diff --git a/android/app/src/main/kotlin/com/stormg/lumadrama/MainActivity.kt b/android/app/src/main/kotlin/com/stormg/lumadrama/MainActivity.kt
index 8f25c38..71a3a09 100644
--- a/android/app/src/main/kotlin/com/stormg/lumadrama/MainActivity.kt
+++ b/android/app/src/main/kotlin/com/stormg/lumadrama/MainActivity.kt
@@ -12,6 +12,7 @@ import android.os.Build
 import android.os.Bundle
 import android.os.Handler
 import android.os.Looper
+import android.provider.Settings
 import android.util.Rational
 import android.content.pm.PackageManager
 import android.view.WindowManager
@@ -65,6 +66,20 @@ class MainActivity : FlutterActivity() {
                 result.success(false)
             }
         }
+        // 设备标识：SSAID 免权限，卸载重装不变，避免客户端自己生成的 id 每次重装都变
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "com.stormg.lumadrama/device")
+            .setMethodCallHandler { call, result ->
+                if (call.method != "ssaid") {
+                    result.notImplemented()
+                    return@setMethodCallHandler
+                }
+                val value = try {
+                    Settings.Secure.getString(contentResolver, Settings.Secure.ANDROID_ID)
+                } catch (_: Exception) {
+                    null
+                }
+                result.success(value)
+            }
         MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "com.stormg.lumadrama/share")
             .setMethodCallHandler { call, result ->
                 if (call.method != "shareText") {
diff --git a/ios/Runner/AppDelegate.swift b/ios/Runner/AppDelegate.swift
index b33feff..43a3513 100644
--- a/ios/Runner/AppDelegate.swift
+++ b/ios/Runner/AppDelegate.swift
@@ -63,6 +63,7 @@ final class RunnerFlutterViewController: FlutterViewController {
   func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
     GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
     registerWirelessDataChannel(engineBridge)
+    registerDeviceIdChannel(engineBridge)
     let channel = FlutterMethodChannel(
       name: "com.stormg.lumadrama/share",
       binaryMessenger: engineBridge.applicationRegistrar.messenger()
@@ -144,6 +145,21 @@ final class RunnerFlutterViewController: FlutterViewController {
     }
   }
 
+  /// 设备标识：IDFV 免权限，卸载本 App 不变，避免客户端自生成的 id 每次重装都变。
+  private func registerDeviceIdChannel(_ engineBridge: FlutterImplicitEngineBridge) {
+    let channel = FlutterMethodChannel(
+      name: "com.stormg.lumadrama/device",
+      binaryMessenger: engineBridge.applicationRegistrar.messenger()
+    )
+    channel.setMethodCallHandler { call, result in
+      guard call.method == "idfv" else {
+        result(FlutterMethodNotImplemented)
+        return
+      }
+      result(UIDevice.current.identifierForVendor?.uuidString)
+    }
+  }
+
   private func registerWirelessDataChannel(_ engineBridge: FlutterImplicitEngineBridge) {
     let channel = FlutterMethodChannel(
       name: WirelessDataPrompt.channelName,
diff --git a/lib/core/data/services/auth_session_store.dart b/lib/core/data/services/auth_session_store.dart
index 20afccb..cf178b7 100644
--- a/lib/core/data/services/auth_session_store.dart
+++ b/lib/core/data/services/auth_session_store.dart
@@ -4,6 +4,7 @@ import 'dart:math';
 import 'package:shared_preferences/shared_preferences.dart';
 
 import '../models/auth_session.dart';
+import 'device_id_provider.dart';
 
 /// 令牌与设备号的本地持久化。
 ///
@@ -11,13 +12,17 @@ import '../models/auth_session.dart';
 /// `SharedPreferences.getInstance()` 在新版本里已标注弃用，两套混用还会让
 /// widget 测试只 mock 到其中一套。
 ///
-/// 设备号是后端注册风控与后续"下载设备绑定"的依据，所以**首次生成后就固定下来**；
-/// 不引 UUID 库（保持极简依赖），用「时间戳 + 随机数」拼一个够用的 id。
+/// 设备号优先取系统标识（Android SSAID / iOS IDFV），这样卸载重装后还是同一台设备；
+/// 系统标识不可用时才回退到本地生成并持久化的 UUID，保证任何环境都能跑。
 class AuthSessionStore {
-  AuthSessionStore({SharedPreferencesAsync? preferences})
-    : _preferences = preferences ?? SharedPreferencesAsync();
+  AuthSessionStore({
+    SharedPreferencesAsync? preferences,
+    DeviceIdProvider? deviceIdProvider,
+  }) : _preferences = preferences ?? SharedPreferencesAsync(),
+       _deviceIdProvider = deviceIdProvider ?? DeviceIdProvider();
 
   final SharedPreferencesAsync _preferences;
+  final DeviceIdProvider _deviceIdProvider;
 
   static const _kAccessToken = 'auth.accessToken';
   static const _kRefreshToken = 'auth.refreshToken';
@@ -28,18 +33,34 @@ class AuthSessionStore {
 
   Future<String> deviceId() async {
     if (_cachedDeviceId != null) return _cachedDeviceId!;
-    var value = await _preferences.getString(_kDeviceId) ?? '';
-    if (value.isEmpty) {
-      final random = Random();
-      value =
-          'd-${DateTime.now().millisecondsSinceEpoch.toRadixString(36)}-'
-          '${random.nextInt(1 << 32).toRadixString(36)}';
-      await _preferences.setString(_kDeviceId, value);
-    }
+    final systemId = await _deviceIdProvider.systemDeviceId();
+    final value = systemId ?? await _localDeviceId();
     _cachedDeviceId = value;
     return value;
   }
 
