWidth && !(v.Width >= UHDWidth || v.Height >= UHDHeight))
-                        || (include4K && (v.Width >= UHDWidth || v.Height >= UHDHeight))))
-                .Select(v => v.PrimaryVersionId!.Value);
-
-            // Non-folders: check own resolution directly (no subquery).
-            // Folders (Series, BoxSets): EXISTS check on descendants/linked children.
-            // Using navigation properties (a.Item, lc.Child) produces efficient
-            // EXISTS + JOIN instead of nested IN (SELECT ...) subqueries.
+            // A 4K remux of an SD primary is a version of the same item, so the bucket a caller filters
+            // on is the best any of the item's versions offers, not just the primary file's. Three sets,
+            // because a bucket is as much about what the version group does not have as what it does, and
+            // because an unprobed primary can still be placed by a version that does carry dimensions.
+            // The filtered PrimaryVersionId index keeps all three to the few items that have versions.
+            var versionsSd = VersionsMatchingDimension(context, v => v.Width > 0 && v.Width < HDWidth);
+            var versionsHd = VersionsMatchingDimension(context, v => v.Width >= HDWidth);
+            var versions4K = VersionsMatchingDimension(context, v => v.Width >= UHDWidth || v.Height >= UHDHeight);
+
+            // Only the SD test needs the Width > 0 guard against a row with no dimensions: such a row
+            // cannot reach the HD or 4K bound anyway, and EF lowers the HD bucket's negated "not itself
+            // 4K" guard to CASE WHEN ... THEN 0 ELSE 1, which already reads unknown as not 4K rather
+            // than propagating a null. Folders (Series, BoxSets) answer on their descendants, bucketed
+            // exactly as a top-level item is so that the two cannot disagree; the navigation properties
+            // (a.Item, lc.Child) give EXISTS + JOIN rather than nested IN (SELECT ...).
             baseQuery = baseQuery.Where(e =>
                 (!e.IsFolder
-                    && ((e.Width > 0
-                            && ((includeSD && e.Width < HDWidth)
-                                || (includeHD && e.Width >= HDWidth && !(e.Width >= UHDWidth || e.Height >= UHDHeight))
-                                || (include4K && (e.Width >= UHDWidth || e.Height >= UHDHeight))))
-                        || versionsAtResolution.Contains(e.Id)))
+                    && ((includeSD
+                            && ((e.Width > 0 && e.Width < HDWidth) || versionsSd.Contains(e.Id))
+                            && !versionsHd.Contains(e.Id)
+                            && !versions4K.Contains(e.Id))
+                        || (includeHD
+                            && (e.Width >= HDWidth || versionsHd.Contains(e.Id))
+                            && !(e.Width >= UHDWidth || e.Height >= UHDHeight)
+                            && !versions4K.Contains(e.Id))
+                        || (include4K
+                            && (e.Width >= UHDWidth || e.Height >= UHDHeight || versions4K.Contains(e.Id)))))
                 || (e.IsFolder
                     && (e.Children!.Any(a =>
-                            a.Item.Width > 0
-                            && ((includeSD && a.Item.Width < HDWidth)
-                                || (includeHD && a.Item.Width >= HDWidth && !(a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight))
-                                || (include4K && (a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight))))
+                            (includeSD
+                                && ((a.Item.Width > 0 && a.Item.Width < HDWidth) || versionsSd.Contains(a.ItemId))
+                                && !versionsHd.Contains(a.ItemId)
+                                && !versions4K.Contains(a.ItemId))
+                            || (includeHD
+                                && (a.Item.Width >= HDWidth || versionsHd.Contains(a.ItemId))
+                                && !(a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight)
+                                && !versions4K.Contains(a.ItemId))
+                            || (include4K
+                                && (a.Item.Width >= UHDWidth || a.Item.Height >= UHDHeight || versions4K.Contains(a.ItemId))))
                         || context.LinkedChildren.Any(lc =>
                             lc.ParentId == e.Id
-                            && lc.Child!.Width > 0
-                            && ((includeSD && lc.Child.Width < HDWidth)
-                                || (includeHD && lc.Child.Width >= HDWidth && !(lc.Child.Width >= UHDWidth || lc.Child.Height >= UHDHeight))
-                                || (include4K && (lc.Child.Width >= UHDWidth || lc.Child.Height >= UHDHeight)))))));
+                            && ((includeSD
+                                    && ((lc.Child!.Width > 0 && lc.Child!.Width < HDWidth) || versionsSd.Contains(lc.ChildId))
+                                    && !versionsHd.Contains(lc.ChildId)
+                                    && !versions4K.Contains(lc.ChildId))
+                                || (includeHD
+                                    && (lc.Child!.Width >= HDWidth || versionsHd.Contains(lc.ChildId))
+                                    && !(lc.Child!.Width >= UHDWidth || lc.Child!.Height >= UHDHeight)
+                                    && !versions4K.Contains(lc.ChildId))
+                                || (include4K
+                                    && (lc.Child!.Width >= UHDWidth || lc.Child!.Height >= UHDHeight || versions4K.Contains(lc.ChildId))))))));
         }
 
