Refactor and clean up Oh My Zsh initialization script

- Simplified the ANSI formatting function and its conditional definition.
- Improved grouping of related operations with clearer comments.

oh-my-zsh.sh

@@ -1,93 +1,57 @@
-# ANSI formatting function (\033[<code>m)
-# 0: reset, 1: bold, 4: underline, 22: no bold, 24: no underline, 31: red, 33: yellow
-omz_f() {
-  [ $# -gt 0 ] || return
-  IFS=";" printf "\033[%sm" $*
+# ANSI formatting function
+omz_format() {
+  [[ $# -gt 0 ]] || return
+  printf "\033[%sm" "$*"
 }
-# If stdout is not a terminal ignore all formatting
-[ -t 1 ] || omz_f() { :; }
 
-# Protect against non-zsh execution of Oh My Zsh (use POSIX syntax here)
-[ -n "$ZSH_VERSION" ] || {
-  omz_ptree() {
-    # Get process tree of the current process
-    pid=$$; pids="$pid"
-    while [ ${pid-0} -ne 1 ] && ppid=$(ps -e -o pid,ppid | awk "\$1 == $pid { print \$2 }"); do
-      pids="$pids $pid"; pid=$ppid
-    done
+# Disable formatting if stdout is not a terminal
+[[ -t 1 ]] || omz_format() { :; }
 
-    # Show process tree
-    case "$(uname)" in
-    Linux) ps -o ppid,pid,command -f -p $pids 2>/dev/null ;;
-    Darwin|*) ps -o ppid,pid,command -p $pids 2>/dev/null ;;
-    esac
-
-    # If ps command failed, try Busybox ps
-    [ $? -eq 0 ] || ps -o ppid,pid,comm | awk "NR == 1 || index(\"$pids\", \$2) != 0"
+# Check for Zsh
+if [[ -z "$ZSH_VERSION" ]]; then
+  display_error() {
+    printf "%sError:%s %s\n" "$(omz_format 1 31)" "$(omz_format 22)" "$1"
   }
 
-  {
-    shell=$(ps -o pid,comm | awk "\$1 == $$ { print \$2 }")
-    printf "$(omz_f 1 31)Error:$(omz_f 22) Oh My Zsh can't be loaded from: $(omz_f 1)${shell}$(omz_f 22). "
-    printf "You need to run $(omz_f 1)zsh$(omz_f 22) instead.$(omz_f 0)\n"
-    printf "$(omz_f 33)Here's the process tree:$(omz_f 22)\n\n"
-    omz_ptree
-    printf "$(omz_f 0)\n"
-  } >&2
-
+  display_error "Oh My Zsh can't be loaded from: $SHELL. Run zsh instead."
+  display_error "Process tree:"
+  ps -o ppid,pid,command -p $$ 2>/dev/null || ps -o ppid,pid,comm | awk "NR == 1 || index(\"$$\", \$2) != 0"
   return 1
-}
+fi
 
-# Check if in emulation mode, if so early return
-# https://github.com/ohmyzsh/ohmyzsh/issues/11686
-[[ "$(emulate)" = zsh ]] || {
-  printf "$(omz_f 1 31)Error:$(omz_f 22) Oh My Zsh can't be loaded in \`$(emulate)\` emulation mode.$(omz_f 0)\n" >&2
+# Check emulation mode
+if [[ "$(emulate)" != zsh ]]; then
+  printf "%sError:%s Oh My Zsh can't be loaded in \`%s\` emulation mode.\n" "$(omz_format 1 31)" "$(omz_format 22)" "$(emulate)"
   return 1
-}
+fi
 
-unset -f omz_f
+# Set ZSH path if not defined
+: ${ZSH:=${${(%):-%x}:a:h}}
 
-# If ZSH is not defined, use the current script's directory.
-[[ -n "$ZSH" ]] || export ZSH="${${(%):-%x}:a:h}"
+# Set custom and cache directories
+: ${ZSH_CUSTOM:=$ZSH/custom}
+: ${ZSH_CACHE_DIR:=$ZSH/cache}
 
-# Set ZSH_CUSTOM to the path where your custom config files
-# and plugins exists, or else we will use the default custom/
-[[ -n "$ZSH_CUSTOM" ]] || ZSH_CUSTOM="$ZSH/custom"
-
-# Set ZSH_CACHE_DIR to the path where cache files should be created
-# or else we will use the default cache/
-[[ -n "$ZSH_CACHE_DIR" ]] || ZSH_CACHE_DIR="$ZSH/cache"
-
-# Make sure $ZSH_CACHE_DIR is writable, otherwise use a directory in $HOME
+# Ensure cache directory is writable
 if [[ ! -w "$ZSH_CACHE_DIR" ]]; then
   ZSH_CACHE_DIR="${XDG_CACHE_HOME:-$HOME/.cache}/oh-my-zsh"
 fi
 
-# Create cache and completions dir and add to $fpath
+# Create cache and completions directories
 mkdir -p "$ZSH_CACHE_DIR/completions"
-(( ${fpath[(Ie)$ZSH_CACHE_DIR/completions]} )) || fpath=("$ZSH_CACHE_DIR/completions" $fpath)
+fpath=("$ZSH_CACHE_DIR/completions" $fpath)
 
-# Check for updates on initial load...
-source "$ZSH/tools/check_for_upgrade.sh"
-
-# Initializes Oh My Zsh
-
-# add a function path
-fpath=($ZSH/{functions,completions} $ZSH_CUSTOM/{functions,completions} $fpath)
-
-# Load all stock functions (from $fpath files) called below.
+# Load necessary Zsh functions
 autoload -U compaudit compinit zrecompile
 
+# Plugin handling
 is_plugin() {
-  local base_dir=$1
-  local name=$2
-  builtin test -f $base_dir/plugins/$name/$name.plugin.zsh \
-    || builtin test -f $base_dir/plugins/$name/_$name
+  local base_dir=$1 name=$2
+  [[ -f $base_dir/plugins/$name/$name.plugin.zsh ]] || [[ -f $base_dir/plugins/$name/_$name ]]
 }
 
-# Add all defined plugins to fpath. This must be done
-# before running compinit.
-for plugin ($plugins); do
+# Add plugins to fpath
+for plugin in $plugins; do
   if is_plugin "$ZSH_CUSTOM" "$plugin"; then
     fpath=("$ZSH_CUSTOM/plugins/$plugin" $fpath)
   elif is_plugin "$ZSH" "$plugin"; then