Approach 2: MCP/Approvals/Tool Contents stabilization

src/Libraries/Microsoft.Extensions.AI.Abstractions/ChatCompletion/ChatResponseExtensions.cs

@@ -196,15 +196,15 @@ private static void CoalesceImageResultContent(IList<AIContent> contents)
 
         for (int i = 0; i < contents.Count; i++)
         {
-            if (contents[i] is ImageGenerationToolResultContent imageResult && !string.IsNullOrEmpty(imageResult.ImageId))
+            if (contents[i] is ImageGenerationToolResultContent imageResult)
             {
-                // Check if there's an existing ImageGenerationToolResultContent with the same ImageId to replace
+                // Check if there's an existing ImageGenerationToolResultContent with the same CallId to replace
                 if (imageResultIndexById is null)
                 {
                     imageResultIndexById = new(StringComparer.Ordinal);
                 }
 
-                if (imageResultIndexById.TryGetValue(imageResult.ImageId!, out int existingIndex))
+                if (imageResultIndexById.TryGetValue(imageResult.CallId, out int existingIndex))
                 {
                     // Replace the existing imageResult with the new one
                     contents[existingIndex] = imageResult;
@@ -213,7 +213,7 @@ private static void CoalesceImageResultContent(IList<AIContent> contents)
                 }
                 else
                 {
-                    imageResultIndexById[imageResult.ImageId!] = i;
+                    imageResultIndexById[imageResult.CallId] = i;
                 }
             }
         }
@@ -320,9 +320,8 @@ internal static void CoalesceContent(IList<AIContent> contents)
                     CoalesceContent(inputs);
                 }
 
-                return new()
+                return new(firstContent.CallId)
                 {
-                    CallId = firstContent.CallId,
                     Inputs = inputs,
                     AdditionalProperties = firstContent.AdditionalProperties?.Clone(),
                 };
@@ -331,7 +330,7 @@ internal static void CoalesceContent(IList<AIContent> contents)
         Coalesce<CodeInterpreterToolResultContent>(
             contents,
             mergeSingle: true,
-            canMerge: static (r1, r2) => r1.CallId is not null && r2.CallId is not null && r1.CallId == r2.CallId,
+            canMerge: static (r1, r2) => r1.CallId == r2.CallId,
             static (contents, start, end) =>
             {
                 var firstContent = (CodeInterpreterToolResultContent)contents[start];
@@ -358,9 +357,8 @@ internal static void CoalesceContent(IList<AIContent> contents)
                     CoalesceContent(output);
                 }
 
-                return new()
+                return new(firstContent.CallId)
                 {
-                    CallId = firstContent.CallId,
                     Outputs = output,
                     AdditionalProperties = firstContent.AdditionalProperties?.Clone(),
                 };

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIContent.cs

@@ -18,20 +18,20 @@ namespace Microsoft.Extensions.AI;
 [JsonDerivedType(typeof(TextReasoningContent), typeDiscriminator: "reasoning")]
 [JsonDerivedType(typeof(UriContent), typeDiscriminator: "uri")]
 [JsonDerivedType(typeof(UsageContent), typeDiscriminator: "usage")]
+[JsonDerivedType(typeof(ToolApprovalRequestContent), typeDiscriminator: "toolApprovalRequest")]
+[JsonDerivedType(typeof(ToolApprovalResponseContent), typeDiscriminator: "toolApprovalResponse")]
+[JsonDerivedType(typeof(McpServerToolCallContent), typeDiscriminator: "mcpServerToolCall")]
+[JsonDerivedType(typeof(McpServerToolResultContent), typeDiscriminator: "mcpServerToolResult")]
 
