TASK 4 ship step 5.5: social bar bug fixes + bar on the live output — direction-snap drag (SocialBarSnap.Decide + ClearValue, local Canvas.Top was overriding the binding), fediverse nodeinfo subdomain probing + load-time heal (settable FediverseSoftware), SocialBarRenderer strip blitted above the flash via a re-read FramePump socialBar seam — 155 tests passing, 0 warnings

Services/Compositor/SceneCompositor.cs

@@ -18,13 +18,16 @@ public sealed class SceneCompositor
     /// Composite <paramref name="scene"/> into the tier's output frame. Layer order (back →
     /// front): live backdrop (the scene's <c>IsBackdrop</c> source) → background image →
     /// visible elements (z-order = <c>Elements</c> order, mirroring the XAML DataTemplate) →
-    /// branding flash. Transparent regions read opaque black.
+    /// branding flash → social bar (a global overlay; spans the master width at
+    /// <paramref name="socialBarTop"/>). Transparent regions read opaque black.
     /// </summary>
     public VideoFrame Render(
         Scene scene,
         Func<SceneElement, VideoFrame?> frameFor,
         VideoFrame? flashFrame,
-        CompositorOptions options)
+        CompositorOptions options,
+        VideoFrame? socialBarFrame = null,
+        int socialBarTop = 0)
     {
         if (scene == null) throw new ArgumentNullException(nameof(scene));
         if (frameFor == null) throw new ArgumentNullException(nameof(frameFor));
@@ -79,7 +82,10 @@ public sealed class SceneCompositor
         }
 
         if (flashFrame != null)
-            BlitFlash(buffer, cropW, cropH, options, flashFrame);
+            BlitOverlay(buffer, cropW, cropH, options, flashFrame, 0, 0);
+
+        if (socialBarFrame != null && socialBarFrame.Width > 0 && socialBarFrame.Height > 0)
+            BlitOverlay(buffer, cropW, cropH, options, socialBarFrame, 0, socialBarTop);
 
         return StretchMath.BilinearScale(
             new VideoFrame(cropW, cropH, buffer), options.OutputWidth, options.OutputHeight);
@@ -166,17 +172,20 @@ public sealed class SceneCompositor
         }
     }
 
-    /// <summary>1:1 copy of the master-sized branding flash, cropped to the active source rect.</summary>
-    private static void BlitFlash(byte[] dst, int dstW, int dstH, CompositorOptions options, VideoFrame flash)
+    /// <summary>1:1 copy of a master-sized overlay (flash, social bar) cropped to the
+    /// active source rect. The overlay is positioned in master space by (sx0, sy0).</summary>
+    private static void BlitOverlay(
+        byte[] dst, int dstW, int dstH, CompositorOptions options,
+        VideoFrame overlay, int sx0, int sy0)
     {
         for (var y = 0; y < dstH; y++)
         {
             for (var x = 0; x < dstW; x++)
             {
-                var sx = x + options.SourceRectX;
-                var sy = y + options.SourceRectY;
-                if (sx >= flash.Width || sy >= flash.Height) continue;
-                var sample = StretchMath.SampleBgra(flash.BgraPixels, flash.Width, flash.Height, sx, sy);
+                var sx = x + options.SourceRectX - sx0;
+                var sy = y + options.SourceRectY - sy0;
+                if (sx < 0 || sy < 0 || sx >= overlay.Width || sy >= overlay.Height) continue;
+                var sample = StretchMath.SampleBgra(overlay.BgraPixels, overlay.Width, overlay.Height, sx, sy);
                 BlendPixel(dst, (y * dstW + x) * 4, sample, 1f);
             }
         }

