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

Services/IGameAudioDetector.cs

@@ -0,0 +1,20 @@
+namespace ytLive.Services;
+
+/// <summary>
+/// Detects "a working game with sound is up in the preview" (TASK 4 game audio
+/// bar): becomes active once a full-screen foreground app is producing desktop
+/// audio, and stays active as long as that full-screen app remains — silence
+/// never hides the bar, only the game leaving fullscreen/foreground does. Seam
+/// so the VM and tests never touch Win32 or audio interop directly.
+/// </summary>
+public interface IGameAudioDetector
+{
+    /// <summary>True while the game audio bar should be visible.</summary>
+    bool IsGameAudioActive { get; }
+
+    /// <summary>Raised when the bar should appear or disappear.</summary>
+    event Action<bool>? IsGameAudioActiveChanged;
+
+    /// <summary>Samples the injected providers and advances the state machine.</summary>
+    void Poll();
+}