 // These should be added in once they're no longer [Experimental]. If they're included while still
 // experimental, any JsonSerializerContext that includes AIContent will incur errors about using
 // experimental types in its source generated files. When [Experimental] is removed from these types,
 // these lines should be uncommented and the corresponding lines in AIJsonUtilities.CreateDefaultOptions
 // as well as the [JsonSerializable] attributes for them on the JsonContext should be removed.
-// [JsonDerivedType(typeof(FunctionApprovalRequestContent), typeDiscriminator: "functionApprovalRequest")]
-// [JsonDerivedType(typeof(FunctionApprovalResponseContent), typeDiscriminator: "functionApprovalResponse")]
-// [JsonDerivedType(typeof(McpServerToolCallContent), typeDiscriminator: "mcpServerToolCall")]
-// [JsonDerivedType(typeof(McpServerToolResultContent), typeDiscriminator: "mcpServerToolResult")]
-// [JsonDerivedType(typeof(McpServerToolApprovalRequestContent), typeDiscriminator: "mcpServerToolApprovalRequest")]
-// [JsonDerivedType(typeof(McpServerToolApprovalResponseContent), typeDiscriminator: "mcpServerToolApprovalResponse")]
 // [JsonDerivedType(typeof(CodeInterpreterToolCallContent), typeDiscriminator: "codeInterpreterToolCall")]
 // [JsonDerivedType(typeof(CodeInterpreterToolResultContent), typeDiscriminator: "codeInterpreterToolResult")]
+// [JsonDerivedType(typeof(ImageGenerationToolCallContent), typeDiscriminator: "imageGenerationToolCall")]
+// [JsonDerivedType(typeof(ImageGenerationToolResultContent), typeDiscriminator: "imageGenerationToolResult")]
 
 public class AIContent
 {

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/CodeInterpreterToolCallContent.cs

@@ -15,20 +15,17 @@ namespace Microsoft.Extensions.AI;
 /// It is informational only and represents the call itself, not the result.
 /// </remarks>
 [Experimental(DiagnosticIds.Experiments.AICodeInterpreter, UrlFormat = DiagnosticIds.UrlFormat)]
-public sealed class CodeInterpreterToolCallContent : AIContent
+public sealed class CodeInterpreterToolCallContent : ToolCallContent
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="CodeInterpreterToolCallContent"/> class.
     /// </summary>
-    public CodeInterpreterToolCallContent()
+    /// <param name="callId">The tool call ID.</param>
+    public CodeInterpreterToolCallContent(string callId)
+        : base(callId)
     {
     }
 
-    /// <summary>
-    /// Gets or sets the tool call ID.
-    /// </summary>
-    public string? CallId { get; set; }
-
     /// <summary>
     /// Gets or sets the inputs to the code interpreter tool.
     /// </summary>

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/CodeInterpreterToolResultContent.cs

@@ -11,20 +11,17 @@ namespace Microsoft.Extensions.AI;
 /// Represents the result of a code interpreter tool invocation by a hosted service.
 /// </summary>
 [Experimental(DiagnosticIds.Experiments.AICodeInterpreter, UrlFormat = DiagnosticIds.UrlFormat)]
-public sealed class CodeInterpreterToolResultContent : AIContent
+public sealed class CodeInterpreterToolResultContent : ToolResultContent
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="CodeInterpreterToolResultContent"/> class.
     /// </summary>
-    public CodeInterpreterToolResultContent()
+    /// <param name="callId">The tool call ID.</param>
+    public CodeInterpreterToolResultContent(string callId)
+        : base(callId)
     {
     }
 
-    /// <summary>
-    /// Gets or sets the tool call ID that this result corresponds to.
-    /// </summary>
-    public string? CallId { get; set; }
-
     /// <summary>
     /// Gets or sets the output of code interpreter tool.
     /// </summary>

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/FunctionCallContent.cs

@@ -14,7 +14,7 @@ namespace Microsoft.Extensions.AI;
 /// Represents a function call request.
 /// </summary>
 [DebuggerDisplay("{DebuggerDisplay,nq}")]
-public class FunctionCallContent : AIContent
+public class FunctionCallContent : ToolCallContent
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="FunctionCallContent"/> class.
@@ -24,17 +24,12 @@ public class FunctionCallContent : AIContent
     /// <param name="arguments">The function original arguments.</param>
     [JsonConstructor]
     public FunctionCallContent(string callId, string name, IDictionary<string, object?>? arguments = null)
+        : base(callId)
     {
-        CallId = Throw.IfNull(callId);
         Name = Throw.IfNull(name);
         Arguments = arguments;
     }
 
-    /// <summary>
-    /// Gets the function call ID.
-    /// </summary>
-    public string CallId { get; }
-
     /// <summary>
     /// Gets the name of the function requested.
     /// </summary>
@@ -51,7 +46,7 @@ public FunctionCallContent(string callId, string name, IDictionary<string, objec
     /// <remarks>
     /// This property is for information purposes only. The <see cref="Exception"/> is not serialized as part of serializing
     /// instances of this class with <see cref="JsonSerializer"/>; as such, upon deserialization, this property will be <see langword="null"/>.
-    /// Consumers should not rely on <see langword="null"/> indicating success. 
+    /// Consumers should not rely on <see langword="null"/> indicating success.
     /// </remarks>
     [JsonIgnore]
     public Exception? Exception { get; set; }

