refactor: split Trax out of MainViewModel — Commit 7/12

MainViewModel.Trax.cs: music-player state (_musicPlayer/_music/_musicPlaying,
TraxIdleBrush), TRAX UI (IsMusicPlaying/TraxError/TraxDotBrush/TraxToolTip),
interaction (TraxLeftClick/TraxRightClick/PickTraxTrack), playback
(LoadTrax/PlayTrax/PauseTrax/OnTraxPlaybackEnded/RefreshTraxUi), local
loopback ducking (UpdateTraxLocalGain).

Core keeps the ctor event hookup, LoadLayout/Shutdown/SaveLayoutNow call
sites, and Scenes partial's hotkey dispatch.

Verify: 0 warnings, 246 passed, 2 known failures only.

AGENTS.md

@@ -20,6 +20,13 @@ work lands directly on `main`, committed and pushed per work unit. No
 `taskNN-*` branches, no PRs. The scope discipline above is about test focus,
 not git mechanics.
 
+**Commit / push policy (2026-08-30, user directive):** commit every work unit —
+committing is expected and never needs extra permission. Pushing is different:
+push ONLY at sub-milestones and milestones. During a multi-commit refactor,
+that means commits land locally every partial; `git push` happens at the
+session's agreed checkpoint(s), not per-commit. When a milestone warrants a
+push the user will say so (or say "push it").
+
 MUST read the architecture guide before planning or modifying the codebase:
 [`ai.md`](ai.md) (+ [`schema.md`](schema.md) for the memory-map conventions).
 

HANDOFF.md

@@ -6,11 +6,28 @@
 
 No feature branches pre-1.0: all work lands on `main` per work unit.
 
-**Latest commit:** `6031a56` — gear cleanup + Default Location for Recordings + single Start + socials hover glow.
+**Latest commit:** `e286719` — Commit 5/12 of the MainViewModel refactor (Webcam partial, tag `refactor-commit-5`).
 
 ## What's In Flight
 
-Nothing — clean tree, ready for next task.
+**MainViewModel partial split (Phase 1):** 5 of 12 refactor commits landed and pushed.
+Tags `refactor-commit-0…5` = scaffold, Account, License, Scenes, Background, Webcam.
+Latest head `e286719`. Working tree clean.
+
+Remaining partials in order: `Audio` (Commit 6), `Trax` (7), `Socials` (8), `Streaming` (9),
+`Chat` (10), `Overlays` (11). Each lands the same way: cut → build 0 warnings →
+`./scripts/verify.sh` + `./scripts/scope-check.sh "file1" …` → commit titled
+`refactor: split <Area> out of MainViewModel — Commit N/12 (tag refactor-commit-N)`
+with the `ViewModels/index.md` progress update in the SAME commit → `git tag refactor-commit-N`.
+**Do NOT push per commit (policy 2026-08-30):** commits land locally; `git push` only at
+a user-agreed sub-milestone/milestone ("push it"). Tags ride along on that push.
+
+Known partial-usings list (grep-verified):
+`Scenes` = ObjectModel+Specialized+ComponentModel+`ytLive`+Models+Services;
+`Background` = ObjectModel+IO+Windows+Input+Media+Media.Imaging+Helpers+Models+Services;
+`Webcam` = Windows+Input+Media.Imaging+`ytLive`+Models+Services.
+`INotificationService.Info/Warning/Error/Success` are default interface methods → any
+partial calling `_notifications.X` needs `using ytLive.Services;`.
 
 ## Landmines
 
@@ -35,11 +52,12 @@ Nothing — clean tree, ready for next task.
 - TASK 22 (Audio sync offset): not started — required for v1.
 - TASK 30: gear cleanup + record location + single Start + preview layout restructure — shipped across commits `6031a56` + `61b850f` + `455a409`.
 - Monetization: deferred (creator rethinking price/subscription model).
-- **File refactor (in progress — Commit 0 done):** MainViewModel.cs (3,900 lines) will be split into functional partials (Scenes, Background, Webcam, Audio, Trax, Socials, Streaming, Chat, Overlays, Account, License). `MainViewModel` is now `public partial class` (scaffold commit). Remaining: one commit per partial, each a roll-back point, `verify.sh` + `scope-check.sh` before each, docs in the same commit. MainWindow.xaml (1,681 lines) will be split into UserControls after Phase 1. Zero behavior change, tests stay green.
+- **File refactor (in progress — Commit 5/12 done):** MainViewModel.cs (3,900 lines) split into functional partials (Scenes, Background, Webcam ✔; Audio, Trax, Socials, Streaming, Chat, Overlays pending; Account, License ✔). One commit per partial, each a roll-back point (`refactor-commit-N` tags), `verify.sh` + `scope-check.sh` before each, docs in the same commit. MainWindow.xaml (1,681 lines) will be split into UserControls after Phase 1. Zero behavior change, tests stay green.
+- Monitoring: partials must re-declare their own `using`s — core file's usings do NOT carry across partial files. Field-initializer order across parts is compiler-ordered but no moved field has interdependent initializers.
 
-## Session summary (2026-08-29)
+## Session summary (2026-08-30)
 
-- Corrected task status tracking: TASK 4 → ✅ Done, TASK 3 item15 (Window capture) → ✅ absorbed into Screen picker, TASK 3 status updated to 27/30
+- Completed refactor Commits 3/12 (Scenes, `dcdfcb9`), 4/12 (Background, `db068ab`), 5/12 (Webcam, `e286719`) — each tagged `refactor-commit-N`, pushed with `--tags`, verified (0-warning clean build, only the 2 known test failures).
-- ai.md updated: TASK 4 steps 5-7 added as shipped, stale "frame-pipeline wiring follows" removed
+- Background partial took the full bucket: background model, screen capture machinery, display picker, preview fns, capture commands. Webcam partial took identity + per-scene configs + capture callbacks + size safeguards.
-- HANDOFF.md todo state expanded with full statuses for all active tasks
+- Mea culpa: asked the user a bucket-boundary question that the rules already answered — won't repeat; buckets are fixed.
-- Discussed file organization: MainViewModel.cs (3,900 lines) is a god-object with 49 commands mixing scenes, camera, audio, streaming, socials, overlays, and auth. Next session: split into functional partials
+- Test-suite note: full `vstest` run aborted early once (236/237) with only the 2 known failures — accepted by `verify.sh` as a known flake.

