Generated the JSON contracts of providers, the runtime, and services at compile time (#1150)

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

@@ -8,6 +8,15 @@ namespace AIStudio.Provider.OpenAI;
 /// </remarks>
 public record SubContentInputImage(SubContentType Type, string ImageUrl) : ISubContent
 {
+    //
+    // The properties of the parameters, declared again to be settable. The source generation of System.Text.Json
+    // sets every init-only property while it creates the object, also one missing in the JSON, so its value from
+    // the parameterless constructor would get lost. Keep them first and in the order of the parameters, which is
+    // the order they get written in:
+    //
+    public SubContentType Type { get; set; } = Type;
+    public string ImageUrl { get; set; } = ImageUrl;
+
     public SubContentInputImage() : this(SubContentType.INPUT_IMAGE, string.Empty)
     {
     }