Merge branch 'master' into fix/livetv-channel-icon-refresh

Resolve GuideManager conflict by keeping LiveTvChannelImageHelper so
channel icons re-fetch on every guide refresh, including when the URL
is unchanged.

tests/Jellyfin.Api.Tests/Helpers/MediaInfoHelperTests.cs

@@ -0,0 +1,99 @@
+using System;
+using System.Globalization;
+using Jellyfin.Api.Helpers;
+using MediaBrowser.Common.Net;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Devices;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.MediaEncoding;
+using MediaBrowser.Model.Dto;
+using MediaBrowser.Model.MediaInfo;
+using Microsoft.Extensions.Logging;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Api.Tests.Helpers
+{
+    public class MediaInfoHelperTests
+    {
+        private static MediaInfoHelper CreateHelper()
+        {
+            return new MediaInfoHelper(
+                Mock.Of<IUserManager>(),
+                Mock.Of<ILibraryManager>(),
+                Mock.Of<IMediaSourceManager>(),
+                Mock.Of<IMediaEncoder>(),
+                Mock.Of<IServerConfigurationManager>(),
+                Mock.Of<ILogger<MediaInfoHelper>>(),
+                Mock.Of<INetworkManager>(),
+                Mock.Of<IDeviceManager>());
+        }
+
+        private static MediaSourceInfo CreateSource(Guid itemId, int bitrate, bool supportsDirectPlay = true)
+        {
+            return new MediaSourceInfo
+            {
+                Id = itemId.ToString("N", CultureInfo.InvariantCulture),
+                Protocol = MediaProtocol.File,
+                Bitrate = bitrate,
+                SupportsDirectPlay = supportsDirectPlay,
+                SupportsDirectStream = true,
+                SupportsTranscoding = true
+            };
+        }
+
+        [Fact]
+        public void SortMediaSources_PreferredItemExceedsBitrate_StaysDefault()
+        {
+            // The version the user was watching (the queried item) must stay the default
+            // even when a sibling version fits the bitrate limit better, since the resume
+            // position belongs to that exact version.
+            var preferredItemId = Guid.NewGuid();
+            var preferredSource = CreateSource(preferredItemId, bitrate: 80_000_000, supportsDirectPlay: false);
+            var siblingSource = CreateSource(Guid.NewGuid(), bitrate: 8_000_000);
+
+            var result = new PlaybackInfoResponse
+            {
+                MediaSources = [siblingSource, preferredSource]
+            };
+
+            CreateHelper().SortMediaSources(result, maxBitrate: 20_000_000, preferredItemId);
+
+            Assert.Equal(preferredSource.Id, result.MediaSources[0].Id);
+        }
+
+        [Fact]
+        public void SortMediaSources_NoPreferredItem_OrdersByPlayability()
+        {
+            var directPlay = CreateSource(Guid.NewGuid(), bitrate: 8_000_000);
+            var transcodeOnly = CreateSource(Guid.NewGuid(), bitrate: 8_000_000, supportsDirectPlay: false);
+            transcodeOnly.SupportsDirectStream = false;
+
+            var result = new PlaybackInfoResponse
+            {
+                MediaSources = [transcodeOnly, directPlay]
+            };
+
+            CreateHelper().SortMediaSources(result, maxBitrate: 20_000_000);
+
+            Assert.Equal(directPlay.Id, result.MediaSources[0].Id);
+        }
+
+        [Fact]
+        public void SortMediaSources_PreferredIdNotInSources_KeepsPlayabilityOrder()
+        {
+            var directPlay = CreateSource(Guid.NewGuid(), bitrate: 8_000_000);
+            var transcodeOnly = CreateSource(Guid.NewGuid(), bitrate: 8_000_000, supportsDirectPlay: false);
+            transcodeOnly.SupportsDirectStream = false;
+
+            var result = new PlaybackInfoResponse
+            {
+                MediaSources = [transcodeOnly, directPlay]
+            };
+
+            CreateHelper().SortMediaSources(result, maxBitrate: 20_000_000, Guid.NewGuid());
+
+            Assert.Equal(directPlay.Id, result.MediaSources[0].Id);
+        }
+    }
+}

tests/Jellyfin.Controller.Tests/MediaEncoding/EncodingHelperAudioBitStreamTests.cs

