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

HANDOFF.md

@@ -7,18 +7,29 @@
 
 ## Session state (last updated: 2026-08-13)
 
-- **Branch:** `main`. TASK 4 ship step 5 (the live frame pipeline) is **shipped
-  and committed** — the `FramePump` frame producer
-  (`Services/Encoder/FramePump.cs`), `ScreenCaptureManager.GetLatestFrame(key)`,
-  the `MainViewModel` resolver/option-builders/pump lifecycle wiring, `FramePumpTests`
-  (7) + the `GetLatestFrame` test (1), and the memory updates (TASKS.md, ai.md,
-  Services/index.md — the previous session left `Services/index.md` stale and
-  HANDOFF unrewritten; both were fixed before the commit). Build **0 warnings**,
-  **147 tests passing**. A Windows patch reboot killed the prior session right
-  after the work was verified but before the commit.
-- **Finished this session:** ship step 5 (re-verified: 0 warnings, 147/147 pass),
-  the `Services/index.md` FramePump row + de-stale'd encoder rows, and this
-  HANDOFF rewrite.
+- **Branch:** `main`. TASK 4 **ship step 5.5 is implemented, tested, and staged for
+  commit** — the social bar bug-fix branch (drag snap + fediverse heal + the bar on
+  the live output). Uncommitted: the feature work, tests (+8 → 155), and the memory
+  updates in TASKS.md / ai.md / Services/index.md / this file. Next action is
+  `git add` + commit + push (feature + its memory docs in ONE commit, per the
+  working rules).
+- **Finished this session:** both reported bugs diagnosed to root cause and fixed;
+  compositor rendering of the social bar added per user approval.
+  - **Bug 1 — drag didn't snap:** `Canvas.SetTop` set a local value that permanently
+    overrides `{Binding SocialBarTop}`; the release-time snap could never win. Fixed
+    with `SocialBarSnap.Decide` (direction-snap during drag, ±6px deadzone) +
+    `bar.ClearValue(Canvas.TopProperty)` on release.
+  - **Bug 2 — Mastodon showed the generic honeycomb:** `@gramps@llamachile.tube`
+    had `Software = NULL` (nodeinfo only ever asked of the landing-page domain).
+    Fixed via subdomain probing (`mastodon.` → `social.` → … candidates, ~15s
+    budget), a load-time heal (`MainViewModel.HealFediverseSoftwareAsync`), and a
+    settable `SocialEntry.FediverseSoftware` that raises `LogoData`.
+  - **Compositor bar:** `Services/Compositor/SocialBarRenderer.cs` (new, WPF
+    RenderTargetBitmap → straight-alpha strip), `SceneCompositor` blits it above
+    the flash, `FramePump` gains a re-read-each-frame `socialBar:` seam,
+    `MainViewModel` owns the strip frame.
+- **Verified:** Windows-host build **0 warnings**; **155/155 tests passing**
+  (147 baseline + 8 new). Full commit contents pending.
 - **Landmines:**
   - The pump reads the active scene on a background thread while the UI can still
     edit it — a concurrent-mutation exception is contained (logged + `Failed` +
@@ -31,11 +42,18 @@
     delay can run the first iteration synchronously on the caller's thread).
   - `StartAsync` never throws; the VM fires-and-forgets it. `Failed` while live
     flips `StreamStatus.Error` (minimal — real health surfacing is ship step 6).
+  - The heal runs off the UI thread and applies via the dispatcher; a config swap
+    mid-heal (dialog Save) can orphan the healed values on the old entries — harmless
+    (best-effort, re-healed next load).
   - Tests never instantiate `MainViewModel` directly except the round-clip
     integration test (a real `MainWindow`), which never goes live — keep it that way.
-- **Next step:** TASK 4 ship step 6 — health stats: bind `FramePump.HealthUpdated`
+  - Sandbox can't reach outbound HTTPS — the subdomain-probe logic is verified via
+    stub-handler tests only, not against the real `mastodon.llamachile.tube`.
+- **Next step:** commit + push ship step 5.5 (one commit incl. memory docs). Then
+  TASK 4 ship step 6 — health stats: bind `FramePump.HealthUpdated`
   (bitrate/FPS/duration) into the bottom bar. Nothing else queued — do not expand
-  the task queue on your own.
+  the task queue on your own. Optional, not queued: rewriting the healed entry's
+  `ProfileUrl` to `https://mastodon.llamachile.tube/@gramps` (user must say the word).
 
 - **Secret/DB/port facts live:** OAuth client id/secret in `Helpers/OAuthCredentials.cs`;
   OAuth session token in `Helpers/TokenStore.cs` (DPAPI → `%APPDATA%\ytLlive\ytLlive.auth`);

MainWindow.xaml.cs

@@ -254,18 +254,20 @@ public partial class MainWindow : Window
     private void OpacitySlider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
         => OpacityValueText.Text = $"{Math.Round(e.NewValue * 100)}%";
 
-    // ─── Social bar drag: vertical only, snaps to top/bottom on release ───
+    // ─── Social bar drag: vertical only, direction-snaps to the top/bottom edge ───
     private const double SocialBarBottomTop = 1040;
     private bool _isDraggingSocialBar;
-    private double _socialBarGrabOffsetY;
+    private double _socialBarDragStartY;
+    private SocialBarPosition? _socialBarDragDirection;
 
     private void SocialBar_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
     {
         var bar = (FrameworkElement)sender;
         _isDraggingSocialBar = true;
+        _socialBarDragDirection = null;
         var toCanvas = CanvasGrid.TransformToVisual(bar).Inverse;
         var p = toCanvas.Transform(e.GetPosition(bar));
-        _socialBarGrabOffsetY = p.Y - Canvas.GetTop(bar);
+        _socialBarDragStartY = p.Y;
         bar.CaptureMouse();
         e.Handled = true;
     }
@@ -276,7 +278,17 @@ public partial class MainWindow : Window
         var bar = (FrameworkElement)sender;
         var toCanvas = CanvasGrid.TransformToVisual(bar).Inverse;
         var p = toCanvas.Transform(e.GetPosition(bar));
-        Canvas.SetTop(bar, Math.Clamp(p.Y - _socialBarGrabOffsetY, 0, SocialBarBottomTop));
+
+        // Derive the drag direction once it commits (past the deadzone) and keep it
+        // for the rest of the drag — the bar snaps to the edge it's being dragged
+        // toward and is never left mid-screen.
+        var direction = _socialBarDragDirection
+            ?? SocialBarSnap.Decide(p.Y - _socialBarDragStartY);
+        if (direction != null)
+        {
+            _socialBarDragDirection = direction;
+            Canvas.SetTop(bar, direction == SocialBarPosition.Top ? 0 : SocialBarBottomTop);
+        }
         e.Handled = true;
     }
 
