Snapshot all enabled participants in one click

Header button 'Snapshot all' fires SnapshotAllCommand which iterates every enabled participant, grabs the latest ProcessedFrame, encodes as PNG into a fresh timestamped subfolder under %USERPROFILE%\\Pictures\\TeamsISO\\snapshots-yyyyMMdd_HHmmss\\. One folder per click so back-to-back snapshot sessions don't comingle.

Reuses the per-participant snapshot path established earlier — same WriteableBitmap(Bgra32) → PngBitmapEncoder pipeline. Reports saved + failed counts in the toast so the operator knows if anything was missed (typical failure: pipeline still warming up, no frame yet).

src/TeamsISO.App/MainWindow.xaml

@@ -776,6 +776,26 @@
                                            VerticalAlignment="Center"/>
                             </StackPanel>
                         </Button>
+                        <Button Style="{StaticResource Wd.Button.Ghost}"
+                                Command="{Binding SnapshotAllCommand}"
+                                VerticalAlignment="Center"
+                                Margin="0,0,8,0"
+                                ToolTip="Save a PNG of every enabled participant's current frame. One folder per click under %USERPROFILE%\Pictures\TeamsISO\snapshots-&lt;timestamp&gt;.">
+                            <StackPanel Orientation="Horizontal">
+                                <Path Data="M 1,3 L 4,3 L 5,1 L 11,1 L 12,3 L 15,3 L 15,13 L 1,13 Z M 8,5 A 3,3 0 1 1 8,11 A 3,3 0 1 1 8,5"
+                                      Stroke="{DynamicResource Wd.Text.Primary}"
+                                      StrokeThickness="1.2"
+                                      Fill="Transparent"
+                                      Width="16" Height="14"
+                                      Stretch="None"
+                                      VerticalAlignment="Center"
+                                      Margin="0,0,8,0"/>
+                                <TextBlock Text="Snapshot all"
+                                           Style="{StaticResource Wd.Text.Body}"
+                                           FontSize="12"
+                                           VerticalAlignment="Center"/>
+                            </StackPanel>
+                        </Button>
                         <Button Style="{StaticResource Wd.Button.Ghost}"
                                 Click="OnPresetsClick"
                                 VerticalAlignment="Center"

src/TeamsISO.App/ViewModels/MainViewModel.cs

@@ -178,6 +178,9 @@ public sealed class MainViewModel : ObservableObject, IDisposable
     /// <summary>Join a Teams meeting from a pasted URL — see <see cref="JoinMeetingUrl"/>.</summary>
     public RelayCommand JoinMeetingCommand { get; }
 
+    /// <summary>Save a PNG snapshot of every enabled participant's current frame.</summary>
+    public RelayCommand SnapshotAllCommand { get; }
+
     /// <summary>
     /// Two-way bound to the quick-join input. Whatever the operator pastes
     /// gets handed to <see cref="TeamsLauncher.TryJoinMeeting"/> when the
@@ -407,6 +410,8 @@ public sealed class MainViewModel : ObservableObject, IDisposable
             notes.Show(); // non-modal so operators can stamp + read alongside the show
         });
 
+        SnapshotAllCommand = new RelayCommand(SnapshotAll, () => Participants.Any(p => p.IsEnabled));
+
         JoinMeetingCommand = new RelayCommand(() =>
         {
             // Trim + handle the operator pasting whitespace around the URL.
@@ -587,6 +592,72 @@ public sealed class MainViewModel : ObservableObject, IDisposable
         Toast.Show($"Stopped {enabled.Length} ISO(s)");
     }
 
+    /// <summary>
+    /// Save a PNG of every currently-enabled participant's latest processed
+    /// frame to a timestamped subdirectory under
+    /// %USERPROFILE%\Pictures\TeamsISO\. One folder per Snapshot All click
+    /// so back-to-back clicks don't comingle. Useful for end-of-meeting
+    /// archives, recapping who showed up, etc.
+    /// </summary>
+    private void SnapshotAll()
+    {
+        var enabled = Participants.Where(p => p.IsEnabled).ToArray();
+        if (enabled.Length == 0)
+        {
+            Toast.Warn("No enabled participants to snapshot");
+            return;
+        }
+
+        var rootDir = System.IO.Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.MyPictures),
+            "TeamsISO",
+            $"snapshots-{DateTimeOffset.Now:yyyyMMdd_HHmmss}");
+
+        try
+        {
+            System.IO.Directory.CreateDirectory(rootDir);
+        }
+        catch (Exception ex)
+        {
+            Toast.Warn($"Couldn't create snapshot dir: {ex.Message}");
+            return;
+        }
+
+        var saved = 0;
+        var failed = 0;
+        foreach (var p in enabled)
+        {
+            try
+            {
+                var frame = _controller.GetLatestProcessedFrame(p.Id);
+                if (frame is null || frame.Pixels.IsEmpty) { failed++; continue; }
+
+                var safeName = string.Join("_", p.DisplayName.Split(System.IO.Path.GetInvalidFileNameChars()));
+                if (string.IsNullOrWhiteSpace(safeName)) safeName = "participant";
+                var path = System.IO.Path.Combine(rootDir, $"{safeName}.png");
+
+                var stride = frame.Width * 4;
+                var bmp = new System.Windows.Media.Imaging.WriteableBitmap(
+                    frame.Width, frame.Height, 96, 96,
+                    System.Windows.Media.PixelFormats.Bgra32, null);
+                bmp.WritePixels(
+                    new System.Windows.Int32Rect(0, 0, frame.Width, frame.Height),
+                    frame.Pixels.ToArray(), stride, 0);
+
+                using var fs = new System.IO.FileStream(path, System.IO.FileMode.Create);
+                var encoder = new System.Windows.Media.Imaging.PngBitmapEncoder();
+                encoder.Frames.Add(System.Windows.Media.Imaging.BitmapFrame.Create(bmp));
+                encoder.Save(fs);
+                saved++;
+            }
+            catch { failed++; }
+        }
+
+        Toast.Show(failed > 0
+            ? $"Saved {saved} snapshot(s) ({failed} failed) to Pictures\\TeamsISO\\{System.IO.Path.GetFileName(rootDir)}"
+            : $"Saved {saved} snapshot(s) to Pictures\\TeamsISO\\{System.IO.Path.GetFileName(rootDir)}");
+    }
+
     /// <summary>
     /// Format a byte count as a human-readable string with 0-1 decimal
     /// places — e.g. "8.4 GB", "245 GB", "1.2 TB". Optimized for footer