Added the visual briefing assistant (#893)

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingBuildProgressService.cs

@@ -0,0 +1,36 @@
+using System.Collections.Concurrent;
+using System.Text.Json;
+
+namespace AIStudio.Assistants.VisualBriefing;
+
+/// <summary>
+/// Publishes content-free live build snapshots while persistent records remain authoritative.
+/// </summary>
+public sealed class VisualBriefingBuildProgressService
+{
+    private readonly ConcurrentDictionary<Guid, VisualBriefingBuildRecord> latest = [];
+
+    /// <summary>
+    /// Raised whenever the latest safe build snapshot changes.
+    /// </summary>
+    public event Action<Guid>? Changed;
+
+    /// <summary>
+    /// Publishes the latest build record for one briefing.
+    /// </summary>
+    public void Publish(VisualBriefingBuildRecord build)
+    {
+        var snapshot = JsonSerializer.Deserialize<VisualBriefingBuildRecord>(
+            JsonSerializer.Serialize(build, VisualBriefingJson.Canonical),
+            VisualBriefingJson.Canonical)!;
+        snapshot.Instruction = string.Empty;
+        this.latest[build.BriefingId] = snapshot;
+        this.Changed?.Invoke(build.BriefingId);
+    }
+
+    /// <summary>
+    /// Gets the most recent live snapshot, if one exists.
+    /// </summary>
+    public VisualBriefingBuildRecord? GetLatest(Guid briefingId) =>
+        this.latest.GetValueOrDefault(briefingId);
+}