@@ -284,11 +296,18 @@ public partial class MainWindow : Window
     {
         if (!_isDraggingSocialBar) return;
         var bar = (FrameworkElement)sender;
-        var top = Canvas.GetTop(bar);
         bar.ReleaseMouseCapture();
         _isDraggingSocialBar = false;
-        var position = top <= SocialBarBottomTop / 2.0 ? SocialBarPosition.Top : SocialBarPosition.Bottom;
-        _viewModel.SetSocialBarPosition(position);
+
+        var direction = _socialBarDragDirection
+            ?? (Canvas.GetTop(bar) <= SocialBarBottomTop / 2.0
+                ? SocialBarPosition.Top : SocialBarPosition.Bottom);
+
+        // ClearValue removes the local value Canvas.SetTop applied during the drag —
+        // a local value permanently overrides the {Binding SocialBarTop}, which is
+        // why the release snap never used to show. Clearing re-engages the binding.
+        bar.ClearValue(Canvas.TopProperty);
+        _viewModel.SetSocialBarPosition(direction);
         e.Handled = true;
     }
 

Models/Socials.cs

@@ -19,8 +19,22 @@ public sealed class SocialEntry : INotifyPropertyChanged
     public string Handle { get; init; } = string.Empty;
     public string ProfileUrl { get; init; } = string.Empty;
 
-    /// <summary>Fediverse instance software (nodeinfo) for <see cref="Service"/> = Fediverse.</summary>
-    public string? FediverseSoftware { get; init; }
+    private string? _fediverseSoftware;
+
+    /// <summary>Fediverse instance software (nodeinfo) for <see cref="Service"/> = Fediverse.
+    /// Settable so the load-time heal can fill a missing name and the bar icon
+    /// updates in place.</summary>
+    public string? FediverseSoftware
+    {
+        get => _fediverseSoftware;
+        set
+        {
+            if (_fediverseSoftware == value) return;
+            _fediverseSoftware = value;
+            Raise(nameof(FediverseSoftware));
+            Raise(nameof(LogoData));
+        }
+    }
 
     public string ServiceName => Service.ToString();
     public string LogoData => Service == SocialService.Fediverse
@@ -238,7 +252,7 @@ public static class SocialServiceIcons
     }
 
     /// <summary>True when the input is a fediverse handle (@user@domain); out the parts.</summary>
-    private static bool TryParseFediverse(string input, out string user, out string domain)
+    public static bool TryParseFediverse(string input, out string user, out string domain)
     {
         user = domain = string.Empty;
         if (string.IsNullOrWhiteSpace(input) || input[0] != '@') return false;
@@ -249,3 +263,19 @@ public static class SocialServiceIcons
         return true;
     }
 }
+
+/// <summary>
+/// Direction-based snap for the social bar drag (preview): a drag toward the top
+/// edge snaps the bar to the top, toward the bottom snaps it to the bottom — the
+/// bar is never left mid-screen. Returns null inside the deadzone so a drag that
+/// hasn't committed to a direction doesn't flip the bar.
+/// </summary>
+public static class SocialBarSnap
+{
+    public static SocialBarPosition? Decide(double deltaY, double deadzone = 6)
+    {
+        if (deltaY <= -deadzone) return SocialBarPosition.Top;
+        if (deltaY >= deadzone) return SocialBarPosition.Bottom;
+        return null;
+    }
+}

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);
+    }
+}

Services/Encoder/FramePump.cs

@@ -28,6 +28,7 @@ public sealed class FramePump : IDisposable
     private readonly Func<IFfmpegEncoder> _encoderFactory;
     private readonly Action<string>? _log;
     private readonly Func<TimeSpan, CancellationToken, Task> _pacingDelay;
+    private readonly Func<(VideoFrame? Frame, SocialBarPosition Position)>? _socialBar;
     private readonly SceneCompositor _compositor = new();
 
     private readonly object _gate = new();
@@ -49,7 +50,8 @@ public sealed class FramePump : IDisposable
         Func<EncoderOptions?> encoderOptions,
         Func<IFfmpegEncoder> encoderFactory,
         Action<string>? log = null,
-        Func<TimeSpan, CancellationToken, Task>? pacingDelay = null)
+        Func<TimeSpan, CancellationToken, Task>? pacingDelay = null,
+        Func<(VideoFrame? Frame, SocialBarPosition Position)>? socialBar = null)
     {
         _sceneProvider = sceneProvider ?? throw new ArgumentNullException(nameof(sceneProvider));
         _frameResolver = frameResolver ?? throw new ArgumentNullException(nameof(frameResolver));
@@ -58,6 +60,7 @@ public sealed class FramePump : IDisposable
         _encoderFactory = encoderFactory ?? throw new ArgumentNullException(nameof(encoderFactory));
         _log = log;
         _pacingDelay = pacingDelay ?? ((delay, ct) => Task.Delay(delay, ct));
+        _socialBar = socialBar;
     }
 
     public bool IsRunning { get; private set; }
@@ -212,7 +215,20 @@ public sealed class FramePump : IDisposable
                 var scene = _sceneProvider();
                 if (scene != null)
                 {
-                    var frame = _compositor.Render(scene, _frameResolver, null, _compositorOptions());
+                    var compositorOptions = _compositorOptions();
+                    VideoFrame? socialBarFrame = null;
+                    var socialBarTop = 0;
+                    if (_socialBar != null)
+                    {
+                        var (barFrame, position) = _socialBar();
+                        socialBarFrame = barFrame;
+                        if (barFrame != null)
+                            socialBarTop = position == SocialBarPosition.Top
+                                ? 0
+                                : compositorOptions.SourceRectHeight - barFrame.Height;
+                    }
+                    var frame = _compositor.Render(
+                        scene, _frameResolver, null, compositorOptions, socialBarFrame, socialBarTop);
                     IFfmpegEncoder? encoder;
                     lock (_gate) encoder = _encoder;
                     if (encoder == null) break; // _encoder is only cleared after the loop ends; defensive

Services/SocialValidator.cs

@@ -23,6 +23,11 @@ public sealed class SocialLookupResult
 public interface ISocialValidator
 {
     Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl, CancellationToken ct);
+
+    /// <summary>Best-effort nodeinfo software name (mastodon/peertube/...) for a
+    /// fediverse domain, or null when it can't be resolved. The load-time heal
+    /// uses this to fix a bar entry whose stored software is missing.</summary>
+    Task<string?> ResolveFediverseSoftwareAsync(string domain, CancellationToken ct);
 }
 
 /// <summary>
@@ -35,14 +40,19 @@ public interface ISocialValidator
 public sealed class HttpSocialValidator : ISocialValidator
 {
     private readonly HttpClient _client;
+    private readonly Action<string>? _log;
 
