Description

Summary

Two chained defects make the Responses API unusable against third-party OpenAI-compatible endpoints that emit "status": null on reasoning items:

1. 2.13.0: DeserializeReasoningResponseItem lacks a null guard for the optional status property, so "status": null throws ArgumentOutOfRangeException and aborts the entire SSE stream.
2. 2.14.0: the null guard was added, but the release also removed the public (experimental) struct OpenAI.Responses.GlobalMcpToolCallApprovalPolicy, which Microsoft.Extensions.AI.OpenAI 10.10.0 references from OpenAIResponsesChatClient.ToResponseTool. Any tool-carrying Responses call through the M.E.AI adapter now dies with TypeLoadException at JIT time.

Environment

• OpenAI SDK: 2.13.0 (also tested 2.14.0)
• Microsoft.Agents.AI.OpenAI 1.21.0 / Microsoft.Extensions.AI.OpenAI 10.10.0
• .NET 10

Defect 1 — 2.13.0: no null guard on status (repro)

Third-party Responses-compatible backends may serialize the optional status field of a reasoning item as JSON null instead of omitting it (same class of report as openai/openai-dotnet#1342). Since status is optional per spec, null should deserialize the same as "absent".

This issue has already been addressed openai/openai-dotnet#1346 repaired.

Minimal repro — no network or API key required, uses the exact entry point the SSE pipeline uses (AsyncSseUpdateCollection → ModelReaderWriter):

using System.ClientModel.Primitives;
using OpenAI.Responses;

var json = """
           {"type":"response.output_item.added","output_index":0,
            "item":{"type":"reasoning","id":"rs_1","status":null,"summary":[]}}
           """;

#pragma warning disable OPENAI001
var update = ModelReaderWriter.Read<StreamingResponseUpdate>(BinaryData.FromString(json));
#pragma warning restore OPENAI001

Actual (2.13.0):

System.ArgumentOutOfRangeException: Unknown ReasoningStatus value. (Parameter 'value')
   at OpenAI.Responses.ReasoningStatusExtensions.ToReasoningStatus(String value)
   at OpenAI.Responses.ReasoningResponseItem.DeserializeReasoningResponseItem(...)

Expected: status: null treated as absent (ReasoningStatus? status = null).

Actual (2.14.0): passes — decompilation confirms the guard was added:

// 2.13.0 (generated) — no null check; GetString() on JSON null returns C# null
else if (item.NameEquals("status"))
{
    status = item.Value.GetString().ToReasoningStatus();  // throws
}

// 2.14.0 (generated)
else if (item.NameEquals("status"))
{
    if (item.Value.ValueKind != JsonValueKind.Null)
    {
        status = item.Value.GetString().ToReasoningStatus();
    }
}

Defect 2 — 2.14.0: breaking removal of GlobalMcpToolCallApprovalPolicy

I tried importing OpenAI 2.14.0 package directly, but it caused this problem:

System.TypeLoadException: Could not load type 'OpenAI.Responses.GlobalMcpToolCallApprovalPolicy'
from assembly 'OpenAI, Version=2.14.0.0, Culture=neutral, PublicKeyToken=b4187f3e65366280'.
   at Microsoft.Extensions.AI.OpenAIResponsesChatClient.ToResponseTool(AITool tool, ChatOptions options, ToolSearchLookup toolSearchLookup)
   at Microsoft.Extensions.AI.OpenAIResponsesChatClient.AsCreateResponseOptions(...)
   at Microsoft.Extensions.AI.OpenAIResponsesChatClient.GetStreamingResponseAsync(...)

In 2.14.0, GlobalMcpToolCallApprovalPolicy has been renamed to DefaultMcpToolCallApprovalPolicy. The following is a screenshot of openai-dotnet CHANGELOG.

Reproduction Steps

using System.ClientModel.Primitives;
using OpenAI.Responses;

var json = """
           {"type":"response.output_item.added","output_index":0,
            "item":{"type":"reasoning","id":"rs_1","status":null,"summary":[]}}
           """;

#pragma warning disable OPENAI001
var update = ModelReaderWriter.Read<StreamingResponseUpdate>(BinaryData.FromString(json));
#pragma warning restore OPENAI001

Expected behavior

Correct deserialization to obtain StreamResponseUpdate: status: null treated as absent (ReasoningStatus? status = null).

Actual behavior

2.13.0:

System.ArgumentOutOfRangeException: Unknown ReasoningStatus value. (Parameter 'value')
   at OpenAI.Responses.ReasoningStatusExtensions.ToReasoningStatus(String value)
   at OpenAI.Responses.ReasoningResponseItem.DeserializeReasoningResponseItem(...)

Unhandled exception. System.ArgumentOutOfRangeException: Unknown ReasoningStatus value. (Parameter 'value')
   at OpenAI.Responses.ReasoningStatusExtensions.ToReasoningStatus(String value)
   at OpenAI.Responses.ReasoningResponseItem.DeserializeReasoningResponseItem...

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response