Lower AIJsonUtilities to STJv8 and move to Abstractions library.

eng/MSBuild/LegacySupport.props

@@ -43,6 +43,10 @@
     <Compile Include="$(MSBuildThisFileDirectory)\..\..\src\LegacySupport\StringSyntaxAttribute\*.cs" LinkBase="LegacySupport\StringSyntaxAttribute" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(InjectJsonSchemaExporterOnLegacy)' == 'true' AND ('$(TargetFramework)' == 'net462' or '$(TargetFramework)' == 'netstandard2.0' or '$(TargetFramework)' == 'netcoreapp3.1' or '$(TargetFramework)' == 'net6.0' or '$(TargetFramework)' == 'net7.0' or '$(TargetFramework)' == 'net8.0')">
+    <Compile Include="$(MSBuildThisFileDirectory)\..\..\src\Shared\JsonSchemaExporter\**\*.cs" LinkBase="Shared\EmptyCollections" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(InjectGetOrAddOnLegacy)' == 'true' AND ('$(TargetFramework)' == 'net462' or '$(TargetFramework)' == 'netstandard2.0')">
     <Compile Include="$(MSBuildThisFileDirectory)\..\..\src\LegacySupport\GetOrAdd\*.cs" LinkBase="LegacySupport\GetOrAdd" />
   </ItemGroup>

eng/packages/TestOnly.props

@@ -20,6 +20,8 @@
     <PackageVersion Include="Verify.Xunit" Version="20.4.0" />
     <PackageVersion Include="Xunit.Combinatorial" Version="1.6.24" />
     <PackageVersion Include="xunit.extensibility.execution" Version="2.4.2" />
+    <PackageVersion Include="JsonSchema.Net" Version="7.2.3" />
+    <PackageVersion Include="JsonSchema.Net.Generation" Version="4.3.0.2" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net462'">

src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.csproj

@@ -19,6 +19,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
+    <InjectJsonSchemaExporterOnLegacy>true</InjectJsonSchemaExporterOnLegacy>
     <InjectSharedEmptyCollections>true</InjectSharedEmptyCollections>
     <InjectStringHashOnLegacy>true</InjectStringHashOnLegacy>
     <InjectStringSyntaxAttributeOnLegacy>true</InjectStringSyntaxAttributeOnLegacy>

src/Libraries/Microsoft.Extensions.AI/Utilities/AIJsonUtilities.Schema.cs → src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Schema.cs

@@ -5,6 +5,9 @@
 using System.Collections.Concurrent;
 using System.ComponentModel;
 using System.Diagnostics;
+#if !NET9_0_OR_GREATER
+using System.Diagnostics.CodeAnalysis;
+#endif
 using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
@@ -16,6 +19,7 @@
 #pragma warning disable S1121 // Assignments should not be made from within sub-expressions
 #pragma warning disable S107 // Methods should not have too many parameters
 #pragma warning disable S1075 // URIs should not be hardcoded
+#pragma warning disable SA1118 // Parameter should not span multiple lines
 
 using FunctionParameterKey = (
     System.Type? Type,
@@ -174,6 +178,11 @@ private static JsonElement GetJsonSchemaCached(JsonSerializerOptions options, Fu
 #endif
     }
 
+#if !NET9_0_OR_GREATER
+    [UnconditionalSuppressMessage("Trimming", "IL2026:Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access",
+        Justification = "Pre STJ-9 schema extraction can fail with a runtime exception if certain reflection metadata have been trimmed. " +
+                        "The exception message will guide users to turn off 'IlcTrimMetadata' which resolves all issues.")]
+#endif
     private static JsonElement GetJsonSchemaCore(JsonSerializerOptions options, FunctionParameterKey key)
     {
         _ = Throw.IfNull(options);
@@ -236,16 +245,9 @@ JsonNode TransformSchemaNode(JsonSchemaExporterContext ctx, JsonNode schema)
             const string DefaultPropertyName = "default";
             const string RefPropertyName = "$ref";
 
