feat: initial pass at citations in request and response

src/AnthropicClient/Models/CitationType.cs

@@ -0,0 +1,8 @@
+namespace AnthropicClient.Models;
+
+public static class CitationType
+{
+  public const string CharacterLocation = "char_location";
+  public const string PageLocation = "page_location";
+  public const string ContentBlockLocation = "content_block_location";
+}

src/AnthropicClient/Models/DocumentContent.cs

@@ -14,6 +14,12 @@ public class DocumentContent : Content
   /// </summary>
   public DocumentSource Source { get; init; } = new();
 
+  public string Title { get; init; } = string.Empty;
+
+  public string Context { get; init; } = string.Empty;
+
+  public CitationOption Citations { get; init; } = new CitationOption();
+
   [JsonConstructor]
   internal DocumentContent()
   {
@@ -53,4 +59,24 @@ public class DocumentContent : Content
 
     Source = new(mediaType, data);
   }
+
+  public DocumentContent(DocumentSource source) : base(ContentType.Document)
+  {
+    ArgumentValidator.ThrowIfNull(source, nameof(source));
+
+    Source = source;
+  }
+
+  public DocumentContent(DocumentSource source, CacheControl cacheControl) : base(ContentType.Document, cacheControl)
+  {
+    ArgumentValidator.ThrowIfNull(source, nameof(source));
+
+    Source = source;
+  }
+}
+
+
+public class CitationOption
+{
+  public bool Enabled { get; init; }
 }

src/AnthropicClient/Models/TextContent.cs

@@ -14,6 +14,8 @@ public class TextContent : Content
   /// </summary>
   public string Text { get; init; } = string.Empty;
 
+  public Citation[] Citations { get; init; } = [];
+
   [JsonConstructor]
   internal TextContent() : base(ContentType.Text)
   {
@@ -50,4 +52,45 @@ public class TextContent : Content
 
     Text = text;
   }
+}
+
+public abstract class Citation
+{
+  public string Type { get; init; } = string.Empty;
+
+  [JsonPropertyName("cited_text")]
+  public string CitedText { get; init; } = string.Empty;
+
+  [JsonPropertyName("document_index")]
+  public int DocumentIndex { get; init; }
+
+  [JsonPropertyName("document_title")]
+  public string DocumentTitle { get; init; } = string.Empty;
+}
+
+public class CharacterLocationCitation : Citation
+{
+  [JsonPropertyName("start_char_index")]
+  public int StartCharIndex { get; init; }
+
+  [JsonPropertyName("end_char_index")]
+  public int EndCharIndex { get; init; }
+}
+
+public class PageLocationCitation : Citation
+{
+  [JsonPropertyName("start_page_number")]
+  public int StartPageNumber { get; init; }
+
+  [JsonPropertyName("end_page_number")]
+  public int EndPageNumber { get; init; }
+}
+
+public class ContentBlockLocationCitation : Citation
+{
+  [JsonPropertyName("start_block_index")]
+  public int StartBlockIndex { get; init; }
+
+  [JsonPropertyName("end_block_index")]
+  public int EndBlockIndex { get; init; }
 }

src/AnthropicClient/Models/TextDocumentSource.cs

@@ -0,0 +1,11 @@
+namespace AnthropicClient.Models;
+
+public class TextDocumentSource : DocumentSource
+{
+  public TextDocumentSource(string data) : base("text/plain", data)
+  {
+    Type = "text";
+  }
+}
+
+