retryDelay as a function how to check the number of retry attempt?

[voidtask]

Hey! I'm currently working on implementation of exponential backoff technique in ofetch retryDelay and currently I have this

	retryDelay: (ctx) => {
		const initialDelay = 1000;
		const exponentialBase = 2;

		const attempt = getAttempt(ctx.options.headers.get(HEADER_RETRY_ATTEMPT));
		ctx.options.headers.set(HEADER_RETRY_ATTEMPT, `${attempt + 1}`);

		const exponentialDelay = initialDelay * Math.pow(exponentialBase, attempt - 1);
		const jitter = getRandomInt(200, 500);

		const delay = Math.min(exponentialDelay + jitter, 20_000);
		console.debug(`Retrying request in ${delay}ms`);

		return delay;
	},

The solution isn't exactly ideal since I'm using headers to store data, how can I track what number of attempt is currently being retried? I might be missing something here or I could solve it somehow with scopes, but I'm not sure, maybe it has to be implemented within the library and I should make a feature request/pull request?