Fix MIME type handling for image URIs in DataContent and UriContent constructors

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/ChatCompletions/Converters/MessageContentPartConverter.cs

@@ -26,7 +26,7 @@ private static string AudioFormatToMediaType(string format) =>
             // image
             ImageContentPart imagePart when !string.IsNullOrEmpty(imagePart.UrlOrData) =>
                 imagePart.UrlOrData.StartsWith("data:", StringComparison.OrdinalIgnoreCase)
-                    ? new DataContent(imagePart.UrlOrData, "image/*")
+                    ? new DataContent(imagePart.UrlOrData)
                     : new UriContent(imagePart.Url, ImageUriToMediaType(imagePart.Url)),
 
             // audio

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/Responses/Converters/ItemContentConverter.cs

@@ -28,6 +28,19 @@ private static string MediaTypeToAudioFormat(string mediaType) =>
         mediaType.Equals("audio/flac", StringComparison.OrdinalIgnoreCase) ? "flac" :
         mediaType.Equals("audio/pcm", StringComparison.OrdinalIgnoreCase) ? "pcm16" :
         "mp3";
+
+    private static string ImageUriToMediaType(string uri)
+    {
+        return
+            uri.EndsWith(".png", StringComparison.OrdinalIgnoreCase) ? "image/png" :
+            uri.EndsWith(".jpg", StringComparison.OrdinalIgnoreCase) ? "image/jpeg" :
+            uri.EndsWith(".jpeg", StringComparison.OrdinalIgnoreCase) ? "image/jpeg" :
+            uri.EndsWith(".gif", StringComparison.OrdinalIgnoreCase) ? "image/gif" :
+            uri.EndsWith(".bmp", StringComparison.OrdinalIgnoreCase) ? "image/bmp" :
+            uri.EndsWith(".webp", StringComparison.OrdinalIgnoreCase) ? "image/webp" :
+            "image/*";
+    }
+
     /// <summary>
     /// Converts <see cref="ItemContent"/> to <see cref="AIContent"/>.
     /// </summary>
@@ -53,8 +66,8 @@ private static string MediaTypeToAudioFormat(string mediaType) =>
             // Image content
             ItemContentInputImage inputImage when !string.IsNullOrEmpty(inputImage.ImageUrl) =>
                 inputImage.ImageUrl!.StartsWith("data:", StringComparison.OrdinalIgnoreCase)
-                    ? new DataContent(inputImage.ImageUrl, "image/*")
-                    : new UriContent(inputImage.ImageUrl, "image/*"),
+                    ? new DataContent(inputImage.ImageUrl)
+                    : new UriContent(inputImage.ImageUrl, ImageUriToMediaType(inputImage.ImageUrl)),
             ItemContentInputImage inputImage when !string.IsNullOrEmpty(inputImage.FileId) =>
                 new HostedFileContent(inputImage.FileId!),
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Extensions/ChatMessageExtensions.cs

@@ -174,10 +174,22 @@ private static IEnumerable<AIContent> GetContent(this RecordDataValue message)
         }
     }
 
+    private static string ImageUriToMediaType(string uri)
+    {
+        return
+            uri.EndsWith(".png", StringComparison.OrdinalIgnoreCase) ? "image/png" :
+            uri.EndsWith(".jpg", StringComparison.OrdinalIgnoreCase) ? "image/jpeg" :
+            uri.EndsWith(".jpeg", StringComparison.OrdinalIgnoreCase) ? "image/jpeg" :
+            uri.EndsWith(".gif", StringComparison.OrdinalIgnoreCase) ? "image/gif" :
+            uri.EndsWith(".bmp", StringComparison.OrdinalIgnoreCase) ? "image/bmp" :
+            uri.EndsWith(".webp", StringComparison.OrdinalIgnoreCase) ? "image/webp" :
+            "image/*";
+    }
+
     private static AIContent GetImageContent(string uriText) =>
         uriText.StartsWith("data:", StringComparison.OrdinalIgnoreCase) ?
-            new DataContent(uriText, "image/*") :
-            new UriContent(uriText, "image/*");
+            new DataContent(uriText) :
+            new UriContent(uriText, ImageUriToMediaType(uriText));
 
     private static TValue? GetProperty<TValue>(this RecordDataValue record, string name)
         where TValue : DataValue

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/ItemContentConverterTests.cs