@@ -0,0 +1,99 @@
+using System;
+using System.Globalization;
+using MediaBrowser.Common.Configuration;
+using MediaBrowser.Controller.IO;
+using MediaBrowser.Controller.MediaEncoding;
+using MediaBrowser.Model.Dlna;
+using MediaBrowser.Model.Entities;
+using Microsoft.Extensions.Configuration;
+using Moq;
+using Xunit;
+using IConfigurationManager = MediaBrowser.Common.Configuration.IConfigurationManager;
+
+namespace Jellyfin.Controller.Tests.MediaEncoding
+{
+    public class EncodingHelperAudioBitStreamTests
+    {
+        private const string BothFilters = " -bsf:a noise=drop='lt(pts*tb\\,63.063)',aac_adtstoasc";
+        private const string NoiseOnly = " -bsf:a noise=drop='lt(pts*tb\\,63.063)'";
+        private const string AdtsOnly = " -bsf:a aac_adtstoasc";
+        private const long DefaultSeekTicks = 630_630_000L;
+        private const string DefaultFfmpegVersion = "5.0";
+
+        private static EncodingHelper CreateHelper(string ffmpegVersion)
+        {
+            var mediaEncoder = new Mock<IMediaEncoder>();
+            mediaEncoder
+                .Setup(e => e.GetTimeParameter(It.IsAny<long>()))
+                .Returns((long ticks) => TimeSpan.FromTicks(ticks).ToString(@"hh\:mm\:ss\.fff", CultureInfo.InvariantCulture));
+            mediaEncoder
+                .SetupGet(e => e.EncoderVersion)
+                .Returns(Version.Parse(ffmpegVersion));
+
+            return new EncodingHelper(
+                Mock.Of<IApplicationPaths>(),
+                mediaEncoder.Object,
+                Mock.Of<ISubtitleEncoder>(),
+                Mock.Of<IConfiguration>(),
+                Mock.Of<IConfigurationManager>(),
+                Mock.Of<IPathManager>());
+        }
+
+        private static EncodingJobInfo CreateState(
+            TranscodingJobType jobType,
+            string outputVideoCodec,
+            string outputAudioCodec,
+            string audioStreamCodec,
+            string inputContainer,
+            long startTimeTicks)
+        {
+            return new EncodingJobInfo(jobType)
+            {
+                IsVideoRequest = true,
+                OutputVideoCodec = outputVideoCodec,
+                OutputAudioCodec = outputAudioCodec,
+                InputContainer = inputContainer,
+                RunTimeTicks = TimeSpan.FromMinutes(10).Ticks,
+                AudioStream = new MediaStream
+                {
+                    Type = MediaStreamType.Audio,
+                    Codec = audioStreamCodec
+                },
+                BaseRequest = new BaseEncodingJobOptions
+                {
+                    StartTimeTicks = startTimeTicks
+                }
+            };
+        }
+
+        [Theory]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "ts", BothFilters)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "aac", BothFilters)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "hls", BothFilters)]
+        [InlineData(TranscodingJobType.Progressive, "libx264", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "ts", AdtsOnly)]
+        [InlineData(TranscodingJobType.Hls, "copy", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "ts", AdtsOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "aac", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "ts", AdtsOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "wtv", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "ts", AdtsOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", 0L, DefaultFfmpegVersion, "mp4", "ts", AdtsOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", DefaultSeekTicks, "4.4.6", "mp4", "ts", AdtsOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "ts", "ts", NoiseOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "aac", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "mkv", NoiseOnly)]
+        [InlineData(TranscodingJobType.Hls, "libx264", "copy", "ac3", "ts", DefaultSeekTicks, DefaultFfmpegVersion, "mp4", "ts", NoiseOnly)]
+        public void AudioBitStreamArguments_AppliesGates(
+            TranscodingJobType jobType,
+            string outputVideoCodec,
+            string outputAudioCodec,
+            string audioStreamCodec,
+            string inputContainer,
+            long startTicks,
+            string ffmpegVersion,
+            string segmentContainer,
+            string mediaSourceContainer,
+            string expected)
+        {
+            var state = CreateState(jobType, outputVideoCodec, outputAudioCodec, audioStreamCodec, inputContainer, startTicks);
+            var result = CreateHelper(ffmpegVersion).GetAudioBitStreamArguments(state, segmentContainer, mediaSourceContainer);
+            Assert.Equal(expected, result);
+        }
+    }
+}

