Function fetchWithRateLimit

apps/cursor/src/lib/github-plugin/parse.ts:142–179

(
  url: string,
  init: RequestInit & { maxWaitMs?: number } = {},
)

 * Bulk scripts can pass a larger budget.
 */
export async function fetchWithRateLimit(
  url: string,
  init: RequestInit & { maxWaitMs?: number } = {},
): Promise<Response> {
  const maxWaitMs = init.maxWaitMs ?? 30_000;
  const maxAttempts = 4;
  let totalWait = 0;
  let lastRes: Response | null = null;

  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
    const res = await fetch(url, init);
    lastRes = res;

    if (res.status !== 429 && res.status !== 403) return res;

    // Distinguish "rate-limited" 403 from "forbidden" 403 by checking the
    // X-RateLimit-Remaining header. A real auth/permission 403 has remaining > 0.
    const remaining = Number(res.headers.get("x-ratelimit-remaining") ?? "");
    if (res.status === 403 && Number.isFinite(remaining) && remaining > 0) {
      return res;
    }

    const retryAfter = Number(res.headers.get("retry-after") ?? "");
    const reset = Number(res.headers.get("x-ratelimit-reset") ?? "0") * 1000;
    let waitMs =
      Number.isFinite(retryAfter) && retryAfter > 0
        ? retryAfter * 1000
        : Math.max(reset - Date.now(), 1000);
    waitMs = Math.min(waitMs, maxWaitMs - totalWait);

    if (waitMs <= 0 || attempt === maxAttempts) return res;

    totalWait += waitMs;
    await sleep(waitMs);
  }

  return lastRes as Response;
}

/**
 * Caller-controlled retry budget for GitHub API rate-limits.