.Net: Add FunctionChoiceBehavior support to Google Gemini connector

dotnet/src/Connectors/Connectors.Google.UnitTests/GeminiToolCallBehaviorTests.cs

@@ -194,6 +194,111 @@ public void KernelFunctionsCloneReturnsCorrectClone()
         Assert.Equivalent(toolcallbehavior, clone, strict: true);
     }
 
+    [Fact]
+    public void FunctionChoiceBehaviorAutoConvertsToAutoInvokeKernelFunctions()
+    {
+        // Arrange
+        var settings = new GeminiPromptExecutionSettings
+        {
+            FunctionChoiceBehavior = FunctionChoiceBehavior.Auto()
+        };
+
+        // Act
+        var converted = GeminiPromptExecutionSettings.FromExecutionSettings(settings);
+
+        // Assert
+        Assert.NotNull(converted.ToolCallBehavior);
+        Assert.IsType<GeminiToolCallBehavior.KernelFunctions>(converted.ToolCallBehavior);
+        Assert.True(converted.ToolCallBehavior.MaximumAutoInvokeAttempts > 0);
+    }
+
+    [Fact]
+    public void FunctionChoiceBehaviorAutoWithNoAutoInvokeConvertsToEnableKernelFunctions()
+    {
+        // Arrange
+        var settings = new GeminiPromptExecutionSettings
+        {
+            FunctionChoiceBehavior = FunctionChoiceBehavior.Auto(autoInvoke: false)
+        };
+
+        // Act
+        var converted = GeminiPromptExecutionSettings.FromExecutionSettings(settings);
+
+        // Assert
+        Assert.NotNull(converted.ToolCallBehavior);
+        Assert.IsType<GeminiToolCallBehavior.KernelFunctions>(converted.ToolCallBehavior);
+        Assert.Equal(0, converted.ToolCallBehavior.MaximumAutoInvokeAttempts);
+    }
+
+    [Fact]
+    public void FunctionChoiceBehaviorRequiredConvertsToAutoInvokeKernelFunctions()
+    {
+        // Arrange
+        var settings = new GeminiPromptExecutionSettings
+        {
+            FunctionChoiceBehavior = FunctionChoiceBehavior.Required()
+        };
+
+        // Act
+        var converted = GeminiPromptExecutionSettings.FromExecutionSettings(settings);
+
+        // Assert
+        Assert.NotNull(converted.ToolCallBehavior);
+        Assert.IsType<GeminiToolCallBehavior.KernelFunctions>(converted.ToolCallBehavior);
+        Assert.True(converted.ToolCallBehavior.MaximumAutoInvokeAttempts > 0);
+    }
+
+    [Fact]
+    public void FunctionChoiceBehaviorNoneConvertsToEnableKernelFunctions()
+    {
+        // Arrange
+        var settings = new GeminiPromptExecutionSettings
+        {
+            FunctionChoiceBehavior = FunctionChoiceBehavior.None()
+        };
+
+        // Act
+        var converted = GeminiPromptExecutionSettings.FromExecutionSettings(settings);
+
+        // Assert
+        Assert.NotNull(converted.ToolCallBehavior);
+        Assert.IsType<GeminiToolCallBehavior.KernelFunctions>(converted.ToolCallBehavior);
+        // None behavior doesn't auto-invoke
+        Assert.Equal(0, converted.ToolCallBehavior.MaximumAutoInvokeAttempts);
+    }
+
+    [Fact]
+    public void GeminiPromptExecutionSettingsWithNoFunctionChoiceBehaviorDoesNotSetToolCallBehavior()
+    {
+        // Arrange
+        var settings = new GeminiPromptExecutionSettings();
+
+        // Act
+        var converted = GeminiPromptExecutionSettings.FromExecutionSettings(settings);
+
+        // Assert
+        Assert.Null(converted.ToolCallBehavior);
+    }
+
+    [Fact]
+    public void GeminiPromptExecutionSettingsPreservesExistingToolCallBehavior()
+    {
+        // Arrange
+        var settings = new GeminiPromptExecutionSettings
+        {
+            ToolCallBehavior = GeminiToolCallBehavior.EnableKernelFunctions,
+            FunctionChoiceBehavior = FunctionChoiceBehavior.Auto()
+        };
+
+        // Act
+        var converted = GeminiPromptExecutionSettings.FromExecutionSettings(settings);
+
+        // Assert - ToolCallBehavior should be preserved when already set
+        Assert.NotNull(converted.ToolCallBehavior);
+        Assert.IsType<GeminiToolCallBehavior.KernelFunctions>(converted.ToolCallBehavior);
+        Assert.Equal(0, converted.ToolCallBehavior.MaximumAutoInvokeAttempts);
+    }
+
     private static KernelPlugin GetTestPlugin()
     {
         var function = KernelFunctionFactory.CreateFromMethod(