tests/Jellyfin.Extensions.Tests/StreamExtensionsTests.cs

@@ -0,0 +1,397 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Jellyfin.Extensions.Tests;
+
+public class StreamExtensionsTests
+{
+    [Fact]
+    public async Task IsStreamIdenticalAsync_SeekableDifferentLengths_ReturnsFalse()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = new MemoryStream(new byte[] { 1, 2, 3 });
+        await using var b = new MemoryStream(new byte[] { 1, 2, 3, 4 });
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.False(result);
+    }
+
+    [Fact]
+    public async Task IsStreamIdenticalAsync_NonSeekableIdenticalStreams_ReturnsTrue()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = new NonSeekableReadStream(new byte[] { 1, 2, 3, 4 });
+        await using var b = new NonSeekableReadStream(new byte[] { 1, 2, 3, 4 });
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public async Task IsStreamIdenticalAsync_NonSeekableDifferentStreams_ReturnsFalse()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = new NonSeekableReadStream(new byte[] { 1, 2, 3, 4 });
+        await using var b = new NonSeekableReadStream(new byte[] { 1, 2, 9, 4 });
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.False(result);
+    }
+
+    [Fact]
+    public async Task IsFileIdenticalAsync_NonSeekableStream_ThrowsArgumentException()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        var path = Path.Join(Path.GetTempPath(), Path.GetRandomFileName());
+        await File.WriteAllBytesAsync(path, new byte[] { 1, 2, 3, 4 }, cancellationToken);
+
+        try
+        {
+            await using var stream = new NonSeekableReadStream(new byte[] { 1, 2, 3, 4 });
+
+            await Assert.ThrowsAsync<ArgumentException>(async () =>
+                await stream.IsFileIdenticalAsync(path, cancellationToken));
+        }
+        finally
+        {
+            File.Delete(path);
+        }
+    }
+
+    // Both publiclyVisible values are exercised so the test runs once under the fast path
+    // (TryGetBuffer succeeds) and once under the slow path (TryGetBuffer returns false).
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task IsFileIdenticalAsync_UsesStartOfStreamAndRestoresPosition_OnMatch(bool publiclyVisible)
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        var path = Path.Join(Path.GetTempPath(), Path.GetRandomFileName());
+        var bytes = new byte[] { 10, 20, 30, 40, 50 };
+        await File.WriteAllBytesAsync(path, bytes, cancellationToken);
+
+        try
+        {
+            await using var stream = CreateMemoryStream(bytes, publiclyVisible);
+            stream.Position = 3;
+
+            var result = await stream.IsFileIdenticalAsync(path, cancellationToken);
+
+            Assert.True(result);
+            Assert.Equal(3, stream.Position);
+        }
+        finally
+        {
+            File.Delete(path);
+        }
+    }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task IsFileIdenticalAsync_RestoresPosition_OnMismatch(bool publiclyVisible)
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        var path = Path.Join(Path.GetTempPath(), Path.GetRandomFileName());
+        await File.WriteAllBytesAsync(path, new byte[] { 10, 20, 30, 40, 99 }, cancellationToken);
+
+        try
+        {
+            await using var stream = CreateMemoryStream(new byte[] { 10, 20, 30, 40, 50 }, publiclyVisible);
+            stream.Position = 2;
+
+            var result = await stream.IsFileIdenticalAsync(path, cancellationToken);
+
+            Assert.False(result);
+            Assert.Equal(2, stream.Position);
+        }
+        finally
+        {
+            File.Delete(path);
+        }
+    }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task IsStreamIdenticalAsync_BothMemoryStreams_NonZeroPositions_SeeksToStart(bool publiclyVisible)
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = CreateMemoryStream(new byte[] { 1, 2, 3, 4, 5 }, publiclyVisible);
+        await using var b = CreateMemoryStream(new byte[] { 1, 2, 3, 4, 5 }, publiclyVisible);
+        a.Position = 3;
+        b.Position = 1;
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.True(result);
+    }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task IsStreamIdenticalAsync_MemoryStreamPairedWithSeekableNonMemoryStream_NonZeroPositions_SeeksToStart(bool publiclyVisible)
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = CreateMemoryStream(new byte[] { 1, 2, 3, 4 }, publiclyVisible);
+        await using var b = new SeekableNonMemoryStream(new byte[] { 1, 2, 3, 4 });
+        a.Position = 2;
+        b.Position = 3;
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.True(result);
+    }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task IsStreamIdenticalAsync_NonMemoryStreamPairedWithMemoryStream_Swaps_ReturnsTrue(bool publiclyVisible)
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = new SeekableNonMemoryStream(new byte[] { 1, 2, 3, 4 });
+        await using var b = CreateMemoryStream(new byte[] { 1, 2, 3, 4 }, publiclyVisible);
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public async Task IsStreamIdenticalAsync_BothSeekableNonMemoryStreams_NonZeroPositions_SeeksToStart()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = new SeekableNonMemoryStream(new byte[] { 1, 2, 3, 4 });
+        await using var b = new SeekableNonMemoryStream(new byte[] { 1, 2, 3, 4 });
+        a.Position = 1;
+        b.Position = 2;
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public async Task IsStreamIdenticalAsync_NonSeekableShortReads_Identical_ReturnsTrue()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        var data = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+        await using var a = new ShortReadingNonSeekableStream(data, maxReadSize: 3);
+        await using var b = new ShortReadingNonSeekableStream(data, maxReadSize: 5);
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public async Task IsStreamIdenticalAsync_NonSeekableShortReads_DifferentLengths_ReturnsFalse()
+    {
+        var cancellationToken = TestContext.Current.CancellationToken;
+        await using var a = new ShortReadingNonSeekableStream(new byte[] { 1, 2, 3, 4 }, maxReadSize: 3);
+        await using var b = new ShortReadingNonSeekableStream(new byte[] { 1, 2, 3, 4, 5 }, maxReadSize: 5);
+
+        var result = await a.IsStreamIdenticalAsync(b, cancellationToken);
+
+        Assert.False(result);
+    }
+
+    private static MemoryStream CreateMemoryStream(byte[] data, bool publiclyVisible)
+        => publiclyVisible
+            ? new MemoryStream(data, 0, data.Length, writable: false, publiclyVisible: true)
+            : new MemoryStream(data);
+
+    private sealed class NonSeekableReadStream : Stream
+    {
+        private readonly Stream _inner;
+
+        public NonSeekableReadStream(byte[] data)
+        {
+            _inner = new MemoryStream(data, writable: false);
+        }
+
+        public override bool CanRead => true;
+
+        public override bool CanSeek => false;
+
+        public override bool CanWrite => false;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+            => _inner.Read(buffer, offset, count);
+
+        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+            => _inner.ReadAsync(buffer, cancellationToken);
+
+        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            => _inner.ReadAsync(buffer.AsMemory(offset, count), cancellationToken).AsTask();
+
+        public override long Seek(long offset, SeekOrigin origin)
+            => throw new NotSupportedException();
+
+        public override void SetLength(long value)
+            => throw new NotSupportedException();
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException();
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _inner.Dispose();
+            }
+
+            base.Dispose(disposing);
+        }
+
+        public override async ValueTask DisposeAsync()
+        {
+            await _inner.DisposeAsync();
+            await base.DisposeAsync();
+        }
+    }
+
+    private sealed class SeekableNonMemoryStream : Stream
+    {
+        private readonly MemoryStream _inner;
+
+        public SeekableNonMemoryStream(byte[] data)
+        {
+            _inner = new MemoryStream(data, writable: false);
+        }
+
+        public override bool CanRead => true;
+
+        public override bool CanSeek => true;
+
+        public override bool CanWrite => false;
+
+        public override long Length => _inner.Length;
+
+        public override long Position
+        {
+            get => _inner.Position;
+            set => _inner.Position = value;
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+            => _inner.Read(buffer, offset, count);
+
+        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+            => _inner.ReadAsync(buffer, cancellationToken);
+
+        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            => _inner.ReadAsync(buffer.AsMemory(offset, count), cancellationToken).AsTask();
+
+        public override long Seek(long offset, SeekOrigin origin)
+            => _inner.Seek(offset, origin);
+
+        public override void SetLength(long value)
+            => throw new NotSupportedException();
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException();
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _inner.Dispose();
+            }
+
+            base.Dispose(disposing);
+        }
+
+        public override async ValueTask DisposeAsync()
+        {
+            await _inner.DisposeAsync();
+            await base.DisposeAsync();
+        }
+    }
+
+    private sealed class ShortReadingNonSeekableStream : Stream
+    {
+        private readonly Stream _inner;
+        private readonly int _maxReadSize;
+
+        public ShortReadingNonSeekableStream(byte[] data, int maxReadSize)
+        {
+            _inner = new MemoryStream(data, writable: false);
+            _maxReadSize = maxReadSize;
+        }
+
+        public override bool CanRead => true;
+
+        public override bool CanSeek => false;
+
+        public override bool CanWrite => false;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+            => _inner.Read(buffer, offset, Math.Min(count, _maxReadSize));
+
+        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+            => _inner.ReadAsync(buffer[..Math.Min(buffer.Length, _maxReadSize)], cancellationToken);
+
+        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            => _inner.ReadAsync(buffer.AsMemory(offset, Math.Min(count, _maxReadSize)), cancellationToken).AsTask();
+
+        public override long Seek(long offset, SeekOrigin origin)
+            => throw new NotSupportedException();
+
+        public override void SetLength(long value)
+            => throw new NotSupportedException();
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException();
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _inner.Dispose();
+            }
+
+            base.Dispose(disposing);
+        }
+
+        public override async ValueTask DisposeAsync()
+        {
+            await _inner.DisposeAsync();
+            await base.DisposeAsync();
+        }
+    }
+}

