Mic audio UX: realtime read-only meter + mic picker

- Meter is a READ-ONLY realtime level display: fill = Math.Min(1, AudioLevel * MicVolume) (AudioLevel = live input from the future mixer, 0 with no input; MicVolume is gain on ambient noise). While the slider is dragged the bar previews the slider position (PreviewMouseLeftButtonDown/Up + LostMouseCapture -> SetVolumeAdjusting); on release it returns to the live level (bounces to 0 with no input). Clicking the meter does nothing.
- MicVolume drives MicMuted (read-only, muted <=> volume 0): sliding to 0 flips the speaker to the red slashed mute icon, sliding up from 0 clears it; speaker button runs volume to 0 or restores the prior level (_volumeBeforeMute, default 0.8) and flashes the meter to the restored position for ~300ms (BeginVolumeFlash/EndVolumeFlash DispatcherTimer, cancelled if the slider is grabbed).
- MIC label opens MicPickerDialog (WinRT audio-capture device enumeration, mirrors camera picker, no new packages); the chosen voice source name shows left-justified INSIDE the meter bar (fill at 75% opacity so text + ruler markings show through).
- New files: Services/IMicrophoneEnumerator, MicrophoneDeviceInfo, WinRtMicrophoneEnumerator; ViewModels/MicPickerViewModel; MicPickerDialog.
- Docs updated (ai.md, TASKS.md, Services/index.md, ViewModels/index.md); build 0 warnings, 65 tests passing

ViewModels/MainViewModel.cs

@@ -22,6 +22,7 @@ public class MainViewModel : ViewModelBase
     private readonly YouTubeStreamService _youtubeStream;
     private readonly YouTubeChatService _youtubeChat;
     private readonly DispatcherTimer _liveTimer;
+    private readonly DispatcherTimer _volumeFlashTimer;
 
     private Scene? _activeScene;
     private SceneElement? _selectedElement;
@@ -30,8 +31,12 @@ public class MainViewModel : ViewModelBase
     private string _accountAvatarUrl = string.Empty;
     private string _accountDisplayName = string.Empty;
     private double _audioLevel;
-    private double _micVolume = 1.0;
+    private bool _volumeAdjusting;
+    private bool _volumeFlash;
+    private double _micVolume = 0.8;
     private bool _micMuted;
+    private double? _volumeBeforeMute;
+    private string? _micSourceName;
     private StreamStatus _streamStatus = StreamStatus.Offline;
     private StreamHealth _currentHealth = new();
     private string _streamTitle = string.Empty;
@@ -70,6 +75,8 @@ public class MainViewModel : ViewModelBase
     private readonly CameraManager _cameraManager;
     private Webcam? _webcam;
 
+    private readonly IMicrophoneEnumerator _microphoneEnumerator;
+
     // Screen backdrop: a permanent live capture (desktop/game) that every scene
     // shows at the bottom layer. One shared capture session per key — the
     // ScreenCaptureManager refcounts by key, mirroring CameraManager.
@@ -209,8 +216,8 @@ public class MainViewModel : ViewModelBase
     // ─── Audio (KISS: desktop/game audio is automatic — zero UI. The creator's
     // ─── only audio control is the mic: meter + volume + mute.) ───
 
-    /// <summary>Current level 0..1 — fed by the audio mixer once capture lands.
-    /// Drives the sound meter's fill width + zone color.</summary>
+    /// <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;
@@ -224,33 +231,127 @@ public class MainViewModel : ViewModelBase
         }
     }
 
-    public double MeterFillWidth => AudioLevel * 360;
+    /// <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, AudioLevel * MicVolume);
 
-    public string MeterBrush => AudioLevel switch
+    public double MeterFillWidth => MeterLevel * 288;
+
+    public string MeterBrush => MeterLevel switch
     {
         < 0.6 => "#22c55e",
         < 0.8 => "#eab308",
         _ => "#ef4444",
     };
 
