Avoid duplication of tool JSON settings with MEAI

Integrate more seamlessly with the AIJsonUtilities default JSON settings by just adding our delta on top.

This includes honoring its type info resolver chain and default settings,

Author: kzu

src/Extensions/ToolJsonOptions.cs

@@ -1,7 +1,6 @@
 using System.Diagnostics;
 using System.Text.Json;
-using System.Text.Json.Serialization;
-using System.Text.Json.Serialization.Metadata;
+using Microsoft.Extensions.AI;
 
 namespace Devlooped.Extensions.AI;
 
@@ -16,19 +15,14 @@ public static class ToolJsonOptions
     /// <summary>
     /// Default <see cref="JsonSerializerOptions"/> for function calling and tools.
     /// </summary>
-    public static JsonSerializerOptions Default { get; } = new(JsonSerializerDefaults.Web)
+    public static JsonSerializerOptions Default { get; } = new(AIJsonUtilities.DefaultOptions)
     {
         Converters =
         {
             new AdditionalPropertiesDictionaryConverter(),
-            new JsonStringEnumConverter(),
         },
-        DefaultIgnoreCondition =
-            JsonIgnoreCondition.WhenWritingDefault |
-            JsonIgnoreCondition.WhenWritingNull,
-        Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
         PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
-        WriteIndented = Debugger.IsAttached,
-        TypeInfoResolver = new TypeInjectingResolver(new DefaultJsonTypeInfoResolver())
+        WriteIndented = Debugger.IsAttached || AIJsonUtilities.DefaultOptions.WriteIndented,
+        TypeInfoResolver = new TypeInjectingResolver(AIJsonUtilities.DefaultOptions.TypeInfoResolverChain)
     };
 }

src/Extensions/TypeInjectingResolver.cs

@@ -18,8 +18,7 @@ public static JsonSerializerOptions WithTypeInjection(this JsonSerializerOptions
         if (options.IsReadOnly)
             options = new(options);
 
-        options.TypeInfoResolver = new TypeInjectingResolver(
-            JsonTypeInfoResolver.Combine([.. options.TypeInfoResolverChain]));
+        options.TypeInfoResolver = new TypeInjectingResolver(options.TypeInfoResolverChain);
 
         return options;
     }
@@ -29,12 +28,15 @@ public static JsonSerializerOptions WithTypeInjection(this JsonSerializerOptions
 /// A custom <see cref="IJsonTypeInfoResolver"/> that injects a $type property into object types
 /// so they can be automatically distinguished during deserialization or inspection.
 /// </summary>
-public class TypeInjectingResolver(IJsonTypeInfoResolver inner) : IJsonTypeInfoResolver
+public class TypeInjectingResolver(IList<IJsonTypeInfoResolver> chain) : IJsonTypeInfoResolver
 {
+    readonly IJsonTypeInfoResolver resolver = JsonTypeInfoResolver.Combine([.. chain]);
+
     /// <inheritdoc />
     public JsonTypeInfo? GetTypeInfo(Type type, JsonSerializerOptions options)
     {
-        var info = inner.GetTypeInfo(type, options);
+        var info = resolver.GetTypeInfo(type, options);
+
         // The $type would already be present for polymorphic serialization.
         if (info?.Kind == JsonTypeInfoKind.Object && !info.Properties.Any(x => x.Name == "$type"))
         {
@@ -43,6 +45,7 @@ public class TypeInjectingResolver(IJsonTypeInfoResolver inner) : IJsonTypeInfoR
             prop.Order = -1000; // Ensure it is serialized first
             info.Properties.Add(prop);
         }
+
         return info;
     }
 }