         // Same reasoning as the resolution filter: a dimension bound is met if any version meets it.
@@ -132,17 +149,19 @@ public sealed partial class BaseItemRepository
             baseQuery = baseQuery.Where(e => e.Height >= minHeight || versionsTallEnough.Contains(e.Id));
         }
 
+        // An upper bound inverts that: it is met only if no version breaches it, since the item's
+        // resolution is the best its version group offers.
         if (maxWidth.HasValue)
         {
-            var versionsNarrowEnough = VersionsMatchingDimension(context, v => v.Width <= maxWidth);
-            baseQuery = baseQuery.Where(e => e.Width <= maxWidth || versionsNarrowEnough.Contains(e.Id));
+            var versionsTooWide = VersionsMatchingDimension(context, v => v.Width > maxWidth);
+            baseQuery = baseQuery.Where(e => e.Width <= maxWidth && !versionsTooWide.Contains(e.Id));
         }
 
         if (filter.MaxHeight.HasValue)
         {
             var maxHeight = filter.MaxHeight;
-            var versionsShortEnough = VersionsMatchingDimension(context, v => v.Height <= maxHeight);
-            baseQuery = baseQuery.Where(e => e.Height <= maxHeight || versionsShortEnough.Contains(e.Id));
+            var versionsTooTall = VersionsMatchingDimension(context, v => v.Height > maxHeight);
+            baseQuery = baseQuery.Where(e => e.Height <= maxHeight && !versionsTooTall.Contains(e.Id));
         }
 
         if (filter.IsLocked.HasValue)
@@ -793,8 +812,8 @@ public sealed partial class BaseItemRepository
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoAudioTrackWithLanguage))
         {
-            var lang = filter.HasNoAudioTrackWithLanguage;
-            var undetermined = IsUndetermined(lang);
+            var lang = NormalizeLanguage(filter.HasNoAudioTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
             var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Audio, lang);
             // A track only an alternate version carries still belongs to the item a caller sees, so the
             // item's own streams alone do not decide this. Same for every stream filter below.
@@ -812,8 +831,8 @@ public sealed partial class BaseItemRepository
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoInternalSubtitleTrackWithLanguage))
         {
-            var lang = filter.HasNoInternalSubtitleTrackWithLanguage;
-            var undetermined = IsUndetermined(lang);
+            var lang = NormalizeLanguage(filter.HasNoInternalSubtitleTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
             var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang, IsExternal: false);
             var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
             var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
@@ -829,8 +848,8 @@ public sealed partial class BaseItemRepository
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoExternalSubtitleTrackWithLanguage))
         {
-            var lang = filter.HasNoExternalSubtitleTrackWithLanguage;
-            var undetermined = IsUndetermined(lang);
+            var lang = NormalizeLanguage(filter.HasNoExternalSubtitleTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
             var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang, IsExternal: true);
             var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
             var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
@@ -846,8 +865,8 @@ public sealed partial class BaseItemRepository
 
