diff --git a/scripts/core/common.sh b/scripts/core/common.sh
index 4207cca..2838e8c 100644
--- a/scripts/core/common.sh
+++ b/scripts/core/common.sh
@@ -1145,8 +1145,104 @@ guard_unsafe_sudo_auto_install() {
   fi
 }
 
+install_sudo_available() {
+  command -v sudo >/dev/null 2>&1 || return 1
+  sudo -n true >/dev/null 2>&1 && return 0
+  id -nG 2>/dev/null | tr ' ' '\n' | grep -Eq '^(sudo|wheel|admin)$'
+}
+
+install_scope_choice_tty() {
+  [ -t 0 ] && [ -t 2 ]
+}
+
+install_prompt_scope_choice() {
+  local selected=0 key
+  local root_label="root 安装（推荐）"
+  local user_label="user 安装"
+  local root_desc="安装到系统命令路径，支持 systemd 后端，适合长期运行、开机自启、全局可用。"
+  local user_desc="不写系统目录，安装到当前用户环境，适合无 root 权限或只给当前用户使用。"
+
+  if ! install_scope_choice_tty; then
+    warn "检测到当前用户可使用 sudo；非交互终端默认使用 user 安装"
+    printf 'ℹ %s\n' "如需 root 安装，请显式执行：sudo bash install.sh system" >&2
+    echo "user"
+    return 0
+  fi
+
+  while true; do
+    printf '\033[2J\033[H' >&2
+    echo "检测到当前用户可使用 sudo，请选择安装方式：" >&2
+    echo >&2
+
+    if [ "$selected" -eq 0 ]; then
+      echo "> $root_label" >&2
+    else
+      echo "  $root_label" >&2
+    fi
+    echo "  $root_desc" >&2
+    echo >&2
+
+    if [ "$selected" -eq 1 ]; then
+      echo "> $user_label" >&2
+    else
+      echo "  $user_label" >&2
+    fi
+    echo "  $user_desc" >&2
+    echo >&2
+    echo "使用 ↑/↓ 或 j/k 移动，Enter 确认。" >&2
+
+    IFS= read -rsn1 key || {
+      echo "user"
+      return 0
+    }
+
+    case "$key" in
+      "")
+        if [ "$selected" -eq 0 ]; then
+          echo "system"
+        else
+          echo "user"
+        fi
+        return 0
+        ;;
+      j|J)
+        selected=1
+        ;;
+      k|K)
+        selected=0
+        ;;
+      $'\033')
+        IFS= read -rsn2 -t 0.1 key || key=""
+        case "$key" in
+          "[A") selected=0 ;;
+          "[B") selected=1 ;;
+        esac
+        ;;
+      1)
+        echo "system"
+        return 0
+        ;;
+      2)
+        echo "user"
+        return 0
+        ;;
+    esac
+  done
+}
+
+rerun_install_as_root_system() {
+  local install_script
+
+  install_script="$PROJECT_DIR/install.sh"
+  [ -f "$install_script" ] || die "未找到安装脚本：$install_script"
+
+  echo "👉 将使用 root/system 方式重新执行安装"
+  exec sudo bash "$install_script" system
+}
+
 detect_install_scope() {
   local requested="${1:-auto}"
+  local selected_scope
 
   case "$requested" in
     system)
@@ -1159,7 +1255,23 @@ detect_install_scope() {
       if [ "$(id -u)" -eq 0 ]; then
         INSTALL_SCOPE="system"
       else
-        INSTALL_SCOPE="user"
+        if install_sudo_available; then
+          selected_scope="$(install_prompt_scope_choice)"
+          case "$selected_scope" in
+            system)
+              rerun_install_as_root_system
+              return $?
