feat: add support for citations when streaming

src/AnthropicClient/Models/CitationDelta.cs

@@ -0,0 +1,30 @@
+using System.Text.Json.Serialization;
+
+using AnthropicClient.Utils;
+
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a citation delta.
+/// </summary>
+public class CitationDelta : ContentDelta
+{
+  /// <summary>
+  /// Gets the citation associated with this delta.
+  /// </summary>
+  public Citation Citation { get; init; } = new CharacterLocationCitation();
+
+  [JsonConstructor]
+  internal CitationDelta() : base(ContentDeltaType.CitationDelta)
+  {
+  }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="CitationDelta"/> class.
+  /// </summary>
+  public CitationDelta(Citation citation) : base(ContentDeltaType.CitationDelta)
+  {
+    ArgumentValidator.ThrowIfNull(citation, nameof(citation));
+    Citation = citation;
+  }
+}

src/AnthropicClient/Models/ContentDeltaType.cs

@@ -14,4 +14,9 @@ public static class ContentDeltaType
   /// The input_json_delta.
   /// </summary>
   public const string JsonDelta = "input_json_delta";
+
+  /// <summary>
+  /// The citation_delta.
+  /// </summary>
+  public const string CitationDelta = "citations_delta";
 }