TASK 24 post-pause polish batch (creator's 8 review issues, 2026-08-15): (1) desktop/game audio volume slider + (2) mute were no-ops — the AudioMixer's gain Func seams defaulted to unity because the VM never passed them; new AudioGainProvider (Services/Audio/) wires MicMuted/MicVolume/GameMuted/GameAudioVolume into the mixer at construction, read live each mix tick, so sliders and mutes are stream-honest; the game bar also scales TRAX locally via new MusicPlayer.LocalGain (UpdateTraxLocalGain on every game volume/mute change + on load) so the creator HEARS the controls work on the music in the headphones. (3) TRAX played once then stopped — OnPlaybackStopped only looped on Position>=Length (unreliable for MediaFoundationReader); now any clean stop rewinds + replays, errors/explicit stops surface via PlaybackEnded; unused using dropped. (4+6) TRAX moved right of Socials in the footer's left cluster (centered under scenes/sources); the mic cluster is now MIC + meter + mute + volume. (5) mic source persists — LayoutStore gains a Settings key/value table (SaveMicSourceName/LoadMicSourceName); the VM saves on pick and restores before the mixer's first Start, so a restart reconnects the same vetted device (green) or reports it missing (yellow). (7) Backdrop's missing trashcan shifted the edit/eye icons right — new HiddenBoolToVisibilityConverter keeps the trash column reserved (Hidden, not Collapsed) so every source row's icons stay in fixed columns. (8) a 1px hairline with top/bottom padding separates scenes from sources in the left panel. Docs in the same commit: ai.md (gains honest + drive TRAX locally, TRAX loops, mic persistence, footer layout), TASKS.md TASK 24, HANDOFF.md shipped state, ViewModels/index.md. ONE integration test: AudioPipelineTests.Mix_HonorsProviderGains_AndGameMute_KillsTheLoopback (real mixer + provider gains through the pipe harness: scaled loopback audible, silence after mute). Build 0 warnings, 197 tests passing

Helpers/HiddenBoolToVisibilityConverter.cs

@@ -0,0 +1,20 @@
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+
+namespace ytLive.Helpers;
+
+/// <summary>
+/// Maps bool → Visibility, collapsing nothing: true becomes <c>Hidden</c> (keeps
+/// its layout slot) rather than <c>Collapsed</c> (releases it). Used where a row
+/// must keep its column grid aligned — e.g. the Backdrop source's missing
+/// trashcan must not shift the edit/eye icons one slot to the right.
+/// </summary>
+public class HiddenBoolToVisibilityConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        => value is true ? Visibility.Hidden : Visibility.Visible;
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => value is Visibility.Visible;
+}