Reasoning

Reasoning models (like OpenAI’s o3 and o4 series) perform internal chain-of-thought processing before generating a final answer. The HasteKit SDK allows you to configure reasoning parameters and access these reasoning steps. Non-reasoning models (such as gpt-4o) do not emit reasoning summaries.

Enabling Reasoning

To use reasoning features, you typically need to use a compatible model and configure the Reasoning parameters in your request. The ReasoningParam struct supports the following fields:

Summary (*string): Reasoning summary level: "auto", "concise", or "detailed".
Effort (*string): Reasoning effort level: "none", "low", "medium", "high", or "xhigh".
BudgetTokens (*int): Maximum tokens to allocate for reasoning steps. Used by Anthropic and Gemini; not used for OpenAI.

resp, err := model.NewResponses(ctx, &responses.Request{
    Input: responses.InputUnion{
        OfString: utils.Ptr("If 2+4=6, what would be 22+44=?"),
    },
    Parameters: responses.Parameters{
        Reasoning: &responses.ReasoningParam{
            Summary: utils.Ptr("detailed"),
            Effort:  utils.Ptr("medium"),
        },
		Include: []responses.Includable{
            responses.IncludableReasoningEncryptedContent,
        },
    },
})

Reasoning Output

Reasoning steps are returned as distinct output items, separate from the final text response. You can access them like this:

resp, err := model.NewResponses(ctx, request)
if err != nil {
    panic(err)
}

for _, output := range resp.Output {
    if output.OfReasoning != nil {
        fmt.Println("Reasoning Steps:")
        for _, s := range output.OfReasoning.Summary {
            fmt.Printf("- %s\n", s.Text)
        }
    }
}

Streaming Reasoning

When streaming, reasoning steps are emitted as chunks. You can detect when a reasoning item is completed.

acc := ""
for chunk := range stream {
    if chunk.ChunkType() == "response.reasoning_summary_text.delta" {
		acc += chunk.OfReasoningSummaryTextDelta.Delta
    }
}

SDK

LLM Gateway

Agents

Workflows

Enabling Reasoning

Reasoning Output

Streaming Reasoning

​Enabling Reasoning

​Reasoning Output

​Streaming Reasoning

Enabling Reasoning

Reasoning Output

Streaming Reasoning