Added the BeyondFacts Lab as a prototype (#1175)

app/MindWork AI Studio/Assistants/BeyondFactsLab/BflProjectSelection.cs

@@ -0,0 +1,29 @@
+namespace AIStudio.Assistants.BeyondFactsLab;
+
+/// <summary>
+/// Decides which preparation the BeyondFacts Lab shows after its list changed.
+/// </summary>
+public static class BflProjectSelection
+{
+    /// <summary>
+    /// Chooses the preparation to show: the one asked for, else the one selected last, else the one changed last.
+    /// </summary>
+    /// <param name="projects">The preparations, the one changed last first.</param>
+    /// <param name="preferredId">The preparation asked for, e.g., one just created or the one shown so far.</param>
+    /// <param name="lastSelectedId">The preparation the person selected last, from an earlier session.</param>
+    /// <returns>The preparation to show, or null when there is none.</returns>
+    public static BflProjectEntry? Choose(IReadOnlyList<BflProjectEntry> projects, Guid? preferredId, Guid? lastSelectedId)
+    {
+        foreach (var candidateId in new[] { preferredId, lastSelectedId })
+        {
+            if (candidateId is null)
+                continue;
+
+            var candidate = projects.FirstOrDefault(project => project.ProjectId == candidateId);
+            if (candidate is not null)
+                return candidate;
+        }
+
+        return projects.Count > 0 ? projects[0] : null;
+    }
+}