T34: review round 1: PowerShell reads a native program's code only when one ran in the command, by the new object each run stores, and 1 for any other failure; bash 3.2 runs the user's own DEBUG trap after its own and keeps $_, and a line that is only a subshell sends its D from the prompt by the command number; zsh marks the first prompt under a theme that sets PS1 in its own hook, through sched; each shell run gets its own folder

assets/shell-integration/bash/elyterminal.bash

@@ -13,28 +13,37 @@ else
   [ -r ~/.bashrc ] && builtin source ~/.bashrc
 fi
 _ely_ran=
+_ely_sent=
+_ely_n=0
 _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
+else
+  # bash 3.2 has no PS0: the DEBUG trap sends C, then runs the user's own trap with $? and $_ kept.
   _ely_debug() {
-    [ -n "$_ely_armed" ] || builtin return 0
-    case $BASH_COMMAND in _ely_*) builtin return 0 ;; esac
-    _ely_armed=
-    _ely_ran=1
-    builtin printf '\e]133;C\a'
+    builtin local status=$?
+    if [ -n "$_ely_armed" ] && [[ $BASH_COMMAND != _ely_* ]]; then
+      _ely_armed=
+      _ely_ran=1
+      builtin printf '\e]133;C\a'
+    fi
+    builtin return $status
   }
-  builtin trap '_ely_debug' DEBUG
+  builtin eval "_ely_trap=($(builtin trap -p DEBUG))"
+  builtin trap "_ely_debug \"\$_\"${_ely_trap[2]:+; ${_ely_trap[2]}}" DEBUG
+  builtin unset _ely_trap
 fi
 _ely_prompt() {
   builtin local ret=$? LC_ALL=C char url= i title
   _ely_armed=
+  _ely_sent=$_ely_ran
   if [ -n "$_ely_ran" ]; then
     builtin printf '\e]133;D;%s\a' "$ret"
     _ely_ran=
   fi
+  _ely_d=([1]=$'\e]133;D;'"$ret"$'\a')
   for (( i = 0; i < ${#PWD}; i++ )); do
     char=${PWD:i:1}
     case $char in
@@ -48,7 +57,14 @@ _ely_prompt() {
 }
 # 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 [[ $PS1 != *'\e]133;A'* ]]; then
+    if builtin shopt -q promptvars; then
+      # bash 3.2 traps no line that is only a subshell; \# counts it, so the prompt sends its D.
+      PS1='\[${_ely_d[!_ely_sent && _ely_n && \# != _ely_n]-}${_ely_note[_ely_n = \#]-}\e]133;A\a\]'"$PS1"'\[\e]133;B\a\]'
+    else
+      PS1='\[\e]133;A\a\]'"$PS1"'\[\e]133;B\a\]'
+    fi
+  fi
   if [ -n "$_ely_ps0" ] && builtin shopt -q promptvars && [[ ${PS0-} != *"$_ely_ps0"* ]]; then
     PS0=$_ely_ps0${PS0-}
   fi