-    public HttpSocialValidator(HttpClient? client = null)
+    public HttpSocialValidator(HttpClient? client = null, Action<string>? log = null)
     {
         _client = client ?? new HttpClient();
         _client.DefaultRequestHeaders.UserAgent.ParseAdd(
             "Mozilla/5.0 (compatible; ytLlive social validator)");
+        _log = log;
     }
 
+    public Task<string?> ResolveFediverseSoftwareAsync(string domain, CancellationToken ct)
+        => TryFetchFediverseSoftwareAsync(domain, ct);
+
     public async Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl, CancellationToken ct)
     {
         var input = handleOrUrl.Trim();
@@ -127,32 +137,67 @@ public sealed class HttpSocialValidator : ISocialValidator
     /// nodeinfo link, read `software.name`. If the identity domain is itself a
     /// redirect (e.g. a YunoHost domain whose default app lives on a subdomain),
     /// the bare root 302s to the real instance — follow it and ask that host.
-    /// Failures return null — validation still succeeds, the icon just falls
-    /// back to the generic fediverse glyph.
+    /// If neither answers, probe well-known subdomains (mastodon.example.com)
+    /// so a landing-page domain still resolves its real instance. The whole
+    /// resolution is bounded by a ~15s budget. Failures return null — validation
+    /// still succeeds, the icon just falls back to the generic fediverse glyph.
     /// </summary>
     private async Task<string?> TryFetchFediverseSoftwareAsync(string domain, CancellationToken ct)
     {
         try
         {
-            var software = await FetchSoftwareNameAsync(domain, ct);
+            using var budget = System.Threading.CancellationTokenSource.CreateLinkedTokenSource(ct);
+            budget.CancelAfter(TimeSpan.FromSeconds(15));
+
+            var software = await FetchSoftwareNameAsync(domain, budget.Token);
             if (software != null) return software;
 
-            var resolved = await ResolveInstanceHostAsync(domain, ct);
-            if (resolved == null
-                || string.Equals(resolved, domain, System.StringComparison.OrdinalIgnoreCase))
+            var resolved = await ResolveInstanceHostAsync(domain, budget.Token);
+            if (resolved != null
+                && !string.Equals(resolved, domain, System.StringComparison.OrdinalIgnoreCase))
+            {
+                software = await FetchSoftwareNameAsync(resolved, budget.Token);
+                if (software != null) return software;
+            }
+
+            foreach (var sub in FediverseSubdomainCandidates)
+            {
+                var host = $"{sub}.{domain}";
+                software = await FetchSoftwareNameAsync(host, budget.Token);
+                if (software != null)
+                {
+                    _log?.Invoke($"SocialValidator: fediverse software '{software}' for '{domain}' resolved via {host}");
+                    return software;
+                }
+            }
+            _log?.Invoke($"SocialValidator: no nodeinfo found for '{domain}'");
             return null;
-            return await FetchSoftwareNameAsync(resolved, ct);
         }
         catch (System.OperationCanceledException) when (ct.IsCancellationRequested)
         {
             return null; // caller checks ct.IsCancellationRequested and reports Canceled
         }
-        catch
+        catch (System.OperationCanceledException)
         {
+            _log?.Invoke($"SocialValidator: nodeinfo resolution for '{domain}' timed out");
+            return null;
+        }
+        catch (System.Exception ex)
+        {
+            _log?.Invoke($"SocialValidator: nodeinfo resolution for '{domain}' failed: {ex.Message}");
             return null;
         }
     }
 
+    /// <summary>Common instance subdomains, probed in order when the identity
+    /// domain itself doesn't serve nodeinfo (a landing page or SSO gate in front
+    /// of a self-hosted instance).</summary>
+    private static readonly string[] FediverseSubdomainCandidates =
+    {
+        "mastodon", "social", "fediverse", "tube", "peertube",
+        "pixelfed", "lemmy", "pleroma", "misskey", "gotosocial", "fedi", "instance",
+    };
+
     private async Task<string?> FetchSoftwareNameAsync(string domain, CancellationToken ct)
     {
         var nodeInfoUrl = await FetchNodeInfoUrlAsync(domain, ct);

