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

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;
+    }
+}