Add per-answer thinking disclosure

app/MindWork AI Studio/Provider/ContentStreamChunk.cs

@@ -4,13 +4,18 @@ namespace AIStudio.Provider;
 /// A chunk of content from a content stream, along with its associated sources.
 /// </summary>
 /// <param name="Content">The text content of the chunk.</param>
+/// <param name="Thinking">The provider-exposed thinking content of the chunk.</param>
 /// <param name="Sources">The list of sources associated with the chunk.</param>
-public sealed record ContentStreamChunk(string Content, IList<ISource> Sources)
+public sealed record ContentStreamChunk(string Content, string Thinking, IList<ISource> Sources)
 {
+    public ContentStreamChunk(string content, IList<ISource> sources) : this(content, string.Empty, sources)
+    {
+    }
+
     /// <summary>
     /// Implicit conversion to string.
     /// </summary>
     /// <param name="chunk">The content stream chunk.</param>
     /// <returns>The text content of the chunk.</returns>
     public static implicit operator string(ContentStreamChunk chunk) => chunk.Content;
-}
+}