dotnet/src/Connectors/Connectors.Google/GeminiPromptExecutionSettings.cs

@@ -188,6 +188,9 @@ public IDictionary<string, string>? Labels
     /// the function, and sending back the result. The intermediate messages will be retained in the
     /// <see cref="ChatHistory"/> if an instance was provided.
     /// </remarks>
+    /// <remarks>
+    /// This property is deprecated. Use <see cref="PromptExecutionSettings.FunctionChoiceBehavior"/> instead.
+    /// </remarks>
     public GeminiToolCallBehavior? ToolCallBehavior
     {
         get => this._toolCallBehavior;
@@ -357,11 +360,72 @@ public static GeminiPromptExecutionSettings FromExecutionSettings(PromptExecutio
         {
             case null:
                 return new GeminiPromptExecutionSettings();
-            case GeminiPromptExecutionSettings settings:
-                return settings;
+            case GeminiPromptExecutionSettings geminiSettings:
+                // If FunctionChoiceBehavior is set and ToolCallBehavior is not, convert it
+                if (geminiSettings.FunctionChoiceBehavior is not null && geminiSettings.ToolCallBehavior is null)
+                {
+                    geminiSettings.ToolCallBehavior = ConvertFunctionChoiceBehaviorToToolCallBehavior(geminiSettings.FunctionChoiceBehavior);
+                }
+                return geminiSettings;
         }
 
         var json = JsonSerializer.Serialize(executionSettings);
-        return JsonSerializer.Deserialize<GeminiPromptExecutionSettings>(json, JsonOptionsCache.ReadPermissive)!;
+        var settings = JsonSerializer.Deserialize<GeminiPromptExecutionSettings>(json, JsonOptionsCache.ReadPermissive)!;
+
+        // If FunctionChoiceBehavior is set and ToolCallBehavior is not, convert it
+        if (executionSettings.FunctionChoiceBehavior is not null && settings.ToolCallBehavior is null)
+        {
+            settings.ToolCallBehavior = ConvertFunctionChoiceBehaviorToToolCallBehavior(executionSettings.FunctionChoiceBehavior);
+        }
+
+        return settings;
+    }
+
+    /// <summary>
+    /// Converts a <see cref="FunctionChoiceBehavior"/> to a <see cref="GeminiToolCallBehavior"/>.
+    /// </summary>
+    /// <param name="functionChoiceBehavior">The <see cref="FunctionChoiceBehavior"/> to convert.</param>
+    /// <returns>The converted <see cref="GeminiToolCallBehavior"/>.</returns>
+    internal static GeminiToolCallBehavior? ConvertFunctionChoiceBehaviorToToolCallBehavior(FunctionChoiceBehavior? functionChoiceBehavior)
+    {
+        if (functionChoiceBehavior is null)
+        {
+            return null;
+        }
+
+        // Static empty kernel to avoid creating new instances for each conversion
+        static Kernel GetEmptyKernel()
+        {
+            return new Kernel();
+        }
+
+        // Check the type and determine auto-invoke by reflection or known behavior types
+        // All FunctionChoiceBehavior types (Auto, Required, None) support auto-invoke
+        // We use a simple approach: get the configuration with minimal context to check AutoInvoke
+        try
+        {
+            var context = new FunctionChoiceBehaviorConfigurationContext(new ChatHistory())
+            {
+                Kernel = GetEmptyKernel(), // Provide an empty kernel for the configuration
+                RequestSequenceIndex = 0
+            };
+            var config = functionChoiceBehavior.GetConfiguration(context);
+
+            // Return appropriate GeminiToolCallBehavior based on AutoInvoke setting
+            if (config.AutoInvoke)
+            {
+                return GeminiToolCallBehavior.AutoInvokeKernelFunctions;
+            }
+
+            return GeminiToolCallBehavior.EnableKernelFunctions;
+        }
+#pragma warning disable CA1031 // Do not catch general exception types
+        catch
+#pragma warning restore CA1031
+        {
+            // If we can't get configuration (e.g., due to missing dependencies or unexpected state),
+            // default to EnableKernelFunctions as the safer option that doesn't auto-invoke
+            return GeminiToolCallBehavior.EnableKernelFunctions;
+        }
     }
 }

