gistfile1.txt

_tmux_pane_words() {
  local current_word="${${=LBUFFER}[-1]}"
  local prompt="${LBUFFER% *} ␣ $RBUFFER "

  local selected_word=$(tmux capture-pane -p -J -S 0 -E - | tr ' ' '\n' | sort -u | rg '[a-zA-Z0-9]+' | fzf --select-1 --exit-0 --query="$current_word" --prompt="$prompt" --height=20 --layout=reverse)
  if [[ -n $selected_word ]]; then
    BUFFER="${LBUFFER% *} $selected_word$RBUFFER"
  fi

  zle redisplay
}

zle -N _tmux_pane_words
bindkey '^U' _tmux_pane_words