Function drainSamplingStream

pkg/runtime/sampling.go:230–251

drainSamplingStream reads a chat completion stream to completion and returns the concatenated assistant content alongside the final finish reason. The stream is always closed before returning.

(stream chat.MessageStream)

// returns the concatenated assistant content alongside the final finish
// reason. The stream is always closed before returning.
func drainSamplingStream(stream chat.MessageStream) (string, chat.FinishReason, error) {
	defer stream.Close()

	var content strings.Builder
	var finishReason chat.FinishReason
	for {
		response, err := stream.Recv()
		if errors.Is(err, io.EOF) {
			return content.String(), finishReason, nil
		}
		if err != nil {
			return "", "", err
		}
		if len(response.Choices) > 0 {
			choice := response.Choices[0]
			content.WriteString(choice.Delta.Content)
			if choice.FinishReason != "" {
				finishReason = choice.FinishReason
			}
		}
	}
}

// stopReason maps a chat finish reason into the MCP stopReason vocabulary
// used in CreateMessageResult. Unknown values fall back to "endTurn",