dotnet/src/Connectors/Connectors.Google/Models/Gemini/GeminiChatMessageContent.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -38,6 +39,16 @@ public GeminiChatMessageContent(GeminiFunctionToolResult calledToolResult)
         Verify.NotNull(calledToolResult);
 
         this.CalledToolResult = calledToolResult;
+
+        // Parse plugin and function names from FullyQualifiedName
+        var (pluginName, functionName) = ParseFullyQualifiedName(calledToolResult.FullyQualifiedName);
+
+        // Also populate Items collection with FunctionResultContent for compatibility with FunctionChoiceBehavior
+        this.Items.Add(new FunctionResultContent(
+            functionName: functionName,
+            pluginName: pluginName,
+            callId: null, // Gemini doesn't provide call IDs
+            result: calledToolResult.FunctionResult));
     }
 
     /// <summary>
@@ -63,6 +74,35 @@ internal GeminiChatMessageContent(
             metadata: metadata)
     {
         this.CalledToolResult = calledToolResult;
+
+        // Also populate Items collection with FunctionResultContent for compatibility with FunctionChoiceBehavior
+        if (calledToolResult is not null)
+        {
+            // Parse plugin and function names from FullyQualifiedName
+            var (pluginName, functionName) = ParseFullyQualifiedName(calledToolResult.FullyQualifiedName);
+
+            this.Items.Add(new FunctionResultContent(
+                functionName: functionName,
+                pluginName: pluginName,
+                callId: null, // Gemini doesn't provide call IDs
+                result: calledToolResult.FunctionResult));
+        }
+    }
+
+    /// <summary>
+    /// Parses a fully qualified function name into plugin name and function name.
+    /// </summary>
+    private static (string? PluginName, string FunctionName) ParseFullyQualifiedName(string fullyQualifiedName)
+    {
+        int separatorPos = fullyQualifiedName.IndexOf(GeminiFunction.NameSeparator, StringComparison.Ordinal);
+        if (separatorPos >= 0)
+        {
+            string pluginName = fullyQualifiedName.Substring(0, separatorPos).Trim();
+            string functionName = fullyQualifiedName.Substring(separatorPos + GeminiFunction.NameSeparator.Length).Trim();
+            return (pluginName, functionName);
+        }
+
+        return (null, fullyQualifiedName);
     }
 
     /// <summary>
@@ -88,6 +128,29 @@ internal GeminiChatMessageContent(
             metadata: metadata)
     {
         this.ToolCalls = functionsToolCalls?.Select(tool => new GeminiFunctionToolCall(tool)).ToList();
+
+        // Also populate Items collection with FunctionCallContent for compatibility with FunctionChoiceBehavior
+        if (this.ToolCalls is not null)
+        {
+            foreach (var toolCall in this.ToolCalls)
+            {
+                KernelArguments? arguments = null;
+                if (toolCall.Arguments is not null)
+                {
+                    arguments = new KernelArguments();
+                    foreach (var arg in toolCall.Arguments)
+                    {
+                        arguments[arg.Key] = arg.Value;
+                    }
+                }
+
+                this.Items.Add(new FunctionCallContent(
+                    functionName: toolCall.FunctionName,
+                    pluginName: toolCall.PluginName,
+                    id: null, // Gemini doesn't provide call IDs
+                    arguments: arguments));
+            }
+        }
     }
 
     /// <summary>

dotnet/src/Connectors/Connectors.Google/Models/Gemini/GeminiStreamingChatMessageContent.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System;
 using System.Collections.Generic;
 using System.Text;
 using Microsoft.SemanticKernel.ChatCompletion;