[FEATURE REQ] Support for Reasoning Effort "minimal" in GPT-5 (.NET SDK 2.6.0)

[dciechanowicz]

Describe the feature or improvement you are requesting

Problem: The REST API accepts reasoning: { "effort": "minimal" }. The .NET SDK 2.6.0 exposes Low | Medium | High only. There is no enum value or first-class API for "minimal".

Ask: Add full support for "minimal" across the Responses and Chat APIs.

Proposed API changes:

Add Minimal to ResponseReasoningEffortLevel and ChatReasoningEffortLevel.

Ensure ResponseReasoningOptions serializes "minimal" correctly.

Update samples and docs.

Why: Parity with REST API, lower latency and cost in production.

Additional context

Environment

OS: Windows 11 x64

.NET: .NET 9, C# 13

Package: OpenAI .NET SDK 2.6.0

Repro (SDK today): Enum lacks Minimal. You can set Low/Medium/High only.

Workaround (works): Use Protocol/Raw JSON with the Responses API.

[benjimac93]

This works great for me in 2.6.0 "options.ReasoningEffortLevel = ChatReasoningEffortLevel.Minimal;"

See #673

[dciechanowicz]

Thanks for the clarification, @benjimac93. Turns out minimal is indeed supported. My earlier conclusion was influenced by a discussion with ChatGPT and quirks in my own LLM model-adapter logic. Resolving and closing.