Services/index.md

@@ -27,12 +27,13 @@ External-facing logic: YouTube API, persistence. See
 | `ScreenCaptureFrameSource.cs` | One `Direct3D11CaptureFramePool` (free-threaded, 2 buffers) + session per target; frames → `SoftwareBitmap.CreateCopyFromSurfaceAsync` (BGRA, alpha ignored) → `VideoFrame`, bytes read via `WindowsRuntimeMarshal.TryGetDataUnsafe` (CsWinRT-safe — the `IMemoryBufferByteAccess` ComImport cast fails on every frame and is gone). Surfaces > 1920×1080 downscaled bilinearly to the master; conversion failures logged ≤ once/5 s. DRM content = black frames (OS limit). `CreateForMonitor`/`CreateForWindow`/`CreateForPicker` |
 | `ScreenCaptureManager.cs` | Screen-capture ownership mirroring `CameraManager`: refcounted by target key, one shared `WriteableBitmap`, dispatcher-coalesced latest-frame copies; `PreviewBitmapChanged`/`CaptureFailed` events; `ReleaseAllAsync` used on re-designation |
 | `ScreenCaptureSourceFactory.cs` | `Resolve(key)` parses `monitor:<n>` / `window:<hwnd>` / `picker:<name>` into a source; `PickAsync()` shows the OS `GraphicsCapturePicker` and returns the `picker:` key (transient — a reload falls back to auto-detection) |
-| `Compositor/SceneCompositor.cs` | **The output compositor (TASK 4 ship step 1)**: renders a scene into the encoder's master `VideoFrame` (tightly-packed BGRA8), mirroring the XAML preview minus editing chrome — backdrop → background → elements (`UniformToFill` cover-crop, round clip, mirror, opacity, border) → branding flash. Pure and WPF-free: frames injected via a `Func<SceneElement, VideoFrame?>` resolver (webcam → DeviceId, image → AssetId, backdrop → CaptureKey); output sized by `CompositorOptions` (16:9 = full master 1:1; vertical 9:16 = 607×1080 crop → 1080×1920 bilinear). Preview stays XAML (editing view); this is the output view — see `ai.md` "Scene compositor" |
+| `Compositor/SceneCompositor.cs` | **The output compositor (TASK 4 ship step 1)**: renders a scene into the encoder's master `VideoFrame` (tightly-packed BGRA8), mirroring the XAML preview minus editing chrome — backdrop → background → elements (`UniformToFill` cover-crop, round clip, mirror, opacity, border) → branding flash → social bar (optional `socialBarFrame` + `socialBarTop` in master space, blitted last so the bar sits above the flash; the old `BlitFlash` generalized to `BlitOverlay` with source offsets). Pure and WPF-free: frames injected via a `Func<SceneElement, VideoFrame?>` resolver (webcam → DeviceId, image → AssetId, backdrop → CaptureKey); output sized by `CompositorOptions` (16:9 = full master 1:1; vertical 9:16 = 607×1080 crop → 1080×1920 bilinear). Preview stays XAML (editing view); this is the output view — see `ai.md` "Scene compositor" |
 | `Compositor/CompositorOptions.cs` | The active tier's output rect (source space over the 1920×1080 master, integer-aligned — `MainViewModel.OutputRectX` can be 656.5) + target W×H |
 | `Compositor/StretchMath.cs` | Pure pixel math: the WPF `UniformToFill` cover-crop, clamped bilinear sample/scale (unit-tested half of the compositor) |
 | `Compositor/StaticPixelCache.cs` | Asset bytes → cached BGRA8 `VideoFrame`, decoded once per content hash — the output path's raw-pixel source (the preview uses ImageCache's `BitmapImage`) |
 | `Encoder/IFfmpegLocator.cs` | **TASK 4 ship step 2 seam**: resolves an absolute path to `ffmpeg.exe` (PATH first → cached `%APPDATA%\ytLlive\tools\ffmpeg.exe` → pinned BtbN LGPL-shared zip download). The encoder step and tests fake it |
-| `SocialValidator.cs` | `ISocialValidator` seam + `HttpSocialValidator` default: validates a social handle/URL by constructing the canonical profile URL and issuing an HTTP GET — the "act of validation" before adding to the bar. 200/redirect = exists; 404/connection failure = rejected. Fediverse `@user@domain` additionally does a best-effort nodeinfo lookup (`/.well-known/nodeinfo` → `software.name`) so the entry can show the instance's real logo; nodeinfo failure still validates (generic fediverse glyph). If the identity domain's nodeinfo is blocked (SSO) but the bare root 302s to the real instance (YunoHost default-app subdomains), the lookup follows the redirect and asks that host instead. Constructor takes optional `HttpClient` for tests |
+| `SocialValidator.cs` | `ISocialValidator` seam + `HttpSocialValidator` default: validates a social handle/URL by constructing the canonical profile URL and issuing an HTTP GET — the "act of validation" before adding to the bar. 200/redirect = exists; 404/connection failure = rejected. Fediverse `@user@domain` additionally does a best-effort nodeinfo lookup (`/.well-known/nodeinfo` → `software.name`) so the entry can show the instance's real logo; nodeinfo failure still validates (generic fediverse glyph). If the identity domain's nodeinfo is blocked (SSO) but the bare root 302s to the real instance (YunoHost default-app subdomains), the lookup follows the redirect and asks that host. Since the bar bug-fix branch the resolution **probes well-known subdomains** (`mastodon.`, `social.`, ... order in `FediverseSubdomainCandidates`) when both the identity domain and its redirect come up empty, bounded by a ~15s linked-CTS budget; `ResolveFediverseSoftwareAsync(domain, ct)` on the seam powers the load-time heal. Constructor takes optional `HttpClient` + `Action<string>` log for tests |
+| `Compositor/SocialBarRenderer.cs` | **Social bar output strip** (bar bug-fix branch): rasterizes the global social bar into a transparent straight-alpha BGRA8 `VideoFrame` strip (1920 wide, 40px content + 24px glow pad) via `RenderTargetBitmap` — one Path (logo) + one TextBlock (handle) per entry, white on transparent with the preview's green `#2ecc71` glow baked in (Pbgra32 → straight-alpha unpremultiply). UI thread only; the frame is immutable afterwards so the `FramePump` reads it from its own thread |
 | `Encoder/EncoderOptions.cs` | One go-live's encoder config: full `RtmpUrl` (ingest + stream key), W×H/FPS/bitrate from the quality tier, `VideoEncoder` (null = probe), audio sample rate/channels, `GopSize` = FPS×4 (the ≤4s keyframe bound) |
 | `Encoder/IFfmpegEncoder.cs` | **TASK 4 ship step 3 seam**: start/feed/stop the live encoder; `HealthUpdated` (parsed `StreamHealth`), `ProcessFailed` on unexpected non-zero exit. Constructor-injected locator + process factory (tests fake both) |
 | `Encoder/FfmpegEncoder.cs` | The default encoder: spawn `ffmpeg.exe` (probe `-encoders` first → hardware NVENC/QSV/AMF, OpenH264 fallback — never libx264), feed raw BGRA frames into stdin, parse `-stats` lines into `StreamHealth`, graceful stop via stdin EOF + 10s kill watchdog. Constructed by `MainViewModel` since ship step 5 (`new FfmpegEncoder(new FfmpegLocator())`), driven by the `FramePump` |
@@ -41,7 +42,7 @@ External-facing logic: YouTube API, persistence. See
 | `Encoder/FfmpegArgs.cs` | Pure FFmpeg command-line builder: rawvideo `pipe:0` input, `anullsrc` silent audio (WASAPI replaces it), H.264+AAC, closed GOP (`-g fps×4 -keyint_min -sc_threshold 0 -bf 0`, `yuv420p`), FLV → RTMP |
 | `Encoder/FfmpegProgressParser.cs` | Pure parser for `frame=/fps=/size=/time=/bitrate=` stats lines → `FfmpegProgress` |
 | `Encoder/FfmpegEncoderPicker.cs` | Pure H.264 encoder picker from `-encoders` output: NVENC → QSV → AMF → OpenH264; **never returns libx264** (GPL) |
-| `Encoder/FramePump.cs` | **TASK 4 ship step 5**: the live frame producer — while live it snapshots the active scene each tick, resolves every element to its latest frame (`Func<SceneElement, VideoFrame?>` resolver), composites it into the tier's output frame, and paces frames into the encoder at the tier's FPS. All collaborators constructor-injected seams; free of WPF and the capture managers. `StartAsync` never throws (failures log + `Failed`); no RTMP URL = encoder skipped; `StopAsync` stops the encoder before awaiting the loop (backpressure deadlock); `ProcessFailed` self-stops. See `ai.md` "Live frame pipeline" |
+| `Encoder/FramePump.cs` | **TASK 4 ship step 5**: the live frame producer — while live it snapshots the active scene each tick, resolves every element to its latest frame (`Func<SceneElement, VideoFrame?>` resolver), composites it into the tier's output frame, and paces frames into the encoder at the tier's FPS. All collaborators constructor-injected seams; free of WPF and the capture managers. `StartAsync` never throws (failures log + `Failed`); no RTMP URL = encoder skipped; `StopAsync` stops the encoder before awaiting the loop (backpressure deadlock); `ProcessFailed` self-stops. Since the bar bug-fix branch it takes an optional `socialBar: Func<(VideoFrame? Frame, SocialBarPosition Position)>?` seam — a pre-rendered bar strip composited last (above the flash) at the top edge or `SourceRectHeight − bar height`. See `ai.md` "Live frame pipeline" |
 | `Encoder/FfmpegLocator.cs` | The default locator: PATH probe wins, then the cache, then pull+extract (`ffmpeg.exe` **+ the `libav*.dll` family** via a staging dir, failures via `AppLog`). Pinned to BtbN `autobuild-2026-08-09-13-03` **lgpl-shared** (dynamic linking = LGPL compliance without static-relink §6 material; no GPL libx264; NVENC/QSV/AMF + libopenh264 + native AAC — see `ai.md` → Licensing). Search dirs / tools dir / downloader constructor-injected for hermetic tests. Wired into the encoder since ship step 5 |
 | `Audio/IAudioSource.cs` | **TASK 4 ship step 4 seam**: live capture source — `Start`/`Stop`/`SampleReady(AudioSample)`/`Failed(Exception)`, `IDisposable`; runs only while live. The app consumes this seam; tests inject hermetic fakes |
 | `Audio/AudioSample.cs` | One captured chunk: interleaved PCM float (-1..1) + sample rate + channels |

