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/Audio/AudioMixer.cs

@@ -4,15 +4,18 @@ namespace ytLive.Services.Audio;
 
 /// <summary>
 /// Owns the mic + desktop/game capture sources (TASK 4 ship step 4) and drives
-/// the live mic meter. Runs only while live: started when go-live succeeds,
-/// stopped on end-stream. Mic samples are level-metered and forwarded; loopback
-/// samples are currently dropped (consumed by the encoder mix in a later step).
+/// the footer meters. Capture runs for the app's lifetime (started once at
+/// startup, stopped on shutdown) so both bars stay live in preview: mic samples
+/// are level-metered and forwarded, loopback samples feed the game bar's meter.
+/// The mixer surfaces mic connection state (Connected/Failed) for the status
+/// dot and can restart the mic source mid-session when a device is re-picked.
 /// </summary>
 public sealed class AudioMixer : IDisposable
 {
     private readonly IAudioSource _mic;
     private readonly IAudioSource _loopback;
     private readonly AudioLevelMeter _meter;
+    private readonly AudioLevelMeter _loopbackMeter;
     private readonly Action<string>? _log;
     private bool _started;
 
@@ -21,8 +24,10 @@ public sealed class AudioMixer : IDisposable
         _mic = mic;
         _loopback = loopback;
         _meter = new AudioLevelMeter();
+        _loopbackMeter = new AudioLevelMeter();
         _log = log;
 
+        _mic.Started += OnMicStarted;
         _mic.SampleReady += OnMicSample;
         _loopback.SampleReady += OnLoopbackSample;
         _mic.Failed += OnMicFailed;
@@ -32,9 +37,21 @@ public sealed class AudioMixer : IDisposable
     /// <summary>Current smoothed mic level (0..1).</summary>
     public float MicLevel => _meter.Level;
 
+    /// <summary>Current smoothed desktop/game level (0..1).</summary>
+    public float LoopbackLevel => _loopbackMeter.Level;
+
     /// <summary>Raised whenever the smoothed mic level changes.</summary>
     public event Action<float>? MicLevelChanged;
 
+    /// <summary>Raised whenever the smoothed desktop/game level changes.</summary>
+    public event Action<float>? LoopbackLevelChanged;
+
+    /// <summary>Raised when the mic capture comes up (the status dot goes green).</summary>
+    public event Action? MicConnected;
+
+    /// <summary>Raised when the mic capture fails or dies (the status dot goes yellow).</summary>
+    public event Action<Exception>? MicFailed;
+
     public void Start()
     {
         if (_started)
@@ -46,6 +63,17 @@ public sealed class AudioMixer : IDisposable
         _mic.Start();
     }
 
+    /// <summary>Swaps the mic source without touching loopback — used when the
+    /// creator picks a different device mid-session. The level resets and the
+    /// new source raises <see cref="MicConnected"/> or <see cref="MicFailed"/>.</summary>
+    public void RestartMic()
+    {
+        _mic.Stop();
+        _meter.Reset();
+        MicLevelChanged?.Invoke(0);
+        _mic.Start();
+    }
+
     public void Stop()
     {
         if (!_started)
@@ -55,12 +83,15 @@ public sealed class AudioMixer : IDisposable
         _mic.Stop();
         _loopback.Stop();
         _meter.Reset();
+        _loopbackMeter.Reset();
         MicLevelChanged?.Invoke(0);
+        LoopbackLevelChanged?.Invoke(0);
     }
 
     public void Dispose()
     {
         Stop();
+        _mic.Started -= OnMicStarted;
         _mic.SampleReady -= OnMicSample;
         _loopback.SampleReady -= OnLoopbackSample;
         _mic.Failed -= OnMicFailed;
@@ -69,20 +100,30 @@ public sealed class AudioMixer : IDisposable
         _loopback.Dispose();
     }
 
+    private void OnMicStarted()
+    {
+        MicConnected?.Invoke();
+    }
+
     private void OnMicSample(AudioSample sample)
     {
-        MicLevelChanged?.Invoke(_meter.Push(sample));
+        // Push unconditionally: the ?. on the event would otherwise skip the
+        // argument (and the meter update) when nothing is subscribed yet.
+        var level = _meter.Push(sample);
+        MicLevelChanged?.Invoke(level);
     }
 
     private void OnLoopbackSample(AudioSample sample)
     {
-        // Desktop/game audio: captured for the future encoder mix; no UI yet.
+        var level = _loopbackMeter.Push(sample);
+        LoopbackLevelChanged?.Invoke(level);
     }
 
     private void OnMicFailed(Exception ex)
     {
         _log?.Invoke($"Mic capture failed: {ex.Message}");
         MicLevelChanged?.Invoke(0);
+        MicFailed?.Invoke(ex);
     }
 
     private void OnLoopbackFailed(Exception ex)