-    public double MicVolume
+    /// <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)
     {
-        get => _micVolume;
-        set => SetProperty(ref _micVolume, Math.Clamp(value, 0, 1));
-    }
-
-    public bool MicMuted
-    {
-        get => _micMuted;
-        set
+        if (adjusting)
+            CancelVolumeFlash();
+        if (SetProperty(ref _volumeAdjusting, adjusting))
         {
-            if (SetProperty(ref _micMuted, value))
-                OnPropertyChanged(nameof(MicMuteText));
+            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 under the meter on line 2.</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;
+    }
+
     public bool IsOffline => StreamStatus == StreamStatus.Offline;
     public bool IsLive => StreamStatus == StreamStatus.Streaming;
     public bool LiveIndicatorVisible => IsLive;
@@ -598,6 +699,7 @@ public class MainViewModel : ViewModelBase
     public ICommand RefreshCaptureCommand { get; }
     public ICommand SetBackdropDisplayCommand { get; }
     public ICommand ToggleMicMuteCommand { get; }
+    public ICommand OpenMicPickerCommand { get; }
     public ICommand StartStreamCommand { get; }
     public ICommand EndStreamCommand { get; }
     public ICommand OpenSettingsCommand { get; }
@@ -629,6 +731,9 @@ public class MainViewModel : ViewModelBase
         _liveTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
         _liveTimer.Tick += OnLiveTimerTick;
 
+        _volumeFlashTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(300) };
+        _volumeFlashTimer.Tick += (_, _) => EndVolumeFlash();
+
         _saveDebounce = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(1500) };
         _saveDebounce.Tick += (_, _) => SaveLayoutNow();
 
@@ -652,7 +757,8 @@ public class MainViewModel : ViewModelBase
         ChangeCaptureCommand = new RelayCommand(_ => _ = ChangeBackdropCaptureAsync());
         RefreshCaptureCommand = new RelayCommand(_ => RefreshBackdropAutoCapture());
         SetBackdropDisplayCommand = new RelayCommand(display => SetBackdropCapture(display as DisplayInfo));
-        ToggleMicMuteCommand = new RelayCommand(_ => MicMuted = !MicMuted);
+        ToggleMicMuteCommand = new RelayCommand(_ => ToggleMicMute());
+        OpenMicPickerCommand = new RelayCommand(_ => PickMicrophone());
         OpenSettingsCommand = new RelayCommand(_ => ShowOverlay(nameof(IsSettingsOpen), "App Settings"));
         OpenBugCommand = new RelayCommand(_ => ShowOverlay(nameof(IsBugOpen), "Report Bug"));
         OpenFeatureCommand = new RelayCommand(_ => ShowOverlay(nameof(IsFeatureOpen), "Feature Request"));
@@ -677,6 +783,8 @@ public class MainViewModel : ViewModelBase
             System.Windows.Application.Current?.Dispatcher);
         _cameraManager.PreviewBitmapChanged += OnCameraPreviewBitmapChanged;
 
+        _microphoneEnumerator = new WinRtMicrophoneEnumerator();
+
         _fullScreenDetector = new Win32FullScreenDetector();
         foreach (var display in _fullScreenDetector.GetDisplays())
             Displays.Add(display);