TASKS.md

@@ -475,6 +475,46 @@ added, `MainViewModel` wired end-to-end (resolver + both option builders + pump
 the pump reads the active scene on a background thread while the UI can still edit it; a concurrent-mutation
 exception is contained (logged + `Failed` + pump stops) rather than crashing.
 
+#### Ship step 5.5 — Social bar bug fixes + the bar on the live output (2026-08-13)
+
+**Bug 1 — drag doesn't snap (root cause found):** `SocialBar_PreviewMouseMove` set `Canvas.SetTop(bar, …)`
+with a local value, which permanently overrides the `Canvas.Top="{Binding SocialBarTop}"` binding — the
+release-time `SetSocialBarPosition` → `PropertyChanged(SocialBarTop)` could never beat it, so the bar stayed
+wherever it was dropped. Fixed by direction-snapping **during** the drag (`SocialBarSnap.Decide` — deadzone
+±6px, once the direction commits the bar rides the edge it's dragged toward, never mid-screen) and on release
+`bar.ClearValue(Canvas.TopProperty)` re-engages the binding before `SetSocialBarPosition`.
+
+**Bug 2 — Mastodon showed the generic 7-star honeycomb (root cause found):** the DB row
+`@gramps@llamachile.tube` had `Software = NULL` — nodeinfo was only ever resolved against the identity domain
+(`llamachile.tube`, a landing page), never probed for the real instance at `mastodon.llamachile.tube`.
+Fixed on three fronts: `HttpSocialValidator` now **probes well-known subdomains** (mastodon. → social. →
+… `FediverseSubdomainCandidates`) when the identity domain and its redirect both come up empty, under a
+~15s linked-CTS budget, with an optional `Action<string>` log; `MainViewModel` **heals** any fediverse entry
+missing a software name on layout load (`HealFediverseSoftwareAsync` — static, testable; instance wrapper
+runs it off the UI thread, applies via the dispatcher, saves); `SocialEntry.FediverseSoftware` is now
+**settable** and raises `PropertyChanged` for `LogoData`, so the heal updates the icon in place. If the user
+later re-saves the entry with the icon fixed, the name persists with it.
+
+**Compositor rendering (user-approved scope):** the social bar now appears **on the live output**, not just
+the preview — `Compositor/SocialBarRenderer.cs` rasterizes the entries into a transparent straight-alpha
+BGRA strip (1920-wide, 40px content + 24px glow pad, green `#2ecc71` glow baked in) via `RenderTargetBitmap`
+(WPF glue like `StaticPixelCache`; the compositor core stays pure). `SceneCompositor.Render` takes optional
+`socialBarFrame` + `socialBarTop` (master space) and blits it **last — above the branding flash** (the old
+`BlitFlash` generalized to offset `BlitOverlay`). `FramePump` gains a `socialBar:` seam
+(`Func<(VideoFrame?, SocialBarPosition)>`, re-read every frame) and places the bar at `0` or
+`SourceRectHeight − bar height`. `MainViewModel` owns the frame (`RenderSocialBarFrame`, re-rendered on
+load/save/notify) and feeds the seam.
+
+**Tests (+8 → 155 passing, 0 warnings):** `SocialBarSnap.Decide` units (direction + deadzone + custom
+deadzone), settable `FediverseSoftware` updates `LogoData`, subdomain-probe unit + null-when-silent unit,
+the branch's **one integration test** `Socials_HealMissingFediverseSoftware_RoundTripsThroughDb`
+(temp-DB roundtrip: NULL software → healed via the validator → persisted), compositor bar overlay
+(top/bottom + above-flash), `FramePump` bar pass-through (Top then flipped to Bottom mid-run — the seam is
+re-read each frame), and both `ISocialValidator` fakes (`FakeValidator`/`BlockingValidator`) gained
+`ResolveFediverseSoftwareAsync`.
+
+**Not included (say the word):** rewriting the healed entry's `ProfileUrl` to `https://mastodon.llamachile.tube/@gramps`.
+
 ---
 
 ## TASK 5 — YouTube Live Stream Management

ViewModels/MainViewModel.cs

@@ -80,6 +80,7 @@ public class MainViewModel : ViewModelBase
     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,
@@ -872,7 +873,8 @@ public class MainViewModel : ViewModelBase
             compositorOptions: BuildCompositorOptions,
             encoderOptions: BuildEncoderOptions,
             encoderFactory: () => new FfmpegEncoder(new FfmpegLocator()),
-            log: message => AppLog.Write(message));
+            log: message => AppLog.Write(message),
+            socialBar: () => (_socialBarFrame, _socials?.BarPosition ?? SocialBarPosition.Bottom));
         _framePump.Failed += OnFramePumpFailed;
 
         LoadLayout();
@@ -966,6 +968,8 @@ public class MainViewModel : ViewModelBase
         ReacquireWebcam();
         ReacquireScreenCaptures();
         _socials = _layoutStore.Socials;
+        RenderSocialBarFrame();
+        HealFediverseSoftwareInBackground();
         OnPropertyChanged(nameof(HasSocials));
         OnPropertyChanged(nameof(SocialBarVisible));
         OnPropertyChanged(nameof(SocialBarDotBrush));
@@ -1902,6 +1906,83 @@ public class MainViewModel : ViewModelBase
 