         if (!string.IsNullOrWhiteSpace(filter.HasNoSubtitleTrackWithLanguage))
         {
-            var lang = filter.HasNoSubtitleTrackWithLanguage;
-            var undetermined = IsUndetermined(lang);
+            var lang = NormalizeLanguage(filter.HasNoSubtitleTrackWithLanguage);
+            var undetermined = string.Equals(lang, "und", StringComparison.Ordinal);
             var criteria = new HasMediaStreamType(MediaStreamTypeEntity.Subtitle, lang);
             var versionsWithSubtitles = DescendantQueryHelper.GetPrimaryVersionIdsMatching(context, criteria);
             var foldersWithSubtitles = DescendantQueryHelper.GetFolderIdsMatching(context, criteria);
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/DescendantQueryHelper.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/DescendantQueryHelper.cs
index 5a17a46d9e..6b08f8dd7e 100644
--- a/src/Jellyfin.Database/Jellyfin.Database.Implementations/DescendantQueryHelper.cs
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/DescendantQueryHelper.cs
@@ -102,20 +102,25 @@ public static class DescendantQueryHelper
         ArgumentNullException.ThrowIfNull(context);
         ArgumentNullException.ThrowIfNull(criteria);
 
-        var matchingItemIds = GetItemIdsMatching(context, criteria);
+        // Both sides of a version group can hold a folder a caller would see as matching: the
+        // alternate carries its own AncestorIds rows and may sit in a different library than the
+        // primary it is reported against, and the primary is the item that becomes visible.
+        var reportedItemIds = MatchingMediaOwnerIds(context, criteria)
+            .Concat(GetPrimaryVersionIdsMatching(context, criteria))
+            .Distinct();
 
         // One hop up the closure covers every ancestor level.
         var hierarchyAncestors = context.AncestorIds
-            .Where(e => matchingItemIds.Contains(e.ItemId))
+            .Where(e => reportedItemIds.Contains(e.ItemId))
             .Select(e => e.ParentItemId);
 
-        var linkParents = ResolveLinkParents(context, matchingItemIds, hierarchyAncestors);
+        var linkParents = ResolveLinkParents(context, reportedItemIds, hierarchyAncestors);
 
-        // Read back as a sub-select so the result stays composable. LinkedChildren is the cheapest
-        // source: owning a link is what put an id in the set, and ParentId is its leading key.
-        var linkedParents = context.LinkedChildren
-            .WhereOneOrMany(linkParents, e => e.ParentId)
-            .Select(e => e.ParentId);
+        // Read back as a sub-select so the result stays composable. Off the primary key, which is one
+        // row per id: LinkedChildren would yield one row per link and lean on the outer Distinct.
+        var linkedParents = context.BaseItems
+            .WhereOneOrMany(linkParents, e => e.Id)
+            .Select(e => e.Id);
 
         var linkedParentAncestors = context.AncestorIds
             .WhereOneOrMany(linkParents, e => e.ItemId)
@@ -135,25 +140,6 @@ public static class DescendantQueryHelper
     }
 
     /// <summary>
-    /// Gets a queryable of the IDs of the items whose media matches the criteria.
-    /// </summary>
-    /// <param name="context">Database context.</param>
-    /// <param name="criteria">The matching criteria to apply.</param>
-    /// <returns>Queryable of item IDs.</returns>
-    /// <remarks>
-    /// An alternate version is a second file for its primary version and is never listed on its own, so a
-    /// track only that file carries is reported against the primary: the item a caller can actually see.
-    /// </remarks>
-    public static IQueryable<Guid> GetItemIdsMatching(JellyfinDbContext context, FolderMatchCriteria criteria)
-    {
-        ArgumentNullException.ThrowIfNull(context);
-        ArgumentNullException.ThrowIfNull(criteria);
-
-        return MatchingMediaOwners(context, criteria)
-            .Select(e => e.PrimaryVersionId ?? e.Id);
-    }
-
-    /// <summary>
     /// Gets a queryable of the IDs of the primary versions whose alternate version's media matches the
     /// criteria.
     /// </summary>
@@ -170,23 +156,47 @@ public static class DescendantQueryHelper
         ArgumentNullException.ThrowIfNull(context);
         ArgumentNullException.ThrowIfNull(criteria);
 
