Function iterate

design/src/iterate.ts:23–77

(options: IterateOptions)

 * Iterate on an existing design using session state.
 */
export async function iterate(options: IterateOptions): Promise<void> {
  const apiKey = requireApiKey();
  const session = readSession(options.session);

  console.error(`Iterating on session ${session.id}...`);
  console.error(`  Previous iterations: ${session.feedbackHistory.length}`);
  console.error(`  Feedback: "${options.feedback}"`);

  const startTime = Date.now();

  // Try multi-turn with previous_response_id first
  let success = false;
  let responseId = "";

  try {
    const result = await callWithThreading(apiKey, session.lastResponseId, options.feedback);
    responseId = result.responseId;

    fs.mkdirSync(path.dirname(options.output), { recursive: true });
    fs.writeFileSync(options.output, Buffer.from(result.imageData, "base64"));
    success = true;
  } catch (err: any) {
    console.error(`  Threading failed: ${err.message}`);
    console.error("  Falling back to re-generation with accumulated feedback...");

    // Fallback: re-generate with original brief + all feedback
    const accumulatedPrompt = buildAccumulatedPrompt(
      session.originalBrief,
      [...session.feedbackHistory, options.feedback]
    );

    const result = await callFresh(apiKey, accumulatedPrompt);
    responseId = result.responseId;

    fs.mkdirSync(path.dirname(options.output), { recursive: true });
    fs.writeFileSync(options.output, Buffer.from(result.imageData, "base64"));
    success = true;
  }

  if (success) {
    const elapsed = ((Date.now() - startTime) / 1000).toFixed(1);
    const size = fs.statSync(options.output).size;
    console.error(`Generated (${elapsed}s, ${(size / 1024).toFixed(0)}KB) → ${options.output}`);

    // Update session
    updateSession(session, responseId, options.feedback, options.output);

    console.log(JSON.stringify({
      outputPath: options.output,
      sessionFile: options.session,
      responseId,
      iteration: session.feedbackHistory.length + 1,
    }, null, 2));
  }
}

async function callWithThreading(
  apiKey: string,