Fix by-name endpoints reporting TotalRecordCount=0 next to a populated Items array

`GetItemValues` -- the shared path behind `/Artists`, `/AlbumArtists`, `/Genres`,
`/MusicGenres` and `/Studios` -- disabled the total record count whenever the
query carried no `Limit`:

    if (!filter.Limit.HasValue)
    {
        filter.EnableTotalRecordCount = false;
    }

A request without an explicit limit therefore came back with N entries in `Items`
and `TotalRecordCount = 0`. Clients that page on the reported total -- the
documented contract every other list endpoint honours -- read that as an empty
library. `/Items` and `/Persons` do not share this path and report the count
correctly, which is what makes the inconsistency visible from the outside.

Measured against master with a 62-track music library:

    GET /Artists?UserId=...              -> TotalRecordCount=0  Items=5
    GET /Artists?UserId=...&limit=100    -> TotalRecordCount=5  Items=5

Dropping the block costs nothing: `representativeIds` is materialised into a
`List<Guid>` a few lines below regardless, so `.Count` was already available and
the count is now reported from it. Callers that genuinely want to skip the count
still can -- `EnableTotalRecordCount = false` is honoured as before.

The block also mutated the caller's own query object, so a query instance reused
across calls silently lost its total after the first limitless one. That is
covered by a test as well.

2 files changed, 199 insertions, 5 deletions

diff --git a/Jellyfin.Server.Implementations/Item/BaseItemRepository.ByName.cs b/Jellyfin.Server.Implementations/Item/BaseItemRepository.ByName.cs
index 8e917f6951..5a41619390 100644
--- a/Jellyfin.Server.Implementations/Item/BaseItemRepository.ByName.cs
+++ b/Jellyfin.Server.Implementations/Item/BaseItemRepository.ByName.cs
@@ -144,11 +144,6 @@ public sealed partial class BaseItemRepository
     {
         ArgumentNullException.ThrowIfNull(filter);
 
-        if (!filter.Limit.HasValue)
-        {
-            filter.EnableTotalRecordCount = false;
-        }
-
         using var context = _dbProvider.CreateDbContext();
 
         var innerQueryFilter = TranslateQuery(context.BaseItems.Where(e => e.Id != EF.Constant(PlaceholderId)), context, new InternalItemsQuery(filter.User)
diff --git a/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryByNameTotalCountTests.cs b/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryByNameTotalCountTests.cs
new file mode 100644
index 0000000000..f675621e21
--- /dev/null
+++ b/tests/Jellyfin.Server.Implementations.Tests/Item/BaseItemRepositoryByNameTotalCountTests.cs
@@ -0,0 +1,199 @@
+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 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;
+
+/// <summary>
+/// The by-name endpoints (artists, album artists, genres, studios) all funnel through
+/// <c>GetItemValues</c>. A query without a <c>Limit</c> used to have its total record count
+/// silently disabled, so callers got a populated <c>Items</c> array next to a zero total.
+/// </summary>
+public sealed class BaseItemRepositoryByNameTotalCountTests : IDisposable
+{
+    private readonly SqliteConnection _connection;
+    private readonly DbContextOptions<JellyfinDbContext> _dbOptions;
+    private readonly BaseItemRepository _repository;
+    private readonly ItemTypeLookup _itemTypeLookup;
+
+    public BaseItemRepositoryByNameTotalCountTests()
+    {
+        _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);
+
+        _itemTypeLookup = new ItemTypeLookup();
+
+        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 GetArtists_WithoutLimit_ReportsTotalRecordCount()
+    {
+        SeedArtists(3);
+
+        var result = _repository.GetArtists(CreateQuery(limit: null));
+
+        Assert.Equal(3, result.Items.Count);
+        Assert.Equal(3, result.TotalRecordCount);
+    }
+
+    [Fact]
+    public void GetArtists_WithLimit_ReportsTotalBeyondThePage()
+    {
+        SeedArtists(3);
+
+        var result = _repository.GetArtists(CreateQuery(limit: 2));
+
+        Assert.Equal(2, result.Items.Count);
+        Assert.Equal(3, result.TotalRecordCount);
+    }
+
+    [Fact]
+    public void GetArtists_TotalRecordCountDisabled_StaysZero()
+    {
+        SeedArtists(3);
+
+        var query = CreateQuery(limit: null);
+        query.EnableTotalRecordCount = false;
+
+        var result = _repository.GetArtists(query);
+
+        Assert.Equal(3, result.Items.Count);
+        Assert.Equal(0, result.TotalRecordCount);
+    }
+
+    [Fact]
+    public void GetArtists_WithoutLimit_DoesNotMutateCallerQuery()
+    {
+        SeedArtists(1);
+
+        var query = CreateQuery(limit: null);
+        Assert.True(query.EnableTotalRecordCount);
+
+        _repository.GetArtists(query);
+
+        // The repository used to flip this flag on the caller's own query object, so a
+        // reused query silently lost its total on every subsequent call.
+        Assert.True(query.EnableTotalRecordCount);
+    }
+
+    private static InternalItemsQuery CreateQuery(int? limit)
+    {
+        return new InternalItemsQuery(new User("test", "auth", "reset"))
+        {
+            Limit = limit
+        };
+    }
+
+    /// <summary>
+    /// Creates <paramref name="count"/> artists, each credited on one song, which is what
+    /// makes them visible to the item-value join behind the by-name endpoints.
+    /// </summary>
+    private void SeedArtists(int count)
+    {
+        using var ctx = CreateDbContext();
+
+        for (var i = 0; i < count; i++)
+        {
+            var name = $"Artist {i}";
+            var cleanName = name.ToLowerInvariant();
+
+            var artistId = Guid.Parse($"aaaaaaaa-0000-0000-0000-{i:D12}");
+            var songId = Guid.Parse($"55555555-0000-0000-0000-{i:D12}");
+            var valueId = Guid.Parse($"cccccccc-0000-0000-0000-{i:D12}");
+
+            var artist = new BaseItemEntity
+            {
+                Id = artistId,
+                Type = _itemTypeLookup.BaseItemKindNames[BaseItemKind.MusicArtist],
+                Name = name,
+                CleanName = cleanName,
+                PresentationUniqueKey = artistId.ToString("N"),
+                IsFolder = true,
+                IsVirtualItem = false
+            };
+
+            var song = new BaseItemEntity
+            {
+                Id = songId,
+                Type = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Audio],
+                Name = $"Song {i}",
+                CleanName = $"song {i}",
+                PresentationUniqueKey = songId.ToString("N"),
+                MediaType = "Audio",
+                IsFolder = false,
+                IsVirtualItem = false
+            };
+
+            var itemValue = new ItemValue
+            {
+                ItemValueId = valueId,
+                Type = ItemValueType.Artist,
+                Value = name,
+                CleanValue = cleanName
+            };
+
+            ctx.BaseItems.Add(artist);
+            ctx.BaseItems.Add(song);
+            ctx.ItemValues.Add(itemValue);
+            ctx.ItemValuesMap.Add(new ItemValueMap
+            {
+                ItemId = songId,
+                ItemValueId = valueId,
+                Item = song,
+                ItemValue = itemValue
+            });
+        }
+
+        ctx.SaveChanges();
+    }
+
+    private JellyfinDbContext CreateDbContext()
+    {
+        return new JellyfinDbContext(
+            _dbOptions,
+            NullLogger<JellyfinDbContext>.Instance,
+            new SqliteDatabaseProvider(null!, NullLogger<SqliteDatabaseProvider>.Instance),
+            new NoLockBehavior(NullLogger<NoLockBehavior>.Instance));
+    }
+}