feat(tmux): refresh global environments automatically (#5282)

plugins/tmux/tmux.plugin.zsh

@@ -15,6 +15,8 @@ fi
 : ${ZSH_TMUX_AUTOQUIT:=$ZSH_TMUX_AUTOSTART}
 # Automatically name the new session based on the basename of PWD
 : ${ZSH_TMUX_AUTONAME_SESSION:=false}
+# Automatically pick up tmux environments
+: ${ZSH_TMUX_AUTOREFRESH:=true}
 # Set term to screen or screen-256color based on current terminal support
 : ${ZSH_TMUX_DETACHED:=false}
 # Set detached mode
@@ -158,6 +160,15 @@ function _zsh_tmux_plugin_run() {
   fi
 }
 
+# Refresh tmux environment variables.
+function _zsh_tmux_plugin_preexec()
+{
+  local -a tmux_cmd
+  tmux_cmd=(command tmux)
+
+  eval $($tmux_cmd show-environment -s)
+}
+
 # Use the completions for tmux for our function
 compdef _tmux _zsh_tmux_plugin_run
 # Alias tmux to our wrapper function.
@@ -184,3 +195,9 @@ if [[ -z "$TMUX" && "$ZSH_TMUX_AUTOSTART" == "true" && -z "$INSIDE_EMACS" && -z
     _zsh_tmux_plugin_run
   fi
 fi
+
+# Automatically refresh tmux environments if tmux is running.
+if [[ -n "$TMUX" && "$ZSH_TMUX_AUTOREFRESH" == "true" ]] && tmux ls >/dev/null 2>/dev/null; then
+  autoload -U add-zsh-hook
+  add-zsh-hook preexec _zsh_tmux_plugin_preexec
+fi