Add support for InputImageUrl via reflection in OpenAIResponsesChatClient

src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIResponsesChatClient.cs

@@ -46,6 +46,12 @@ private static readonly Func<ResponsesClient, GetResponseOptions, RequestOptions
             null, [typeof(GetResponseOptions), typeof(RequestOptions)], null)
         ?.CreateDelegate(typeof(Func<ResponsesClient, GetResponseOptions, RequestOptions, AsyncCollectionResult<StreamingResponseUpdate>>));
 
+    // Workaround for https://github.com/openai/openai-dotnet/pull/874.
+    // The OpenAI library doesn't yet expose InputImageUrl as a public property, so we access it via reflection.
+    // Replace this with the actual public property once it's available (e.g., part.InputImageUrl).
+    private static readonly PropertyInfo? _inputImageUrlProperty =
+        Type.GetType("OpenAI.Responses.InternalItemContentInputImage, OpenAI")?.GetProperty("ImageUrl");
+
     /// <summary>Metadata about the client.</summary>
     private readonly ChatClientMetadata _metadata;
 
@@ -1192,11 +1198,38 @@ private static List<AIContent> ToAIContents(IEnumerable<ResponseContentPart> con
                     break;
 
                 case ResponseContentPartKind.InputFile or ResponseContentPartKind.InputImage:
-                    content =
-                        !string.IsNullOrWhiteSpace(part.InputImageFileId) ? new HostedFileContent(part.InputImageFileId) { MediaType = "image/*" } :
-                        !string.IsNullOrWhiteSpace(part.InputFileId) ? new HostedFileContent(part.InputFileId) { Name = part.InputFilename } :
-                        part.InputFileBytes is not null ? new DataContent(part.InputFileBytes, part.InputFileBytesMediaType ?? "application/octet-stream") { Name = part.InputFilename } :
-                        null;
+                    if (!string.IsNullOrWhiteSpace(part.InputImageFileId))
+                    {
+                        content = new HostedFileContent(part.InputImageFileId) { MediaType = "image/*" };
+                    }
+                    else if (!string.IsNullOrWhiteSpace(part.InputFileId))
+                    {
+                        content = new HostedFileContent(part.InputFileId) { Name = part.InputFilename };
+                    }
+                    else if (part.InputFileBytes is not null)
+                    {
+                        content = new DataContent(part.InputFileBytes, part.InputFileBytesMediaType ?? "application/octet-stream") { Name = part.InputFilename };
+                    }
+                    else if (_inputImageUrlProperty?.GetValue(part) is string inputImageUrl)
+                    {
+                        if (inputImageUrl.StartsWith("data:", StringComparison.OrdinalIgnoreCase))
+                        {
+                            content = new DataContent(inputImageUrl);
+                        }
+                        else if (Uri.TryCreate(inputImageUrl, UriKind.Absolute, out Uri? imageUri))
+                        {
+                            content = new UriContent(imageUri, "image/*");
+                        }
+                        else
+                        {
+                            content = null;
+                        }
+                    }
+                    else
+                    {
+                        content = null;
+                    }
+
                     break;
 
                 case ResponseContentPartKind.Refusal:

test/Libraries/Microsoft.Extensions.AI.OpenAI.Tests/OpenAIResponseClientTests.cs

@@ -5198,6 +5198,132 @@ public async Task ResponseWithRefusalContent_ParsesCorrectly()
         Assert.Equal("Refusal", errorContent.ErrorCode);
     }
 
