TRAX: toggle refreshes the status light on play/pause, terse scrolling error on failure, fixed quiet volume (0.5), ITraxPlayer seam. Deadlocked test fixed via RunAsync (was GetAwaiter().GetResult on the UI thread). 416 pass / 1 known env flake. Refs: https://learn.microsoft.com/en-us/dotnet/standard/asynchronous-programming-patterns/async-programming-model-tap#dont-block-on-async-code (Unit: trax toggle)

Services/Audio/ITraxPlayer.cs

@@ -0,0 +1,14 @@
+namespace ytLive.Services.Audio;
+
+/// <summary>Seam over the TRAX background-music player (<see cref="MusicPlayer"/>) so the
+/// toggle/status-light logic is testable without a real audio device.</summary>
+public interface ITraxPlayer : IDisposable
+{
+    event Action<Exception?>? PlaybackEnded;
+    string? TrackName { get; }
+    bool IsPlaying { get; }
+    float LocalGain { get; set; }
+    void Load(string path);
+    void Play();
+    void Pause();
+}

Services/Audio/MusicPlayer.cs

@@ -11,12 +11,17 @@ namespace ytLive.Services.Audio;
 /// The desktop/game bar's gain and mute scale <see cref="LocalGain"/>, so the
 /// creator hears the game-audio controls work on the music too.
 /// </summary>
-public sealed class MusicPlayer : IDisposable
+public sealed class MusicPlayer : ITraxPlayer
 {
-    /// <summary>The one and only music bed — quiet, no slider (the creator's
-    /// voice must stay on top; game/music loudness is the ducker's job). The
-    /// desktop audio bar scales this via <see cref="LocalGain"/>.</summary>
-    public const float MusicVolume = 0.20f;
+    /// <summary>The one and only music bed — no slider (the creator's voice must stay on
+    /// top; that's the ducker's job, −12 dB while they talk). The desktop audio bar scales
+    /// this via <see cref="LocalGain"/>.
+    /// <para>2026-10-09: was 0.20 (−14 dB) — "even at max volume I can barely discern it".
+    /// The creator's track masters at −11.3 LUFS (typical: −9..−14), so 0.20 put the bed at
+    /// ~−25 LUFS, and ducked under speech ~−37 LUFS: inaudible on stream too, because the
+    /// loopback carries exactly what plays locally. 0.5 (−6 dB) lands a typical master at
+    /// ~−15..−20 LUFS — beside the leveled voice (≈ −17 LUFS), and well under it when ducked.</para></summary>
+    public const float MusicVolume = 0.5f;
 
     private MediaFoundationReader? _reader;
     private VolumeWaveProvider16? _volume;