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/GameAudioHysteresisTests.cs

@@ -0,0 +1,82 @@
+using Xunit;
+using ytLive.Services;
+
+namespace ytLive.Tests;
+
+/// <summary>
+/// TASK 4 game audio bar: the pure show/hide state machine. Show = a full-screen
+/// app holds sound for half a second; hide = the app leaves fullscreen for a
+/// second. Silence never hides an active bar — only the game leaving the preview
+/// does (per the creator's rule).
+/// </summary>
+public class GameAudioHysteresisTests
+{
+    private static readonly DateTime T0 = new(2026, 8, 13, 12, 0, 0);
+
+    [Fact]
+    public void StaysInactive_WhileSilent()
+    {
+        var h = new GameAudioHysteresis();
+
+        for (var i = 0; i < 30; i++)
+        {
+            h.Update(true, false, T0.AddSeconds(i));
+            Assert.False(h.IsActive);
+        }
+    }
+
+    [Fact]
+    public void StaysInactive_UntilSoundHoldsHalfSecond()
+    {
+        var h = new GameAudioHysteresis();
+        h.Update(true, true, T0);
+        Assert.False(h.IsActive);
+        h.Update(true, true, T0.AddMilliseconds(400));
+        Assert.False(h.IsActive);
+
+        h.Update(true, true, T0.AddMilliseconds(600));
+        Assert.True(h.IsActive);
+    }
+
+    [Fact]
+    public void NeverHides_WhileGameStillFullScreen_EvenWhenSilent()
+    {
+        var h = new GameAudioHysteresis();
+        h.Update(true, true, T0);
+        h.Update(true, true, T0.AddSeconds(1));
+        Assert.True(h.IsActive);
+
+        for (var i = 2; i < 40; i++)
+        {
+            h.Update(true, false, T0.AddSeconds(i));
+            Assert.True(h.IsActive);
+        }
+    }
+
+    [Fact]
+    public void Hides_AfterAppLeavesFullScreen()
+    {
+        var h = new GameAudioHysteresis();
+        h.Update(true, true, T0);
+        h.Update(true, true, T0.AddSeconds(1));
+        Assert.True(h.IsActive);
+
+        h.Update(false, true, T0.AddSeconds(2));
+        Assert.True(h.IsActive);
+
+        h.Update(false, true, T0.AddSeconds(4));
+        Assert.False(h.IsActive);
+    }
+
+    [Fact]
+    public void StaysInactive_WhenNoFullScreen_EvenWithSound()
+    {
+        var h = new GameAudioHysteresis();
+
+        for (var i = 0; i < 30; i++)
+        {
+            h.Update(false, true, T0.AddSeconds(i));
+            Assert.False(h.IsActive);
+        }
+    }
+}