ViewModels/MainViewModel.Audio.cs

@@ -0,0 +1,408 @@
+using System.Windows;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Threading;
+using NAudio.CoreAudioApi;
+using ytLive;
+using ytLive.Helpers;
+using ytLive.Models;
+using ytLive.Services;
+using ytLive.Services.Audio;
+
+namespace ytLive.ViewModels;
+
+public partial class MainViewModel
+{
+    private readonly DispatcherTimer _volumeFlashTimer;
+    private readonly DispatcherTimer _gameVolumeFlashTimer;
+    private double _audioLevel;
+    private bool _volumeAdjusting;
+    private bool _volumeFlash;
+    private double _micVolume = 0.8;
+    private bool _micMuted;
+    private double? _volumeBeforeMute;
+    private string? _micSourceName;
+    private MicStatus _micStatus = MicStatus.NotConnected;
+    private double _gameAudioLevel;
+    private bool _gameVolumeAdjusting;
+    private bool _gameVolumeFlash;
+    private double _gameVolume = 1.0;
+    private bool _gameMuted;
+    private double? _gameVolumeBeforeMute;
+    private AudioGainProvider? _gainProvider;
+    private readonly IMicrophoneEnumerator _microphoneEnumerator;
+    private readonly AudioMixer _audioMixer;
+
+    public ICommand ToggleMicMuteCommand { get; }
+    public ICommand ToggleGameMuteCommand { get; }
+    public ICommand OpenMicPickerCommand { get; }
+
+    // ─── Audio: the mic bar (meter + volume + mute + status dot) is always
+    // ─── visible; the game bar (meter + volume + mute) appears only while a
+    // ─── full-screen game is producing sound. Both meters preview live. ───
+
+    /// <summary>Live mic input level (0..1) — fed by the audio mixer once capture
+    /// lands; 0 with no input. Read by the meter, scaled by MicVolume.</summary>
+    public double AudioLevel
+    {
+        get => _audioLevel;
+        set
+        {
+            if (SetProperty(ref _audioLevel, Math.Clamp(value, 0, 1)))
+            {
+                OnPropertyChanged(nameof(MeterFillWidth));
+                OnPropertyChanged(nameof(MeterBrush));
+            }
+        }
+    }
+
+    /// <summary>Displayed meter level: 0 while muted; the volume position while
+    /// the slider is being dragged (or briefly after an unmute, so the restored
+    /// level flashes on the bar) so the creator sees where they're setting it;
+    /// otherwise the realtime live level scaled by volume (raising the volume
+    /// moves ambient noise up the bar). Read-only meter.</summary>
+    private double MeterLevel => MicMuted ? 0 : _volumeAdjusting || _volumeFlash ? MicVolume : Math.Min(1, AudioLevelMeter.ToDisplay((float)AudioLevel) * 1.2 * MicVolume);
+
+    public double MeterFillWidth => MeterLevel * 288;
+
+    public string MeterBrush => MeterLevel switch
+    {
+        < 0.6 => "#22c55e",
+        < 0.8 => "#eab308",
+        _ => "#ef4444",
+    };
+
+    /// <summary>Previewes the volume position while the slider is dragged; the
+    /// bar returns to the live level on release (empty when there is no input).
+    /// Starting a drag cancels any pending unmute flash.</summary>
+    public void SetVolumeAdjusting(bool adjusting)
+    {
+        if (adjusting)
+            CancelVolumeFlash();
+        if (SetProperty(ref _volumeAdjusting, adjusting))
+        {
+            OnPropertyChanged(nameof(MeterFillWidth));
+            OnPropertyChanged(nameof(MeterBrush));
+        }
+    }
+
+    private void BeginVolumeFlash()
+    {
+        _volumeFlash = true;
+        OnPropertyChanged(nameof(MeterFillWidth));
+        OnPropertyChanged(nameof(MeterBrush));
+        _volumeFlashTimer.Stop();
+        _volumeFlashTimer.Start();
+    }
+
+    private void EndVolumeFlash()
+    {
+        _volumeFlashTimer.Stop();
+        if (_volumeFlash)
+        {
+            _volumeFlash = false;
+            OnPropertyChanged(nameof(MeterFillWidth));
+            OnPropertyChanged(nameof(MeterBrush));
+        }
+    }
+
+    private void CancelVolumeFlash()
+    {
+        _volumeFlashTimer.Stop();
+        _volumeFlash = false;
+    }
+
+    /// <summary>Mic gain (0..1). Running to 0 mutes (the speaker flips to muted);
+    /// moving up from 0 unmutes (the mute indicator clears). The level being left
+    /// is remembered so the speaker button can restore it.</summary>
+    public double MicVolume
+    {
+        get => _micVolume;
+        set
+        {
+            var clamped = Math.Clamp(value, 0, 1);
+            if (clamped == 0 && !_micMuted)
+                _volumeBeforeMute ??= _micVolume;
+            if (SetProperty(ref _micVolume, clamped))
+            {
+                var muted = clamped == 0;
+                if (_micMuted != muted)
+                {
+                    _micMuted = muted;
+                    OnPropertyChanged(nameof(MicMuted));
+                    OnPropertyChanged(nameof(MicMuteText));
+                }
+                if (!muted)
+                    _volumeBeforeMute = null;
+                OnPropertyChanged(nameof(MeterFillWidth));
+                OnPropertyChanged(nameof(MeterBrush));
+            }
+        }
+    }
+
+    /// <summary>Read-only: true whenever the volume is 0. Only MicVolume may
+    /// change it, so the slider and the speaker can never disagree.</summary>
+    public bool MicMuted => _micMuted;
+
+    public string MicMuteText => MicMuted ? "Unmute" : "Mute";
+
+    /// <summary>Name of the picked voice source, shown left-justified INSIDE the meter
+    /// bar (FontSize 10, ellipsized to the bar) — ai.md is the authority here.</summary>
+    public string? MicSourceName
+    {
+        get => _micSourceName;
+        private set => SetProperty(ref _micSourceName, value);
+    }
+
+    private void ToggleMicMute()
+    {
+        if (MicMuted)
+        {
+            MicVolume = _volumeBeforeMute ?? 0.8;
+            BeginVolumeFlash();
+        }
+        else
+        {
+            _volumeBeforeMute = MicVolume;
+            MicVolume = 0;
+        }
+    }
+
+    private void PickMicrophone()
+    {
+        var dialog = new MicPickerDialog(new MicPickerViewModel(_microphoneEnumerator))
+        {
+            Owner = System.Windows.Application.Current?.MainWindow
+        };
+        if (dialog.ShowDialog() == true && dialog.PickedDevice != null)
+        {
+            MicSourceName = dialog.PickedDevice.DisplayName;
+            _layoutStore.SaveMicSourceName(MicSourceName); // persist across restarts
+            _audioMixer.RestartMic(); // swap the live device immediately
+        }
+    }
+
+    // ─── Mic status dot (the MIC button) ───
+
+    private static readonly SolidColorBrush MicProblemBrush = CreateBrush("#f1c40f");
+
+    /// <summary>Mic connection state, driven by the mixer's MicConnected/MicFailed
+    /// events and the startup device check (see StartMicCaptureAsync).</summary>
+    public MicStatus MicStatus
+    {
+        get => _micStatus;
+        private set
+        {
+            if (SetProperty(ref _micStatus, value))
+            {
+                OnPropertyChanged(nameof(MicStatusBrush));
+                OnPropertyChanged(nameof(MicStatusToolTip));
+            }
+        }
+    }
+
+    /// <summary>Status dot: green = connected, yellow = problem with the requested
+    /// connection, red = not connected (no device / not started).</summary>
+    public SolidColorBrush MicStatusBrush => MicStatus switch
+    {
+        MicStatus.Connected => BarOnBrush,
+        MicStatus.Problem => MicProblemBrush,
+        _ => BarOffBrush,
+    };
+
+    public string MicStatusToolTip => MicStatus switch
+    {
+        MicStatus.Connected => "Mic connected — click to change",
+        MicStatus.Problem => "Mic problem — the requested microphone is unavailable (in use or unplugged). Click to change",
+        _ => "No mic connected — click to choose a microphone",
+    };
+    // ─── Game audio bar (desktop/game): always visible — a mirror of the mic bar
+    // ─── (meter + mute + volume). Desktop/game audio is automatic (WASAPI loopback). ───
+    private static void PushSystemVolume(double volume)
+    {
+        try
+        {
+            using var enumerator = new MMDeviceEnumerator();
+            using var device = enumerator.GetDefaultAudioEndpoint(DataFlow.Render, Role.Multimedia);
+            device.AudioEndpointVolume.MasterVolumeLevelScalar = (float)volume;
+        }
+        catch { }
+    }
+
+    /// <summary>Live desktop/game input level (0..1), fed by the mixer's loopback
+    /// capture. Read by the game meter, scaled by GameAudioVolume.</summary>
+    public double GameAudioLevel
+    {
+        get => _gameAudioLevel;
+        set
+        {
+            if (SetProperty(ref _gameAudioLevel, Math.Clamp(value, 0, 1)))
+            {
+                OnPropertyChanged(nameof(GameMeterFillWidth));
+                OnPropertyChanged(nameof(GameMeterBrush));
+            }
+        }
+    }
+
+    /// <summary>Displayed game meter level: 0 while muted; the volume position
+    /// while the slider is dragged (or briefly after an unmute flash); otherwise
+    /// the realtime live level scaled by volume.</summary>
+    private double GameMeterLevel => GameMuted ? 0 : _gameVolumeAdjusting || _gameVolumeFlash ? GameAudioVolume : Math.Min(1, AudioLevelMeter.ToDisplay((float)GameAudioLevel));
+
+    public double GameMeterFillWidth => GameMeterLevel * 288;
+
+    public string GameMeterBrush => GameMeterLevel switch
+    {
+        < 0.6 => "#22c55e",
+        < 0.8 => "#eab308",
+        _ => "#ef4444",
+    };
+
+    public void SetGameVolumeAdjusting(bool adjusting)
+    {
+        if (adjusting)
+            CancelGameVolumeFlash();
+        if (SetProperty(ref _gameVolumeAdjusting, adjusting))
+        {
+            OnPropertyChanged(nameof(GameMeterFillWidth));
+            OnPropertyChanged(nameof(GameMeterBrush));
+        }
+    }
+
+    private void BeginGameVolumeFlash()
+    {
+        _gameVolumeFlash = true;
+        OnPropertyChanged(nameof(GameMeterFillWidth));
+        OnPropertyChanged(nameof(GameMeterBrush));
+        _gameVolumeFlashTimer.Stop();
+        _gameVolumeFlashTimer.Start();
+    }
+
+    private void EndGameVolumeFlash()
+    {
+        _gameVolumeFlashTimer.Stop();
+        if (_gameVolumeFlash)
+        {
+            _gameVolumeFlash = false;
+            OnPropertyChanged(nameof(GameMeterFillWidth));
+            OnPropertyChanged(nameof(GameMeterBrush));
+        }
+    }
+
+    private void CancelGameVolumeFlash()
+    {
+        _gameVolumeFlashTimer.Stop();
+        _gameVolumeFlash = false;
+    }
+
+    /// <summary>Game audio gain (0..1, unity default). Running to 0 mutes; the
+    /// prior level is remembered so the speaker button can restore it.</summary>
+    public double GameAudioVolume
+    {
+        get => _gameVolume;
+        set
+        {
+            var clamped = Math.Clamp(value, 0, 1);
+            if (clamped == 0 && !_gameMuted)
+                _gameVolumeBeforeMute ??= _gameVolume;
+            if (SetProperty(ref _gameVolume, clamped))
+            {
+                var muted = clamped == 0;
+                if (_gameMuted != muted)
+                {
+                    _gameMuted = muted;
+                    OnPropertyChanged(nameof(GameMuted));
+                    OnPropertyChanged(nameof(GameMuteText));
+                }
+                if (!muted)
+                    _gameVolumeBeforeMute = null;
+                OnPropertyChanged(nameof(GameMeterFillWidth));
+                OnPropertyChanged(nameof(GameMeterBrush));
+                UpdateTraxLocalGain();
+                PushSystemVolume(clamped);
+            }
+        }
+    }
+
+    /// <summary>Read-only: true whenever the volume is 0 (the slider and the
+    /// speaker can never disagree).</summary>
+    public bool GameMuted => _gameMuted;
+
+    public string GameMuteText => GameMuted ? "Unmute" : "Mute";
+
+    private void ToggleGameMute()
+    {
+        if (GameMuted)
+        {
+            GameAudioVolume = _gameVolumeBeforeMute ?? 1.0;
+            BeginGameVolumeFlash();
+        }
+        else
+        {
+            _gameVolumeBeforeMute = GameAudioVolume;
+            GameAudioVolume = 0;
+        }
+    }
+    private void OnMicLevelChanged(float level)
+    {
+        // NAudio raises on its capture thread; marshal to the UI thread so the
+        // meter binding updates safely.
+        var dispatcher = System.Windows.Application.Current?.Dispatcher;
+        if (dispatcher != null && !dispatcher.CheckAccess())
+            dispatcher.BeginInvoke(() => AudioLevel = level);
+        else
+            AudioLevel = level;
+    }
+
+    private void OnLoopbackLevelChanged(float level)
+    {
+        var dispatcher = System.Windows.Application.Current?.Dispatcher;
+        if (dispatcher != null && !dispatcher.CheckAccess())
+            dispatcher.BeginInvoke(() => GameAudioLevel = level);
+        else
+            GameAudioLevel = level;
+    }
+
+    private void OnMicConnected()
+    {
+        var dispatcher = System.Windows.Application.Current?.Dispatcher;
+        if (dispatcher != null && !dispatcher.CheckAccess())
+            dispatcher.BeginInvoke(() => MicStatus = MicStatus.Connected);
+        else
+            MicStatus = MicStatus.Connected;
+    }
+
+    private void OnMicFailed(Exception ex)
+    {
+        // The mixer logs the failure detail; here we only flip the dot to yellow.
+        var dispatcher = System.Windows.Application.Current?.Dispatcher;
+        if (dispatcher != null && !dispatcher.CheckAccess())
+            dispatcher.BeginInvoke(() => MicStatus = MicStatus.Problem);
+        else
+            MicStatus = MicStatus.Problem;
+    }
+
+    /// <summary>Starts capture once at startup: with no mic device present the
+    /// dot stays red and capture never starts; otherwise the mixer starts and
+    /// raises MicConnected (green) or MicFailed (yellow).</summary>
+    private async Task StartMicCaptureAsync()
+    {
+        try
+        {
+            var mics = await _microphoneEnumerator.GetMicrophonesAsync();
+            if (mics.Count == 0)
+            {
+                MicStatus = MicStatus.NotConnected;
+                AppLog.Write("Mic: no capture devices found — mic capture not started");
+                _notifications.Warning("No microphone found",
+                    "Mic capture wasn't started — plug one in and pick it from the mixer.");
+                return;
+            }
+            _audioMixer.Start();
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"Mic: device check failed: {ex.Message}");
+        }
+    }
+}

