Lab: Send, Inspect, and Log Your First Model Request

import { appendFile } from "node:fs/promises";

const fixtures = {
  "wrong-colour": {
    message: "My demo order arrived with the wrong colour.",
    output: "category: product issue\nreason: The delivered colour differs from the order."
  },
  "tracking": {
    message: "My demo order tracking link has not updated.",
    output: "category: tracking issue\nreason: The tracking information has not updated."
  }
};

try {
  const mode = process.env.LAB_MODE ?? "fixture";
  if (!["fixture", "live"].includes(mode)) throw new Error("Invalid LAB_MODE");
  const caseId = process.env.LAB_CASE ?? "wrong-colour";
  if (!Object.hasOwn(fixtures, caseId)) throw new Error("Unknown LAB_CASE");
  const sample = fixtures[caseId];
  const prompt = "Classify this synthetic support message. Return two lines only: "
    + "category and one-sentence reason. Do not invent policy or actions. Message: "
    + sample.message;
  if (prompt.length > 500) throw new Error("Input cap exceeded");

  const configuredModel = mode === "live" ? process.env.OPENAI_MODEL : null;
  if (mode === "live" && (!process.env.OPENAI_API_KEY || !configuredModel)) {
    throw new Error("Live mode needs OPENAI_API_KEY and OPENAI_MODEL");
  }
  const startedAt = new Date().toISOString();
  const startMs = performance.now();
  let response;
  if (mode === "fixture") {
    response = {status:"completed", output_text:sample.output,
      id:null, model:null, usage:null};
  } else {
    const {default: OpenAI} = await import("openai");
    const client = new OpenAI({apiKey:process.env.OPENAI_API_KEY,
      maxRetries:0, timeout:30_000});
    response = await client.responses.create({model:configuredModel,
      input:prompt, max_output_tokens:1024, store:false});
  }
  if (response.status !== "completed") throw new Error("Response incomplete");
  const output = response.output_text?.trim() ?? "";
  const lineCount = output.split(/\r?\n/).filter(Boolean).length;
  if (!output || lineCount !== 2) throw new Error("Expected two nonempty lines");
  const record = {timestamp:startedAt, mode, case_id:caseId,
    response_id:response.id ?? null, configured_model:configuredModel,
    returned_model:response.model ?? null,
    elapsed_ms:Math.round(performance.now()-startMs), usage:response.usage ?? null,
    output_review:{non_empty:true,line_count:lineCount}};
  console.log(output); // only synthetic text belongs in this lab
  await appendFile("request-log.jsonl", JSON.stringify(record)+"\n", "utf8");
  console.log(record);
} catch (error) {
  console.error({category:Number.isInteger(error?.status)
    ? "api_error" : "local_or_transport_error",
    status:Number.isInteger(error?.status) ? error.status : null});
  process.exitCode = 1;
}