feat(install): optional add-ons via --with and interactive prompt

Wire install_<name>.sh into the main installer through a shared catalog
so fnm/pyenv/nvm (and future tools) share one CLI and prompt path.

install.sh

@@ -5,27 +5,120 @@ set -euo pipefail
 # Save the original working directory
 ORIGINAL_DIR="$(pwd)"
 
+# Optional add-ons: each name maps to install_<name>.sh in this repo.
+# Append here when adding a new optional installer.
+OPTIONAL_ADDONS=(fnm pyenv nvm)
+
+# When run from a git checkout, prefer local install_*.sh; curl|bash uses EASYZSH_RAW_BASE.
+SCRIPT_DIR=""
+if [[ -n "${BASH_SOURCE[0]:-}" && "${BASH_SOURCE[0]}" != "bash" && -f "${BASH_SOURCE[0]}" ]]; then
+    SCRIPT_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+fi
+
 # Flags to determine if the arguments were passed
 cp_hist_flag=false
 noninteractive_flag=false
+with_flag_set=false
+selected_addons=()
 
-# Loop through all arguments
-for arg in "$@"
-do
-    case $arg in
+usage() {
+    cat <<'EOF'
+Usage: install.sh [options]
+
+Options:
+  -c, --cp-hist              Copy bash history into zsh history
+  -n, --non-interactive      Skip default-shell change and optional prompts
+      --with <names>         Install optional add-ons (comma-separated).
+                             Repeatable. Names match install_<name>.sh
+                             (currently: fnm, pyenv, nvm).
+  -h, --help                 Show this help
+
+Examples:
+  ./install.sh
+  ./install.sh --with fnm
+  ./install.sh --with fnm,pyenv -n
+  curl -fsSL …/install.sh | bash -s -- --with fnm
+EOF
+}
+
+is_known_addon() {
+    local name="$1"
+    local known
+    for known in "${OPTIONAL_ADDONS[@]}"; do
+        [[ "$known" == "$name" ]] && return 0
+    done
+    return 1
+}
+
+append_addons_csv() {
+    local csv="$1"
+    local part
+    local IFS=','
+    # shellcheck disable=SC2086
+    for part in $csv; do
+        part="${part#"${part%%[![:space:]]*}"}"
+        part="${part%"${part##*[![:space:]]}"}"
+        [[ -z "$part" ]] && continue
+        if ! is_known_addon "$part"; then
+            echo "Unknown optional add-on: $part (known: ${OPTIONAL_ADDONS[*]})" >&2
+            exit 2
+        fi
+        selected_addons+=("$part")
+    done
+}
+
+while [[ $# -gt 0 ]]; do
+    case $1 in
         --cp-hist|-c)
             cp_hist_flag=true
+            shift
             ;;
         --non-interactive|-n)
             noninteractive_flag=true
+            shift
+            ;;
+        --with)
+            with_flag_set=true
+            shift
+            if [[ $# -eq 0 || "$1" == -* ]]; then
+                echo "--with requires a comma-separated list of add-on names" >&2
+                exit 2
+            fi
+            append_addons_csv "$1"
+            shift
+            ;;
+        --with=*)
+            with_flag_set=true
+            append_addons_csv "${1#--with=}"
+            shift
+            ;;
+        -h|--help)
+            usage
+            exit 0
             ;;
         *)
-            echo "Unknown option: $arg" >&2
+            echo "Unknown option: $1" >&2
+            usage >&2
             exit 2
             ;;
     esac
 done
 
+dedupe_selected_addons() {
+    local _deduped=()
+    local _name _d _seen
+    for _name in "${selected_addons[@]+"${selected_addons[@]}"}"; do
+        _seen=false
+        for _d in "${_deduped[@]+"${_deduped[@]}"}"; do
+            [[ "$_d" == "$_name" ]] && _seen=true && break
+        done
+        [[ "$_seen" == false ]] && _deduped+=("$_name")
+    done
+    selected_addons=("${_deduped[@]+"${_deduped[@]}"}")
+}
+
+dedupe_selected_addons
+
 if [ -f ~/.gitconfig ]; then
     cp ~/.gitconfig ~/.gitconfig.backup
     echo "Backup of .gitconfig created."
@@ -424,6 +517,45 @@ else
     echo -e "\nNot copying bash_history to zsh_history, as --cp-hist or -c is not supplied\n"
 fi
 
+# Optional add-ons (install_<name>.sh). After shell stubs so patches land correctly.
+run_optional_addon() {
+    local name="$1"
+    local script="install_${name}.sh"
+    echo -e "\n=== Optional add-on: ${name} ===\n"
+    if [[ -n "$SCRIPT_DIR" && -f "$SCRIPT_DIR/$script" ]]; then
+        bash "$SCRIPT_DIR/$script"
+    else
+        curl -fsSL "${EASYZSH_RAW_BASE}/${script}" | bash
+    fi
+}
+
+prompt_optional_addons() {
+    # Only when interactive and user did not pass --with.
+    echo -e "\nOptional add-ons (each is install_<name>.sh):"
+    local name
+    for name in "${OPTIONAL_ADDONS[@]}"; do
+        echo "  - $name"
+    done
+    echo -n "Install which? Comma-separated names, or Enter to skip: "
+    local reply
+    read -r reply || reply=""
+    [[ -z "${reply//[[:space:]]/}" ]] && return 0
+    append_addons_csv "$reply"
+}
+
+if [[ "$with_flag_set" == false && "$noninteractive_flag" == false ]]; then
+    prompt_optional_addons
+    dedupe_selected_addons
+fi
+
+if ((${#selected_addons[@]})); then
+    for name in "${selected_addons[@]}"; do
+        run_optional_addon "$name"
+    done
+elif [[ "$with_flag_set" == true ]]; then
+    echo -e "\n--with given but no add-ons selected; skipping optionals\n"
+fi
+
 if [ "$noninteractive_flag" = true ]; then
     echo -e "Installation complete, exit terminal and enter a new zsh session\n"
     echo -e "Make sure to change zsh to default shell by running: chsh -s $(command -v zsh)"