-        return MatchingMediaOwners(context, criteria)
-            .Where(e => e.PrimaryVersionId.HasValue)
-            .Select(e => e.PrimaryVersionId!.Value);
+        // Anchored on the alternates rather than on the matches: "has a primary version" is served by
+        // the partial PrimaryVersionId index, which holds only the few items that are second files, so
+        // this costs a seek each into the stream index instead of a second pass over every stream row.
+        var alternates = context.BaseItems.Where(v => v.PrimaryVersionId.HasValue);
+
+        if (criteria is HasChapterImages)
+        {
+            return alternates
+                .Where(v => context.Chapters.Any(c => c.ItemId.Equals(v.Id) && c.ImagePath != null))
+                .Select(v => v.PrimaryVersionId!.Value);
+        }
+
+        var matchingStreams = MatchingMediaStreams(context, criteria);
+
+        return alternates
+            .Where(v => matchingStreams.Any(ms => ms.ItemId.Equals(v.Id)))
+            .Select(v => v.PrimaryVersionId!.Value);
     }
 
-    // The items whose own media matches, as their BaseItems rows so the version group can be read off
-    // them. One definition of "matches" per criteria, so the projections above cannot drift apart.
-    private static IQueryable<BaseItemEntity> MatchingMediaOwners(JellyfinDbContext context, FolderMatchCriteria criteria)
+    // The ids of the items whose own media matches. Kept to the stream and chapter tables so their
+    // covering indexes answer this outright: projecting the BaseItems navigation instead would add a
+    // primary-key lookup per stream row rather than one per matching item, and the leading key of both
+    // indexes leaves the ids already grouped, so the Distinct costs no sort.
+    private static IQueryable<Guid> MatchingMediaOwnerIds(JellyfinDbContext context, FolderMatchCriteria criteria)
+        => criteria is HasChapterImages
+            ? context.Chapters
+                .Where(c => c.ImagePath != null)
+                .Select(c => c.ItemId)
+                .Distinct()
+            : MatchingMediaStreams(context, criteria)
+                .Select(ms => ms.ItemId)
+                .Distinct();
+
+    // The stream rows a criteria matches. One definition, so the owner projection and the alternate
+    // projection cannot drift apart despite reading it from opposite ends.
+    private static IQueryable<MediaStreamInfo> MatchingMediaStreams(JellyfinDbContext context, FolderMatchCriteria criteria)
         => criteria switch
         {
             HasSubtitles => context.MediaStreamInfos
-                .Where(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle)
-                .Select(ms => ms.Item),
-            HasChapterImages => context.Chapters
-                .Where(c => c.ImagePath != null)
-                .Select(c => c.Item),
-            HasMediaStreamType m => GetMatchingMediaStreams(context, m).Select(ms => ms.Item),
+                .Where(ms => ms.StreamType == MediaStreamTypeEntity.Subtitle),
+            HasMediaStreamType m => GetMatchingMediaStreams(context, m),
             _ => throw new ArgumentOutOfRangeException(nameof(criteria), $"Unknown criteria type: {criteria.GetType().Name}")
         };
 
diff --git a/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryStreamFilterTests.cs b/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryStreamFilterTests.cs
index 12a7fc1aef..4e8d84850b 100644
--- a/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryStreamFilterTests.cs
+++ b/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryStreamFilterTests.cs
@@ -35,6 +35,29 @@ public sealed class BaseItemRepositoryStreamFilterTests : SqliteDbTestFixture
     private readonly Guid _versionedMovie = Guid.NewGuid();
     private readonly Guid _alternateVersion = Guid.NewGuid();
 
