How do I limit the size of the cache?

I'm trying to translate this nginx config to Caddy:
https://github.com/grishka/Smithereen/blob/4dcad9dd968b2ae6be04281d6a9ca72d13d4cfc8/examples/nginx.conf

This works but doesn't do so optimally because it would hit imgproxy every time a client requests a resized image:

smithereen.local

encode

# Static files
handle /s/* {
	root /var/www/smithereen
	file_server
}

# imgproxy
handle /i/* {
	reverse_proxy 127.0.0.1:4560
}

# Server application itself
handle {
	reverse_proxy 127.0.0.1:4567
}

So I started looking into replicating my nginx setup, where I cache the images processed by imgproxy, and this plugin seems to be the way to do cache on Caddy. Except I couldn't find a way to limit the cache by the combined size of all cached responses instead of the time, so least-recently used responses would get deleted to make room for new ones. Ideally I would just not have any expiration component whatsoever to my caching strategy, but nginx can't do that so I set the TTL to 10 years.

Does this plugin not support this sort of LRU strategy, or did I overlook it? The docs all only talk about the expiration time.

Start with the referenced examples/nginx.conf and the cache plugin's documentation, which currently describes expiration-based caching. Investigate whether the cache implementation exposes a combined response-size limit or LRU eviction, and identify the relevant configuration and tests. Done means documenting the supported behavior or specifying the missing size-based LRU strategy clearly.