rework the bash PS1 prompt

.bashrc

@@ -9,20 +9,6 @@
 [[ $- != *i* ]] && return
 [[ -z "${PS1-}" ]] && return
 
-# wrapper for lazily loading __git_ps1 whenever it is actually needed
-_lazy_git_ps1() {
-	if [[ -z $__GIT_PROMPT_SOURCED ]]; then
-		. /usr/share/bash-completion/completions/git &>/dev/null
-		. /usr/share/git/completion/git-prompt.sh &>/dev/null
-		if [ -d .git ] || git worktree list &>/dev/null; then
-			export __GIT_PROMPT_SOURCED=1
-			__git_ps1 "$@"
-		fi
-	else
-		__git_ps1 "$@"
-	fi
-}
-
 # lazy loading of ssh agents
 _lazy_ssh() {
 	if [[ -z $SSH_AUTH_SOCK ]]; then
@@ -43,16 +29,37 @@ _make() {
 		-e "s/^.*error.*$/\x1b[31m&\x1b[0m/I" >&2)
 }
 
-#
-# envs
-#
-# set PS1
-PS1='\[\033[?25h\]'                         # show cursor
-PS1="$PS1"'\[\033[01;35m\]\u@\h'            # user@host
-PS1="$PS1"'\[\033[00m\]:'                   # separator
-PS1="$PS1"'\[\033[01;34m\]\w'               # working directory
-PS1="$PS1"'\[\033[01;93m\]$(_lazy_git_ps1)' # github branch
-PS1="$PS1"'\[\033[00m\]\$ '                 # shell sign
+# lazily loads the git utilities, to prevent slowdowns
+__lazy_git_ps1() {
+	if [ -z "$__GIT_PROMPT_SOURCED__" ]; then
+		if [ -d .git ] || git worktree list &>/dev/null; then
+			. /usr/share/bash-completion/completions/git &>/dev/null
+			. /usr/share/git/completion/git-prompt.sh &>/dev/null
+			export __GIT_PROMPT_SOURCED__=1
+			__git_ps1
+		fi
+	else __git_ps1; fi
+	return 0
+}
+
+# regenerates the PS1 prompt
+__regenprompt() {
+	local err=$? # acquire the error code of the last executed command
+	local git=$(__lazy_git_ps1)
+
+	if [ $err -ne 0 ]; then
+		err="\033[s\033[$((COLUMNS - 4))G${err}\033[u"
+	else unset err; fi
+
+	PS1="\[\033[?25h\]"               # show cursor
+	PS1="$PS1\[\033[01;35m\]\u@\h"    # user@host
+	PS1="$PS1\[\033[00m\]:"           # separator
+	PS1="$PS1\[\033[01;34m\]\w"       # working directory
+	PS1="$PS1\[\033[01;93m\]$git"     # git branch
+	PS1="$PS1\[\033[01;31m\]\[$err\]" # error code
+	PS1="$PS1\[\033[00m\]\$ "         # shell sign
+}
+PROMPT_COMMAND=__regenprompt
 
 # history settings
 HISTSIZE=2048