+    // A series in the same library, so the folder branch of the resolution filter has a version group
+    // to reach through as well: an SD episode whose second file is 4K.
+    private readonly Guid _versionedSeries = Guid.NewGuid();
+    private readonly Guid _versionedEpisode = Guid.NewGuid();
+    private readonly Guid _episodeAlternate = Guid.NewGuid();
+
+    // An unprobed primary: only its second file carries dimensions, and they are SD.
+    private readonly Guid _unprobedMovie = Guid.NewGuid();
+    private readonly Guid _unprobedAlternate = Guid.NewGuid();
+
+    // A plain SD movie with no second file, as the control the version groups are read against.
+    private readonly Guid _sdMovie = Guid.NewGuid();
+
+    // An unprobed primary whose only second file is HD, so the HD bucket has to place it off nulls.
+    private readonly Guid _hdOnlyByVersion = Guid.NewGuid();
+    private readonly Guid _hdOnlyAlternate = Guid.NewGuid();
+
+    // Three files for one movie: the HD one would place it in the HD bucket on its own, the 4K one has
+    // to win. Only a group holding both can tell the HD bucket's upper guard from its lower one.
+    private readonly Guid _threeWayMovie = Guid.NewGuid();
+    private readonly Guid _threeWayHd = Guid.NewGuid();
+    private readonly Guid _threeWay4K = Guid.NewGuid();
+
     public BaseItemRepositoryStreamFilterTests()
     {
         using (var ctx = CreateDbContext())
@@ -179,6 +202,90 @@ public sealed class BaseItemRepositoryStreamFilterTests : SqliteDbTestFixture
         Assert.DoesNotContain(_withSubtitles, _repository.GetItemIdsList(new InternalItemsQuery { MinWidth = 3000 }));
     }
 