ViewModels/MicPickerViewModel.cs

@@ -0,0 +1,86 @@
+using System.Collections.ObjectModel;
+using System.Windows.Input;
+using ytLive.Helpers;
+using ytLive.Services;
+
+namespace ytLive.ViewModels;
+
+public class MicPickerCandidate
+{
+    public MicrophoneDeviceInfo Device { get; }
+    public string Name => Device.DisplayName;
+
+    public MicPickerCandidate(MicrophoneDeviceInfo device)
+    {
+        Device = device;
+    }
+}
+
+public class MicPickerViewModel : ViewModelBase
+{
+    private readonly IMicrophoneEnumerator _enumerator;
+    private MicPickerCandidate? _selectedMic;
+    private bool _isLoading = true;
+
+    public ObservableCollection<MicPickerCandidate> Microphones { get; } = new();
+
+    public bool IsLoading
+    {
+        get => _isLoading;
+        private set => SetProperty(ref _isLoading, value);
+    }
+
+    public bool HasMicrophones => !IsLoading && Microphones.Count > 0;
+    public bool NoMicrophones => !IsLoading && Microphones.Count == 0;
+
+    public MicPickerCandidate? SelectedMic
+    {
+        get => _selectedMic;
+        set
+        {
+            if (SetProperty(ref _selectedMic, value))
+                CommandManager.InvalidateRequerySuggested();
+        }
+    }
+
+    public ICommand UseSelectedCommand { get; }
+    public ICommand CancelCommand { get; }
+
+    public event Action<MicrophoneDeviceInfo>? UseRequested;
+    public event Action? CancelRequested;
+
+    public MicPickerViewModel(IMicrophoneEnumerator enumerator)
+    {
+        _enumerator = enumerator;
+        UseSelectedCommand = new RelayCommand(
+            _ => { if (SelectedMic != null) UseRequested?.Invoke(SelectedMic.Device); },
+            _ => SelectedMic != null);
+        CancelCommand = new RelayCommand(_ => CancelRequested?.Invoke());
+        _ = LoadAsync();
+    }
+
+    private async Task LoadAsync()
+    {
+        IsLoading = true;
+        try
+        {
+            var devices = await _enumerator.GetMicrophonesAsync();
+            Microphones.Clear();
+            foreach (var device in devices)
+                Microphones.Add(new MicPickerCandidate(device));
+            if (Microphones.Count > 0)
+                SelectedMic = Microphones[0];
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"MicPickerViewModel: enumerating microphones failed: {ex.Message}");
+        }
+        finally
+        {
+            IsLoading = false;
+            OnPropertyChanged(nameof(HasMicrophones));
+            OnPropertyChanged(nameof(NoMicrophones));
+            CommandManager.InvalidateRequerySuggested();
+        }
+    }
+}

ViewModels/index.md

@@ -4,10 +4,11 @@ MVVM layer. See [`schema.md`](../schema.md) for the memory-map conventions.
 
