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

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

@@ -14,15 +14,25 @@ public record ChatCompletionAPIRequest(
     bool Stream
 )
 {
+    //
+    // 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 string Model { get; set; } = Model;
+    public IList<IMessageBase> Messages { get; set; } = Messages;
+    public bool Stream { get; set; } = Stream;
+
     public ChatCompletionAPIRequest() : this(string.Empty, [], true)
     {
     }
 
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public IList<object>? Tools { get; init; }
+    public IList<object>? Tools { get; set; }
 
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public bool? ParallelToolCalls { get; init; }
+    public bool? ParallelToolCalls { get; set; }
 
     /// <summary>
     /// Asks a streamed request to end with what it cost.
@@ -35,7 +45,10 @@ public record ChatCompletionAPIRequest(
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     public ChatCompletionStreamOptions? StreamOptions => this.Stream ? ChatCompletionStreamOptions.INCLUDE_USAGE : null;
     
-    // Attention: The "required" modifier is not supported for [JsonExtensionData].
+    //
+    // Attention: The "required" modifier is not supported for [JsonExtensionData], and neither is init: the source
+    // generation of System.Text.Json refuses to write the request at all then.
+    //
     [JsonExtensionData]
-    public IDictionary<string, object> AdditionalApiParameters { get; init; } = new Dictionary<string, object>();
+    public IDictionary<string, object> AdditionalApiParameters { get; set; } = new Dictionary<string, object>();
 }