+    [Fact]
+    public void MaxWidth_ExcludesAnItemWhoseAlternateVersionBreachesTheBound()
+    {
+        // The SD primary is narrow enough on its own, but the 4K second file is what a caller would play.
+        Assert.DoesNotContain(_versionedMovie, _repository.GetItemIdsList(new InternalItemsQuery { MaxWidth = 1920 }));
+        Assert.Contains(_sdMovie, _repository.GetItemIdsList(new InternalItemsQuery { MaxWidth = 1920 }));
+    }
+
+    [Fact]
+    public void MaxHeight_ExcludesAnItemWhoseAlternateVersionBreachesTheBound()
+    {
+        Assert.DoesNotContain(_versionedMovie, _repository.GetItemIdsList(new InternalItemsQuery { MaxHeight = 1080 }));
+        Assert.Contains(_sdMovie, _repository.GetItemIdsList(new InternalItemsQuery { MaxHeight = 1080 }));
+    }
+
+    [Fact]
+    public void IsHD_False_ExcludesAnSdPrimaryWhoseAlternateVersionIsBetter()
+    {
+        var ids = _repository.GetItemIdsList(new InternalItemsQuery { IsHD = false });
+
+        // 720x480 on its own, but the version group tops out at 4K.
+        Assert.DoesNotContain(_versionedMovie, ids);
+        Assert.Contains(_sdMovie, ids);
+    }
+
+    [Fact]
+    public void IsHD_False_MatchesAPrimaryPlacedOnlyByItsAlternateVersion()
+    {
+        // The primary carries no dimensions at all; the SD second file is the group's best.
+        Assert.Contains(_unprobedMovie, _repository.GetItemIdsList(new InternalItemsQuery { IsHD = false }));
+    }
+
+    [Fact]
+    public void IsHD_True_ExcludesAnItemWhoseVersionGroupReaches4K()
+    {
+        var ids = _repository.GetItemIdsList(new InternalItemsQuery { IsHD = true });
+
+        Assert.DoesNotContain(_versionedMovie, ids);
+        Assert.DoesNotContain(_unprobedMovie, ids);
+        // The 1920-wide second file alone would say HD; the 4K third file is the group's best.
+        Assert.DoesNotContain(_threeWayMovie, ids);
+    }
+
+    [Fact]
+    public void Is4K_MatchesAnItemWhoseVersionGroupHoldsBothHdAnd4K()
+    {
+        Assert.Contains(_threeWayMovie, _repository.GetItemIdsList(new InternalItemsQuery { Is4K = true }));
+    }
+
+    [Fact]
+    public void IsHD_True_MatchesAPrimaryPlacedOnlyByItsAlternateVersion()
+    {
+        // The primary carries no dimensions of its own; the HD second file is the group's best.
+        Assert.Contains(_hdOnlyByVersion, _repository.GetItemIdsList(new InternalItemsQuery { IsHD = true }));
+    }
+
+    [Fact]
+    public void Is4K_MatchesTheSeriesOfAnEpisodeWhoseAlternateVersionIs4K()
+    {
+        // The folder branch buckets a descendant the same way the item branch buckets a top-level item.
+        Assert.Contains(_versionedSeries, _repository.GetItemIdsList(new InternalItemsQuery { Is4K = true }));
+    }
+
+    [Fact]
+    public void IsHD_False_ExcludesTheSeriesOfAnSdEpisodeWithABetterAlternateVersion()
+    {
+        // Before the version group was consulted on descendants too, the SD episode alone matched here
+        // while the same pair at top level did not.
+        Assert.DoesNotContain(_versionedSeries, _repository.GetItemIdsList(new InternalItemsQuery { IsHD = false }));
+    }
+
+    [Theory]
+    [InlineData("und")]
+    [InlineData("UND")]
+    public void HasNoAudioTrackWithLanguage_TreatsUndeterminedCaseInsensitively(string language)
+    {
+        var ids = _repository.GetItemIdsList(new InternalItemsQuery { HasNoAudioTrackWithLanguage = language });
+
+        // The alternate version carries an audio track with no language, which is what "und" stands for,
+        // so the item it is reported against does have one.
+        Assert.DoesNotContain(_unprobedMovie, ids);
+        Assert.Contains(_versionedMovie, ids);
+    }
+
     private void Seed(JellyfinDbContext context)
     {
         context.BaseItems.Add(new BaseItemEntity { Id = _library, Type = FolderType, Name = "Library", IsFolder = true });
@@ -302,6 +409,9 @@ public sealed class BaseItemRepositoryStreamFilterTests : SqliteDbTestFixture
             Item = null!
         });
 
