T34: prompts and commands carry OSC 133 marks: the tap reads every OSC body and hands 133's marks to the session, which keeps its last command's status; zsh, bash, fish and PowerShell mark what the shell leaves unmarked, and the user's prompt still sees the status

assets/shell-integration/bash/elyterminal.bash

@@ -1,4 +1,4 @@
-# ELYTerminal: load the usual startup files, report folder and title.
+# ELYTerminal: load the usual startup files, report folder and title, mark prompts and commands.
 if [ -n "${ELY_BASH_LOGIN-}" ]; then
   builtin unset ELY_BASH_LOGIN
   [ -r /etc/profile ] && builtin source /etc/profile
@@ -12,8 +12,29 @@ if [ -n "${ELY_BASH_LOGIN-}" ]; then
 else
   [ -r ~/.bashrc ] && builtin source ~/.bashrc
 fi
+_ely_ran=
+_ely_armed=
+_ely_ps0=
+if (( BASH_VERSINFO[0] * 100 + BASH_VERSINFO[1] >= 404 )); then
+  # PS0 runs in the shell, so its subscript can note that a command ran.
+  _ely_ps0='${_ely_note[_ely_ran=1]-}\e]133;C\a'
+elif [ -z "$(builtin trap -p DEBUG)" ]; then
+  _ely_debug() {
+    [ -n "$_ely_armed" ] || builtin return 0
+    case $BASH_COMMAND in _ely_*) builtin return 0 ;; esac
+    _ely_armed=
+    _ely_ran=1
+    builtin printf '\e]133;C\a'
+  }
+  builtin trap '_ely_debug' DEBUG
+fi
 _ely_prompt() {
   builtin local ret=$? LC_ALL=C char url= i title
+  _ely_armed=
+  if [ -n "$_ely_ran" ]; then
+    builtin printf '\e]133;D;%s\a' "$ret"
+    _ely_ran=
+  fi
   for (( i = 0; i < ${#PWD}; i++ )); do
     char=${PWD:i:1}
     case $char in
@@ -25,4 +46,12 @@ _ely_prompt() {
   builtin printf '\e]7;file://%s\a\e]2;%s\a' "$url" "${title//[[:cntrl:]]/}"
   builtin return $ret
 }
-PROMPT_COMMAND="_ely_prompt${PROMPT_COMMAND:+;$PROMPT_COMMAND}"
+# Last, after anything that sets PS1 or PS0.
+_ely_mark() {
+  [[ $PS1 == *'\e]133;A'* ]] || PS1='\[\e]133;A\a\]'"$PS1"'\[\e]133;B\a\]'
+  if [ -n "$_ely_ps0" ] && builtin shopt -q promptvars && [[ ${PS0-} != *"$_ely_ps0"* ]]; then
+    PS0=$_ely_ps0${PS0-}
+  fi
+  _ely_armed=1
+}
+PROMPT_COMMAND="_ely_prompt${PROMPT_COMMAND:+;$PROMPT_COMMAND};_ely_mark"