Convert HTTPS traffic to HTTP securely.
Convert HTTPS traffic to HTTP securely.
It seems you're describing a situation where someone is attempting to climb a tree while trying to use Squid as a caching proxy, and also mentions SSL traffic caching. The example URL provided highlights Squid's capability to handle HTTPS sites effectively.
After a year, the browser stops attempting to enforce HTTPS. Once it hasn't encountered that header again, it will consistently require HTTPS for a full year.