     // ─── Social bar ───
 
+    /// <summary>
+    /// Resolves a missing nodeinfo software name (mastodon, peertube, ...) for every
+    /// fediverse entry that doesn't have one, so the bar shows the instance's real
+    /// logo instead of the generic fediverse glyph. Best-effort: a failed resolution
+    /// leaves the glyph untouched. Returns handle → software for what was resolved —
+    /// the caller applies + persists (the app hops to the dispatcher; a test applies
+    /// directly).
+    /// </summary>
+    public static async Task<Dictionary<string, string>> HealFediverseSoftwareAsync(
+        SocialsConfig socials,
+        ISocialValidator validator,
+        Action<string>? log = null)
+    {
+        var resolved = new Dictionary<string, string>();
+        if (socials == null || validator == null) return resolved;
+        foreach (var entry in socials.Entries)
+        {
+            if (entry.Service != SocialService.Fediverse
+                || !string.IsNullOrWhiteSpace(entry.FediverseSoftware))
+                continue;
+            if (!SocialServiceIcons.TryParseFediverse(entry.Handle, out _, out var domain))
+                continue;
+            var software = await validator.ResolveFediverseSoftwareAsync(
+                domain, System.Threading.CancellationToken.None);
+            if (string.IsNullOrWhiteSpace(software)) continue;
+            resolved[entry.Handle] = software;
+            log?.Invoke($"Socials heal: {entry.Handle} → {software}");
+        }
+        return resolved;
+    }
+
+    /// <summary>Runs the heal off the UI thread and applies + saves any result.</summary>
+    private void HealFediverseSoftwareInBackground()
+    {
+        var socials = _socials;
+        if (socials == null) return;
+        _ = Task.Run(async () =>
+        {
+            try
+            {
+                var resolved = await HealFediverseSoftwareAsync(
+                    socials, _socialValidator, m => AppLog.Write(m));
+                if (resolved.Count == 0) return;
+                await Application.Current.Dispatcher.InvokeAsync(() =>
+                {
+                    var current = _socials;
+                    if (current == null) return;
+                    var applied = false;
+                    foreach (var entry in current.Entries)
+                    {
+                        if (!resolved.TryGetValue(entry.Handle, out var software)) continue;
+                        if (entry.FediverseSoftware == software) continue;
+                        entry.FediverseSoftware = software;
+                        applied = true;
+                    }
+                    if (applied) NotifySocialsChanged(); // re-renders the bar + saves
+                });
+            }
+            catch (Exception ex)
+            {
+                AppLog.Write($"Socials heal failed: {ex.Message}");
+            }
+        });
+    }
+
+    /// <summary>
+    /// Re-rasterizes the social bar strip the output compositor overlays. UI thread
+    /// only (WPF rendering); the resulting frame is immutable, so the frame pump may
+    /// read it from its own thread. Null when the bar is off or empty.
+    /// </summary>
+    private void RenderSocialBarFrame()
+    {
+        _socialBarFrame = _socials != null && _socials.BarEnabled
+            ? SocialBarRenderer.Render(_socials.Entries)
+            : null;
+    }
+
     /// <summary>
     /// Opens the Social Media Site Promotion dialog (6 slots, sign-in gate,
     /// validation). On save the working copy replaces <see cref="_socials"/>.
@@ -1925,6 +2006,7 @@ public class MainViewModel : ViewModelBase
 
     private void NotifySocialsChanged()
     {
+        RenderSocialBarFrame();
         OnPropertyChanged(nameof(HasSocials));
         OnPropertyChanged(nameof(SocialBarVisible));
         OnPropertyChanged(nameof(SocialBarDotBrush));

ai.md

@@ -407,11 +407,19 @@ seam:** `Func<Scene?>`, `Func<SceneElement, VideoFrame?>` resolver, `Func<Compos
   background → `StaticPixelCache.Get(AssetId)`. `BuildCompositorOptions` rounds the VM's `OutputRect*`
   doubles to ints — the vertical 607.5 half-pixel crop rounds to a perfectly-centered **608** (`Math.Round`,
   ToEven); `BuildEncoderOptions` fills W×H/FPS/bitrate from the tier once the URL provider yields one.
+- **Social bar on the output (bar bug-fix branch):** the `FramePump` takes an optional
+  `socialBar: Func<(VideoFrame? Frame, SocialBarPosition Position)>?` seam, re-read **every frame** (so a
+  mid-stream position flip applies immediately). The strip is pre-rasterized by `Compositor/SocialBarRenderer.cs`
+  (WPF glue — WPF glue here is fine because the strip is rendered once per config change on the UI thread,
+  the resulting immutable frame is then composited pure-CPU by `SceneCompositor`), and `SceneCompositor.Render`
+  blits it **last — above the branding flash** at `socialBarTop` (0 = top, `SourceRectHeight − barHeight` =
+  bottom) in master space. `MainViewModel` owns the frame (`_socialBarFrame`, rebuilt by `RenderSocialBarFrame`
+  on load/save/`NotifySocialsChanged`).
 - Known consideration: the pump reads the active scene on a background thread while the UI can still edit
   it; a concurrent-mutation exception is contained (logged + `Failed` + the pump stops) rather than
   crashing. The background thread + video pipeline is the new reality since this step.
 
-### Social bar (TASK 14 — shipped 2026-08-12, plan in TASKS.md)
+### Social bar (TASK 14 — shipped 2026-08-12, plan in TASKS.md; bar bug-fix branch 2026-08-13)
 
 A **global bar layer** (never a Source, no sources-list row) that sits over the bottom or top of the
 output and carries the creator's social links — content-sized, centered, GREEN glow when ON, top/bottom
@@ -437,6 +445,25 @@ honeycomb fallback — Simple Icons CC0 path data, initials badges gone); nodein
 `CancellationToken` (dialog VM owns a CTS; Cancel/X/Save abort in-flight lookups, canceled continuations
 never touch slot state).
 
+**Bar bug-fix branch (2026-08-13) — three changes:**
+
+1. **Drag now direction-snaps** — a local `Canvas.SetTop` value permanently overrides the
+   `{Binding SocialBarTop}` (a binding can never win over a local value), so the old drag left the bar
+   wherever it was dropped. Now `SocialBarSnap.Decide` (pure, in `Models/Socials.cs`) commits a direction
+   once the drag passes the ±6px deadzone and rides the edge it's dragged toward; on release
+   `bar.ClearValue(Canvas.TopProperty)` re-engages the binding before `SetSocialBarPosition`.
+2. **Fediverse software self-heal** — the DB row `@gramps@llamachile.tube` had `Software = NULL` because
+   nodeinfo was only ever asked of the identity domain (a landing page; the real instance is
+   `mastodon.llamachile.tube`). `HttpSocialValidator.ResolveFediverseSoftwareAsync` now **probes
+   well-known subdomains** (`mastodon.` → `social.` → … `FediverseSubdomainCandidates`) when the identity
+   domain and its redirect both come up empty, under a ~15s linked-CTS budget. `MainViewModel` runs the
+   static `HealFediverseSoftwareAsync` off the UI thread on layout load, applies matches via the dispatcher,
+   and saves; `SocialEntry.FediverseSoftware` is settable and raises `LogoData`, so the icon updates in place.
+3. **The bar renders on the live output** — `Compositor/SocialBarRenderer.cs` rasterizes the entries into a
+   transparent straight-alpha BGRA strip (1920-wide, 40px content + 24px glow pad, the green glow baked in,
+   Pbgra32→straight-alpha unpremultiply) and the compositor blits it above the flash (see "Live frame
+   pipeline").
+
 ### Licensing — do not violate (GA = paid product; see `THIRD-PARTY-NOTICES.txt`)
 
