• I have looked for existing issues (including closed) about this

Feature Request

Motivation

Cookie Name Prefixes is defined in the draft RFC6265bis (HTTP WG draft).

It is supported by all modern browsers: https://caniuse.com/mdn-http_headers_set-cookie_cookie_prefixes

Proposal

cookie has https://docs.rs/cookie/latest/cookie/prefix/struct.PrefixedJar.html - can it be used somehow?

Alternatives

Manually doing all this is error prone...