Function generateVariant

design/src/variants.ts:38–135

(
  apiKey: string,
  prompt: string,
  outputPath: string,
  size: string,
  quality: string,
  fetchFn: typeof globalThis.fetch = globalThis.fetch,
)

 * production code uses the global fetch by default.
 */
export async function generateVariant(
  apiKey: string,
  prompt: string,
  outputPath: string,
  size: string,
  quality: string,
  fetchFn: typeof globalThis.fetch = globalThis.fetch,
): Promise<{ path: string; success: boolean; error?: string }> {
  const maxRetries = 3;
  const MAX_RETRY_AFTER_MS = 60_000; // cap honored Retry-After to bound stalls
  let lastError = "";
  let skipLeadingDelay = false;

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    if (attempt > 0 && !skipLeadingDelay) {
      // Exponential backoff: 2s, 4s, 8s
      const delay = Math.pow(2, attempt) * 1000;
      console.error(`  Rate limited, retrying in ${delay / 1000}s...`);
      await new Promise(r => setTimeout(r, delay));
    }
    skipLeadingDelay = false;

    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 240_000);

    try {
      const response = await fetchFn("https://api.openai.com/v1/responses", {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${apiKey}`,
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          model: "gpt-4o",
          input: prompt,
          tools: [{ type: "image_generation", model: "gpt-image-2", size, quality }],
        }),
        signal: controller.signal,
      });

      clearTimeout(timeout);

      if (response.status === 429) {
        lastError = "Rate limited (429)";
        const retryAfter = response.headers.get("retry-after");
        if (retryAfter) {
          const trimmed = retryAfter.trim();
          let waitMs: number | null = null;
          if (/^\d+$/.test(trimmed)) {
            // delta-seconds (RFC 7231)
            waitMs = Math.min(Number.parseInt(trimmed, 10) * 1000, MAX_RETRY_AFTER_MS);
          } else {
            // HTTP-date (RFC 7231)
            const dateMs = Date.parse(trimmed);
            if (!Number.isNaN(dateMs)) {
              waitMs = Math.min(Math.max(0, dateMs - Date.now()), MAX_RETRY_AFTER_MS);
            }
          }