diff --git a/bin/miaou-bash b/bin/miaou-bash
index 677a1c4..45dd88b 100755
--- a/bin/miaou-bash
+++ b/bin/miaou-bash
@@ -1,9 +1,8 @@
-#!/usr/bin/env -S -- bash
+#!/usr/bin/env bash
 #!/usr/bin/env -S -- bash -x
 
 # constants
 
-MIAOU_BASH_ERROR=$(mktemp -t "$(basename "$0").XXXXXXXX" --tmpdir="/run/user/$UID")
 MIAOU_DEBUG=${MIAOU_DEBUG:-false}
 
 declare -A ANSI
@@ -37,7 +36,7 @@ ANSI[BG_WHITE]=47
 ANSI[BG_GRAY]=90
 ANSI[BG_MAGENTA]=95
 
-readonly MIAOU_BASH_ERROR MIAOU_DEBUG ANSI
+readonly MIAOU_DEBUG ANSI
 
 ## functions
 
@@ -148,8 +147,8 @@ function on_error {
         failure_payload="${BASH_COMMAND}"
         print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
 
-        miaou_debug "<investigate_tmp_error pid=${BASHPID}>"
         load_tmp_error # cannot print_miaou_error after investigation
+        miaou_debug "<investigate_tmp_error pid=${BASHPID}>"
 
         if [[ ${#tmp_error[@]} -gt 1 ]]; then
           local last_error regex
@@ -244,7 +243,12 @@ function on_pipe {
 function dump_stderr {
   miaou_debug "<stderr count=${#tmp_error[@]}>"
   tty_ansi FG_LIGHTBLUE
-  for i in "${tmp_error[@]}"; do echo "$i"; done
+  for i in "${tmp_error[@]}"; do
+    is_true "$CHILD_PROCESS" &&
+      miaou_debug "<childerr content={$i}/>" ||
+      miaou_debug "<mainerr content={$i}/>"
+    echo "$i"
+  done
   tty_ansi RESET
   miaou_debug '</stderr>'
 }
@@ -303,15 +307,25 @@ function dump_stacktrace {
 }
 
 function load_tmp_error {
-  [[ -v tmp_error ]] && return 0
-
-  mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
-  local count=${#tmp_error[@]}
-  if [[ $count == 0 ]]; then
-    miaou_debug "<tmp_error empty/>"
+  miaou_debug "<load_tmp_error from=$MIAOU_BASH_ERROR>"
+  if [[ ! -v tmp_error ]]; then
+    mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
+    local count=${#tmp_error[@]}
+    if [[ $count == 0 ]]; then
+      miaou_debug "<tmp_error empty/>"
+    else
+      miaou_debug "<tmp_error count=${count}>"
+      local i
+      for i in "${tmp_error[@]}"; do
+        miaou_debug "<tmperr content={$i}/>"
+      done
+      miaou_debug "</tmp_error>"
+    fi
   else
-    miaou_debug "<tmp_error count=${count}/>"
+    local count=${#tmp_error[@]}
+    miaou_debug "<already_loaded count=$count/>"
   fi
+  miaou_debug '</load_tmp_error>'
 }
 
 function on_exit {
@@ -339,12 +353,12 @@ function on_exit {
 
   elif [[ -v failure_type && "$failure_type" == 'COMMAND_NOT_FOUND' ]]; then
     unset 'tmp_error[-1]' 'tmp_error[-1]'
-    add_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
+    add_miaou_error "${BASH_SOURCE[2]}" "${BASH_LINENO[1]}" "${failure_code}" "${failure_type}" "${failure_payload}"
     miaou_debug '<command_not_found change_stderr />'
 
   elif [[ -v failure_type && "$failure_type" == 'FILE_NOT_FOUND' ]]; then
     unset 'tmp_error[-1]' 'tmp_error[-1]'
-    add_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
+    add_miaou_error "${BASH_SOURCE[2]}" "${BASH_LINENO[1]}" "${failure_code}" "${failure_type}" "${failure_payload}"
     miaou_debug '<file_not_found change_stderr />'
 