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/FunctionResultContent.cs

@@ -5,15 +5,14 @@
 using System.Diagnostics;
 using System.Text.Json;
 using System.Text.Json.Serialization;
-using Microsoft.Shared.Diagnostics;
 
 namespace Microsoft.Extensions.AI;
 
 /// <summary>
 /// Represents the result of a function call.
 /// </summary>
 [DebuggerDisplay("{DebuggerDisplay,nq}")]
-public class FunctionResultContent : AIContent
+public class FunctionResultContent : ToolResultContent
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="FunctionResultContent"/> class.
@@ -26,20 +25,11 @@ public class FunctionResultContent : AIContent
     /// </param>
     [JsonConstructor]
     public FunctionResultContent(string callId, object? result)
+        : base(callId)
     {
-        CallId = Throw.IfNull(callId);
         Result = result;
     }
 
-    /// <summary>
-    /// Gets the ID of the function call for which this is the result.
-    /// </summary>
-    /// <remarks>
-    /// If this is the result for a <see cref="FunctionCallContent"/>, this property should contain the same
-    /// <see cref="FunctionCallContent.CallId"/> value.
-    /// </remarks>
-    public string CallId { get; }
-
     /// <summary>
     /// Gets or sets the result of the function call, or a generic error message if the function call failed.
     /// </summary>

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/ImageGenerationToolCallContent.cs

@@ -10,17 +10,14 @@ namespace Microsoft.Extensions.AI;
 /// Represents the invocation of an image generation tool call by a hosted service.
 /// </summary>
 [Experimental(DiagnosticIds.Experiments.AIImageGeneration, UrlFormat = DiagnosticIds.UrlFormat)]
-public sealed class ImageGenerationToolCallContent : AIContent
+public sealed class ImageGenerationToolCallContent : ToolCallContent
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="ImageGenerationToolCallContent"/> class.
     /// </summary>
-    public ImageGenerationToolCallContent()
+    /// <param name="callId">The tool call ID.</param>
+    public ImageGenerationToolCallContent(string callId)
+        : base(callId)
     {
     }
-
-    /// <summary>
-    /// Gets or sets the unique identifier of the image generation item.
-    /// </summary>
-    public string? ImageId { get; set; }
 }

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/ImageGenerationToolResultContent.cs

@@ -15,20 +15,17 @@ namespace Microsoft.Extensions.AI;
 /// It is informational only and represents the call itself, not the result.
 /// </remarks>
 [Experimental(DiagnosticIds.Experiments.AIImageGeneration, UrlFormat = DiagnosticIds.UrlFormat)]
-public sealed class ImageGenerationToolResultContent : AIContent
+public sealed class ImageGenerationToolResultContent : ToolResultContent
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="ImageGenerationToolResultContent"/> class.
     /// </summary>
-    public ImageGenerationToolResultContent()
+    /// <param name="callId">The tool call ID.</param>
+    public ImageGenerationToolResultContent(string callId)
+        : base(callId)
     {
     }
 
-    /// <summary>
-    /// Gets or sets the unique identifier of the image generation item.
-    /// </summary>
-    public string? ImageId { get; set; }
-
     /// <summary>
     /// Gets or sets the generated content items.
     /// </summary>

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/InputRequestContent.cs

@@ -0,0 +1,31 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Text.Json.Serialization;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Extensions.AI;
+
+/// <summary>
+/// Represents a request for input from the user or application.
+/// </summary>
+[JsonDerivedType(typeof(ToolApprovalRequestContent), "toolApprovalRequest")]
+public class InputRequestContent : AIContent
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="InputRequestContent"/> class.
+    /// </summary>
+    /// <param name="requestId">The unique identifier that correlates this request with its corresponding response.</param>
+    /// <exception cref="ArgumentNullException"><paramref name="requestId"/> is <see langword="null"/>.</exception>
+    /// <exception cref="ArgumentException"><paramref name="requestId"/> is empty or composed entirely of whitespace.</exception>
+    protected InputRequestContent(string requestId)
+    {
+        RequestId = Throw.IfNullOrWhitespace(requestId);
+    }
+
+    /// <summary>
+    /// Gets the unique identifier that correlates this request with its corresponding <see cref="InputResponseContent"/>.
+    /// </summary>
+    public string RequestId { get; }
+}