Services/Compositor/SocialBarRenderer.cs

@@ -0,0 +1,107 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Media;
+using System.Windows.Media.Effects;
+using System.Windows.Media.Imaging;
+using System.Windows.Shapes;
+using ytLive.Models;
+
+namespace ytLive.Services.Compositor;
+
+/// <summary>
+/// Rasterizes the global social bar into a transparent BGRA8 strip the output
+/// compositor overlays onto the master frame (top or bottom edge). Replicates the
+/// preview's bar DataTemplate in code — one Path (logo) + one TextBlock (handle)
+/// per entry, white on transparent, green glow — then software-renders it via
+/// <c>RenderTargetBitmap</c> and converts Pbgra32 (premultiplied) to straight-alpha
+/// BGRA for the compositor. WPF glue like <see cref="StaticPixelCache"/>: the
+/// compositor core itself stays pure byte-math. Renders on the UI thread only;
+/// the returned frame is immutable afterwards, so the frame pump may read it from
+/// any thread.
+/// </summary>
+public static class SocialBarRenderer
+{
+    /// <summary>Icon size + the preview's 8px top/bottom margins.</summary>
+    private const int ContentHeight = 40;
+
+    /// <summary>Room for the green DropShadowEffect blur to bleed past the content.</summary>
+    private const int GlowPad = 24;
+
+    /// <summary>Master-frame width — the bar spans the full 1920px output.</summary>
+    public const int Width = 1920;
+
+    /// <summary>Returns the strip frame, or null when there is nothing to render.</summary>
+    public static VideoFrame? Render(IEnumerable<SocialEntry>? entries)
+    {
+        var list = entries?.Where(e => e != null).ToList();
+        if (list == null || list.Count == 0) return null;
+
+        var height = ContentHeight + GlowPad * 2;
+
+        var row = new StackPanel { Orientation = Orientation.Horizontal };
+        foreach (var entry in list)
+        {
+            var item = new StackPanel
+            {
+                Orientation = Orientation.Horizontal,
+                Margin = new Thickness(0, 0, 20, 0),
+            };
+            item.Children.Add(new Path
+            {
+                Data = Geometry.Parse(entry.LogoData),
+                Fill = Brushes.White,
+                Width = 24,
+                Height = 24,
+                Stretch = Stretch.Uniform,
+                VerticalAlignment = VerticalAlignment.Center,
+            });
+            item.Children.Add(new TextBlock
+            {
+                Text = entry.Handle,
+                Foreground = Brushes.White,
+                FontSize = 14,
+                VerticalAlignment = VerticalAlignment.Center,
+                Margin = new Thickness(8, 0, 0, 0),
+                MaxWidth = 200,
+                TextTrimming = TextTrimming.CharacterEllipsis,
+            });
+            row.Children.Add(item);
+        }
+
+        // The glow is baked in so the output bar matches the preview's green halo.
+        var container = new Grid
+        {
+            Width = Width,
+            Height = height,
+            Background = Brushes.Transparent,
+            Effect = new DropShadowEffect { Color = Color.FromRgb(0x2e, 0xcc, 0x71), BlurRadius = 18, ShadowDepth = 0, Opacity = 0.9 },
+        };
+        var centered = new Grid { HorizontalAlignment = HorizontalAlignment.Center, Margin = new Thickness(0, GlowPad, 0, 0) };
+        centered.Children.Add(row);
+        container.Children.Add(centered);
+
+        container.Measure(new Size(Width, height));
+        container.Arrange(new Rect(0, 0, Width, height));
+
+        var bitmap = new RenderTargetBitmap(Width, height, 96, 96, PixelFormats.Pbgra32);
+        bitmap.Render(container);
+
+        var pixels = new byte[Width * height * 4];
+        bitmap.CopyPixels(pixels, Width * 4, 0);
+
+        // Pbgra32 is premultiplied — unpremultiply so the compositor's straight-alpha
+        // source-over blend doesn't darken the logo edges with a halo.
+        for (var i = 0; i < pixels.Length; i += 4)
+        {
+            var a = pixels[i + 3];
+            if (a == 0 || a == 255) continue;
+            pixels[i] = (byte)(pixels[i] * 255 / a);
+            pixels[i + 1] = (byte)(pixels[i + 1] * 255 / a);
+            pixels[i + 2] = (byte)(pixels[i + 2] * 255 / a);
+        }
+
+        return new VideoFrame(Width, height, pixels);
+    }
+}