When using precompressed static files, the Content-Length header seems to be missing.
Basically, I want to get the rough file size of compressed resources using HEAD requests. encode doesn't return the Content-Length as described in #4902, but the suggested solution with precompressed doesn't work for me. The precompressed files are present (index.html.zst, index.html.gz, index.html.br).

I tested this same scenario with nginx's gzip_static on; directive, and it works like expected.

I tested using a browser and these curl commands:

$ curl -I HEAD http://localhost:8080/
HTTP/1.1 200 OK
Accept-Ranges: bytes
Content-Length: 1210
Content-Type: text/html; charset=utf-8
Last-Modified: Thu, 01 Jan 1970 00:00:01 GMT
Server: Caddy
Vary: Accept-Encoding
Date: Tue, 27 May 2025 16:46:08 GMT

$ curl -H "Accept-Encoding: gzip" -I HEAD http://localhost:8080/
HTTP/1.1 200 OK
Accept-Ranges: bytes
Content-Encoding: gzip
Content-Type: text/html; charset=utf-8
Last-Modified: Thu, 01 Jan 1970 00:00:01 GMT
Server: Caddy
Vary: Accept-Encoding
Date: Tue, 27 May 2025 16:46:02 GMT

This is the Caddyfile I am using:

http://localhost:8080 {
    file_server {
        precompressed
    }

    root * /var/www/
}

Caddy version 2.10.0.