-            // Find the first DescriptionAttribute, starting first from the property, then the parameter, and finally the type itself.
-            Type descAttrType = typeof(DescriptionAttribute);
-            var descriptionAttribute =
-                GetAttrs(descAttrType, ctx.PropertyInfo?.AttributeProvider)?.FirstOrDefault() ??
-                GetAttrs(descAttrType, ctx.PropertyInfo?.AssociatedParameter?.AttributeProvider)?.FirstOrDefault() ??
-                GetAttrs(descAttrType, ctx.TypeInfo.Type)?.FirstOrDefault();
-
-            if (descriptionAttribute is DescriptionAttribute attr)
+            if (ctx.ResolveAttribute<DescriptionAttribute>() is { } attr)
             {
-                ConvertSchemaToObject(ref schema).Insert(0, DescriptionPropertyName, (JsonNode)attr.Description);
+                ConvertSchemaToObject(ref schema).InsertAtStart(DescriptionPropertyName, (JsonNode)attr.Description);
             }
 
             if (schema is JsonObject objSchema)
@@ -268,7 +270,7 @@ JsonNode TransformSchemaNode(JsonSchemaExporterContext ctx, JsonNode schema)
                 // Include the type keyword in enum types
                 if (key.IncludeTypeInEnumSchemas && ctx.TypeInfo.Type.IsEnum && objSchema.ContainsKey(EnumPropertyName) && !objSchema.ContainsKey(TypePropertyName))
                 {
-                    objSchema.Insert(0, TypePropertyName, "string");
+                    objSchema.InsertAtStart(TypePropertyName, "string");
                 }
 
                 // Disallow additional properties in object schemas
@@ -303,7 +305,7 @@ JsonNode TransformSchemaNode(JsonSchemaExporterContext ctx, JsonNode schema)
                     if (index < 0)
                     {
                         // If there's no description property, insert it at the beginning of the doc.
-                        obj.Insert(0, DescriptionPropertyName, (JsonNode)key.Description!);
+                        obj.InsertAtStart(DescriptionPropertyName, (JsonNode)key.Description!);
                     }
                     else
                     {
@@ -321,15 +323,12 @@ JsonNode TransformSchemaNode(JsonSchemaExporterContext ctx, JsonNode schema)
                 if (key.IncludeSchemaUri)
                 {
                     // The $schema property must be the first keyword in the object
-                    ConvertSchemaToObject(ref schema).Insert(0, SchemaPropertyName, (JsonNode)SchemaKeywordUri);
+                    ConvertSchemaToObject(ref schema).InsertAtStart(SchemaPropertyName, (JsonNode)SchemaKeywordUri);
                 }
             }
 
             return schema;
 
-            static object[]? GetAttrs(Type attrType, ICustomAttributeProvider? provider) =>
-                provider?.GetCustomAttributes(attrType, inherit: false);
-
             static JsonObject ConvertSchemaToObject(ref JsonNode schema)
             {
                 JsonObject obj;
@@ -368,6 +367,62 @@ private static bool TypeIsArrayContainingInteger(JsonObject schema)
         return false;
     }
 
+    private static void InsertAtStart(this JsonObject jsonObject, string key, JsonNode value)
+    {
+#if NET9_0_OR_GREATER
+        jsonObject.Insert(0, key, value);
+#else
+        jsonObject.Remove(key);
+        var copiedEntries = jsonObject.ToArray();
+        jsonObject.Clear();
+
+        jsonObject.Add(key, value);
+        foreach (var entry in copiedEntries)
+        {
+            jsonObject[entry.Key] = entry.Value;
+        }
+#endif
+    }
+
+#if !NET9_0_OR_GREATER
+    private static int IndexOf(this JsonObject jsonObject, string key)
+    {
+        int i = 0;
+        foreach (var entry in jsonObject)
+        {
+            if (string.Equals(entry.Key, key, StringComparison.Ordinal))
+            {
+                return i;
+            }
+
+            i++;
+        }
+
+        return -1;
+    }
+#endif
+
+    private static TAttribute? ResolveAttribute<TAttribute>(this JsonSchemaExporterContext ctx)
+        where TAttribute : Attribute
+    {
+        // Resolve attributes from locations in the following order:
+        // 1. Property-level attributes
+        // 2. Parameter-level attributes and
+        // 3. Type-level attributes.
+        return
+#if NET9_0_OR_GREATER
+            GetAttrs(ctx.PropertyInfo?.AttributeProvider) ??
+            GetAttrs(ctx.PropertyInfo?.AssociatedParameter?.AttributeProvider) ??
+#else
+            GetAttrs(ctx.PropertyAttributeProvider) ??
+            GetAttrs(ctx.ParameterInfo) ??
+#endif
+            GetAttrs(ctx.TypeInfo.Type);
+
+        static TAttribute? GetAttrs(ICustomAttributeProvider? provider) =>
+            (TAttribute?)provider?.GetCustomAttributes(typeof(TAttribute), inherit: false).FirstOrDefault();
+    }
+
     private static JsonElement ParseJsonElement(ReadOnlySpan<byte> utf8Json)
     {
         Utf8JsonReader reader = new(utf8Json);