feat: implement GetMessageBatchResultsAsync method

src/AnthropicClient/AnthropicApiClient.cs

@@ -34,14 +34,21 @@ public interface IAnthropicApiClient
   /// <param name="request">The message batch request to create.</param>
   /// <returns>A task that represents the asynchronous operation. The task result contains the response as an <see cref="AnthropicResult{T}"/> where T is <see cref="MessageBatchResponse"/>.</returns>
   Task<AnthropicResult<MessageBatchResponse>> CreateMessageBatchAsync(MessageBatchRequest request);
-  
+
   /// <summary>
   /// Gets a message batch asynchronously.
   /// </summary>
   /// <param name="batchId">The ID of the message batch to get.</param>
   /// <returns>A task that represents the asynchronous operation. The task result contains the response as an <see cref="AnthropicResult{T}"/> where T is <see cref="MessageBatchResponse"/>.</returns>
   Task<AnthropicResult<MessageBatchResponse>> GetMessageBatchAsync(string batchId);
-  
+
+  /// <summary>
+  /// Gets the results of a message batch asynchronously.
+  /// </summary>
+  /// <param name="batchId">The ID of the message batch to get the results for.</param>
+  /// <returns>A task that represents the asynchronous operation. The task result contains the response as an <see cref="AnthropicResult{T}"/> where T is <see cref="IAsyncEnumerable{T}"/> where T is <see cref="MessageBatchResultItem"/>.</returns>
+  Task<AnthropicResult<IAsyncEnumerable<MessageBatchResultItem>>> GetMessageBatchResultsAsync(string batchId);
+
   /// <summary>
   /// Counts the tokens in a message asynchronously.
   /// </summary>
@@ -325,17 +332,49 @@ public class AnthropicApiClient : IAnthropicApiClient
     var response = await SendRequestAsync($"{MessageBatchesEndpoint}/{batchId}");
     var anthropicHeaders = new AnthropicHeaders(response.Headers);
     var responseContent = await response.Content.ReadAsStringAsync();
-    
+
     if (response.IsSuccessStatusCode is false)
     {
       var error = Deserialize<AnthropicError>(responseContent) ?? new AnthropicError();
       return AnthropicResult<MessageBatchResponse>.Failure(error, anthropicHeaders);
     }
-    
+
     var msgBatchResponse = Deserialize<MessageBatchResponse>(responseContent) ?? new MessageBatchResponse();
     return AnthropicResult<MessageBatchResponse>.Success(msgBatchResponse, anthropicHeaders);
   }
 
+  /// <inheritdoc/>
+  public async Task<AnthropicResult<IAsyncEnumerable<MessageBatchResultItem>>> GetMessageBatchResultsAsync(string batchId)
+  {
+    var response = await SendRequestAsync($"{MessageBatchesEndpoint}/{batchId}/results");
+    var anthropicHeaders = new AnthropicHeaders(response.Headers);
+
+    if (response.IsSuccessStatusCode is false)
+    {
+      var content = await response.Content.ReadAsStringAsync();
+      var error = Deserialize<AnthropicError>(content) ?? new AnthropicError();
+      return AnthropicResult<IAsyncEnumerable<MessageBatchResultItem>>.Failure(error, anthropicHeaders);
+    }
+
+    async IAsyncEnumerable<MessageBatchResultItem> ReadResults()
+    {
+      using var responseContent = await response.Content.ReadAsStreamAsync();
+      using var streamReader = new StreamReader(responseContent);
+
+      var line = await streamReader.ReadLineAsync();
+
+      while (line is not null)
+      {
+        var resultItem = Deserialize<MessageBatchResultItem>(line) ?? new MessageBatchResultItem();
+        yield return resultItem;
+
+        line = await streamReader.ReadLineAsync();
+      }
+    }
+
+    return AnthropicResult<IAsyncEnumerable<MessageBatchResultItem>>.Success(ReadResults(), anthropicHeaders);
+  }
+
   /// <inheritdoc/>
   public async Task<AnthropicResult<TokenCountResponse>> CountMessageTokensAsync(CountMessageTokensRequest request)
   {

src/AnthropicClient/Json/JsonSerializationOptions.cs

@@ -17,6 +17,7 @@ static class JsonSerializationOptions
       new EventDataConverter(),
       new ContentDeltaConverter(),
       new JsonStringEnumConverter(),
+      new MessageBatchResultConverter(),
     },
     DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
   };