+    [Fact]
+    public async Task ResponseWithInputImageHttpUrl_ParsesAsUriContent()
+    {
+        const string Input = """
+            {
+                "model":"gpt-4o-mini",
+                "input":[{"type":"message","role":"user","content":[{"type":"input_text","text":"What is in this image?"}]}]
+            }
+            """;
+
+        // The output includes a message with input_image content that has an image_url property with HTTP URL.
+        const string Output = """
+            {
+              "id":"resp_001",
+              "object":"response",
+              "created_at":1741892091,
+              "status":"completed",
+              "model":"gpt-4o-mini",
+              "output":[
+                {
+                  "type":"message",
+                  "id":"msg_001",
+                  "status":"completed",
+                  "role":"user",
+                  "content":[
+                    {"type":"input_image","image_url":"https://example.com/image.png"}
+                  ]
+                },
+                {
+                  "type":"message",
+                  "id":"msg_002",
+                  "status":"completed",
+                  "role":"assistant",
+                  "content":[
+                    {"type":"output_text","text":"This is a cat.","annotations":[]}
+                  ]
+                }
+              ]
+            }
+            """;
+
+        using VerbatimHttpHandler handler = new(Input, Output);
+        using HttpClient httpClient = new(handler);
+        using IChatClient client = CreateResponseClient(httpClient, "gpt-4o-mini");
+
+        var response = await client.GetResponseAsync("What is in this image?");
+
+        Assert.NotNull(response);
+
+        var userMessage = response.Messages.FirstOrDefault(m => m.Role == ChatRole.User);
+        Assert.NotNull(userMessage);
+
+        // HTTP URL should be returned as UriContent
+        var imageContent = userMessage.Contents.OfType<UriContent>().FirstOrDefault();
+        Assert.NotNull(imageContent);
+        Assert.Equal("https://example.com/image.png", imageContent.Uri.ToString());
+        Assert.Equal("image/*", imageContent.MediaType);
+
+        var assistantMessage = response.Messages.LastOrDefault(m => m.Role == ChatRole.Assistant);
+        Assert.NotNull(assistantMessage);
+        Assert.Equal("This is a cat.", assistantMessage.Text);
+    }
+
+    [Fact]
+    public async Task ResponseWithInputImageDataUri_ParsesAsDataContent()
+    {
+        const string Input = """
+            {
+                "model":"gpt-4o-mini",
+                "input":[{"type":"message","role":"user","content":[{"type":"input_text","text":"What is in this image?"}]}]
+            }
+            """;
+
+        // The output includes a message with input_image content that has an image_url property with a data URI.
+        const string Output = """
+            {
+              "id":"resp_001",
+              "object":"response",
+              "created_at":1741892091,
+              "status":"completed",
+              "model":"gpt-4o-mini",
+              "output":[
+                {
+                  "type":"message",
+                  "id":"msg_001",
+                  "status":"completed",
+                  "role":"user",
+                  "content":[
+                    {"type":"input_image","image_url":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg=="}
+                  ]
+                },
+                {
+                  "type":"message",
+                  "id":"msg_002",
+                  "status":"completed",
+                  "role":"assistant",
+                  "content":[
+                    {"type":"output_text","text":"This is a red pixel.","annotations":[]}
+                  ]
+                }
+              ]
+            }
+            """;
+
+        using VerbatimHttpHandler handler = new(Input, Output);
+        using HttpClient httpClient = new(handler);
+        using IChatClient client = CreateResponseClient(httpClient, "gpt-4o-mini");
+
+        var response = await client.GetResponseAsync("What is in this image?");
+
+        Assert.NotNull(response);
+
+        var userMessage = response.Messages.FirstOrDefault(m => m.Role == ChatRole.User);
+        Assert.NotNull(userMessage);
+
+        // Data URI should be returned as DataContent
+        var imageContent = userMessage.Contents.OfType<DataContent>().FirstOrDefault();
+        Assert.NotNull(imageContent);
+        Assert.Equal("image/png", imageContent.MediaType);
+        Assert.True(imageContent.Data.Length > 0);
+
+        var assistantMessage = response.Messages.LastOrDefault(m => m.Role == ChatRole.Assistant);
+        Assert.NotNull(assistantMessage);
+        Assert.Equal("This is a red pixel.", assistantMessage.Text);
+    }
+
     [Fact]
     public async Task HostedImageGenerationTool_NonStreaming()
     {