Use bindkey to track terminal focused state

focus.sh

function got-focus() {
  echo $(date) $TTY got focus >> ~/focus.log
  export ACTIVE=1
}

function lost-focus() {
  echo $(date) $TTY lost focus >> ~/focus.log
  export ACTIVE=0
}

on-prompt() {
  echo $(date) $TTY showing prompt\; "active?" $ACTIVE >> ~/focus.log
}

zle -N lost-focus
zle -N got-focus

autoload add-zsh-hook
add-zsh-hook precmd on-prompt

printf "\033[?1004h" 
bindkey "\033[O" lost-focus
bindkey "\033[I" got-focus