 | File | Purpose |
 |------|---------|
-| `MainViewModel.cs` | The app brain: scenes/elements collections + commands, stream state (`IsLive`/`IsOffline`/`IsConnected`), chat feed, overlays, layout save/open, **resolution dropdown** (`QualityOptions`, `SelectedQuality`, `ResolutionHelp`, `ApplyStreamQuality`) that computes the output rect over the 1920×1080 master (`OutputRectX/Y/W/H`, `DimRects`, `IsOutputCropped`, `ResolutionBadgeText`). Auth: loads the saved DPAPI session at startup (`LoadSavedSessionAsync`), `SignInAsync` feeds the GoLive dialog; **End Livestream signs out** (`StopStream` clears session + token — crash-safe). **Connected account:** top-bar avatar/name (`AccountAvatarUrl`/`AccountDisplayName` via `SyncConnectedAccount`, cleared on End). **Audio (KISS — the mic is the creator's only audio control; capture pipeline still pending):** `AudioLevel` (0..1) drives the bottom-bar sound meter (`MeterFillWidth`/`MeterBrush`, green→yellow→red with zone markers at 60%/80%), `MicVolume` slider + `MicMuteText`/`ToggleMicMuteCommand`; desktop/game audio is automatic (WASAPI loopback at unity, zero UI). **Webcam:** owns `CameraManager` (MediaCapture), `AddWebcamToActiveSceneAsync` (picker → default 480×270 bottom-right placement → acquire; the Windows camera picker ALWAYS opens so the creator chooses — never silently reuses the previous camera; picking a different camera swaps the app-wide identity via `SwapWebcamIdentityAsync`, same path as `ChangeWebcamAsync`; propagates the running shared bitmap via `CameraManager.GetPreviewBitmap` first, so a webcam added mid-session never renders a transparent container; greys out when the active scene already has a config via `CanAddWebcamToActiveScene`), `ChangeWebcamAsync` (device swap — `ReleaseAllAsync` old + re-acquire), `ShowWebcamInActiveScene` (reveal hidden config / empty-canvas right-click), `ReacquireWebcam` after layout load (re-propagates the shared bitmap to every config), `OnCameraPreviewBitmapChanged` forwards the shared bitmap into every `WebcamSceneConfig.VideoImageSource`; `SelectedElement` drives the preview overlay + `internal ClampWebcamToBounds(config, sceneName)` (per-scene size cap seam: 50%-per-dimension everywhere, half-screen-AREA in Chat via `MaxWebcamWidthFor`/`MaxWebcamHeightFor`). **Scenes (five-scene catalog):** empty DB seeds Starting/Live/BRB/Chat/Ending (`SceneCatalog.All`); `AddScene(name)` accepts only canonical, missing names; `MissingScenes`/`ShowAddScene` drive the "+" button (hidden once all five exist; its menu lists only the missing scenes via `AddSceneCommand`). **Screen backdrop (Live-only by policy):** owns `ScreenCaptureManager` + `ScreenCaptureSourceFactory` (WinRT GraphicsCapture), `internal static EnsureBackdrop` heals one per backdrop-enabled scene (gated on `Scene.HasBackdrop`), `ReacquireScreenCaptures`/`RefreshBackdropAutoCapture`/`NoteBackgroundWindow` key by full-screen game monitor or the **primary display** via `Win32FullScreenDetector` (`GetDisplays()`/`PrimaryMonitorIndex()`), `ChangeBackdropCaptureAsync` (OS picker) + `SetBackdropCapture(DisplayInfo)` (in-app "Capture Display"), `RedesignateBackdropAsync` re-targets all backdrops and releases orphaned sessions, `internal static EnforceBackdropPolicy` normalizes `Scene.HasBackdrop` by name on every load + strips lingering non-Live backdrops, `CanChangeBackdrop` gates the capture menu to Live (the only scene with a backdrop), `BackdropImage` hides the preview watermark (`ShowPreviewPlaceholder`) |
+| `MainViewModel.cs` | The app brain: scenes/elements collections + commands, stream state (`IsLive`/`IsOffline`/`IsConnected`), chat feed, overlays, layout save/open, **resolution dropdown** (`QualityOptions`, `SelectedQuality`, `ResolutionHelp`, `ApplyStreamQuality`) that computes the output rect over the 1920×1080 master (`OutputRectX/Y/W/H`, `DimRects`, `IsOutputCropped`, `ResolutionBadgeText`). Auth: loads the saved DPAPI session at startup (`LoadSavedSessionAsync`), `SignInAsync` feeds the GoLive dialog; **End Livestream signs out** (`StopStream` clears session + token — crash-safe). **Connected account:** top-bar avatar/name (`AccountAvatarUrl`/`AccountDisplayName` via `SyncConnectedAccount`, cleared on End). **Audio (KISS — the mic is the creator's only audio control; capture pipeline still pending):** the sound meter is a **READ-ONLY realtime level