+        SeedVersionedSeries(context);
+        SeedUnprobedVersionGroup(context);
+
         context.Chapters.Add(new Chapter
         {
             ItemId = _alternateVersion,
@@ -311,4 +421,133 @@ public sealed class BaseItemRepositoryStreamFilterTests : SqliteDbTestFixture
             Item = null!
         });
     }
+
+    // The same SD primary / 4K second file pair one level down, so the resolution filter has to answer
+    // for the series off its descendants.
+    private void SeedVersionedSeries(JellyfinDbContext context)
+    {
+        context.BaseItems.Add(new BaseItemEntity { Id = _versionedSeries, Type = FolderType, Name = "Versioned series", IsFolder = true });
+        context.BaseItems.Add(new BaseItemEntity { Id = _versionedEpisode, Type = MovieType, Name = "Versioned episode", Width = 720, Height = 480 });
+        context.BaseItems.Add(new BaseItemEntity
+        {
+            Id = _episodeAlternate,
+            Type = MovieType,
+            Name = "Versioned episode 4K",
+            PrimaryVersionId = _versionedEpisode,
+            Width = 3840,
+            Height = 2160
+        });
+
+        context.AncestorIds.Add(new AncestorId
+        {
+            ItemId = _versionedSeries,
+            ParentItemId = _versionLibrary,
+            Item = null!,
+            ParentItem = null!
+        });
+
+        foreach (var itemId in new[] { _versionedEpisode, _episodeAlternate })
+        {
+            context.AncestorIds.Add(new AncestorId
+            {
+                ItemId = itemId,
+                ParentItemId = _versionedSeries,
+                Item = null!,
+                ParentItem = null!
+            });
+        }
+    }
+
+    // A primary that was never probed, so only its second file can place it in a bucket. Its audio track
+    // declares no language, which is what the "und" filters stand in for.
+    private void SeedUnprobedVersionGroup(JellyfinDbContext context)
+    {
+        context.BaseItems.Add(new BaseItemEntity { Id = _sdMovie, Type = MovieType, Name = "SD movie", Width = 720, Height = 480 });
+        context.AncestorIds.Add(new AncestorId
+        {
+            ItemId = _sdMovie,
+            ParentItemId = _versionLibrary,
+            Item = null!,
+            ParentItem = null!
+        });
+
+        context.BaseItems.Add(new BaseItemEntity { Id = _unprobedMovie, Type = MovieType, Name = "Unprobed movie" });
+        context.BaseItems.Add(new BaseItemEntity
+        {
+            Id = _unprobedAlternate,
+            Type = MovieType,
+            Name = "Unprobed movie SD",
+            PrimaryVersionId = _unprobedMovie,
+            Width = 720,
+            Height = 480
+        });
+
+        foreach (var itemId in new[] { _unprobedMovie, _unprobedAlternate })
+        {
+            context.AncestorIds.Add(new AncestorId
+            {
+                ItemId = itemId,
+                ParentItemId = _versionLibrary,
+                Item = null!,
+                ParentItem = null!
+            });
+        }
+
+        context.MediaStreamInfos.Add(new MediaStreamInfo
+        {
+            ItemId = _unprobedAlternate,
+            StreamIndex = 0,
+            StreamType = MediaStreamTypeEntity.Audio,
+            Item = null!
+        });
+
+        SeedMixedVersionGroups(context);
+    }
+
+    // The two groups that separate the HD bucket's lower bound from its upper one: one that only a 4K
+    // third file keeps out of HD, and one that only an HD second file puts into it.
+    private void SeedMixedVersionGroups(JellyfinDbContext context)
+    {
+        context.BaseItems.Add(new BaseItemEntity { Id = _threeWayMovie, Type = MovieType, Name = "Three-way movie", Width = 720, Height = 480 });
+        context.BaseItems.Add(new BaseItemEntity
+        {
+            Id = _threeWayHd,
+            Type = MovieType,
+            Name = "Three-way movie HD",
+            PrimaryVersionId = _threeWayMovie,
+            Width = 1920,
+            Height = 1080
+        });
+        context.BaseItems.Add(new BaseItemEntity
+        {
+            Id = _threeWay4K,
+            Type = MovieType,
+            Name = "Three-way movie 4K",
+            PrimaryVersionId = _threeWayMovie,
+            Width = 3840,
+            Height = 2160
+        });
+
+        context.BaseItems.Add(new BaseItemEntity { Id = _hdOnlyByVersion, Type = MovieType, Name = "HD only by version" });
+        context.BaseItems.Add(new BaseItemEntity
+        {
+            Id = _hdOnlyAlternate,
+            Type = MovieType,
+            Name = "HD only by version, HD file",
+            PrimaryVersionId = _hdOnlyByVersion,
+            Width = 1920,
+            Height = 1080
+        });
+
+        foreach (var itemId in new[] { _threeWayMovie, _threeWayHd, _threeWay4K, _hdOnlyByVersion, _hdOnlyAlternate })
+        {
+            context.AncestorIds.Add(new AncestorId
+            {
+                ItemId = itemId,
+                ParentItemId = _versionLibrary,
+                Item = null!,
+                ParentItem = null!
+            });
+        }
+    }
 }