zsh/tmux: add prompt marker/add copy-mode shortcuts

tmux allows moving between shell prompts when the prompt is marked with
the OSC 133 escape sequence (`\033[133;A\033\\]`).

This is added to the zsh prompt and `next-prompt` and `previous-prompt`
are bound to `n` and `p` in tmux copy mode.

themes/brethil.zsh-theme

@@ -81,13 +81,18 @@ function __prompt_too_long(){
   # prints a newline if less than $COLUMNS/2 characters remain to the right margin, see end of `man zshmisc`
   echo "%-$((COLUMNS/2))(l..\n)"
 }
+function __print_prompt_marker(){
+  # prints the escape sequence that tmux interprets as prompt start (see next-prompt/previous-prompt in `man tmux`)
+  printf '\033]133;A\033\\'
+}
 
 ## oh-my-zsh vi-mode plugins indicators:
 export MODE_INDICATOR="[%B%K{red}nav%k%b]" # red background
 export INSERT_MODE_INDICATOR="[%B%K{28}ins%k%b]" # green background
 
-# put it all together
-PROMPT='$(__virtualenv_info)'"${user_prompt}${path_prompt}${git_prompt}${job_prompt}${shlvl_prompt}$(__prompt_too_long)${prompt_with_previous_return_status}"
-
-# Right prompt is just return code and time
+## put it all together
+# Note: wrapping __print_prompt_marker in extra %{...%} works around an issue with zsh autosuggestions with escape sequences
+#       see https://github.com/zsh-users/zsh-autosuggestions/issues/570 for more information
+PROMPT='$(__virtualenv_info)'"${user_prompt}${path_prompt}${git_prompt}${job_prompt}${shlvl_prompt}$(__prompt_too_long)${prompt_with_previous_return_status}%{$(__print_prompt_marker)%} "
+# right prompt indicator: return code, vi mode prompt info and current time
 RPS1="${return_code_RPS1}"'$(vi_mode_prompt_info)[%*]'

tmux.conf

@@ -103,3 +103,6 @@ bind-key W choose-window 'swap-window -t "%%"'
 bind A command-prompt "rename-window \"%%\""
 
 bind C customize-mode
+
+bind-key -T copy-mode-vi n send-keys -X next-prompt
+bind-key -T copy-mode-vi p send-keys -X previous-prompt