Function createResponsesFetchLanguageModel

typescript/src/model.ts:231–278

* OpenAI Responses API endpoint encapsulation using the fetch API. * * The Responses API uses a different request and response shape from Chat Completions: * - **Request body**: `input` (string or array of `PromptSection`) instead of `messages`. * - **Response body**: text is returned inside `ou

(url: string, headers: object, defaultParams: object)

 * @param defaultParams Additional JSON body parameters merged into every request (e.g. `{ model }`).
 */
function createResponsesFetchLanguageModel(url: string, headers: object, defaultParams: object) {
    const model: TypeChatLanguageModel = {
        complete
    };
    return model;

    async function complete(prompt: string | PromptSection[]) {
        let retryCount = 0;
        const retryMaxAttempts = model.retryMaxAttempts ?? 3;
        const retryPauseMs = model.retryPauseMs ?? 1000;
        const input = typeof prompt === "string" ? prompt : (prompt as PromptSection[]);
        while (true) {
            const options = {
                method: "POST",
                body: JSON.stringify({
                    ...defaultParams,
                    input,
                    temperature: 0,
                }),
                headers: {
                    "content-type": "application/json",
                    ...headers
                }
            }
            const response = await fetch(url, options);
            if (response.ok) {
                type ResponsesAPIOutputItem = {
                    type: string;
                    role?: string;
                    content: { type: string; text: string }[];
                };
                const json = await response.json() as { output: ResponsesAPIOutputItem[] };
                const message = json.output?.find(o => o.type === "message");
                const textContent = message?.content?.find(c => c.type === "output_text");
                if (textContent?.text !== undefined) {
                    return success(textContent.text);
                } else {
                    return error(`REST API unexpected response format: ${JSON.stringify(json)}`);
                }
            }
            if (!isTransientHttpError(response.status) || retryCount >= retryMaxAttempts) {
                return error(`REST API error ${response.status}: ${response.statusText}`);
            }
            await sleep(getRetryDelayMs(response, retryPauseMs, retryPauseMs * retryMaxAttempts));
            retryCount++;
        }
    }
}

/**
 * Returns the number of milliseconds to wait before the next retry attempt.