.Net: OpenAIResponseAgent should apply `OpenAIPromptExecutionSettings.ResponseFormat` (structured outputs)

[CynthiaLuijkx]

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When using OpenAIResponseAgent, the ResponseFormat from OpenAIPromptExecutionSettings is ignored. This prevents responses from being emitted in a typed/structured (JSON-schema) shape, even though structured outputs work elsewhere in SK (e.g., Chat Completions / IChatCompletionService and Assistant samples).

This looks like a gap in the Responses pipeline: ResponseCreationOptionsFactory doesn’t propagate ResponseFormat, while the Assistants path (AssistantRunOptionsFactory) does handle response formatting options.

• Responses factory: dotnet/src/Agents/OpenAI/Internal/ResponseCreationOptionsFactory.cs ([GitHub])
• Assistants factory: dotnet/src/Agents/OpenAI/Internal/AssistantRunOptionsFactory.cs ([GitHub])

Expected behavior

OpenAIResponseAgent should honor OpenAIPromptExecutionSettings.ResponseFormat (JSON mode / JSON Schema, including typeof(T)), so the model returns the requested schema—just like the documented structured-outputs flow. ([GitHub][3])

Actual behavior

OpenAIResponseAgent returns free-form text; ResponseFormat appears to be ignored by the Responses agent path.

Repro (minimal)

// .NET 8, SK 1.61.0
// NuGet: Microsoft.SemanticKernel, Microsoft.SemanticKernel.Connectors.OpenAI

using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.Agents.OpenAI;
using Microsoft.SemanticKernel.Connectors.OpenAI;

public record Answer(string Response, string Details);

var agent = new OpenAIResponseAgent(_client)
{
    Name = Name,
    Instructions = DefaultInstructions,
    StoreEnabled = true 
};

var executionSettings = new OpenAIPromptExecutionSettings
{
    ResponseFormat = typeof(Answer)
};

var options = new AgentInvokeOptions { KernelArguments = new KernelArguments(executionSettings), };

var result = "";
await foreach (var response in agent.InvokeAsync(messages, agentThread, options))
{
    result += response.Message;
    agentThread = response.Thread;
}

Environment

• Semantic Kernel: 1.61.0
• .NET: 8
• Model: gpt-4.1

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