+              ;;
+            user)
+              INSTALL_SCOPE="user"
+              ;;
+            *)
+              die "未知安装选择：$selected_scope"
+              ;;
+          esac
+        else
+          INSTALL_SCOPE="user"
+        fi
       fi
       ;;
     *)
diff --git a/scripts/dev/check-install-scope-selector.sh b/scripts/dev/check-install-scope-selector.sh
new file mode 100644
index 0000000..8c728a9
--- /dev/null
+++ b/scripts/dev/check-install-scope-selector.sh
@@ -0,0 +1,126 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_DIR="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+# shellcheck source=scripts/core/common.sh
+source "$PROJECT_DIR/scripts/core/common.sh"
+
+tmp_dir="$(mktemp -d)"
+trap 'rm -rf "$tmp_dir"' EXIT
+
+PROJECT_DIR="$tmp_dir/project"
+mkdir -p "$PROJECT_DIR"
+touch "$PROJECT_DIR/install.sh"
+
+reset_scope_state() {
+  INSTALL_SCOPE=""
+  INSTALL_HOME=""
+  RUNTIME_DIR=""
+  BIN_DIR=""
+  LOG_DIR=""
+  SELECTOR_PROMPTED="false"
+  RERUN_AS_ROOT="false"
+  MOCK_IS_ROOT="false"
+  MOCK_SUDO_AVAILABLE="false"
+  MOCK_TTY="false"
+  MOCK_SELECTED_SCOPE="user"
+  : > "$tmp_dir/prompted"
+  : > "$tmp_dir/rerun"
+}
+
+id() {
+  if [ "${1:-}" = "-u" ]; then
+    if [ "$MOCK_IS_ROOT" = "true" ]; then
+      printf '0\n'
+    else
+      printf '1000\n'
+    fi
+    return 0
+  fi
+
+  command id "$@"
+}
+
+install_sudo_available() {
+  [ "$MOCK_SUDO_AVAILABLE" = "true" ]
+}
+
+install_scope_choice_tty() {
+  [ "$MOCK_TTY" = "true" ]
+}
+
+install_prompt_scope_choice() {
+  printf 'prompted\n' >> "$tmp_dir/prompted"
+  if ! install_scope_choice_tty; then
+    printf 'user\n'
+    return 0
+  fi
+
+  printf '%s\n' "$MOCK_SELECTED_SCOPE"
+}
+
+rerun_install_as_root_system() {
+  printf 'rerun\n' >> "$tmp_dir/rerun"
+  return 77
+}
+
+assert_equal() {
+  local name="$1"
+  local actual="$2"
+  local expected="$3"
+
+  if [ "$actual" != "$expected" ]; then
+    echo "not ok - $name: got '$actual', expected '$expected'" >&2
+    return 1
+  fi
+
+  echo "ok - $name"
+}
+
+reset_scope_state
+detect_install_scope user
+assert_equal "explicit user selects user scope" "$INSTALL_SCOPE" "user"
+assert_equal "explicit user does not prompt" "$(wc -l < "$tmp_dir/prompted" | tr -d ' ')" "0"
+
+reset_scope_state
+detect_install_scope system
+assert_equal "explicit system selects system scope" "$INSTALL_SCOPE" "system"
+assert_equal "explicit system does not prompt" "$(wc -l < "$tmp_dir/prompted" | tr -d ' ')" "0"
+
+reset_scope_state
+MOCK_IS_ROOT="true"
+detect_install_scope auto
+assert_equal "root auto selects system scope" "$INSTALL_SCOPE" "system"
+assert_equal "root auto does not prompt" "$(wc -l < "$tmp_dir/prompted" | tr -d ' ')" "0"
+
+reset_scope_state
+detect_install_scope auto
+assert_equal "non-root without sudo selects user scope" "$INSTALL_SCOPE" "user"
+assert_equal "non-root without sudo does not prompt" "$(wc -l < "$tmp_dir/prompted" | tr -d ' ')" "0"
+
+reset_scope_state
+MOCK_SUDO_AVAILABLE="true"
+detect_install_scope auto
+assert_equal "non-root sudo non-tty prompts through default path" "$(wc -l < "$tmp_dir/prompted" | tr -d ' ')" "1"
+assert_equal "non-root sudo non-tty selects user scope" "$INSTALL_SCOPE" "user"
+
+reset_scope_state
+MOCK_SUDO_AVAILABLE="true"
+MOCK_TTY="true"
+MOCK_SELECTED_SCOPE="user"
+detect_install_scope auto
+assert_equal "non-root sudo tty user choice prompts" "$(wc -l < "$tmp_dir/prompted" | tr -d ' ')" "1"
+assert_equal "non-root sudo tty user choice selects user scope" "$INSTALL_SCOPE" "user"
+
+reset_scope_state
+MOCK_SUDO_AVAILABLE="true"
+MOCK_TTY="true"
+MOCK_SELECTED_SCOPE="system"
+set +e
+detect_install_scope auto
+rc=$?
+set -e
+assert_equal "non-root sudo tty system choice calls root rerun" "$(wc -l < "$tmp_dir/rerun" | tr -d ' ')" "1"
+assert_equal "non-root sudo tty system choice stops current flow" "$rc" "77"