LLM APIs - lesson 5 | HackIndia Skills

LLM APIs - lesson 5 | HackIndia Skills | HackIndia

Example

Retry wrapper

This example is for a server route. It keeps the key on the backend, caps output, and turns API failures into app-friendly errors.

Older tutorials may use max_tokens or Chat Completions. For the Responses API, use max_output_tokens.

import OpenAI from "openai";

const client = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

function retryDelayMs(error, attempt) {
  const retryAfter = error?.headers?.get?.("retry-after");
  if (retryAfter) return Number(retryAfter) * 1000;

  const base = 500 * 2 ** attempt;
  const jitter = Math.floor(Math.random() * 250);
  return base + jitter;
}

export async function createAiReply(userText) {
  if (!userText || userText.length > 4000) {
    return { ok: false, status: 400, message: "Please send a shorter prompt." };
  }

  for (let attempt = 0; attempt < 3; attempt++) {
    try {
      const response = await client.responses.create({
        model: "gpt-4o-mini",
        instructions: "You help students improve hackathon project descriptions.",
        input: userText,
        max_output_tokens: 300
      });

      return { ok: true, text: response.output_text };
    } catch (error) {
      const status = error?.status;
      const temporary = status === 429 || status === 503;

      if (!temporary || attempt === 2) {
        console.error("OpenAI request failed", {
          status,
          code: error?.code,
          message: error?.message
        });

        const message = status === 429
          ? "AI is busy or this project hit a limit. Try again in a minute."
          : status === 503
            ? "AI service is temporarily overloaded. Try again shortly."
            : "AI request failed. Please try again.";

        return { ok: false, status: status || 500, message };
      }

      await sleep(retryDelayMs(error, attempt));
    }
  }
}

Handle failures and limits

One idea

Know the errors

Set safe limits

Common mistake

Retry wrapper

Good user messages

Do this now

Quick check