tests/Jellyfin.MediaEncoding.Tests/Subtitles/FilterEventsTests.cs

@@ -1,282 +0,0 @@
-using System;
-using AutoFixture;
-using AutoFixture.AutoMoq;
-using MediaBrowser.MediaEncoding.Subtitles;
-using MediaBrowser.Model.MediaInfo;
-using Xunit;
-
-namespace Jellyfin.MediaEncoding.Subtitles.Tests
-{
-    public class FilterEventsTests
-    {
-        private readonly SubtitleEncoder _encoder;
-
-        public FilterEventsTests()
-        {
-            var fixture = new Fixture().Customize(new AutoMoqCustomization { ConfigureMembers = true });
-            _encoder = fixture.Create<SubtitleEncoder>();
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleSpanningSegmentBoundary_IsRetained()
-        {
-            // Subtitle starts at 5s, ends at 15s.
-            // Segment requested from 10s to 20s.
-            // The subtitle is still on screen at 10s and should NOT be dropped.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Still on screen")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(5).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "Next subtitle")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(17).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            Assert.Equal("1", track.TrackEvents[0].Id);
-            Assert.Equal("2", track.TrackEvents[1].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleFullyBeforeSegment_IsDropped()
-        {
-            // Subtitle starts at 2s, ends at 5s.
-            // Segment requested from 10s.
-            // The subtitle ended before the segment — should be dropped.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Already gone")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(2).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(5).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "Visible")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(17).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Single(track.TrackEvents);
-            Assert.Equal("2", track.TrackEvents[0].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleAfterSegment_IsDropped()
-        {
-            // Segment is 10s-20s, subtitle starts at 25s.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "In range")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "After segment")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(25).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(30).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Single(track.TrackEvents);
-            Assert.Equal("1", track.TrackEvents[0].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_PreserveTimestampsFalse_AdjustsTimestamps()
-        {
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Subtitle")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(15).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(20).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(30).Ticks,
-                preserveTimestamps: false);
-
-            Assert.Single(track.TrackEvents);
-            // Timestamps should be shifted back by 10s
-            Assert.Equal(TimeSpan.FromSeconds(5).Ticks, track.TrackEvents[0].StartPositionTicks);
-            Assert.Equal(TimeSpan.FromSeconds(10).Ticks, track.TrackEvents[0].EndPositionTicks);
-        }
-
-        [Fact]
-        public void FilterEvents_PreserveTimestampsTrue_KeepsOriginalTimestamps()
-        {
-            var startTicks = TimeSpan.FromSeconds(15).Ticks;
-            var endTicks = TimeSpan.FromSeconds(20).Ticks;
-
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Subtitle")
-                    {
-                        StartPositionTicks = startTicks,
-                        EndPositionTicks = endTicks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(30).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Single(track.TrackEvents);
-            Assert.Equal(startTicks, track.TrackEvents[0].StartPositionTicks);
-            Assert.Equal(endTicks, track.TrackEvents[0].EndPositionTicks);
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleEndingExactlyAtSegmentStart_IsRetained()
-        {
-            // Subtitle ends exactly when the segment begins.
-            // EndPositionTicks == startPositionTicks means (end - start) == 0, not < 0,
-            // so SkipWhile stops and the subtitle is retained.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Boundary subtitle")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(5).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(10).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "In range")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            Assert.Equal("1", track.TrackEvents[0].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_SpanningBoundaryWithTimestampAdjustment_DoesNotProduceNegativeTimestamps()
-        {
-            // Subtitle starts at 5s, ends at 15s.
-            // Segment requested from 10s to 20s, preserveTimestamps = false.
-            // The subtitle spans the boundary and is retained, but shifting
-            // StartPositionTicks by -10s would produce -5s (negative).
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Spans boundary")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(5).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "Fully in range")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(17).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: false);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            // Subtitle 1: start should be clamped to 0, not -5s
-            Assert.True(track.TrackEvents[0].StartPositionTicks >= 0, "StartPositionTicks must not be negative");
-            Assert.Equal(TimeSpan.FromSeconds(5).Ticks, track.TrackEvents[0].EndPositionTicks);
-            // Subtitle 2: normal shift (12s - 10s = 2s, 17s - 10s = 7s)
-            Assert.Equal(TimeSpan.FromSeconds(2).Ticks, track.TrackEvents[1].StartPositionTicks);
-            Assert.Equal(TimeSpan.FromSeconds(7).Ticks, track.TrackEvents[1].EndPositionTicks);
-        }
-
-        [Fact]
-        public void FilterEvents_NoEndTimeTicks_ReturnsAllFromStartPosition()
-        {
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Before")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(2).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(4).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "After")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("3", "Much later")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(500).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(505).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: 0,
-                preserveTimestamps: true);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            Assert.Equal("2", track.TrackEvents[0].Id);
-            Assert.Equal("3", track.TrackEvents[1].Id);
-        }
-    }
-}

tests/Jellyfin.Naming.Tests/TV/SeasonPathParserTests.cs

@@ -83,4 +83,26 @@ public class SeasonPathParserTests
         Assert.Equal(seasonNumber, result.SeasonNumber);
         Assert.Equal(isSeasonDirectory, result.IsSeasonFolder);
     }
+
+    [Theory]
+    [InlineData("/Drive/300 Collection/300 (2006)", "/Drive/300 Collection", null, false)]
+    [InlineData("/Drive/300 Collection/300 Rise of an Empire", "/Drive/300 Collection", null, false)]
+    [InlineData("/Drive/300 Collection/1", "/Drive/300 Collection", null, false)]
+    [InlineData("/Drive/300 Collection/300 Disc 1", "/Drive/300 Collection", null, false)]
+    [InlineData("/Drive/28 Years Later Collection/28 Days Later", "/Drive/28 Years Later Collection", null, false)]
+    [InlineData("/Drive/28 Years Later Collection/28 Weeks Later (2007)", "/Drive/28 Years Later Collection", null, false)]
+    [InlineData("/Drive/28 Years Later Collection/28 Years Later 2025", "/Drive/28 Years Later Collection", null, false)]
+    [InlineData("/Drive/300 Collection/Season 1", "/Drive/300 Collection", 1, true)]
+    [InlineData("/Drive/28 Years Later Collection/Season 01", "/Drive/28 Years Later Collection", 1, true)]
+    [InlineData("/Drive/300 Collection/S01", "/Drive/300 Collection", 1, true)]
+    [InlineData("/Drive/300 Collection/S1", "/Drive/300 Collection", 1, true)]
+
+    public void GetSeasonNumberFromPathMixedLibraryTest(string path, string? parentPath, int? seasonNumber, bool isSeasonDirectory)
+    {
+        var result = SeasonPathParser.Parse(path, parentPath, false, false);
+
+        Assert.Equal(result.SeasonNumber is not null, result.Success);
+        Assert.Equal(seasonNumber, result.SeasonNumber);
+        Assert.Equal(isSeasonDirectory, result.IsSeasonFolder);
+    }
 }