display**: fill = `Math.Min(1, AudioLevel * MicVolume)` (`MeterFillWidth`/`MeterBrush`, green→yellow→red, zone markers at 60%/80%), where `AudioLevel` (live input, 0 with no input) is fed by the audio mixer once capture lands and `MicVolume` acts as a gain on ambient noise; while the slider is dragged the bar previews the slider position (`SetVolumeAdjusting`), returning to the live level on release (0 with no input — clicking the meter does nothing); `MicVolume` (default 0.8) + read-only `MicMuted`/`MicMuteText`/`ToggleMicMuteCommand` — **MicVolume drives MicMuted** (muted ⇔ volume 0): sliding to 0 flips the speaker to muted, sliding up from 0 clears it; muting stores the prior volume, unmuting restores it (default 0.8 if unknown) and flashes the meter to the restored position ~300ms (`BeginVolumeFlash`/`EndVolumeFlash`); `MicSourceName` = picked voice source, shown left-justified inside the meter bar (the fill runs at 75% opacity so the text + ruler markings show through); `OpenMicPickerCommand`/`PickMicrophone()` open the `MicPickerDialog`; desktop/game audio is automatic (WASAPI loopback at unity, zero UI). **Webcam:** owns `CameraManager` (MediaCapture), `AddWebcamToActiveSceneAsync` (picker → default 480×270 bottom-right placement → acquire; the Windows camera picker ALWAYS opens so the creator chooses — never silently reuses the previous camera; picking a different camera swaps the app-wide identity via `SwapWebcamIdentityAsync`, same path as `ChangeWebcamAsync`; propagates the running shared bitmap via `CameraManager.GetPreviewBitmap` first, so a webcam added mid-session never renders a transparent container; greys out when the active scene already has a config via `CanAddWebcamToActiveScene`), `ChangeWebcamAsync` (device swap — `ReleaseAllAsync` old + re-acquire), `ShowWebcamInActiveScene` (reveal hidden config / empty-canvas right-click), `ReacquireWebcam` after layout load (re-propagates the shared bitmap to every config), `OnCameraPreviewBitmapChanged` forwards the shared bitmap into every `WebcamSceneConfig.VideoImageSource`; `SelectedElement` drives the preview overlay + `internal ClampWebcamToBounds(config, sceneName)` (per-scene size cap seam: 50%-per-dimension everywhere, half-screen-AREA in Chat via `MaxWebcamWidthFor`/`MaxWebcamHeightFor`). **Scenes (five-scene catalog):** empty DB seeds Starting/Live/BRB/Chat/Ending (`SceneCatalog.All`); `AddScene(name)` accepts only canonical, missing names; `MissingScenes`/`ShowAddScene` drive the "+" button (hidden once all five exist; its menu lists only the missing scenes via `AddSceneCommand`). **Screen backdrop (Live-only by policy):** owns `ScreenCaptureManager` + `ScreenCaptureSourceFactory` (WinRT GraphicsCapture), `internal static EnsureBackdrop` heals one per backdrop-enabled scene (gated on `Scene.HasBackdrop`), `ReacquireScreenCaptures`/`RefreshBackdropAutoCapture`/`NoteBackgroundWindow` key by full-screen game monitor or the **primary display** via `Win32FullScreenDetector` (`GetDisplays()`/`PrimaryMonitorIndex()`), `ChangeBackdropCaptureAsync` (OS picker) + `SetBackdropCapture(DisplayInfo)` (in-app "Capture Display"), `RedesignateBackdropAsync` re-targets all backdrops and releases orphaned sessions, `internal static EnforceBackdropPolicy` normalizes `Scene.HasBackdrop` by name on every load + strips lingering non-Live backdrops, `CanChangeBackdrop` gates the capture menu to Live (the only scene with a backdrop), `BackdropImage` hides the preview watermark (`ShowPreviewPlaceholder`) |
 | `GoLiveViewModel.cs` | Start Stream dialog: **account row** (saved channel shown with Change Account, or Sign in to YouTube; Start gated on `IsSignedIn`/`IsBusy`) + title/description/visibility, start/cancel requests |
 | `ReuseImageViewModel.cs` | Add Image dialog: candidate list (`ReuseImageCandidate`), reuse/new/cancel |
 | `CameraPickerViewModel.cs` | Add Webcam dialog: async camera list (loading / has / none states), `UseRequested(CameraDeviceInfo)`/`CancelRequested` |
+| `MicPickerViewModel.cs` | Select Microphone dialog (voice source): async mic list (loading / has / none states), `UseRequested(MicrophoneDeviceInfo)`/`CancelRequested` |
 
 Related: [`Models/index.md`](../Models/index.md) for the data; [`Services/index.md`](../Services/index.md)
 for what the ViewModels drive; base class in [`Helpers/ViewModelBase.cs`](../Helpers/ViewModelBase.cs).