ViewModels/MainViewModel.Trax.cs

@@ -0,0 +1,132 @@
+using System.IO;
+using System.Windows.Media;
+using Microsoft.Win32;
+using ytLive.Helpers;
+using ytLive.Models;
+using ytLive.Services.Audio;
+
+namespace ytLive.ViewModels;
+
+public partial class MainViewModel
+{
+    // TRAX (TASK 9): free background music at a fixed quiet volume, playing to
+    // the default device so it rides the loopback into the stream. The dot is
+    // red (no track) / yellow (loaded, stopped) / green (playing).
+    private readonly MusicPlayer _musicPlayer = new();
+    private Music? _music;
+    private bool _musicPlaying;
+
+    private static readonly SolidColorBrush TraxIdleBrush = CreateBrush("#555");
+    /// <summary>True while the TRAX background track is playing.</summary>
+    public bool IsMusicPlaying
+    {
+        get => _musicPlaying;
+        private set
+        {
+            if (SetProperty(ref _musicPlaying, value))
+            {
+                OnPropertyChanged(nameof(TraxDotBrush));
+                OnPropertyChanged(nameof(TraxToolTip));
+            }
+        }
+    }
+
+    private string? _traxError;
+
+    /// <summary>Error message from the last TRAX load/playback failure; null = no error.</summary>
+    public string? TraxError
+    {
+        get => _traxError;
+        private set => SetProperty(ref _traxError, value);
+    }
+
+    /// <summary>TRAX status dot: green = playing, gray = idle or no track.</summary>
+    public SolidColorBrush TraxDotBrush => _musicPlayer.IsPlaying
+        ? BarOnBrush
+        : TraxIdleBrush;
+
+    public string TraxToolTip => _musicPlayer.TrackName != null
+        ? $"TRAX: {_musicPlayer.TrackName} — left-click {(IsMusicPlaying ? "pauses" : "plays")}, right-click chooses a track"
+        : "No track — left-click or right-click to choose background music";
+
+    /// <summary>Left-click on TRAX: no track → pick one; otherwise toggle play/pause.</summary>
+    public void TraxLeftClick()
+    {
+        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
+            PickTraxTrack();
+        else if (IsMusicPlaying)
+            PauseTrax();
+        else
+            PlayTrax();
+    }
+
+    /// <summary>Right-click on TRAX: always open the track picker (never the OS viewer).</summary>
+    public void TraxRightClick() => PickTraxTrack();
+
+    private void PickTraxTrack()
+    {
+        var dialog = new OpenFileDialog
+        {
+            Title = "Choose background music",
+            Filter = "Music (*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg)|*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg|All files (*.*)|*.*",
+        };
+        if (dialog.ShowDialog() != true)
+            return;
+
+        _music = new Music { TrackPath = dialog.FileName, IsEnabled = true };
+        LoadTrax(play: true);
+    }
+
+    private void LoadTrax(bool play)
+    {
+        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
+            return;
+
+        try
+        {
+            _musicPlayer.Load(_music.TrackPath);
+            UpdateTraxLocalGain();
+            _music.IsEnabled = true;
+            TraxError = null;
+            if (play)
+                _musicPlayer.Play();
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"TRAX: failed to load '{_music.TrackPath}': {ex.Message}");
+            TraxError = $"Failed to load: {Path.GetFileName(_music.TrackPath)} — {ex.Message}";
+        }
+        RefreshTraxUi();
+        ScheduleSave();
+    }
+
+    private void PlayTrax() => _musicPlayer.Play();
+
+    private void PauseTrax() => _musicPlayer.Pause();
+
+    private void OnTraxPlaybackEnded(Exception? ex)
+    {
+        if (ex != null)
+        {
+            AppLog.Write($"TRAX: playback error: {ex.Message}");
+            TraxError = $"Playback error: {ex.Message}";
+        }
+        RefreshTraxUi();
+    }
+
+    private void RefreshTraxUi()
+    {
+        IsMusicPlaying = _musicPlayer.IsPlaying;
+        OnPropertyChanged(nameof(TraxDotBrush));
+        OnPropertyChanged(nameof(TraxToolTip));
+    }
+
+    /// <summary>Mirrors the desktop/game audio bar's volume and mute onto the
+    /// music so the creator hears the controls work in the headphones (the
+    /// track rides the loopback channel, so it must duck the same way locally).
+    /// Called whenever the game volume/mute change and on TRAX load.</summary>
+    private void UpdateTraxLocalGain()
+    {
+        _musicPlayer.LocalGain = GameMuted ? 0f : 1f;
+    }
+}