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

@@ -0,0 +1,137 @@
+using System;
+using Emby.Server.Implementations.Dto;
+using Emby.Server.Implementations.Playlists;
+using Jellyfin.Data.Enums;
+using MediaBrowser.Common;
+using MediaBrowser.Controller.Chapters;
+using MediaBrowser.Controller.Drawing;
+using MediaBrowser.Controller.Dto;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.LiveTv;
+using MediaBrowser.Controller.MediaEncoding;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Controller.Trickplay;
+using MediaBrowser.Model.Entities;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Dto;
+
+public class DtoServiceImageInheritanceTests
+{
+    [Fact]
+    public void GetBaseItemDto_PlaylistsUserViewWithDisplayParentPrimary_UsesDisplayParentPrimaryImage()
+    {
+        var displayParent = new PlaylistsFolder
+        {
+            Id = Guid.NewGuid(),
+            ImageInfos =
+            [
+                new ItemImageInfo
+                {
+                    Type = ImageType.Primary,
+                    Path = "/images/playlists-custom.jpg",
+                    DateModified = new DateTime(2026, 1, 15, 12, 0, 0, DateTimeKind.Utc)
+                }
+            ]
+        };
+
+        var userView = new UserView
+        {
+            Id = Guid.NewGuid(),
+            ViewType = CollectionType.playlists,
+            DisplayParentId = displayParent.Id,
+            ImageInfos =
+            [
+                new ItemImageInfo
+                {
+                    Type = ImageType.Primary,
+                    Path = "/images/generated.png",
+                    DateModified = new DateTime(2026, 1, 10, 12, 0, 0, DateTimeKind.Utc)
+                }
+            ]
+        };
+
+        var dtoService = BuildDtoService(displayParent);
+
+        var dto = dtoService.GetBaseItemDto(userView, new DtoOptions(false));
+
+        Assert.NotNull(dto.ParentPrimaryImageItemId);
+        Assert.Equal(displayParent.Id, dto.ParentPrimaryImageItemId);
+        Assert.Equal("/images/playlists-custom.jpg", dto.ParentPrimaryImageTag);
+        Assert.False(dto.ImageTags?.ContainsKey(ImageType.Primary));
+    }
+
+    [Fact]
+    public void GetBaseItemDto_PlaylistsUserViewWithoutDisplayParentPrimary_KeepsOwnPrimaryImage()
+    {
+        var displayParent = new PlaylistsFolder
+        {
+            Id = Guid.NewGuid(),
+            ImageInfos = []
+        };
+
+        var userView = new UserView
+        {
+            Id = Guid.NewGuid(),
+            ViewType = CollectionType.playlists,
+            DisplayParentId = displayParent.Id,
+            ImageInfos =
+            [
+                new ItemImageInfo
+                {
+                    Type = ImageType.Primary,
+                    Path = "/images/generated.png",
+                    DateModified = new DateTime(2026, 1, 10, 12, 0, 0, DateTimeKind.Utc)
+                }
+            ]
+        };
+
+        var dtoService = BuildDtoService(displayParent);
+
+        var dto = dtoService.GetBaseItemDto(userView, new DtoOptions(false));
+
+        Assert.Null(dto.ParentPrimaryImageItemId);
+        Assert.Null(dto.ParentPrimaryImageTag);
+        Assert.NotNull(dto.ImageTags);
+        Assert.True(dto.ImageTags.ContainsKey(ImageType.Primary));
+        Assert.Equal("/images/generated.png", dto.ImageTags[ImageType.Primary]);
+    }
+
+    private static DtoService BuildDtoService(BaseItem displayParent)
+    {
+        var libraryManager = new Mock<ILibraryManager>();
+        var userDataManager = new Mock<IUserDataManager>();
+        var imageProcessor = new Mock<IImageProcessor>();
+        var providerManager = new Mock<IProviderManager>();
+        var recordingsManager = new Mock<IRecordingsManager>();
+        var appHost = new Mock<IApplicationHost>();
+        var mediaSourceManager = new Mock<IMediaSourceManager>();
+        var liveTvManager = new Mock<ILiveTvManager>();
+        var trickplayManager = new Mock<ITrickplayManager>();
+        var chapterManager = new Mock<IChapterManager>();
+        var logger = new Mock<Microsoft.Extensions.Logging.ILogger<DtoService>>();
+
+        libraryManager
+            .Setup(x => x.GetItemById(displayParent.Id))
+            .Returns(displayParent);
+
+        imageProcessor
+            .Setup(x => x.GetImageCacheTag(It.IsAny<BaseItem>(), It.IsAny<ItemImageInfo>()))
+            .Returns<BaseItem, ItemImageInfo>((_, image) => image.Path);
+
+        return new DtoService(
+            logger.Object,
+            libraryManager.Object,
+            userDataManager.Object,
+            imageProcessor.Object,
+            providerManager.Object,
+            recordingsManager.Object,
+            appHost.Object,
+            mediaSourceManager.Object,
+            new Lazy<ILiveTvManager>(() => liveTvManager.Object),
+            trickplayManager.Object,
+            chapterManager.Object);
+    }
+}