 This product is closed-source and paid. Every third-party component must stay inside the LGPL/BSD/MIT

ytLive.Tests/FramePumpTests.cs

@@ -66,7 +66,8 @@ public class FramePumpTests
 
     private static FramePump NewPump(FakeEncoder encoder, Func<EncoderOptions?>? options = null,
         Func<Scene?>? scene = null, Func<SceneElement, VideoFrame?>? resolve = null,
-        List<string>? log = null)
+        List<string>? log = null,
+        Func<(VideoFrame? Frame, SocialBarPosition Position)>? socialBar = null)
     {
         return new FramePump(
             sceneProvider: scene ?? (() => BackdropScene()),
@@ -83,7 +84,8 @@ public class FramePumpTests
             }),
             encoderFactory: () => encoder,
             log: log != null ? m => log.Add(m) : null,
-            pacingDelay: async (_, _) => await Task.Yield()); // deterministic: no real waits
+            pacingDelay: async (_, _) => await Task.Yield(), // deterministic: no real waits
+            socialBar: socialBar);
     }
 
     private static void AssertColor(VideoFrame frame, int x, int y, byte r, byte g, byte b)
@@ -163,6 +165,49 @@ public class FramePumpTests
         Assert.False(pump.IsRunning);
     }
 
+    [Fact]
+    public async Task Start_WithSocialBarSeam_PlacesBarAtTopThenBottomEdge()
+    {
+        var red = SceneCompositorTests.Solid(64, 48, 255, 0, 0);
+        var bar = new VideoFrame(64, 8, new byte[64 * 8 * 4]);
+        Array.Fill(bar.BgraPixels, (byte)255); // opaque white strip
+
+        var encoder = new FakeEncoder();
+        var position = SocialBarPosition.Top;
+        using var pump = NewPump(encoder,
+            resolve: e => e is Source { IsBackdrop: true } ? red : null,
+            socialBar: () => (bar, position));
+
+        await pump.StartAsync();
+        await encoder.FrameArrived.Task.WaitAsync(TimeSpan.FromSeconds(5));
+        Assert.NotEmpty(encoder.Frames);
+        AssertColor(encoder.Frames[0], 0, 0, 255, 255, 255); // bar at the top edge
+
+        // Flip to Bottom: the pump re-reads the seam each frame, so a later frame
+        // lands the bar at the bottom edge (SourceRectHeight - bar height) and the
+        // top corner clears back to backdrop.
+        position = SocialBarPosition.Bottom;
+        VideoFrame? flipped = null;
+        var deadline = DateTime.UtcNow.AddSeconds(5);
+        while (DateTime.UtcNow < deadline && flipped == null)
+        {
+            for (var i = 1; i < encoder.Frames.Count; i++)
+            {
+                var f = encoder.Frames[i];
+                if (f.BgraPixels[2] == 255 && f.BgraPixels[1] == 0 && f.BgraPixels[0] == 0)
+                {
+                    flipped = f;
+                    break;
+                }
+            }
+            if (flipped == null) await Task.Delay(10);
+        }
+        Assert.NotNull(flipped);
+        AssertColor(flipped!, 0, 47, 255, 255, 255); // bar sits on the bottom edge
+
+        await pump.StopAsync();
+    }
+
     [Fact]
     public async Task Start_EncoderThrows_RaisesFailed_AndDisposes()
     {

ytLive.Tests/SceneCompositorTests.cs

@@ -180,6 +180,43 @@ public class SceneCompositorTests
         // untouched corner stays pure red
         AssertColor(output, 0, 0, 255, 0, 0);
     }
+
+    [Fact]
+    public void Composite_WithSocialBar_OverlaysAboveFlash_AtTopOrBottom()
+    {
+        var red = Solid(1920, 1080, 255, 0, 0);
+        var backdrop = new Source { Type = SourceType.DisplayCapture, IsBackdrop = true, CaptureKey = "monitor:0" };
+        var scene = new Scene { Name = "Live" };
+        scene.Elements.Add(backdrop);
+
+        var options = new CompositorOptions
+        {
+            SourceRectX = 0, SourceRectY = 0, SourceRectWidth = 1920, SourceRectHeight = 1080,
+            OutputWidth = 1920, OutputHeight = 1080,
+        };
+        var compositor = new SceneCompositor();
+
+        // master-sized overlay: opaque green at (0,0), 50%-white at the center
+        var bar = new VideoFrame(1920, 1080, new byte[1920 * 1080 * 4]);
+        var g = 0;
+        bar.BgraPixels[g] = 0; bar.BgraPixels[g + 1] = 255; bar.BgraPixels[g + 2] = 0; bar.BgraPixels[g + 3] = 255;
+        var w = (540 * 1920 + 960) * 4;
+        bar.BgraPixels[w] = 255; bar.BgraPixels[w + 1] = 255; bar.BgraPixels[w + 2] = 255; bar.BgraPixels[w + 3] = 128;
+
+        // flash: opaque magenta at (0,0) — the bar must cover it
+        var flash = new VideoFrame(1920, 1080, new byte[1920 * 1080 * 4]);
+        flash.BgraPixels[0] = 255; flash.BgraPixels[1] = 0; flash.BgraPixels[2] = 255; flash.BgraPixels[3] = 255;
+
+        var top = compositor.Render(scene, _ => red, flash, options, bar, 0);
+        AssertColor(top, 0, 0, 0, 255, 0); // bar above flash at the top-left
+        AssertColor(top, 960, 540, 255, 127, 127); // 50% white over red
+        AssertColor(top, 100, 100, 255, 0, 0); // empty overlay area: backdrop
+
+        var bottom = compositor.Render(scene, _ => red, flash, options, bar, 1040);
+        AssertColor(bottom, 0, 1040, 0, 255, 0); // bar drawn at the bottom edge
+        AssertColor(bottom, 0, 1039, 255, 0, 0); // backdrop just above the bar
+        AssertColor(bottom, 960, 540, 255, 0, 0); // bar region moved away from center
+    }
 }
 
 public class StretchMathTests

ytLive.Tests/SocialBarTests.cs

@@ -1,8 +1,11 @@
 using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Data.Sqlite;
 using Xunit;
 using ytLive.Models;
 using ytLive.Services;
+using ytLive.ViewModels;
 
 namespace ytLive.Tests;
 
