Fix GPT 5.4 reasoning input

[victlue]

Summary

GPT-5.4 doesn't support reasoningEffort: "minimal", causing API errors. Changed default from "minimal" to "low", which is supported by all GPT-5 variants.

[changeset-bot]

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Latest commit: 3b8fd48

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[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant App as Application / Eval Runner
    participant Client as AISdkClient / Wrapped
    participant SDK as AI SDK (generateObject)
    participant API as OpenAI API

    App->>Client: generateObject(options)
    
    Note over Client: Internal Model Identification
    Client->>Client: Check modelId (gpt-5, codex, etc.)

    Note over Client: NEW: Unified Reasoning Logic
    alt is GPT-5 model
        alt is Codex variant
            Client->>Client: Set reasoningEffort: "medium"
        else Standard GPT-5 (inc. 5.4)
            Client->>Client: CHANGED: Set reasoningEffort: "low"
        end
    end

    Client->>SDK: call generateObject with providerOptions
    
    SDK->>API: POST /v1/chat/completions
    Note right of API: Payload includes:<br/>openai.reasoning_effort
    
    alt API Success
        API-->>SDK: 200 OK (JSON Response)
        SDK-->>Client: Typed Object
        Client-->>App: result
    else API Error (e.g. Unsupported Option)
        API-->>SDK: 400 Bad Request
        SDK-->>Client: Error
        Client-->>App: throw Error
    end

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