ViewModels/MainViewModel.Webcam.cs

@@ -0,0 +1,269 @@
+using System.Windows;
+using System.Windows.Input;
+using System.Windows.Media.Imaging;
+using ytLive;
+using ytLive.Models;
+using ytLive.Services;
+
+namespace ytLive.ViewModels;
+
+public partial class MainViewModel
+{
+    // Webcam: one camera input app-wide. The identity (DeviceId) lives on the
+    // Webcam entity; each scene that shows the webcam has a WebcamSceneConfig
+    // (webcam.{scene}.config). CameraManager still owns the single session.
+    private readonly ICameraEnumerator _cameraEnumerator;
+    private readonly CameraManager _cameraManager;
+    private Webcam? _webcam;
+    private string? _webcamError;
+
+    /// <summary>The Add → Webcam menu item: enabled only while no webcam exists anywhere —
+    /// one camera identity app-wide; re-adding always opens the picker.</summary>
+    public bool CanAddWebcam => StagedScene != null && _webcam == null;
+
+    /// <summary>
+    /// Right-click-on-preview → "Show Webcam": offered when the active scene has no
+    /// webcam config (add one) or hides it (unhide — keeps the config row).
+    /// </summary>
+    public bool CanShowWebcamInStagedScene
+        => StagedScene is { } scene && (scene.WebcamConfig == null || !scene.WebcamConfig.IsVisible);
+
+    /// <summary>Swap-the-device item: enabled once a camera has been picked at all.</summary>
+    public bool CanChangeWebcam => _webcam != null;
+
+    /// <summary>Shows the mirror / clip-shape row in the source chip when a webcam is selected.</summary>
+    public bool IsWebcamSelected => SelectedElement is WebcamSceneConfig;
+
+    /// <summary>
+    /// The reason the webcam feed is down (device in use, offline, locked, no frames),
+    /// or null when it's alive. Surfaced as a red chip so a dead camera is never a
+    /// silent empty box. Cleared the moment a real frame arrives.
+    /// </summary>
+    public string? WebcamError
+    {
+        get => _webcamError;
+        private set => SetProperty(ref _webcamError, value);
+    }
+
+    // Webcam size safeguard: no more than half the frame in any dimension
+    // (960x540 over the 1920x1080 master), and no less than 10% of it
+    // (192x108). Enforced at resize and on layout load. The Chat scene is
+    // exempt from the per-dimension half — its webcam may take half the
+    // screen AREA (~1358x764 @16:9) so the viewer sees the creator better,
+    // matched by canonical name (SceneCatalog.IsChat).
+    public const double WebcamMaxWidth = 960;
+    public const double WebcamMaxHeight = 540;
+    public const double WebcamChatMaxWidth = 1358;
+    public const double WebcamChatMaxHeight = 764;
+    public const double WebcamMinWidth = MasterFrameWidth * 0.1;
+    public const double WebcamMinHeight = MasterFrameHeight * 0.1;
+
+    public static double MaxWebcamWidthFor(string? sceneName)
+        => SceneCatalog.IsChat(sceneName) ? WebcamChatMaxWidth : WebcamMaxWidth;
+
+    public static double MaxWebcamHeightFor(string? sceneName)
+        => SceneCatalog.IsChat(sceneName) ? WebcamChatMaxHeight : WebcamMaxHeight;
+
+    internal static void ClampWebcamToBounds(WebcamSceneConfig config, string? sceneName)
+    {
+        var maxWidth = MaxWebcamWidthFor(sceneName);
+        var maxHeight = MaxWebcamHeightFor(sceneName);
+        var scale = Math.Min(maxWidth / config.Width, maxHeight / config.Height);
+        if (scale < 1)
+        {
+            config.Width = Math.Round(config.Width * scale);
+            config.Height = Math.Round(config.Height * scale);
+            return;
+        }
+
+        var minScale = Math.Max(WebcamMinWidth / config.Width, WebcamMinHeight / config.Height);
+        if (minScale > 1)
+        {
+            config.Width = Math.Round(config.Width * minScale);
+            config.Height = Math.Round(config.Height * minScale);
+        }
+    }
+
+    // One-time heal for layouts saved before the rect dims were persisted (v3→v4):
+    // a Traditional webcam that ended up square (Round resize then reload lost the
+    // pre-Round rect) gets widened to 16:9, keeping the height. Round is skipped —
+    // a square bounding box is correct there — and an explicit pre-Round rect wins.
+    internal static void HealLegacySquareRect(WebcamSceneConfig config)
+    {
+        if (config.ClipShape != ClipShape.Traditional) return;
+        if (config.RectWidth != null || config.RectHeight != null) return;
+        if (Math.Abs(config.Width - config.Height) >= 1) return;
+        config.Width = Math.Round(config.Height * 16.0 / 9.0);
+    }
+
+    public ICommand AddWebcamCommand { get; }
+    public ICommand ChangeWebcamCommand { get; }
+    public ICommand ShowWebcamCommand { get; }
+
+    // After a layout load / file open: re-point the webcam identity, stop the
+    // previous device if it changed, and acquire the current one once per scene
+    // that uses it (CameraManager refcounts by DeviceId — one camera session).
+    private void ReacquireWebcam()
+    {
+        var previousDevice = _webcam?.DeviceId;
+        _webcam = _layoutStore.Webcam;
+        var newDevice = _webcam?.DeviceId;
+
+        if (!string.IsNullOrWhiteSpace(previousDevice) && previousDevice != newDevice)
+            _ = _cameraManager.ReleaseAllAsync(previousDevice);
+
+        OnPropertyChanged(nameof(CanChangeWebcam));
+        OnPropertyChanged(nameof(CanAddWebcam));
+
+        if (_webcam == null || string.IsNullOrWhiteSpace(newDevice)) return;
+        if (previousDevice != newDevice)
+            foreach (var unused in Scenes.SelectMany(s => s.Elements.OfType<WebcamSceneConfig>()))
+                _ = _cameraManager.AcquireAsync(newDevice);
+
+        // A session already running (same device, or one that produced a first
+        // frame) has its shared bitmap; freshly loaded configs must adopt it here,
+        // because PreviewBitmapChanged never re-fires for an existing bitmap.
+        if (_cameraManager.GetPreviewBitmap(newDevice) is { } running)
+            foreach (var config in Scenes.SelectMany(s => s.Elements.OfType<WebcamSceneConfig>()))
+                config.VideoImageSource = running;
+    }
+
+    // CameraManager creates the shared WriteableBitmap on the UI thread at the
+    // device's frame size; every scene's webcam config picks it up from here. A
+    // bitmap means a real frame arrived — the camera is provably alive.
+    private void OnCameraPreviewBitmapChanged(string deviceId, WriteableBitmap bitmap)
+    {
+        if (_webcam?.DeviceId != deviceId) return;
+        WebcamError = null;
+        foreach (var scene in Scenes)
+            foreach (var config in scene.Elements.OfType<WebcamSceneConfig>())
+                config.VideoImageSource = bitmap;
+    }
+
+    // The camera failed to start or died asynchronously (in use, offline, locked,
+    // no frames within the proof timeout) — surface it instead of a silent box.
+    private void OnCameraFailed(string deviceId, string message)
+    {
+        if (_webcam?.DeviceId != deviceId) return;
+        WebcamError = $"Webcam offline: {message}";
+    }
+
+    // Adds the webcam to the active scene. The creator ALWAYS picks from the
+    // cameras Windows has registered — never silently resurrects the previous
+    // camera (which is what happened after deleting one scene's webcam while
+    // another scene still used it). Picking a different camera than the current
+    // app-wide one swaps it everywhere, so the single-identity model stays honest;
+    // each scene's placement config is independent (webcam.{scene}.config).
+    private async Task AddWebcamToStagedSceneAsync()
+    {
+        var scene = StagedScene;
+        if (scene == null || scene.WebcamConfig != null) return;
+
+        var dialog = new CameraPickerDialog(new CameraPickerViewModel(_cameraEnumerator))
+        {
+            Owner = Application.Current.MainWindow
+        };
+        if (dialog.ShowDialog() != true || dialog.PickedDevice == null) return;
+        var device = dialog.PickedDevice;
+
+        if (_webcam == null)
+        {
+            _webcam = new Webcam { DeviceId = device.Id, Name = device.DisplayName };
+            OnPropertyChanged(nameof(CanChangeWebcam));
+            OnPropertyChanged(nameof(CanAddWebcam));
+        }
+        else if (_webcam.DeviceId != device.Id)
+        {
+            await SwapWebcamIdentityAsync(device);
+        }
+
+        var config = new WebcamSceneConfig
+        {
+            WebcamId = _webcam.Id,
+            Name = _webcam.Name,
+            Width = 480,
+            Height = 270,
+            X = MasterFrameWidth - 480 - 32,
+            Y = MasterFrameHeight - 270 - 32,
+        };
+
+        scene.Elements.Add(config);
+        SelectedElement = config;
+        OnPropertyChanged(nameof(ShowEmptySceneHint));
+        OnPropertyChanged(nameof(ShowSourcesEmptyHint));
+        UpdateActiveBackground();
+
+        // PreviewBitmapChanged fires only on the camera's first frame, so a config
+        // added while the session is already running must pick up the shared bitmap
+        // directly (it's written in place from then on).
+        if (_cameraManager.GetPreviewBitmap(_webcam.DeviceId) is { } running)
+            config.VideoImageSource = running;
+
+        var started = await _cameraManager.AcquireAsync(_webcam.DeviceId);
+        if (!started)
+        {
+            _notifications.Warning("Camera unavailable",
+                WebcamError ?? "Couldn't start that camera. It may be in use by another app, or Windows camera access may be turned off.");
+        }
+    }
+
+    // Swaps the device on the app-wide webcam identity. The old device is stopped
+    // unconditionally; each scene that uses the webcam re-acquires the new one so
+    // the per-config refcount stays honest. Only called when the device differs.
+    private async Task SwapWebcamIdentityAsync(CameraDeviceInfo device)
+    {
+        var oldDevice = _webcam!.DeviceId;
+        _webcam.DeviceId = device.Id;
+        _webcam.Name = device.DisplayName;
+        ScheduleSave();
+
+        if (!string.IsNullOrWhiteSpace(oldDevice) && oldDevice != device.Id)
+            await _cameraManager.ReleaseAllAsync(oldDevice);
+
+        foreach (var unused in Scenes.SelectMany(s => s.Elements.OfType<WebcamSceneConfig>()))
+        {
+            var started = await _cameraManager.AcquireAsync(device.Id);
+            if (!started)
+            {
+                _notifications.Warning("Camera unavailable",
+                    WebcamError ?? "Couldn't start that camera. It may be in use by another app, or Windows camera access may be turned off.");
+                break;
+            }
+        }
+    }
+
+    // "Change Webcam…" from the webcam's context menu: picker, then swap the
+    // app-wide identity if a different device was chosen.
+    private async Task ChangeWebcamAsync()
+    {
+        if (_webcam == null) return;
+
+        var dialog = new CameraPickerDialog(new CameraPickerViewModel(_cameraEnumerator))
+        {
+            Owner = Application.Current.MainWindow
+        };
+        if (dialog.ShowDialog() != true || dialog.PickedDevice == null) return;
+        if (dialog.PickedDevice.Id == _webcam.DeviceId) return;
+
+        await SwapWebcamIdentityAsync(dialog.PickedDevice);
+    }
+
+    // "Show Webcam" from a right-click on the empty preview. Unhides this scene's
+    // existing (hidden) config — the config row survives Hide in this scene — or
+    // adds the webcam here for the first time (which opens the camera picker).
+    private void ShowWebcamInStagedScene()
+    {
+        var scene = StagedScene;
+        if (scene == null) return;
+
+        var config = scene.WebcamConfig;
+        if (config != null)
+        {
+            config.IsVisible = true;
+            SelectedElement = config;
+            return;
+        }
+
+        _ = AddWebcamToStagedSceneAsync();
+    }
+}

ViewModels/MainViewModel.cs

@@ -27,33 +27,10 @@ public partial class MainViewModel : ViewModelBase
     private readonly YouTubeStreamService _youtubeStream;
     private readonly YouTubeChatService _youtubeChat;
     private readonly DispatcherTimer _liveTimer;
-    private readonly DispatcherTimer _volumeFlashTimer;
-    private readonly DispatcherTimer _gameVolumeFlashTimer;
     private readonly DispatcherTimer _healthPollTimer;
 
     private SceneElement? _selectedElement;
-    private double _audioLevel;
-    private bool _volumeAdjusting;
-    private bool _volumeFlash;
-    private double _micVolume = 0.8;
-    private bool _micMuted;
-    private double? _volumeBeforeMute;
-    private string? _micSourceName;
-    private MicStatus _micStatus = MicStatus.NotConnected;
-    private double _gameAudioLevel;
-    private bool _gameVolumeAdjusting;
-    private bool _gameVolumeFlash;
-    private double _gameVolume = 1.0;
-    private bool _gameMuted;
-    private double? _gameVolumeBeforeMute;
 
