TASK 4 audio follow-up: game audio bar + mic status dot + always-on capture — the footer's second audio control (desktop/game, a mirror of the mic bar: meter + mute + volume) appears only while a full-screen game is producing sound (IGameAudioDetector seam + GameAudioHysteresis: show ~500ms of fullscreen+sound, hide ~1s after leaving fullscreen, silence never hides an active bar; VM polls on a 250ms timer); capture now runs for the app's lifetime so both meters preview live (started at startup via StartMicCaptureAsync, disposed in Shutdown — no longer go-live driven); MIC label is a button with a status dot (Models/MicStatus: green via the source Started event, yellow = mic problem, red = no device); PickMicrophone swaps the live device immediately via AudioMixer.RestartMic; fixed a latent ?.Invoke(meter.Push(...)) short-circuit that skipped the meter update when nothing subscribed — 167 tests passing, 0 warnings

ytLive.Tests/GameAudioDetectorTests.cs

@@ -0,0 +1,76 @@
+using Xunit;
+using ytLive.Services;
+
+namespace ytLive.Tests;
+
+/// <summary>
+/// TASK 4 game audio bar: the default detector's provider wiring — it composes
+/// the full-screen monitor + loopback level into the hysteresis and raises
+/// IsGameAudioActiveChanged on transitions. The transition math itself lives in
+/// GameAudioHysteresisTests.
+/// </summary>
+public class GameAudioDetectorTests
+{
+    [Fact]
+    public void Poll_RaisesChanged_WhenGameAppearsAndLeaves()
+    {
+        var now = new DateTime(2026, 8, 13, 12, 0, 0);
+        int? monitor = 0;
+        var level = 0f;
+        var detector = new GameAudioDetector(() => monitor, () => level, () => now);
+        var changes = new List<bool>();
+        detector.IsGameAudioActiveChanged += a => changes.Add(a);
+
+        level = 0.9f;
+        detector.Poll();
+        Assert.False(detector.IsGameAudioActive);
+
+        now = now.AddMilliseconds(600);
+        detector.Poll();
+        Assert.True(detector.IsGameAudioActive);
+        Assert.Equal(new[] { true }, changes);
+
+        level = 0f;
+        now = now.AddSeconds(2);
+        detector.Poll();
+        Assert.True(detector.IsGameAudioActive);
+        Assert.Equal(new[] { true }, changes);
+
+        monitor = null;
+        detector.Poll();
+        Assert.True(detector.IsGameAudioActive);
+
+        now = now.AddSeconds(2);
+        detector.Poll();
+        Assert.False(detector.IsGameAudioActive);
+        Assert.Equal(new[] { true, false }, changes);
+    }
+
+    [Fact]
+    public void Poll_StaysInactive_WhenNoFullScreenMonitor()
+    {
+        var detector = new GameAudioDetector(() => null, () => 0.9f);
+        var changes = 0;
+        detector.IsGameAudioActiveChanged += _ => changes++;
+
+        for (var i = 0; i < 5; i++)
+            detector.Poll();
+
+        Assert.False(detector.IsGameAudioActive);
+        Assert.Equal(0, changes);
+    }
+
+    [Fact]
+    public void Poll_StaysInactive_WhileLoopbackSilent()
+    {
+        var detector = new GameAudioDetector(() => 0, () => 0f);
+        var changes = 0;
+        detector.IsGameAudioActiveChanged += _ => changes++;
+
+        for (var i = 0; i < 5; i++)
+            detector.Poll();
+
+        Assert.False(detector.IsGameAudioActive);
+        Assert.Equal(0, changes);
+    }
+}