@@ -0,0 +1,200 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using Microsoft.Agents.AI.Hosting.OpenAI.Responses.Converters;
+using Microsoft.Agents.AI.Hosting.OpenAI.Responses.Models;
+using Microsoft.Extensions.AI;
+
+namespace Microsoft.Agents.AI.Hosting.OpenAI.UnitTests;
+
+/// <summary>
+/// Tests for ItemContentConverter focusing on MIME type handling for image URIs.
+/// </summary>
+public sealed class ItemContentConverterTests
+{
+    [Theory]
+    [InlineData("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==", "image/png")]
+    [InlineData("data:image/jpeg;base64,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", "image/jpeg")]
+    [InlineData("data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==", "image/gif")]
+    [InlineData("data:image/webp;base64,UklGRiQAAABXRUJQVlA4IBgAAAAwAQCdASoBAAEAAgA0JaQAA3AA/vuUAAA=", "image/webp")]
+    [InlineData("data:image/bmp;base64,Qk0eAAAAAAAAABoAAAAMAAAAAQAAAAEAAAABACAAAAA=", "image/bmp")]
+    public void ToAIContent_DataUri_PreservesMimeType(string dataUri, string expectedMediaType)
+    {
+        // Arrange
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = dataUri
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        DataContent dataContent = Assert.IsType<DataContent>(result);
+        Assert.Equal(expectedMediaType, dataContent.MediaType);
+        Assert.Equal(dataUri, dataContent.Uri);
+    }
+
+    [Theory]
+    [InlineData("https://example.com/image.png", "image/png")]
+    [InlineData("https://example.com/photo.jpg", "image/jpeg")]
+    [InlineData("https://example.com/photo.jpeg", "image/jpeg")]
+    [InlineData("https://example.com/animation.gif", "image/gif")]
+    [InlineData("https://example.com/picture.bmp", "image/bmp")]
+    [InlineData("https://example.com/modern.webp", "image/webp")]
+    [InlineData("https://example.com/IMAGE.PNG", "image/png")] // Case insensitive
+    [InlineData("https://example.com/PHOTO.JPG", "image/jpeg")] // Case insensitive
+    public void ToAIContent_HttpUri_InfersMimeTypeFromExtension(string uri, string expectedMediaType)
+    {
+        // Arrange
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = uri
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        UriContent uriContent = Assert.IsType<UriContent>(result);
+        Assert.Equal(expectedMediaType, uriContent.MediaType);
+        Assert.Equal(uri, uriContent.Uri?.ToString());
+    }
+
+    [Theory]
+    [InlineData("https://example.com/image")]
+    [InlineData("https://example.com/image.unknown")]
+    [InlineData("https://example.com/image.txt")]
+    public void ToAIContent_HttpUri_UnknownExtension_UsesGenericMimeType(string uri)
+    {
+        // Arrange
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = uri
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        UriContent uriContent = Assert.IsType<UriContent>(result);
+        Assert.Equal("image/*", uriContent.MediaType);
+        Assert.Equal(uri, uriContent.Uri?.ToString());
+    }
+
+    [Fact]
+    public void ToAIContent_DataUriPng_CreatesDataContent()
+    {
+        // Arrange
+        const string DataUri = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==";
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = DataUri
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        DataContent dataContent = Assert.IsType<DataContent>(result);
+        Assert.Equal("image/png", dataContent.MediaType);
+        Assert.Equal(DataUri, dataContent.Uri);
+    }
+
+    [Fact]
+    public void ToAIContent_HttpUriPng_CreatesUriContent()
+    {
+        // Arrange
+        const string Uri = "https://example.com/test.png";
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = Uri
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        UriContent uriContent = Assert.IsType<UriContent>(result);
+        Assert.Equal("image/png", uriContent.MediaType);
+        Assert.Equal(Uri, uriContent.Uri?.ToString());
+    }
+
+    [Fact]
+    public void ToAIContent_FileId_CreatesHostedFileContent()
+    {
+        // Arrange
+        const string FileId = "file-abc123";
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            FileId = FileId
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        HostedFileContent hostedFile = Assert.IsType<HostedFileContent>(result);
+        Assert.Equal(FileId, hostedFile.FileId);
+    }
+
+    [Fact]
+    public void ToAIContent_NullImageUrl_ReturnsNull()
+    {
+        // Arrange
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = null
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void ToAIContent_EmptyImageUrl_ReturnsNull()
+    {
+        // Arrange
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = string.Empty
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void ToAIContent_PreservesImageDetail()
+    {
+        // Arrange
+        const string Uri = "https://example.com/test.png";
+        ItemContentInputImage inputImage = new ItemContentInputImage
+        {
+            ImageUrl = Uri,
+            Detail = "high"
+        };
+
+        // Act
+        AIContent? result = ItemContentConverter.ToAIContent(inputImage);
+
+        // Assert
+        Assert.NotNull(result);
+        UriContent uriContent = Assert.IsType<UriContent>(result);
+        Assert.NotNull(uriContent.AdditionalProperties);
+        Assert.True(uriContent.AdditionalProperties.TryGetValue("detail", out object? detail));
+        Assert.Equal("high", detail?.ToString());
+    }
+}