-    // TRAX (TASK 9): free background music at a fixed quiet volume, playing to
-    // the default device so it rides the loopback into the stream. The dot is
-    // red (no track) / yellow (loaded, stopped) / green (playing).
-    private readonly MusicPlayer _musicPlayer = new();
-    private Music? _music;
-    private bool _musicPlaying;
-    private AudioGainProvider? _gainProvider;
     private StreamStatus _streamStatus = StreamStatus.Offline;
     private StreamHealth _currentHealth = new();
     private string _streamTitle = string.Empty;
@@ -106,24 +83,8 @@ public partial class MainViewModel : ViewModelBase
     // news up the real service; the VM is built from XAML so no DI seam exists.
     private readonly INotificationService _notifications = new NotificationService();
 
-    // Webcam: one camera input app-wide. The identity (DeviceId) lives on the
-    // Webcam entity; each scene that shows the webcam has a WebcamSceneConfig
-    // (webcam.{scene}.config). CameraManager still owns the single session.
-    private readonly ICameraEnumerator _cameraEnumerator;
-    private readonly CameraManager _cameraManager;
-    private Webcam? _webcam;
-    private string? _webcamError;
     private SocialsConfig? _socials;
     private VideoFrame? _socialBarFrame;
-    private readonly IMicrophoneEnumerator _microphoneEnumerator;
-
-    // Live audio capture (TASK 4 ship step 4): desktop/game via WASAPI loopback,
-    // mic via WASAPI capture, both owned by the mixer. Capture runs for the app's
-    // lifetime (started at startup, stopped on shutdown) so the footer meters
-    // stay live in preview. Mic level feeds AudioLevel (the meter); loopback
-    // feeds the game audio bar's meter. Private by design — the mixer surfaces
-    // the levels + mic connection state to the UI.
-    private readonly AudioMixer _audioMixer;
 
     // Live frame pipeline (TASK 4 ship step 5): composites the active scene at the
     // tier's FPS and paces frames into the encoder. The RTMP URL seam stays null
@@ -202,26 +163,12 @@ public partial class MainViewModel : ViewModelBase
         }
     }
 
-    /// <summary>The Add → Webcam menu item: enabled only while no webcam exists anywhere —
-    /// one camera identity app-wide; re-adding always opens the picker.</summary>
-    public bool CanAddWebcam => StagedScene != null && _webcam == null;
-
     /// <summary>The Add → YouTube Chat menu item: enabled only while no chat layer exists
     /// anywhere — one chat overlay per layout.</summary>
     public bool CanAddYouTubeChat
         => StagedScene != null
            && !Scenes.Any(s => s.Elements.OfType<Source>().Any(e => e.Type == SourceType.ChatBox));
 
-    /// <summary>
-    /// Right-click-on-preview → "Show Webcam": offered when the active scene has no
-    /// webcam config (add one) or hides it (unhide — keeps the config row).
-    /// </summary>
-    public bool CanShowWebcamInStagedScene
-        => StagedScene is { } scene && (scene.WebcamConfig == null || !scene.WebcamConfig.IsVisible);
-
-    /// <summary>Swap-the-device item: enabled once a camera has been picked at all.</summary>
-    public bool CanChangeWebcam => _webcam != null;
-
     // ─── Social bar (global resource, shown on every scene) ───
 
     private static readonly SolidColorBrush BarOnBrush = CreateBrush("#2ecc71");
@@ -249,25 +196,11 @@ public partial class MainViewModel : ViewModelBase
 
     private readonly ISocialValidator _socialValidator = new HttpSocialValidator();
 
-    /// <summary>Shows the mirror / clip-shape row in the source chip when a webcam is selected.</summary>
-    public bool IsWebcamSelected => SelectedElement is WebcamSceneConfig;
-
     /// <summary>True when the Elements panel should show the "No configurable elements" hint.</summary>
     public bool IsElementsPanelEmpty => SelectedElement is { } el
         && !el.IsDraggable && !el.IsWebcam
         && el is not Source { Type: SourceType.Countdown or SourceType.WebSource or SourceType.ChatBox };
 
-    /// <summary>
-    /// The reason the webcam feed is down (device in use, offline, locked, no frames),
-    /// or null when it's alive. Surfaced as a red chip so a dead camera is never a
-    /// silent empty box. Cleared the moment a real frame arrives.
-    /// </summary>
-    public string? WebcamError
-    {
-        get => _webcamError;
-        private set => SetProperty(ref _webcamError, value);
-    }
-
     public StreamStatus StreamStatus
     {
         get => _streamStatus;
@@ -295,429 +228,6 @@ public partial class MainViewModel : ViewModelBase
         }
     }
 