+  /// 系统标识取不到时的兜底：本地 UUIDv4，生成一次后固定下来。
+  Future<String> _localDeviceId() async {
+    final stored = await _preferences.getString(_kDeviceId) ?? '';
+    if (stored.isNotEmpty) return stored;
+    final generated = 'd-${_uuidV4()}';
+    await _preferences.setString(_kDeviceId, generated);
+    return generated;
+  }
+
+  /// UUIDv4：122 位随机，碰撞概率可忽略，不引第三方依赖。
+  String _uuidV4() {
+    final random = Random.secure();
+    final bytes = List<int>.generate(16, (_) => random.nextInt(256));
+    bytes[6] = (bytes[6] & 0x0f) | 0x40;
+    bytes[8] = (bytes[8] & 0x3f) | 0x80;
+    String hex(int start, int end) => bytes
+        .sublist(start, end)
+        .map((byte) => byte.toRadixString(16).padLeft(2, '0'))
+        .join();
+    return '${hex(0, 4)}-${hex(4, 6)}-${hex(6, 8)}-${hex(8, 10)}-${hex(10, 16)}';
+  }
+
   Future<AuthSession?> read() async {
     final accessToken = await _preferences.getString(_kAccessToken) ?? '';
     final refreshToken = await _preferences.getString(_kRefreshToken) ?? '';
diff --git a/lib/core/data/services/device_id_provider.dart b/lib/core/data/services/device_id_provider.dart
new file mode 100644
index 0000000..ab702db
--- /dev/null
+++ b/lib/core/data/services/device_id_provider.dart
@@ -0,0 +1,36 @@
+// Author: fruit.com.cn
+
+import 'dart:io' show Platform;
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+/// 读取系统级设备标识，两端都不需要任何权限。
+///
+/// - Android：SSAID（`Settings.Secure.ANDROID_ID`），卸载重装不变；
+/// - iOS：IDFV（`identifierForVendor`），卸载本 App 不变，同厂商应用全删才会变。
+///
+/// 两端都由原生侧提供，不引插件：项目 iOS 走 SPM，避免混入 CocoaPods。
+/// 取不到（Web、测试环境、通道异常）时返回 null，由调用方回退到本地生成的 id。
+class DeviceIdProvider {
+  static const MethodChannel _channel = MethodChannel(
+    'com.stormg.lumadrama/device',
+  );
+
+  Future<String?> systemDeviceId() async {
+    if (kIsWeb) return null;
+    try {
+      if (Platform.isAndroid) {
+        final ssaid = await _channel.invokeMethod<String>('ssaid');
+        if (ssaid != null && ssaid.isNotEmpty) return 'a-$ssaid';
+      }
+      if (Platform.isIOS) {
+        final idfv = await _channel.invokeMethod<String>('idfv');
+        if (idfv != null && idfv.isNotEmpty) return 'i-$idfv';
+      }
+    } catch (_) {
+      // 原生通道不可用（widget 测试）时走本地兜底
+    }
+    return null;
+  }
+}
diff --git a/test/core/device_id_test.dart b/test/core/device_id_test.dart
new file mode 100644
index 0000000..1ef86dc
--- /dev/null
+++ b/test/core/device_id_test.dart
@@ -0,0 +1,65 @@
+// Author: fruit.com.cn
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:fruitshorts/core/data/services/auth_session_store.dart';
+import 'package:fruitshorts/core/data/services/device_id_provider.dart';
+import 'package:shared_preferences_platform_interface/in_memory_shared_preferences_async.dart';
+import 'package:shared_preferences_platform_interface/shared_preferences_async_platform_interface.dart';
+
+/// 可控的系统设备标识来源。
+class _FakeDeviceIdProvider implements DeviceIdProvider {
+  _FakeDeviceIdProvider(this.value);
+
+  final String? value;
+  int calls = 0;
+
+  @override
+  Future<String?> systemDeviceId() async {
+    calls++;
+    return value;
+  }
+}
+
+void main() {
+  setUp(() {
+    SharedPreferencesAsyncPlatform.instance =
+        InMemorySharedPreferencesAsync.empty();
+  });
+
+  test('should_prefer_system_device_id_over_local_value', () async {
+    final provider = _FakeDeviceIdProvider('a-9774d56d682e549c');
+    final store = AuthSessionStore(deviceIdProvider: provider);
+
+    expect(await store.deviceId(), 'a-9774d56d682e549c');
+  });
+
+  test('should_fall_back_to_stable_local_uuid_when_system_id_missing', () async {
+    final store = AuthSessionStore(
+      deviceIdProvider: _FakeDeviceIdProvider(null),
+    );
+
+    final first = await store.deviceId();
+    final second = await store.deviceId();
+
+    // 同一次运行内固定，且符合 UUIDv4 形态
+    expect(first, second);
+    expect(first, startsWith('d-'));
+    expect(
+      RegExp(
+        r'^d-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$',
+      ).hasMatch(first),
+      isTrue,
+      reason: '本地兜底必须是 UUIDv4，避免 32 位随机带来的碰撞',
+    );
+  });
+
+  test('should_cache_system_id_within_one_session', () async {
+    final provider = _FakeDeviceIdProvider('i-E621E1F8-C36C-495A-93FC-0C247A3E6E5F');
+    final store = AuthSessionStore(deviceIdProvider: provider);
+
+    await store.deviceId();
+    await store.deviceId();
+
+    expect(provider.calls, 1);
+  });
+}