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

@@ -0,0 +1,131 @@
+using System;
+using Emby.Server.Implementations.Dto;
+using MediaBrowser.Common;
+using MediaBrowser.Controller.Chapters;
+using MediaBrowser.Controller.Drawing;
+using MediaBrowser.Controller.Dto;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Entities.TV;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.LiveTv;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Controller.Trickplay;
+using MediaBrowser.Model.Entities;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Dto;
+
+public class DtoServiceTests
+{
+    private readonly Mock<ILibraryManager> _libraryManagerMock;
+    private readonly DtoService _dtoService;
+
+    public DtoServiceTests()
+    {
+        _libraryManagerMock = new Mock<ILibraryManager>();
+
+        var imageProcessor = new Mock<IImageProcessor>();
+        // Deterministic tag derived from the image so each item gets a distinct, assertable tag.
+        imageProcessor
+            .Setup(x => x.GetImageCacheTag(It.IsAny<BaseItem>(), It.IsAny<ItemImageInfo>()))
+            .Returns((BaseItem _, ItemImageInfo image) => "tag:" + image.Path);
+
+        var appHost = new Mock<IApplicationHost>();
+        appHost.Setup(x => x.SystemId).Returns("test-server");
+
+        // Video.SourceType probes the active-recording manager; provide one so it doesn't NRE.
+        Video.RecordingsManager = new Mock<IRecordingsManager>().Object;
+
+        _dtoService = new DtoService(
+            NullLogger<DtoService>.Instance,
+            _libraryManagerMock.Object,
+            new Mock<IUserDataManager>().Object,
+            imageProcessor.Object,
+            new Mock<IProviderManager>().Object,
+            new Mock<IRecordingsManager>().Object,
+            appHost.Object,
+            new Mock<IMediaSourceManager>().Object,
+            new Lazy<ILiveTvManager>(() => new Mock<ILiveTvManager>().Object),
+            new Mock<ITrickplayManager>().Object,
+            new Mock<IChapterManager>().Object);
+
+        // Episode.Series / Episode.Season resolve through the static BaseItem.LibraryManager.
+        BaseItem.LibraryManager = _libraryManagerMock.Object;
+    }
+
+    [Fact]
+    public void GetBaseItemDto_PreferEpisodeParentPoster_PrefersSeasonPosterOverEpisodeAndSeries()
+    {
+        var (episode, season, series) = BuildEpisode(seasonHasPoster: true);
+        var options = new DtoOptions(false) { PreferEpisodeParentPoster = true };
+
+        var dto = _dtoService.GetBaseItemDto(episode, options);
+
+        // The episode's own 16:9 primary is dropped in favor of the season's portrait poster.
+        Assert.False(dto.ImageTags is not null && dto.ImageTags.ContainsKey(ImageType.Primary));
+        Assert.Null(dto.SeriesPrimaryImageTag);
+        Assert.Equal(season.Id, dto.ParentPrimaryImageItemId);
+        Assert.Equal("tag:" + season.GetImageInfo(ImageType.Primary, 0)!.Path, dto.ParentPrimaryImageTag);
+        // Aspect ratio follows the (portrait) poster, not the episode's 16:9 image.
+        Assert.Equal(season.GetDefaultPrimaryImageAspectRatio(), dto.PrimaryImageAspectRatio);
+    }
+
+    [Fact]
+    public void GetBaseItemDto_PreferEpisodeParentPoster_FallsBackToSeriesWhenSeasonHasNoPoster()
+    {
+        var (episode, _, series) = BuildEpisode(seasonHasPoster: false);
+        var options = new DtoOptions(false) { PreferEpisodeParentPoster = true };
+
+        var dto = _dtoService.GetBaseItemDto(episode, options);
+
+        Assert.False(dto.ImageTags is not null && dto.ImageTags.ContainsKey(ImageType.Primary));
+        Assert.Null(dto.SeriesPrimaryImageTag);
+        Assert.Equal(series.Id, dto.ParentPrimaryImageItemId);
+        Assert.Equal("tag:" + series.GetImageInfo(ImageType.Primary, 0)!.Path, dto.ParentPrimaryImageTag);
+    }
+
+    [Fact]
+    public void GetBaseItemDto_WithoutPreferEpisodeParentPoster_KeepsEpisodePrimary()
+    {
+        var (episode, _, _) = BuildEpisode(seasonHasPoster: true);
+        var options = new DtoOptions(false);
+
+        var dto = _dtoService.GetBaseItemDto(episode, options);
+
+        // Default behavior: the episode keeps its own primary and exposes the series poster as a tag.
+        Assert.NotNull(dto.ImageTags);
+        Assert.True(dto.ImageTags.ContainsKey(ImageType.Primary));
+        Assert.NotNull(dto.SeriesPrimaryImageTag);
+        Assert.Null(dto.ParentPrimaryImageItemId);
+    }
+
+    private (Episode Episode, Season Season, Series Series) BuildEpisode(bool seasonHasPoster)
+    {
+        // Non-local (http) paths keep aspect-ratio resolution off the image processor and on the
+        // item's default ratio, which is portrait (2/3) for Season/Series and 16:9 for Episode.
+        var series = new Series { Id = Guid.NewGuid(), Name = "Series" };
+        series.SetImage(new ItemImageInfo { Type = ImageType.Primary, Path = "http://test/series.jpg" }, 0);
+
+        var season = new Season { Id = Guid.NewGuid(), Name = "Season", SeriesId = series.Id };
+        if (seasonHasPoster)
+        {
+            season.SetImage(new ItemImageInfo { Type = ImageType.Primary, Path = "http://test/season.jpg" }, 0);
+        }
+
+        var episode = new Episode
+        {
+            Id = Guid.NewGuid(),
+            Name = "Episode",
+            SeasonId = season.Id,
+            SeriesId = series.Id
+        };
+        episode.SetImage(new ItemImageInfo { Type = ImageType.Primary, Path = "http://test/episode.jpg" }, 0);
+
+        _libraryManagerMock.Setup(x => x.GetItemById(season.Id)).Returns(season);
+        _libraryManagerMock.Setup(x => x.GetItemById(series.Id)).Returns(series);
+
+        return (episode, season, series);
+    }
+}