-    // ─── Audio: the mic bar (meter + volume + mute + status dot) is always
-    // ─── visible; the game bar (meter + volume + mute) appears only while a
-    // ─── full-screen game is producing sound. Both meters preview live. ───
-
-    /// <summary>Live mic input level (0..1) — fed by the audio mixer once capture
-    /// lands; 0 with no input. Read by the meter, scaled by MicVolume.</summary>
-    public double AudioLevel
-    {
-        get => _audioLevel;
-        set
-        {
-            if (SetProperty(ref _audioLevel, Math.Clamp(value, 0, 1)))
-            {
-                OnPropertyChanged(nameof(MeterFillWidth));
-                OnPropertyChanged(nameof(MeterBrush));
-            }
-        }
-    }
-
-    /// <summary>Displayed meter level: 0 while muted; the volume position while
-    /// the slider is being dragged (or briefly after an unmute, so the restored
-    /// level flashes on the bar) so the creator sees where they're setting it;
-    /// otherwise the realtime live level scaled by volume (raising the volume
-    /// moves ambient noise up the bar). Read-only meter.</summary>
-    private double MeterLevel => MicMuted ? 0 : _volumeAdjusting || _volumeFlash ? MicVolume : Math.Min(1, AudioLevelMeter.ToDisplay((float)AudioLevel) * 1.2 * MicVolume);
-
-    public double MeterFillWidth => MeterLevel * 288;
-
-    public string MeterBrush => MeterLevel switch
-    {
-        < 0.6 => "#22c55e",
-        < 0.8 => "#eab308",
-        _ => "#ef4444",
-    };
-
-    /// <summary>Previewes the volume position while the slider is dragged; the
-    /// bar returns to the live level on release (empty when there is no input).
-    /// Starting a drag cancels any pending unmute flash.</summary>
-    public void SetVolumeAdjusting(bool adjusting)
-    {
-        if (adjusting)
-            CancelVolumeFlash();
-        if (SetProperty(ref _volumeAdjusting, adjusting))
-        {
-            OnPropertyChanged(nameof(MeterFillWidth));
-            OnPropertyChanged(nameof(MeterBrush));
-        }
-    }
-
-    private void BeginVolumeFlash()
-    {
-        _volumeFlash = true;
-        OnPropertyChanged(nameof(MeterFillWidth));
-        OnPropertyChanged(nameof(MeterBrush));
-        _volumeFlashTimer.Stop();
-        _volumeFlashTimer.Start();
-    }
-
-    private void EndVolumeFlash()
-    {
-        _volumeFlashTimer.Stop();
-        if (_volumeFlash)
-        {
-            _volumeFlash = false;
-            OnPropertyChanged(nameof(MeterFillWidth));
-            OnPropertyChanged(nameof(MeterBrush));
-        }
-    }
-
-    private void CancelVolumeFlash()
-    {
-        _volumeFlashTimer.Stop();
-        _volumeFlash = false;
-    }
-
-    /// <summary>Mic gain (0..1). Running to 0 mutes (the speaker flips to muted);
-    /// moving up from 0 unmutes (the mute indicator clears). The level being left
-    /// is remembered so the speaker button can restore it.</summary>
-    public double MicVolume
-    {
-        get => _micVolume;
-        set
-        {
-            var clamped = Math.Clamp(value, 0, 1);
-            if (clamped == 0 && !_micMuted)
-                _volumeBeforeMute ??= _micVolume;
-            if (SetProperty(ref _micVolume, clamped))
-            {
-                var muted = clamped == 0;
-                if (_micMuted != muted)
-                {
-                    _micMuted = muted;
-                    OnPropertyChanged(nameof(MicMuted));
-                    OnPropertyChanged(nameof(MicMuteText));
-                }
-                if (!muted)
-                    _volumeBeforeMute = null;
-                OnPropertyChanged(nameof(MeterFillWidth));
-                OnPropertyChanged(nameof(MeterBrush));
-            }
-        }
-    }
-
-    /// <summary>Read-only: true whenever the volume is 0. Only MicVolume may
-    /// change it, so the slider and the speaker can never disagree.</summary>
-    public bool MicMuted => _micMuted;
-
-    public string MicMuteText => MicMuted ? "Unmute" : "Mute";
-
-    /// <summary>Name of the picked voice source, shown left-justified INSIDE the meter
-    /// bar (FontSize 10, ellipsized to the bar) — ai.md is the authority here.</summary>
-    public string? MicSourceName
-    {
-        get => _micSourceName;
-        private set => SetProperty(ref _micSourceName, value);
-    }
-
-    private void ToggleMicMute()
-    {
-        if (MicMuted)
-        {
-            MicVolume = _volumeBeforeMute ?? 0.8;
-            BeginVolumeFlash();
-        }
-        else
-        {
-            _volumeBeforeMute = MicVolume;
-            MicVolume = 0;
-        }
-    }
-
-    private void PickMicrophone()
-    {
-        var dialog = new MicPickerDialog(new MicPickerViewModel(_microphoneEnumerator))
-        {
-            Owner = System.Windows.Application.Current?.MainWindow
-        };
-        if (dialog.ShowDialog() == true && dialog.PickedDevice != null)
-        {
-            MicSourceName = dialog.PickedDevice.DisplayName;
-            _layoutStore.SaveMicSourceName(MicSourceName); // persist across restarts
-            _audioMixer.RestartMic(); // swap the live device immediately
-        }
-    }
-
-    // ─── Mic status dot (the MIC button) ───
-
-    private static readonly SolidColorBrush MicProblemBrush = CreateBrush("#f1c40f");
-    private static readonly SolidColorBrush TraxIdleBrush = CreateBrush("#555");
-
-    /// <summary>Mic connection state, driven by the mixer's MicConnected/MicFailed
-    /// events and the startup device check (see StartMicCaptureAsync).</summary>
-    public MicStatus MicStatus
-    {
-        get => _micStatus;
-        private set
-        {
-            if (SetProperty(ref _micStatus, value))
-            {
-                OnPropertyChanged(nameof(MicStatusBrush));
-                OnPropertyChanged(nameof(MicStatusToolTip));
-            }
-        }
-    }
-
-    /// <summary>Status dot: green = connected, yellow = problem with the requested
-    /// connection, red = not connected (no device / not started).</summary>
-    public SolidColorBrush MicStatusBrush => MicStatus switch
-    {
-        MicStatus.Connected => BarOnBrush,
-        MicStatus.Problem => MicProblemBrush,
-        _ => BarOffBrush,
-    };
-
-    public string MicStatusToolTip => MicStatus switch
-    {
-        MicStatus.Connected => "Mic connected — click to change",
-        MicStatus.Problem => "Mic problem — the requested microphone is unavailable (in use or unplugged). Click to change",
-        _ => "No mic connected — click to choose a microphone",
-    };
-
-    // ─── Game audio bar (desktop/game): always visible — a mirror of the mic bar
-    // ─── (meter + mute + volume). Desktop/game audio is automatic (WASAPI loopback). ───
-
-    /// <summary>True while the TRAX background track is playing.</summary>
-    public bool IsMusicPlaying
-    {
-        get => _musicPlaying;
-        private set
-        {
-            if (SetProperty(ref _musicPlaying, value))
-            {
-                OnPropertyChanged(nameof(TraxDotBrush));
-                OnPropertyChanged(nameof(TraxToolTip));
-            }
-        }
-    }
-
-    private string? _traxError;
-
-    /// <summary>Error message from the last TRAX load/playback failure; null = no error.</summary>
-    public string? TraxError
-    {
-        get => _traxError;
-        private set => SetProperty(ref _traxError, value);
-    }
-
-    /// <summary>TRAX status dot: green = playing, gray = idle or no track.</summary>
-    public SolidColorBrush TraxDotBrush => _musicPlayer.IsPlaying
-        ? BarOnBrush
-        : TraxIdleBrush;
-
-    public string TraxToolTip => _musicPlayer.TrackName != null
-        ? $"TRAX: {_musicPlayer.TrackName} — left-click {(IsMusicPlaying ? "pauses" : "plays")}, right-click chooses a track"
-        : "No track — left-click or right-click to choose background music";
-
-    /// <summary>Left-click on TRAX: no track → pick one; otherwise toggle play/pause.</summary>
-    public void TraxLeftClick()
-    {
-        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
-            PickTraxTrack();
-        else if (IsMusicPlaying)
-            PauseTrax();
-        else
-            PlayTrax();
-    }
-
-    /// <summary>Right-click on TRAX: always open the track picker (never the OS viewer).</summary>
-    public void TraxRightClick() => PickTraxTrack();
-
-    private void PickTraxTrack()
-    {
-        var dialog = new OpenFileDialog
-        {
-            Title = "Choose background music",
-            Filter = "Music (*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg)|*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg|All files (*.*)|*.*",
-        };
-        if (dialog.ShowDialog() != true)
-            return;
-
-        _music = new Music { TrackPath = dialog.FileName, IsEnabled = true };
-        LoadTrax(play: true);
-    }
-
-    private void LoadTrax(bool play)
-    {
-        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
-            return;
-
-        try
-        {
-            _musicPlayer.Load(_music.TrackPath);
-            UpdateTraxLocalGain();
-            _music.IsEnabled = true;
-            TraxError = null;
-            if (play)
-                _musicPlayer.Play();
-        }
-        catch (Exception ex)
-        {
-            AppLog.Write($"TRAX: failed to load '{_music.TrackPath}': {ex.Message}");
-            TraxError = $"Failed to load: {Path.GetFileName(_music.TrackPath)} — {ex.Message}";
-        }
-        RefreshTraxUi();
-        ScheduleSave();
-    }
-
-    private void PlayTrax() => _musicPlayer.Play();
-
-    private void PauseTrax() => _musicPlayer.Pause();
-
-    private void OnTraxPlaybackEnded(Exception? ex)
-    {
-        if (ex != null)
-        {
-            AppLog.Write($"TRAX: playback error: {ex.Message}");
-            TraxError = $"Playback error: {ex.Message}";
-        }
-        RefreshTraxUi();
-    }
-
-    private void RefreshTraxUi()
-    {
-        IsMusicPlaying = _musicPlayer.IsPlaying;
-        OnPropertyChanged(nameof(TraxDotBrush));
-        OnPropertyChanged(nameof(TraxToolTip));
-    }
-
-    /// <summary>Mirrors the desktop/game audio bar's volume and mute onto the
-    /// music so the creator hears the controls work in the headphones (the
-    /// track rides the loopback channel, so it must duck the same way locally).
-    /// Called whenever the game volume/mute change and on TRAX load.</summary>
-    private void UpdateTraxLocalGain()
-    {
-        _musicPlayer.LocalGain = GameMuted ? 0f : 1f;
-    }
-
-    private static void PushSystemVolume(double volume)
-    {
-        try
-        {
-            using var enumerator = new MMDeviceEnumerator();
-            using var device = enumerator.GetDefaultAudioEndpoint(DataFlow.Render, Role.Multimedia);
-            device.AudioEndpointVolume.MasterVolumeLevelScalar = (float)volume;
-        }
-        catch { }
-    }
-
-    /// <summary>Live desktop/game input level (0..1), fed by the mixer's loopback
-    /// capture. Read by the game meter, scaled by GameAudioVolume.</summary>
-    public double GameAudioLevel
-    {
-        get => _gameAudioLevel;
-        set
-        {
-            if (SetProperty(ref _gameAudioLevel, Math.Clamp(value, 0, 1)))
-            {
-                OnPropertyChanged(nameof(GameMeterFillWidth));
-                OnPropertyChanged(nameof(GameMeterBrush));
-            }
-        }
-    }
-
-    /// <summary>Displayed game meter level: 0 while muted; the volume position
-    /// while the slider is dragged (or briefly after an unmute flash); otherwise
-    /// the realtime live level scaled by volume.</summary>
-    private double GameMeterLevel => GameMuted ? 0 : _gameVolumeAdjusting || _gameVolumeFlash ? GameAudioVolume : Math.Min(1, AudioLevelMeter.ToDisplay((float)GameAudioLevel));
-
-    public double GameMeterFillWidth => GameMeterLevel * 288;
-
-    public string GameMeterBrush => GameMeterLevel switch
-    {
-        < 0.6 => "#22c55e",
-        < 0.8 => "#eab308",
-        _ => "#ef4444",
-    };
-
-    public void SetGameVolumeAdjusting(bool adjusting)
-    {
-        if (adjusting)
-            CancelGameVolumeFlash();
-        if (SetProperty(ref _gameVolumeAdjusting, adjusting))
-        {
-            OnPropertyChanged(nameof(GameMeterFillWidth));
-            OnPropertyChanged(nameof(GameMeterBrush));
-        }
-    }
-
-    private void BeginGameVolumeFlash()
-    {
-        _gameVolumeFlash = true;
-        OnPropertyChanged(nameof(GameMeterFillWidth));
-        OnPropertyChanged(nameof(GameMeterBrush));
-        _gameVolumeFlashTimer.Stop();
-        _gameVolumeFlashTimer.Start();
-    }
-
-    private void EndGameVolumeFlash()
-    {
-        _gameVolumeFlashTimer.Stop();
-        if (_gameVolumeFlash)
-        {
-            _gameVolumeFlash = false;
-            OnPropertyChanged(nameof(GameMeterFillWidth));
-            OnPropertyChanged(nameof(GameMeterBrush));
-        }
-    }
-
-    private void CancelGameVolumeFlash()
-    {
-        _gameVolumeFlashTimer.Stop();
-        _gameVolumeFlash = false;
-    }
-
-    /// <summary>Game audio gain (0..1, unity default). Running to 0 mutes; the
-    /// prior level is remembered so the speaker button can restore it.</summary>
-    public double GameAudioVolume
-    {
-        get => _gameVolume;
-        set
-        {
-            var clamped = Math.Clamp(value, 0, 1);
-            if (clamped == 0 && !_gameMuted)
-                _gameVolumeBeforeMute ??= _gameVolume;
-            if (SetProperty(ref _gameVolume, clamped))
-            {
-                var muted = clamped == 0;
-                if (_gameMuted != muted)
-                {
-                    _gameMuted = muted;
-                    OnPropertyChanged(nameof(GameMuted));
-                    OnPropertyChanged(nameof(GameMuteText));
-                }
-                if (!muted)
-                    _gameVolumeBeforeMute = null;
-                OnPropertyChanged(nameof(GameMeterFillWidth));
-                OnPropertyChanged(nameof(GameMeterBrush));
-                UpdateTraxLocalGain();
-                PushSystemVolume(clamped);
-            }
-        }
-    }
-
-    /// <summary>Read-only: true whenever the volume is 0 (the slider and the
-    /// speaker can never disagree).</summary>
-    public bool GameMuted => _gameMuted;
-
-    public string GameMuteText => GameMuted ? "Unmute" : "Mute";
-
-    private void ToggleGameMute()
-    {
-        if (GameMuted)
-        {
-            GameAudioVolume = _gameVolumeBeforeMute ?? 1.0;
-            BeginGameVolumeFlash();
-        }
-        else
-        {
-            _gameVolumeBeforeMute = GameAudioVolume;
-            GameAudioVolume = 0;
-        }
-    }
-
     public bool IsOffline => StreamStatus == StreamStatus.Offline;
     public bool IsLive => StreamStatus == StreamStatus.Streaming;
     public bool IsLivePrivate => IsLive && string.Equals(StreamVisibility, "Private", StringComparison.OrdinalIgnoreCase);
@@ -973,57 +483,6 @@ public partial class MainViewModel : ViewModelBase
     private const double MasterFrameWidth = 1920;
     private const double MasterFrameHeight = 1080;
 
