Fixed OpenAI Responses API by not discarding whitespace (#661)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Provider/OpenAI/ResponsesDeltaStreamLine.cs

@@ -7,15 +7,15 @@ namespace AIStudio.Provider.OpenAI;
 /// <param name="Delta">The delta content of the response.</param>
 public record ResponsesDeltaStreamLine(
     string Type,
-    string Delta) : IResponseStreamLine
+    string? Delta) : IResponseStreamLine
 {
     #region Implementation of IResponseStreamLine
 
     /// <inheritdoc />
-    public bool ContainsContent() => !string.IsNullOrWhiteSpace(this.Delta);
+    public bool ContainsContent() => this.Delta is not null;
 
     /// <inheritdoc />
-    public ContentStreamChunk GetContent() => new(this.Delta, this.GetSources());
+    public ContentStreamChunk GetContent() => new(this.Delta ?? string.Empty, this.GetSources());
 
     //
     // Please note that there are multiple options where LLM providers might stream sources:

app/MindWork AI Studio/wwwroot/changelog/v26.2.2.md

@@ -7,4 +7,5 @@
 - Improved the workspaces experience by using a different color for the delete button to avoid confusion.
 - Improved the plugins page by adding an action to open the plugin source link. The action opens website URLs in an external browser, supports `mailto:` links for direct email composition.
 - Fixed an issue where manually saving chats in workspace manual-storage mode could appear unreliable during response streaming. The save button is now disabled while streaming to prevent partial saves.
+- Fixed a bug in the Responses API of our OpenAI provider implementation where streamed whitespace chunks were discarded. We thank Oliver Kunc `OliverKunc` for his first contribution in resolving this issue. We appreciate your help, Oliver.
 - Upgraded dependencies.