tests/Jellyfin.Server.Implementations.Tests/Users/UserManagerLockHelperTests.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Threading.Tasks;
+using Jellyfin.Server.Implementations.Users;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Users
+{
+    public class UserManagerLockHelperTests
+    {
+        [Fact]
+        public async Task LockAsync_WhenNested_DoesNotAcquireSecondLockAndRestoresStateOnDispose()
+        {
+            UserManager.LockHelper.IsNestedLock.Value = 0;
+            using var helper = new UserManager.LockHelper();
+            var key = Guid.NewGuid();
+
+            Assert.True(helper.ShouldLock());
+
+            var outerHandle = await helper.LockAsync(key);
+            Assert.False(helper.ShouldLock());
+
+            var innerHandle = await helper.LockAsync(key);
+            Assert.False(helper.ShouldLock());
+
+            innerHandle.Dispose();
+            Assert.False(helper.ShouldLock());
+
+            outerHandle.Dispose();
+            Assert.True(helper.ShouldLock());
+        }
+
+        [Fact]
+        public async Task LockAsync_WithSameKey_BlocksSecondLockUntilFirstIsReleased()
+        {
+            UserManager.LockHelper.IsNestedLock.Value = 0;
+            using var helper = new UserManager.LockHelper();
+            var key = Guid.NewGuid();
+
+            var firstAcquired = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
+            var releaseFirst = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
+            var secondEntered = false;
+
+            var firstTask = Task.Run(
+                async () =>
+                {
+                    using var firstHandle = await helper.LockAsync(key);
+                    firstAcquired.SetResult(true);
+                    await releaseFirst.Task;
+                },
+                TestContext.Current.CancellationToken);
+
+            await firstAcquired.Task;
+
+            var secondTask = Task.Run(
+                async () =>
+                {
+                    using var secondHandle = await helper.LockAsync(key);
+                    secondEntered = true;
+                },
+                TestContext.Current.CancellationToken);
+
+            await Task.Delay(100, TestContext.Current.CancellationToken);
+            Assert.False(secondEntered);
+
+            releaseFirst.SetResult(true);
+
+            await Task.WhenAll(firstTask, secondTask);
+            Assert.True(secondEntered);
+        }
+
+        [Fact]
+        public async Task LockAsync_WhenDisposed_ThrowsObjectDisposedException()
+        {
+            UserManager.LockHelper.IsNestedLock.Value = 0;
+            using var helper = new UserManager.LockHelper();
+            helper.Dispose();
+
+            await Assert.ThrowsAsync<ObjectDisposedException>(async () => await helper.LockAsync(Guid.NewGuid()));
+        }
+
+        [Fact]
+        public void Dispose_WhenCalledMultipleTimes_DoesNotThrow()
+        {
+            UserManager.LockHelper.IsNestedLock.Value = 0;
+            using var helper = new UserManager.LockHelper();
+
+            helper.Dispose();
+            var ex = Record.Exception(() => helper.Dispose());
+
+            Assert.Null(ex);
+        }
+    }
+}

tests/Jellyfin.Server.Implementations.Tests/Users/UserManagerNormalizedUsernameTests.cs