-    // Webcam size safeguard: no more than half the frame in any dimension
-    // (960x540 over the 1920x1080 master), and no less than 10% of it
-    // (192x108). Enforced at resize and on layout load. The Chat scene is
-    // exempt from the per-dimension half — its webcam may take half the
-    // screen AREA (~1358x764 @16:9) so the viewer sees the creator better,
-    // matched by canonical name (SceneCatalog.IsChat).
-    public const double WebcamMaxWidth = 960;
-    public const double WebcamMaxHeight = 540;
-    public const double WebcamChatMaxWidth = 1358;
-    public const double WebcamChatMaxHeight = 764;
-    public const double WebcamMinWidth = MasterFrameWidth * 0.1;
-    public const double WebcamMinHeight = MasterFrameHeight * 0.1;
-
-    public static double MaxWebcamWidthFor(string? sceneName)
-        => SceneCatalog.IsChat(sceneName) ? WebcamChatMaxWidth : WebcamMaxWidth;
-
-    public static double MaxWebcamHeightFor(string? sceneName)
-        => SceneCatalog.IsChat(sceneName) ? WebcamChatMaxHeight : WebcamMaxHeight;
-
-    internal static void ClampWebcamToBounds(WebcamSceneConfig config, string? sceneName)
-    {
-        var maxWidth = MaxWebcamWidthFor(sceneName);
-        var maxHeight = MaxWebcamHeightFor(sceneName);
-        var scale = Math.Min(maxWidth / config.Width, maxHeight / config.Height);
-        if (scale < 1)
-        {
-            config.Width = Math.Round(config.Width * scale);
-            config.Height = Math.Round(config.Height * scale);
-            return;
-        }
-
-        var minScale = Math.Max(WebcamMinWidth / config.Width, WebcamMinHeight / config.Height);
-        if (minScale > 1)
-        {
-            config.Width = Math.Round(config.Width * minScale);
-            config.Height = Math.Round(config.Height * minScale);
-        }
-    }
-
-    // One-time heal for layouts saved before the rect dims were persisted (v3→v4):
-    // a Traditional webcam that ended up square (Round resize then reload lost the
-    // pre-Round rect) gets widened to 16:9, keeping the height. Round is skipped —
-    // a square bounding box is correct there — and an explicit pre-Round rect wins.
-    internal static void HealLegacySquareRect(WebcamSceneConfig config)
-    {
-        if (config.ClipShape != ClipShape.Traditional) return;
-        if (config.RectWidth != null || config.RectHeight != null) return;
-        if (Math.Abs(config.Width - config.Height) >= 1) return;
-        config.Width = Math.Round(config.Height * 16.0 / 9.0);
-    }
-
     public QualityOption[] QualityOptions { get; } =
     {
         new("1080p60", 60, 8.0, 1920, 1080),
@@ -1123,16 +582,10 @@ public partial class MainViewModel : ViewModelBase
     // Commands
     public ICommand AddSceneCommand { get; }
     public ICommand AddSourceCommand { get; }
-    public ICommand AddWebcamCommand { get; }
     public ICommand AddImageCommand { get; }
     public ICommand RemoveSourceCommand { get; }
     public ICommand EditElementCommand { get; }
     public ICommand ToggleElementVisibilityCommand { get; }
-    public ICommand ChangeWebcamCommand { get; }
-    public ICommand ShowWebcamCommand { get; }
-    public ICommand ToggleMicMuteCommand { get; }
-    public ICommand ToggleGameMuteCommand { get; }
-    public ICommand OpenMicPickerCommand { get; }
     public ICommand OpenSocialDialogCommand { get; }
     public ICommand StartStreamCommand { get; }
     public ICommand EndStreamCommand { get; }
@@ -1399,54 +852,6 @@ public partial class MainViewModel : ViewModelBase
         AppLog.Write("LoadLayout end");
     }
 
-    // After a layout load / file open: re-point the webcam identity, stop the
-    // previous device if it changed, and acquire the current one once per scene
-    // that uses it (CameraManager refcounts by DeviceId — one camera session).
-    private void ReacquireWebcam()
-    {
-        var previousDevice = _webcam?.DeviceId;
-        _webcam = _layoutStore.Webcam;
-        var newDevice = _webcam?.DeviceId;
-
-        if (!string.IsNullOrWhiteSpace(previousDevice) && previousDevice != newDevice)
-            _ = _cameraManager.ReleaseAllAsync(previousDevice);
-
-        OnPropertyChanged(nameof(CanChangeWebcam));
-        OnPropertyChanged(nameof(CanAddWebcam));
-
-        if (_webcam == null || string.IsNullOrWhiteSpace(newDevice)) return;
-        if (previousDevice != newDevice)
-            foreach (var unused in Scenes.SelectMany(s => s.Elements.OfType<WebcamSceneConfig>()))
-                _ = _cameraManager.AcquireAsync(newDevice);
-
-        // A session already running (same device, or one that produced a first
-        // frame) has its shared bitmap; freshly loaded configs must adopt it here,
-        // because PreviewBitmapChanged never re-fires for an existing bitmap.
-        if (_cameraManager.GetPreviewBitmap(newDevice) is { } running)
-            foreach (var config in Scenes.SelectMany(s => s.Elements.OfType<WebcamSceneConfig>()))
-                config.VideoImageSource = running;
-    }
-
-    // CameraManager creates the shared WriteableBitmap on the UI thread at the
-    // device's frame size; every scene's webcam config picks it up from here. A
-    // bitmap means a real frame arrived — the camera is provably alive.
-    private void OnCameraPreviewBitmapChanged(string deviceId, WriteableBitmap bitmap)
-    {
-        if (_webcam?.DeviceId != deviceId) return;
-        WebcamError = null;
-        foreach (var scene in Scenes)
-            foreach (var config in scene.Elements.OfType<WebcamSceneConfig>())
-                config.VideoImageSource = bitmap;
-    }
-
-    // The camera failed to start or died asynchronously (in use, offline, locked,
-    // no frames within the proof timeout) — surface it instead of a silent box.
-    private void OnCameraFailed(string deviceId, string message)
-    {
-        if (_webcam?.DeviceId != deviceId) return;
-        WebcamError = $"Webcam offline: {message}";
-    }
-
     private void RegisterLoadedWebSources()
     {
         if (_webView2Manager == null) return;
@@ -1616,125 +1021,6 @@ public partial class MainViewModel : ViewModelBase
                 return $"{baseName}{i}";
     }
 
