What I'd like to be able to do is set the revalidation interval dynamically based on the content of a response, i.e. return it from the called function. Think something like this:

unstable_cache(
  async () => {
    // we want to skip the implicit cache here
    const res = await (await fetch("/...", { cache: "no-store" })).json();
    return {
      data: res.data,
      revalidate: res.revalidate
    };
  },
  ['/...']
);

For comparison, the usual pattern is to pass the revalidation interval up front [1], which works great for most cases:

fetch('https://...', { next: { revalidate: 3600 } })

I've looked into the React cache [2] and Next unstable_cache [3], but the former isn't intended for persistent caching with intervals, and the latter expects the interval to be provided up front as well.

From what I've seen, the only other option is on-demand cache invalidation [4]. Unfortunately, this doesn't really fit the bill either, as it invalidates immediately, rather than after a nonzero amount of time.

[1] https://nextjs.org/docs/app/building-your-application/data-fetching/fetching-caching-and-revalidating#time-based-revalidation
[2] https://react.dev/reference/react/cache
[3] https://nextjs.org/docs/app/api-reference/functions/unstable_cache
[4] https://nextjs.org/docs/app/building-your-application/data-fetching/fetching-caching-and-revalidating#on-demand-revalidation