@@ -16,6 +19,102 @@ public class SocialBarTests
         return path;
     }
 
+    /// <summary>Resolves every fediverse domain as Mastodon — the heal test only
+    /// cares that a missing stored software name gets filled in and persisted.</summary>
+    private sealed class MastodonValidator : ISocialValidator
+    {
+        public Task<string?> ResolveFediverseSoftwareAsync(string domain, CancellationToken ct)
+            => Task.FromResult<string?>("mastodon");
+
+        public Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl, CancellationToken ct)
+            => throw new System.NotSupportedException();
+    }
+
+    [Fact]
+    public void SocialBarSnap_Decide_DirectionAndDeadzone()
+    {
+        Assert.Equal(SocialBarPosition.Top, SocialBarSnap.Decide(-10));
+        Assert.Equal(SocialBarPosition.Top, SocialBarSnap.Decide(-6));
+        Assert.Equal(SocialBarPosition.Bottom, SocialBarSnap.Decide(10));
+        Assert.Equal(SocialBarPosition.Bottom, SocialBarSnap.Decide(6));
+        Assert.Null(SocialBarSnap.Decide(5));
+        Assert.Null(SocialBarSnap.Decide(0));
+        Assert.Null(SocialBarSnap.Decide(-5));
+    }
+
+    [Fact]
+    public void SocialBarSnap_Decide_HonorsCustomDeadzone()
+    {
+        Assert.Null(SocialBarSnap.Decide(10, 20));
+        Assert.Equal(SocialBarPosition.Top, SocialBarSnap.Decide(-21, 20));
+    }
+
+    [Fact]
+    public void SocialEntry_FediverseSoftware_SettableUpdatesLogo()
+    {
+        var entry = new SocialEntry
+        {
+            Service = SocialService.Fediverse,
+            Handle = "@gramps@llamachile.tube",
+            ProfileUrl = "https://llamachile.tube/@gramps",
+        };
+        var honeycomb = entry.LogoData;
+        entry.FediverseSoftware = "mastodon";
+        Assert.Equal(SocialServiceIcons.LogoDataForFediverse("mastodon"), entry.LogoData);
+        Assert.NotEqual(honeycomb, entry.LogoData);
+    }
+
+    /// <summary>The single integration test for this branch: a fediverse entry
+    /// persisted with a NULL software name is loaded, healed via the real validator
+    /// seam, and the resolved name is persisted back — surviving a second load.</summary>
+    [Fact]
+    public async Task Socials_HealMissingFediverseSoftware_RoundTripsThroughDb()
+    {
+        var path = TempDbPath();
+        try
+        {
+            var socials = new SocialsConfig();
+            socials.Entries.Add(new SocialEntry
+            {
+                Service = SocialService.Fediverse,
+                Handle = "@gramps@llamachile.tube",
+                ProfileUrl = "https://llamachile.tube/@gramps",
+            });
+            using (var store = new LayoutStore(path))
+                store.Save(new[] { new Scene { Name = "Live" } }, null, socials);
+
+            SocialsConfig? loaded;
+            using (var store = new LayoutStore(path))
+            {
+                store.Load();
+                loaded = store.Socials;
+                Assert.NotNull(loaded);
+                Assert.Null(loaded!.Entries[0].FediverseSoftware);
+            }
+
+            var healed = await MainViewModel.HealFediverseSoftwareAsync(loaded!, new MastodonValidator());
+            Assert.Single(healed);
+            Assert.Equal("mastodon", healed["@gramps@llamachile.tube"]);
+            loaded.Entries[0].FediverseSoftware = healed["@gramps@llamachile.tube"];
+
+            using (var store = new LayoutStore(path))
+                store.Save(new[] { new Scene { Name = "Live" } }, null, loaded);
+
+            using (var store = new LayoutStore(path))
+            {
+                store.Load();
+                var again = store.Socials;
+                Assert.NotNull(again);
+                Assert.Equal("mastodon", again!.Entries[0].FediverseSoftware);
+            }
+        }
+        finally
+        {
+            SqliteConnection.ClearAllPools();
+            if (File.Exists(path)) File.Delete(path);
+        }
+    }
+
     [Fact]
     public void SocialsConfig_RoundTrip_PersistsEntriesAndBarSettings()
     {

ytLive.Tests/SocialValidatorTests.cs

@@ -103,6 +103,39 @@ public class SocialValidatorTests
         Assert.Null(result.FediverseSoftware);
     }
 
+    [Fact]
+    public async Task FediverseSoftware_IdentityDomainSilent_ProbesWellKnownSubdomains()
+    {
+        // The identity domain is a silent landing page (no nodeinfo, no redirect);
+        // the real instance lives on mastodon.<domain> — the probe must find it.
+        var validator = Validator(new StubHandler(request =>
+        {
+            var host = request.RequestUri!.Host;
+            if (host == "mastodon.llamachile.tube")
+            {
+                if (request.RequestUri.AbsolutePath.StartsWith("/.well-known"))
+                    return Json(new { links = new[] { new { rel = "http://nodeinfo.diaspora.software/ns/schema/2.0", href = "https://mastodon.llamachile.tube/nodeinfo/2.0" } } });
+                if (request.RequestUri.AbsolutePath.StartsWith("/nodeinfo"))
+                    return Json(new { software = new { name = "mastodon", version = "4.6.3" } });
+            }
+            return new HttpResponseMessage(HttpStatusCode.NotFound);
+        }));
+
+        var software = await validator.ResolveFediverseSoftwareAsync("llamachile.tube", CancellationToken.None);
+
+        Assert.Equal("mastodon", software);
+    }
+
+    [Fact]
+    public async Task FediverseSoftware_NoSubdomainAnswers_ReturnsNull()
+    {
+        var validator = Validator(new StubHandler(new HttpResponseMessage(HttpStatusCode.NotFound)));
+
+        var software = await validator.ResolveFediverseSoftwareAsync("silent.example", CancellationToken.None);
+
+        Assert.Null(software);
+    }
+
     [Fact]
     public async Task FediverseHandle_CanceledDuringNodeInfo_IsCanceled()
     {

ytLive.Tests/SocialsDialogViewModelTests.cs

@@ -15,6 +15,9 @@ public class SocialsDialogViewModelTests
     {
         public int LookupCount { get; private set; }
 
+        public Task<string?> ResolveFediverseSoftwareAsync(string domain, CancellationToken ct)
+            => Task.FromResult<string?>("mastodon");
+
         public Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl, CancellationToken ct)
         {
             LookupCount++;
@@ -51,6 +54,9 @@ public class SocialsDialogViewModelTests
 
         public Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl, CancellationToken ct)
             => Gate.Task;
+
+        public Task<string?> ResolveFediverseSoftwareAsync(string domain, CancellationToken ct)
+            => Task.FromResult<string?>(null);
     }
 
     private sealed class SignInFake