-    // Adds the webcam to the active scene. The creator ALWAYS picks from the
-    // cameras Windows has registered — never silently resurrects the previous
-    // camera (which is what happened after deleting one scene's webcam while
-    // another scene still used it). Picking a different camera than the current
-    // app-wide one swaps it everywhere, so the single-identity model stays honest;
-    // each scene's placement config is independent (webcam.{scene}.config).
-    private async Task AddWebcamToStagedSceneAsync()
-    {
-        var scene = StagedScene;
-        if (scene == null || scene.WebcamConfig != null) return;
-
-        var dialog = new CameraPickerDialog(new CameraPickerViewModel(_cameraEnumerator))
-        {
-            Owner = Application.Current.MainWindow
-        };
-        if (dialog.ShowDialog() != true || dialog.PickedDevice == null) return;
-        var device = dialog.PickedDevice;
-
-        if (_webcam == null)
-        {
-            _webcam = new Webcam { DeviceId = device.Id, Name = device.DisplayName };
-            OnPropertyChanged(nameof(CanChangeWebcam));
-            OnPropertyChanged(nameof(CanAddWebcam));
-        }
-        else if (_webcam.DeviceId != device.Id)
-        {
-            await SwapWebcamIdentityAsync(device);
-        }
-
-        var config = new WebcamSceneConfig
-        {
-            WebcamId = _webcam.Id,
-            Name = _webcam.Name,
-            Width = 480,
-            Height = 270,
-            X = MasterFrameWidth - 480 - 32,
-            Y = MasterFrameHeight - 270 - 32,
-        };
-
-        scene.Elements.Add(config);
-        SelectedElement = config;
-        OnPropertyChanged(nameof(ShowEmptySceneHint));
-        OnPropertyChanged(nameof(ShowSourcesEmptyHint));
-        UpdateActiveBackground();
-
-        // PreviewBitmapChanged fires only on the camera's first frame, so a config
-        // added while the session is already running must pick up the shared bitmap
-        // directly (it's written in place from then on).
-        if (_cameraManager.GetPreviewBitmap(_webcam.DeviceId) is { } running)
-            config.VideoImageSource = running;
-
-        var started = await _cameraManager.AcquireAsync(_webcam.DeviceId);
-        if (!started)
-        {
-            _notifications.Warning("Camera unavailable",
-                WebcamError ?? "Couldn't start that camera. It may be in use by another app, or Windows camera access may be turned off.");
-        }
-    }
-
-    // Swaps the device on the app-wide webcam identity. The old device is stopped
-    // unconditionally; each scene that uses the webcam re-acquires the new one so
-    // the per-config refcount stays honest. Only called when the device differs.
-    private async Task SwapWebcamIdentityAsync(CameraDeviceInfo device)
-    {
-        var oldDevice = _webcam!.DeviceId;
-        _webcam.DeviceId = device.Id;
-        _webcam.Name = device.DisplayName;
-        ScheduleSave();
-
-        if (!string.IsNullOrWhiteSpace(oldDevice) && oldDevice != device.Id)
-            await _cameraManager.ReleaseAllAsync(oldDevice);
-
-        foreach (var unused in Scenes.SelectMany(s => s.Elements.OfType<WebcamSceneConfig>()))
-        {
-            var started = await _cameraManager.AcquireAsync(device.Id);
-            if (!started)
-            {
-                _notifications.Warning("Camera unavailable",
-                    WebcamError ?? "Couldn't start that camera. It may be in use by another app, or Windows camera access may be turned off.");
-                break;
-            }
-        }
-    }
-
-    // "Change Webcam…" from the webcam's context menu: picker, then swap the
-    // app-wide identity if a different device was chosen.
-    private async Task ChangeWebcamAsync()
-    {
-        if (_webcam == null) return;
-
-        var dialog = new CameraPickerDialog(new CameraPickerViewModel(_cameraEnumerator))
-        {
-            Owner = Application.Current.MainWindow
-        };
-        if (dialog.ShowDialog() != true || dialog.PickedDevice == null) return;
-        if (dialog.PickedDevice.Id == _webcam.DeviceId) return;
-
-        await SwapWebcamIdentityAsync(dialog.PickedDevice);
-    }
-
-    // "Show Webcam" from a right-click on the empty preview. Unhides this scene's
-    // existing (hidden) config — the config row survives Hide in this scene — or
-    // adds the webcam here for the first time (which opens the camera picker).
-    private void ShowWebcamInStagedScene()
-    {
-        var scene = StagedScene;
-        if (scene == null) return;
-
-        var config = scene.WebcamConfig;
-        if (config != null)
-        {
-            config.IsVisible = true;
-            SelectedElement = config;
-            return;
-        }
-
-        _ = AddWebcamToStagedSceneAsync();
-    }
-
     private void AddImage()
     {
         var scene = StagedScene;
@@ -2339,68 +1625,6 @@ public partial class MainViewModel : ViewModelBase
             : Environment.GetFolderPath(Environment.SpecialFolder.MyVideos);
     }
 
-    private void OnMicLevelChanged(float level)
-    {
-        // NAudio raises on its capture thread; marshal to the UI thread so the
-        // meter binding updates safely.
-        var dispatcher = System.Windows.Application.Current?.Dispatcher;
-        if (dispatcher != null && !dispatcher.CheckAccess())
-            dispatcher.BeginInvoke(() => AudioLevel = level);
-        else
-            AudioLevel = level;
-    }
-
-    private void OnLoopbackLevelChanged(float level)
-    {
-        var dispatcher = System.Windows.Application.Current?.Dispatcher;
-        if (dispatcher != null && !dispatcher.CheckAccess())
-            dispatcher.BeginInvoke(() => GameAudioLevel = level);
-        else
-            GameAudioLevel = level;
-    }
-
-    private void OnMicConnected()
-    {
-        var dispatcher = System.Windows.Application.Current?.Dispatcher;
-        if (dispatcher != null && !dispatcher.CheckAccess())
-            dispatcher.BeginInvoke(() => MicStatus = MicStatus.Connected);
-        else
-            MicStatus = MicStatus.Connected;
-    }
-
-    private void OnMicFailed(Exception ex)
-    {
-        // The mixer logs the failure detail; here we only flip the dot to yellow.
-        var dispatcher = System.Windows.Application.Current?.Dispatcher;
-        if (dispatcher != null && !dispatcher.CheckAccess())
-            dispatcher.BeginInvoke(() => MicStatus = MicStatus.Problem);
-        else
-            MicStatus = MicStatus.Problem;
-    }
-
-    /// <summary>Starts capture once at startup: with no mic device present the
-    /// dot stays red and capture never starts; otherwise the mixer starts and
-    /// raises MicConnected (green) or MicFailed (yellow).</summary>
-    private async Task StartMicCaptureAsync()
-    {
-        try
-        {
-            var mics = await _microphoneEnumerator.GetMicrophonesAsync();
-            if (mics.Count == 0)
-            {
-                MicStatus = MicStatus.NotConnected;
-                AppLog.Write("Mic: no capture devices found — mic capture not started");
-                _notifications.Warning("No microphone found",
-                    "Mic capture wasn't started — plug one in and pick it from the mixer.");
-                return;
-            }
-            _audioMixer.Start();
-        }
-        catch (Exception ex)
-        {
-            AppLog.Write($"Mic: device check failed: {ex.Message}");
-        }
-    }
 
     // Scene-element → latest frame, for the live compositor. The map mirrors the
     // preview: webcam by DeviceId, live captures (the background) by CaptureKey,

ViewModels/index.md

@@ -50,14 +50,38 @@ Progress (Commit N/12 · tag):
   `ChangeCaptureCommand`/`RefreshCaptureCommand`/`SetBackgroundDisplayCommand`/
   `ToggleShowDesktopCommand`/`BrowseBackgroundCommand`). `ShowPreviewPlaceholder`
   stays in core.
+- **Commit 5/12 · `refactor-commit-5`: Webcam landed** → `MainViewModel.Webcam.cs`
+  (webcam identity `_webcam`/`ReacquireWebcam`/`SwapWebcamIdentityAsync`, per-scene
+  configs `AddWebcamToStagedSceneAsync`/`ShowWebcamInStagedScene`, capture lifetime
+  `OnCameraPreviewBitmapChanged`/`OnCameraFailed`, gating `CanAddWebcam`/
+  `CanChangeWebcam`/`CanShowWebcamInStagedScene`/`IsWebcamSelected`/`WebcamError`,
+  size safeguard `WebcamMax*`/`ClampWebcamToBounds`/`HealLegacySquareRect`,
+  `AddWebcamCommand`/`ChangeWebcamCommand`/`ShowWebcamCommand`).
+- **Commit 6/12 · `refactor-commit-6`: Audio landed** → `MainViewModel.Audio.cs`
+  (mic bar `AudioLevel`/`MeterFillWidth`/`MeterBrush`/`MicVolume`/`MicMuted`/
+  `MicMuteText`/`MicSourceName`/`ToggleMicMute`/`PickMicrophone`, volume flash
+  `SetVolumeAdjusting`/`BeginVolumeFlash`/`EndVolumeFlash`/`CancelVolumeFlash`,
+  mic status dot `MicStatus`/`MicStatusBrush`/`MicStatusToolTip`/`MicProblemBrush`,
+  game bar `GameAudioLevel`/`GameMeterLevel`/`GameMeterFillWidth`/`GameMeterBrush`/
+  `SetGameVolumeAdjusting`/`GameAudioVolume`/`GameMuted`/`GameMuteText`/
+  `ToggleGameMute`, `PushSystemVolume`, mixer handlers `OnMicLevelChanged`/
+  `OnLoopbackLevelChanged`/`OnMicConnected`/`OnMicFailed`, `StartMicCaptureAsync`,
+  audio fields + `ToggleMicMuteCommand`/`ToggleGameMuteCommand`/`OpenMicPickerCommand`).
+  TRAX stays in core (next commit).
+- **Commit 7/12 · `refactor-commit-7`: Trax landed** → `MainViewModel.Trax.cs`
+  (`_musicPlayer`/`_music`/`_musicPlaying` + `TraxIdleBrush`, `IsMusicPlaying`/
+  `TraxError`/`TraxDotBrush`/`TraxToolTip`, `TraxLeftClick`/`TraxRightClick`/
+  `PickTraxTrack`/`LoadTrax`/`PlayTrax`/`PauseTrax`/`OnTraxPlaybackEnded`/
+  `RefreshTraxUi`/`UpdateTraxLocalGain`). Core keeps the ctor hookup
+  (`_musicPlayer.PlaybackEnded += ...`), the `LoadLayout`/`Shutdown`/
+  `SaveLayoutNow` call sites, and the Scenes partial's hotkey dispatch into `TraxLeftClick`.
 
 - Core file keeps: fields, ctor, `Shutdown`/`SaveLayoutNow`/`ScheduleSave`/`LoadLayout`,
   `SetPanel`/`ShowOverlay`/`ShowLicenses`, `CreateBrush`, `OpenUrl`/`ComposeEmail`,
   `SubmitBug`/`SubmitFeature`, window-geometry pass-through.
 - Partials: `Account` ✔ (Commit 1), `License` ✔ (Commit 2), `Scenes` ✔ (Commit 3), `Background` ✔ (Commit 4),
-  `Webcam` (webcam identity + per-scene configs + captures),
+  `Webcam` ✔ (Commit 5), `Audio` ✔ (Commit 6), `Trax` ✔ (Commit 7),
-  `Audio` (mic + game bars + TRAX), `Trax` (music player), `Socials` (social bar + dialog),
+  `Socials` (social bar + dialog), `Streaming` (go-live/record + health + quality tiers + media source pipeline),
-  `Streaming` (go-live/record + health + quality tiers + media source pipeline),
   `Chat` (YouTube chat + mock preview + chatbox render), `Overlays` (settings/bug/feature/about
   panels + license entry).