src/AnthropicClient/Json/MessageBatchResultConverter.cs

@@ -0,0 +1,29 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+using AnthropicClient.Models;
+
+namespace AnthropicClient.Json;
+
+class MessageBatchResultConverter : JsonConverter<MessageBatchResult>
+{
+  public override MessageBatchResult Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+  {
+    using var jsonDocument = JsonDocument.ParseValue(ref reader);
+    var root = jsonDocument.RootElement;
+    var type = root.GetProperty("type").GetString();
+    return type switch
+    {
+      MessageBatchResultType.Succeeded => JsonSerializer.Deserialize<SucceededMessageBatchResult>(root.GetRawText(), options)!,
+      MessageBatchResultType.Errored => JsonSerializer.Deserialize<ErroredMessageBatchResult>(root.GetRawText(), options)!,
+      MessageBatchResultType.Canceled => JsonSerializer.Deserialize<CanceledMessageBatchResult>(root.GetRawText(), options)!,
+      MessageBatchResultType.Expired => JsonSerializer.Deserialize<ExpiredMessageBatchResult>(root.GetRawText(), options)!,
+      _ => throw new JsonException($"Unknown message batch result type: {type}")
+    };
+  }
+
+  public override void Write(Utf8JsonWriter writer, MessageBatchResult value, JsonSerializerOptions options)
+  {
+    JsonSerializer.Serialize(writer, value, value.GetType(), options);
+  }
+}

src/AnthropicClient/Models/CanceledMessageBatchResult.cs

@@ -0,0 +1,14 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result that was cancelled.
+/// </summary>
+public class CanceledMessageBatchResult : MessageBatchResult
+{
+  /// <summary>
+  /// Initializes a new instance of the <see cref="CanceledMessageBatchResult"/> class.
+  /// </summary>
+  public CanceledMessageBatchResult() : base(MessageBatchResultType.Canceled)
+  {
+  }
+}

src/AnthropicClient/Models/ErroredMessageBatchResult.cs

@@ -0,0 +1,19 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result that contains an error response.
+/// </summary>
+public class ErroredMessageBatchResult : MessageBatchResult
+{
+  /// <summary>
+  /// Gets the error of the message batch result.
+  /// </summary>
+  public AnthropicError Error { get; init; } = new AnthropicError();
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="ErroredMessageBatchResult"/> class.
+  /// </summary>
+  public ErroredMessageBatchResult() : base(MessageBatchResultType.Errored)
+  {
+  }
+}

src/AnthropicClient/Models/ExpiredMessageBatchResult.cs

@@ -0,0 +1,14 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result that has expired.
+/// </summary>
+public class ExpiredMessageBatchResult : MessageBatchResult
+{
+  /// <summary>
+  /// Initializes a new instance of the <see cref="ExpiredMessageBatchResult"/> class.
+  /// </summary>
+  public ExpiredMessageBatchResult() : base(MessageBatchResultType.Expired)
+  {
+  }
+}

src/AnthropicClient/Models/MessageBatchResult.cs

@@ -0,0 +1,26 @@
+using AnthropicClient.Utils;
+
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result.
+/// </summary>
+public abstract class MessageBatchResult
+{
+  /// <summary>
+  /// Gets the type of the message batch result.
+  /// </summary>
+  public string Type { get; init; } = string.Empty;
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="MessageBatchResult"/> class.
+  /// </summary>
+  /// <param name="type">The type of the message batch result.</param>
+  /// <returns>An instance of the <see cref="MessageBatchResult"/> class.</returns>
+  public MessageBatchResult(string type)
+  {
+    ArgumentValidator.ThrowIfNullOrWhitespace(type, nameof(type));
+
+    Type = type;
+  }
+}

src/AnthropicClient/Models/MessageBatchResultItem.cs

@@ -0,0 +1,20 @@
+using System.Text.Json.Serialization;
+
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result item.
+/// </summary>
+public class MessageBatchResultItem
+{
+  /// <summary>
+  /// Gets the custom ID of the message batch result item.
+  /// </summary>
+  [JsonPropertyName("custom_id")]
+  public string CustomId { get; init; } = string.Empty;
+
+  /// <summary>
+  /// Gets the result of the message batch result item.
+  /// </summary>
+  public MessageBatchResult Result { get; init; } = default!;
+}

src/AnthropicClient/Models/MessageBatchResultType.cs

@@ -0,0 +1,27 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents the types of message batch results.
+/// </summary>
+public static class MessageBatchResultType
+{
+  /// <summary>
+  /// Represents a succeeded message batch result.
+  /// </summary>
+  public const string Succeeded = "succeeded";
+
+  /// <summary>
+  /// Represents an errored message batch result.
+  /// </summary>
+  public const string Errored = "errored";
+
+  /// <summary>
+  /// Represents a canceled message batch result.
+  /// </summary>
+  public const string Canceled = "canceled";
+
+  /// <summary>
+  /// Represents an expired message batch result.
+  /// </summary>
+  public const string Expired = "expired";
+}

src/AnthropicClient/Models/SucceededMessageBatchResult.cs

@@ -0,0 +1,20 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result that contains a message response.
+/// </summary>
+public class SucceededMessageBatchResult : MessageBatchResult
+{
+  /// <summary>
+  /// Gets the message of the message batch result.
+  /// </summary>
+  public MessageResponse Message { get; init; } = new MessageResponse();
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="SucceededMessageBatchResult"/> class.
+  /// </summary>
+  /// <returns>An instance of the <see cref="SucceededMessageBatchResult"/> class.</returns>
+  public SucceededMessageBatchResult() : base(MessageBatchResultType.Succeeded)
+  {
+  }
+}