@@ -0,0 +1,240 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Jellyfin.Database.Implementations;
+using Jellyfin.Database.Implementations.Locking;
+using Jellyfin.Database.Providers.Sqlite;
+using Jellyfin.Server.Implementations.Users;
+using MediaBrowser.Common;
+using MediaBrowser.Common.Net;
+using MediaBrowser.Controller;
+using MediaBrowser.Controller.Authentication;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Drawing;
+using MediaBrowser.Controller.Events;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Model.Cryptography;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Users
+{
+    public sealed class UserManagerNormalizedUsernameTests : IDisposable
+    {
+        private readonly SqliteConnection _connection;
+        private readonly DbContextOptions<JellyfinDbContext> _dbOptions;
+        private readonly UserManager _userManager;
+
+        public UserManagerNormalizedUsernameTests()
+        {
+            _connection = new SqliteConnection("Data Source=:memory:");
+            _connection.Open();
+
+            _dbOptions = new DbContextOptionsBuilder<JellyfinDbContext>()
+                .UseSqlite(_connection)
+                .Options;
+
+            // Create the schema
+            using var ctx = CreateDbContext();
+            ctx.Database.EnsureCreated();
+
+            var factory = new Mock<IDbContextFactory<JellyfinDbContext>>();
+            factory.Setup(f => f.CreateDbContext()).Returns(CreateDbContext);
+            factory.Setup(f => f.CreateDbContextAsync(It.IsAny<CancellationToken>()))
+                .ReturnsAsync(CreateDbContext);
+
+            var cryptoProvider = new Mock<ICryptoProvider>();
+            var configManager = new Mock<IServerConfigurationManager>();
+            var appPaths = new Mock<IServerApplicationPaths>();
+            appPaths.Setup(x => x.ProgramDataPath).Returns(Path.GetTempPath());
+            configManager.Setup(x => x.ApplicationPaths).Returns(appPaths.Object);
+
+            var appHost = new Mock<IApplicationHost>();
+
+            var defaultAuthProvider = new DefaultAuthenticationProvider(
+                NullLogger<DefaultAuthenticationProvider>.Instance,
+                cryptoProvider.Object);
+            var invalidAuthProvider = new InvalidAuthProvider();
+            var defaultPasswordResetProvider = new DefaultPasswordResetProvider(
+                configManager.Object,
+                appHost.Object);
+
+            _userManager = new UserManager(
+                factory.Object,
+                new NoopEventManager(),
+                new Mock<INetworkManager>().Object,
+                appHost.Object,
+                new Mock<IImageProcessor>().Object,
+                NullLogger<UserManager>.Instance,
+                configManager.Object,
+                new IPasswordResetProvider[] { defaultPasswordResetProvider },
+                new IAuthenticationProvider[] { defaultAuthProvider, invalidAuthProvider });
+        }
+
+        public void Dispose()
+        {
+            _userManager.Dispose();
+            _connection.Dispose();
+        }
+
+        private JellyfinDbContext CreateDbContext()
+        {
+            return new JellyfinDbContext(
+                _dbOptions,
+                NullLogger<JellyfinDbContext>.Instance,
+                new SqliteDatabaseProvider(null!, NullLogger<SqliteDatabaseProvider>.Instance),
+                new NoLockBehavior(NullLogger<NoLockBehavior>.Instance));
+        }
+
+        // ----- GetUserByName tests -----
+
+        [Theory]
+        // German umlauts
+        [InlineData("münchen", "MÜNCHEN")]
+        // Spanish tilde-n
+        [InlineData("Ñoño", "ÑOÑO")]
+        // ASCII, invariant uppercase lookup
+        [InlineData("jellyfin", "JELLYFIN")]
+        // Turkish cedilla: invariant 'i' uppercases to 'I' (U+0049), not Turkish 'İ' (U+0130)
+        [InlineData("Çelebi", "ÇELEBI")]
+        public async Task GetUserByName_WithNonAsciiUsername_FindsUserByNormalizedName(
+            string username, string normalizedLookup)
+        {
+            await _userManager.CreateUserAsync(username);
+
+            var found = _userManager.GetUserByName(normalizedLookup);
+
+            Assert.NotNull(found);
+            Assert.Equal(username, found.Username);
+        }
+
+        [Theory]
+        // German umlaut, look up by both upper and lower case
+        [InlineData("münchen")]
+        // Spanish tilde-n
+        [InlineData("Ñoño")]
+        // lowercase 'i' — invariant ToUpperInvariant gives 'I', not Turkish 'İ'
+        [InlineData("ali")]
+        // mixed ASCII + umlaut
+        [InlineData("testüser")]
+        public async Task GetUserByName_WithVariousCase_FindsUserCaseInsensitively(string username)
+        {
+            await _userManager.CreateUserAsync(username);
+
+            var upperFound = _userManager.GetUserByName(username.ToUpperInvariant());
+            var lowerFound = _userManager.GetUserByName(username.ToLowerInvariant());
+            var exactFound = _userManager.GetUserByName(username);
+
+            Assert.NotNull(upperFound);
+            Assert.NotNull(lowerFound);
+            Assert.NotNull(exactFound);
+        }
+
+        [Theory]
+        [InlineData("nonexistent")]
+        // No user with NormalizedUsername = "MÜNCHEN" has been created
+        [InlineData("MÜNCHEN")]
+        public void GetUserByName_WhenUserDoesNotExist_ReturnsNull(string lookupName)
+        {
+            var result = _userManager.GetUserByName(lookupName);
+
+            Assert.Null(result);
+        }
+
+        // ----- CreateUserAsync duplicate detection tests -----
+
+        [Theory]
+        // German umlaut, case-swapped duplicate
+        [InlineData("münchen", "MÜNCHEN")]
+        // Spanish tilde-n, lowercase duplicate
+        [InlineData("Ñoño", "ñoño")]
+        // ASCII, uppercase duplicate
+        [InlineData("alice", "ALICE")]
+        // Turkish cedilla: "çelebi".ToUpperInvariant() == "ÇELEBI" == "ÇELEBI".ToUpperInvariant()
+        [InlineData("çelebi", "ÇELEBI")]
+        public async Task CreateUserAsync_WhenNormalizedNameAlreadyExists_ThrowsArgumentException(
+            string existingUsername, string duplicateUsername)
+        {
+            await _userManager.CreateUserAsync(existingUsername);
+
+            await Assert.ThrowsAsync<ArgumentException>(
+                () => _userManager.CreateUserAsync(duplicateUsername));
+        }
+
+        [Theory]
+        // Different non-ASCII names that do not collide after normalization
+        [InlineData("münchen", "münchen2")]
+        [InlineData("ali", "ali2")]
+        // Visually similar but different Unicode code points: ñ (U+00F1) vs n (U+006E)
+        [InlineData("noño", "nono")]
+        public async Task CreateUserAsync_WithDistinctNonAsciiUsernames_CreatesBothUsers(
+            string firstUsername, string secondUsername)
+        {
+            var first = await _userManager.CreateUserAsync(firstUsername);
+            var second = await _userManager.CreateUserAsync(secondUsername);
+
+            Assert.NotNull(first);
+            Assert.NotNull(second);
+            Assert.NotEqual(first.Id, second.Id);
+        }
+
+        // ----- RenameUser tests -----
+
+        [Theory]
+        // Rename to non-ASCII name
+        [InlineData("alice", "münchen")]
+        // Rename between similar non-ASCII and ASCII
+        [InlineData("müller", "mueller")]
+        // Contains 'i': invariant uppercase is always 'I', never Turkish 'İ'
+        [InlineData("ali", "ALI2")]
+        // Rename to Spanish tilde-n name
+        [InlineData("testuser", "Ñoño")]
+        public async Task RenameUser_SetsNormalizedUsernameToUpperInvariant(
+            string originalName, string newName)
+        {
+            var user = await _userManager.CreateUserAsync(originalName);
+
+            await _userManager.RenameUser(user.Id, originalName, newName);
+
+            var renamed = _userManager.GetUserById(user.Id);
+            Assert.NotNull(renamed);
+            Assert.Equal(newName, renamed.Username);
+            Assert.Equal(newName.ToUpperInvariant(), renamed.NormalizedUsername);
+        }
+
+        [Theory]
+        // Same name different case: NormalizedUsername already taken
+        [InlineData("münchen", "MÜNCHEN")]
+        // Spanish, lowercase conflicts with existing uppercase-normalised entry
+        [InlineData("Ñoño", "ñoño")]
+        // ASCII, capitalised conflict
+        [InlineData("alice", "Alice")]
+        // Mixed ASCII + umlaut
+        [InlineData("testüser", "TESTÜSER")]
+        public async Task RenameUser_WhenNormalizedNameConflictsWithExistingUser_ThrowsArgumentException(
+            string existingUsername, string conflictingNewName)
+        {
+            var targetUser = await _userManager.CreateUserAsync("renametarget");
+            await _userManager.CreateUserAsync(existingUsername);
+
+            await Assert.ThrowsAsync<ArgumentException>(
+                () => _userManager.RenameUser(targetUser.Id, "renametarget", conflictingNewName));
+        }
+
+        private sealed class NoopEventManager : IEventManager
+        {
+            public void Publish<T>(T eventArgs)
+                where T : EventArgs
+            {
+            }
+
+            public Task PublishAsync<T>(T eventArgs)
+                where T : EventArgs
+                => Task.CompletedTask;
+        }
+    }
+}

tests/Jellyfin.Server.Integration.Tests/Controllers/LibraryControllerTests.cs

@@ -23,6 +23,7 @@ public sealed class LibraryControllerTests : IClassFixture<JellyfinApplicationFa
     [InlineData("Items/{0}/ThemeMedia")]
     [InlineData("Items/{0}/Ancestors")]
     [InlineData("Items/{0}/Download")]
+    [InlineData("Items/{0}/Collections")]
     [InlineData("Artists/{0}/Similar")]
     [InlineData("Items/{0}/Similar")]
     [InlineData("Albums/{0}/Similar")]