/**
 * Generates a unique string ID. Uses crypto.randomUUID when available,
 * otherwise falls back to a timestamp + random string.
 *
 * @param prefix - Optional prefix for the fallback format (e.g. "req", "err").
 *                 Only affects fallback; UUIDs have no prefix.
 */
export function createUniqueId(prefix?: string): string {
	if (
		typeof globalThis.crypto !== "undefined" &&
		typeof globalThis.crypto.randomUUID === "function"
	) {
		return globalThis.crypto.randomUUID();
	}
	const fallback = `${Date.now()}_${Math.random().toString(36).slice(2)}`;
	return prefix ? `${prefix}_${fallback}` : fallback;
}