feat: Allow non scalar list elements to be serialized with simple collection node names

src/Kuddle.Net.Tests/Serialization/ObjectMapperTests.cs

@@ -701,6 +701,104 @@ public async Task Deserialize_FlattenedCollection_CollectsAllMatchingNodes()
         await Assert.That(result.FlattenedServers[1].Host).IsEqualTo("remote");
     }
 
+    [Test]
+    public async Task Serialize_WithSimpleCollectionNodeNames_True_UseDashNodeNames()
+    {
+        // Arrange
+        var model = new CollectionModel
+        {
+            WrappedPlugins = [new() { Name = "Auth" }],
+            FlattenedServers = [new() { Host = "localhost" }],
+        };
+
+        var options = new KdlSerializerOptions { SimpleCollectionNodeNames = true };
+
+        // Act
+        var kdl = KdlSerializer.Serialize(model, options);
+
+        // Assert - should use dash (-) for collection items
+        await Assert.That(kdl).Contains("plugins {");
+        await Assert.That(kdl).Contains("- Auth");
+    }
+
+    [Test]
+    public async Task Serialize_WithSimpleCollectionNodeNames_False_UseTypedNodeNames()
+    {
+        // Arrange
+        var model = new CollectionModel
+        {
+            WrappedPlugins = [new() { Name = "Auth" }],
+            FlattenedServers = [new() { Host = "localhost" }],
+        };
+
+        var options = new KdlSerializerOptions { SimpleCollectionNodeNames = false };
+
+        // Act
+        var kdl = KdlSerializer.Serialize(model, options);
+
+        // Assert - should use typed node names
+        await Assert.That(kdl).Contains("plugins {");
+        await Assert.That(kdl).Contains("plugin-info Auth");
+    }
+
+    [Test]
+    public async Task RoundTrip_SerializeAndDeserialize_WithSimpleCollectionNodeNames_True()
+    {
+        // Arrange
+        var originalModel = new CollectionModel
+        {
+            WrappedPlugins = [new() { Name = "Auth" }, new() { Name = "Logging" }],
+            FlattenedServers = [new() { Host = "localhost" }, new() { Host = "remote" }],
+        };
+
+        var options = new KdlSerializerOptions
+        {
+            SimpleCollectionNodeNames = true,
+            UnwrapRoot = true,
+        };
+
+        // Act
+        var kdl = KdlSerializer.Serialize(originalModel, options);
+        var deserializedModel = KdlSerializer.Deserialize<CollectionModel>(kdl, options);
+
+        // Assert
+        await Assert.That(deserializedModel.WrappedPlugins).Count().IsEqualTo(2);
+        await Assert.That(deserializedModel.WrappedPlugins[0].Name).IsEqualTo("Auth");
+        await Assert.That(deserializedModel.WrappedPlugins[1].Name).IsEqualTo("Logging");
+        await Assert.That(deserializedModel.FlattenedServers).Count().IsEqualTo(2);
+        await Assert.That(deserializedModel.FlattenedServers[0].Host).IsEqualTo("localhost");
+        await Assert.That(deserializedModel.FlattenedServers[1].Host).IsEqualTo("remote");
+    }
+
+    [Test]
+    public async Task RoundTrip_SerializeAndDeserialize_WithSimpleCollectionNodeNames_False()
+    {
+        // Arrange
+        var originalModel = new CollectionModel
+        {
+            WrappedPlugins = [new() { Name = "Auth" }, new() { Name = "Logging" }],
+            FlattenedServers = [new() { Host = "localhost" }, new() { Host = "remote" }],
+        };
+
+        var options = new KdlSerializerOptions
+        {
+            SimpleCollectionNodeNames = false,
+            UnwrapRoot = false,
+        };
+
+        // Act
+        var kdl = KdlSerializer.Serialize(originalModel, options);
+        var deserializedModel = KdlSerializer.Deserialize<CollectionModel>(kdl, options);
+
+        // Assert
+        await Assert.That(deserializedModel.WrappedPlugins).Count().IsEqualTo(2);
+        await Assert.That(deserializedModel.WrappedPlugins[0].Name).IsEqualTo("Auth");
+        await Assert.That(deserializedModel.WrappedPlugins[1].Name).IsEqualTo("Logging");
+        await Assert.That(deserializedModel.FlattenedServers).Count().IsEqualTo(2);
+        await Assert.That(deserializedModel.FlattenedServers[0].Host).IsEqualTo("localhost");
+        await Assert.That(deserializedModel.FlattenedServers[1].Host).IsEqualTo("remote");
+    }
+
     #endregion
 
     #region Test Models

src/Kuddle.Net/Serialization/KdlSerializerOptions.cs

@@ -5,6 +5,11 @@ namespace Kuddle.Serialization;
 /// </summary>
 public record KdlSerializerOptions
 {
+    /// <summary>
+    /// Default options instance.
+    /// </summary>
+    public static KdlSerializerOptions Default { get; } = new();
+
     /// <summary>
     /// Whether to ignore null values when serializing. Default is true.
     /// </summary>
@@ -21,8 +26,8 @@ public record KdlSerializerOptions
     public bool WriteTypeAnnotations { get; init; } = true;
 
     /// <summary>
-    /// Default options instance.
+    /// Whether to use simple dash (-) for collection item node names instead of the mapped type name. Default is true.
     /// </summary>
-    public static KdlSerializerOptions Default { get; } = new();
+    public bool SimpleCollectionNodeNames { get; init; } = true;
     public bool UnwrapRoot { get; init; } = false;
 }

src/Kuddle.Net/Serialization/ObjectDeserializer.cs

@@ -25,6 +25,17 @@ internal static T DeserializeDocument<T>(KdlDocument doc, KdlSerializerOptions?
 
         var mapping = KdlTypeMapping.For<T>();
         var instance = new T();
+        if (options?.UnwrapRoot == false)
+        {
+            if (doc.Nodes.Count != 1)
+            {
+                throw new KuddleSerializationException(
+                    $"Expected exactly 1 root node, but found {doc.Nodes.Count}."
+                );
+            }
+            worker.MapNodeToObject(doc.Nodes.First(), instance, mapping);
+            return instance;
+        }
 
         if (mapping.Arguments.Count > 0 || mapping.Properties.Count > 0)
         {

src/Kuddle.Net/Serialization/ObjectSerializer.cs

@@ -60,10 +60,10 @@ internal static KdlDocument SerializeDocument<T>(T? instance, KdlSerializerOptio
                     // Map positional arguments to anonymous nodes
                     doc.Nodes.Add(new KdlNode(KdlValue.From("-")) { Entries = [arg] });
                 }
-                if (rootNode.Children != null)
-                {
-                    doc.Nodes.AddRange(rootNode.Children.Nodes);
-                }
+            }
+            if (rootNode.Children != null)
+            {
+                doc.Nodes.AddRange(rootNode.Children.Nodes);
             }
         }
         else
@@ -198,8 +198,15 @@ private IEnumerable<KdlNode> SerializeCollection(IEnumerable enumerable, KdlMemb
         }
     }
 
-    private static string GetDefaultNodeName(object item) =>
-        item.GetType().IsKdlScalar ? "-" : KdlTypeMapping.For(item.GetType()).NodeName;
+    private string GetDefaultNodeName(object item)
+    {
+        if (item.GetType().IsKdlScalar)
+            return "-";
+
+        return _options.SimpleCollectionNodeNames
+            ? "-"
+            : KdlTypeMapping.For(item.GetType()).NodeName;
+    }
 
     private KdlNode MapToNode(object item, string kdlName, string? typeAnnotation)
     {