function osc7-pwd() {
    emulate -L zsh # also sets localoptions for us
    setopt extendedglob
    local LC_ALL=C
    printf '\e]7;file://%s%s\e\' $HOST ${PWD//(#m)([^@-Za-z&-;_~])/%${(l:2::0:)$(([##16]#MATCH))}}
}

function chpwd-osc7-pwd() {
    (( ZSH_SUBSHELL )) || osc7-pwd
}
add-zsh-hook -Uz chpwd chpwd-osc7-pwd