   elif [[ ! -v failure_type ]]; then
@@ -404,17 +418,42 @@ function on_exit {
   else
     miaou_debug "</on_exit success>"
   fi
+  cleanup
+}
+
+function build_miaou_bash_error {
+  local directory
+  directory="/run/user/$UID/$(basename "$0")"
+
+  CHILD_PROCESS=false
+  [[ -f "${directory}/${PPID}.tmp" ]] && CHILD_PROCESS=true
+
+  mkdir -p "$directory"
+  if is_true $CHILD_PROCESS; then
+    MIAOU_BASH_ERROR="${directory}/${PPID}.$$.tmp"
+  else
+    MIAOU_BASH_ERROR="${directory}/$$.tmp"
+  fi
+  rm -f "$MIAOU_BASH_ERROR"
+
+  readonly MIAOU_BASH_ERROR CHILD_PROCESS
+}
+
+function cleanup {
+  miaou_debug '<cleanup/>'
+  # trap - ERR EXIT PIPE RETURN
+  # rm "$MIAOU_BASH_ERROR"
 }
 
 ## main
 
+[[ $# -lt 1 ]] && >&2 echo 'ERROR: script expected!' && builtin exit 1
+
 set -euo pipefail
 set -E # HALT on subshell error
 set -T # DEBUG RETURN
-
-[[ $# -lt 1 ]] && >&2 echo 'ERROR: script expected!' && builtin exit 1
+build_miaou_bash_error
 BASH_ARGV0="$1" && shift # to pretend script runs by itself
-
 trap 'on_error $?' ERR
 trap 'on_exit $?' EXIT
 trap 'on_pipe' PIPE
@@ -423,6 +462,10 @@ trap 'on_return' RETURN
 if [[ -e /proc/$$/fd/3 ]]; then exec 4>&3 3>&-; else exec 4>/dev/tty; fi # swap fd 3 4 when fd 3 sent off
 exec 3>/dev/stderr 2>"$MIAOU_BASH_ERROR"
 
-miaou_debug "<source file=$BASH_ARGV0 pid=${BASHPID}/>"
+if is_true "$CHILD_PROCESS"; then
+  miaou_debug "<child file=$BASH_ARGV0 pid=${BASHPID} parent=${PPID}>"
+else
+  miaou_debug "<main file=$BASH_ARGV0 pid=${BASHPID}/>"
+fi
 # shellcheck source=/dev/null
 source "$BASH_ARGV0"
diff --git a/test/miaou-bash.test.bash b/test/miaou-bash.test.bash
index db510af..2d052af 100755
--- a/test/miaou-bash.test.bash
+++ b/test/miaou-bash.test.bash
@@ -59,7 +59,7 @@ fail_type exit EXIT
 fail_type command_not_found COMMAND_NOT_FOUND
 fail_type source_not_found SOURCE_NOT_FOUND
 fail_type file_not_found FILE_NOT_FOUND
-fail_type subshell_error COMMAND_NOT_FOUND '(hint: prefer source than subshell)'
+fail_type child_error CHILD_ERROR '(hint: prefer source than subshell)'
 
 failed=${#failures[@]}
 success=$((test_count - failed))
diff --git a/test/stub/scenario.bash b/test/stub/scenario.bash
index 6c42ccf..73953f6 100755
--- a/test/stub/scenario.bash
+++ b/test/stub/scenario.bash
@@ -90,11 +90,10 @@ function do_file_not_found {
   ./lib/fake/nope.bash
 }
 
-function do_subshell_error {
-  output=$(miaou_debug "---subshell1--$$ $BASHPID $PPID--")
-  output=$(miaou_debug "---subshell2--$$ $BASHPID $PPID--")
-  : "$output"
+function do_child_error {
   "$BASEDIR/extra/library.bash"
+  echo SHOULD NOT APPEAR
+  . "$BASEDIR/extra/library.bash"
 }
 
 function do_command_error {