diff --git a/lib/analytics/analytics_service.dart b/lib/analytics/analytics_service.dart
index 64f7cdb..b0e5954 100644
--- a/lib/analytics/analytics_service.dart
+++ b/lib/analytics/analytics_service.dart
@@ -58,6 +58,21 @@ class AnalyticsService {
     return '${Platform.operatingSystem}-${major ?? 'unknown'}';
   }
 
+  /// 平台标识。契约枚举为 android/ios；Web/桌面为开发调试形态，
+  /// 上报值不在枚举内会被服务端逐条 rejected（不影响客户端），属预期。
+  static String _platformName() {
+    if (kIsWeb) {
+      return 'web';
+    }
+    if (Platform.isAndroid) {
+      return 'android';
+    }
+    if (Platform.isIOS) {
+      return 'ios';
+    }
+    return Platform.operatingSystem;
+  }
+
   /// Sets userId after login/restore.
   void identify(String userId) {
     _userId = userId;
@@ -89,7 +104,7 @@ class AnalyticsService {
         'sessionId': getSessionId(),
         'clientTs': DateTime.now().toUtc().toIso8601String(),
         'appVersion': _appVersion,
-        'platform': Platform.isAndroid ? 'android' : 'ios',
+        'platform': _platformName(),
         'osVersion': _osVersion,
         if (props != null && props.isNotEmpty) 'props': props,
       };
@@ -103,6 +118,10 @@ class AnalyticsService {
     }
   }
 
+  /// 立即冲刷队列（退后台/会话切换时调用，避免低活跃用户凑不满
+  /// [_flushThreshold] 条导致事件永不上传）。
+  Future<void> flushNow() => _flush();
+
   Future<void> _flush() async {
     if (_flushing || _pendingEvents.isEmpty) return;
     _flushing = true;
@@ -137,6 +156,15 @@ class AnalyticsService {
     request.add(utf8.encode(jsonEncode({'events': events})));
 
     final response = await request.close();
+    if (response.statusCode >= 400 && response.statusCode < 500) {
+      // 4xx 为永久性拒绝（校验失败/批量超限等），重试不可能成功；
+      // 丢弃并打日志，避免毒丸批次无限重回队列阻塞后续事件。
+      debugPrint(
+        'Analytics batch permanently rejected '
+        '(${response.statusCode}), dropping ${events.length} events',
+      );
+      return;
+    }
     if (response.statusCode != 202) {
       throw Exception('Upload failed with ${response.statusCode}');
     }
diff --git a/lib/analytics/session_tracker.dart b/lib/analytics/session_tracker.dart
index c4668bc..ea9d4d6 100644
--- a/lib/analytics/session_tracker.dart
+++ b/lib/analytics/session_tracker.dart
@@ -14,6 +14,7 @@ import 'package:uuid/uuid.dart';
 class SessionTracker with WidgetsBindingObserver {
   SessionTracker({
     this.timeout = const Duration(minutes: 30),
+    this.onLeaveForeground,
     DateTime Function()? now,
   }) : _now = now ?? DateTime.now,
        _sessionId = const Uuid().v7();
@@ -21,6 +22,9 @@ class SessionTracker with WidgetsBindingObserver {
   /// 后台超时阈值；构造参数化便于测试注入。
   final Duration timeout;
 
+  /// 首次离开前台时回调（app 装配层用于触发埋点队列冲刷）。
+  final VoidCallback? onLeaveForeground;
+
   /// 时钟注入口，测试免真实等待。
   final DateTime Function() _now;
 
@@ -42,6 +46,7 @@ class SessionTracker with WidgetsBindingObserver {
     } else if (_lastState == AppLifecycleState.resumed) {
       // 首次离开前台才记时；inactive/hidden/paused 级联不覆盖。
       _leftForegroundAt = _now();
+      onLeaveForeground?.call();
     }
     _lastState = state;
   }
diff --git a/lib/app/app.dart b/lib/app/app.dart
index daf89e3..247fcef 100644
--- a/lib/app/app.dart
+++ b/lib/app/app.dart
@@ -43,11 +43,13 @@ class _AppState extends State<App> {
         widget.sessionManager ??
         SessionManager(store: const SecureTokenStore());
 
-    _sessionTracker = SessionTracker();
+    _sessionTracker = SessionTracker(
+      onLeaveForeground: () => _analytics.flushNow(),
+    );
     WidgetsBinding.instance.addObserver(_sessionTracker);
 
     _analytics = AnalyticsService(
-      apiBaseUrl: patbondApiBaseUrl,
+      apiBaseUrl: patbondUserApiBaseUrl,
       getAccessToken: () => sessionManager.accessToken,
       getSessionId: () => _sessionTracker.sessionId,
     );
diff --git a/lib/core/network/api_client.dart b/lib/core/network/api_client.dart
index 9a7644d..545afdb 100644
--- a/lib/core/network/api_client.dart
+++ b/lib/core/network/api_client.dart
@@ -10,6 +10,13 @@ const String patbondApiBaseUrl = String.fromEnvironment(
   defaultValue: 'http://127.0.0.1:8081',
 );
 
+/// user 服务基地址（/api/v1/me、/api/v1/events）：MVP 阶段 auth 与 user
+/// 分端口直连（ADR-002 无网关），`--dart-define=PATBOND_USER_API_BASE_URL=...` 注入。
+const String patbondUserApiBaseUrl = String.fromEnvironment(
+  'PATBOND_USER_API_BASE_URL',
+  defaultValue: 'http://127.0.0.1:8082',
+);
+
 /// 构建全局共用的 Dio 实例。
 ///
 /// `validateStatus` 放行所有状态码：错误信封由 [ApiClient] 统一解析成
diff --git a/lib/core/widgets/app_text_field.dart b/lib/core/widgets/app_text_field.dart
index 50a46f2..966ad93 100644
--- a/lib/core/widgets/app_text_field.dart
+++ b/lib/core/widgets/app_text_field.dart
@@ -11,6 +11,7 @@ class AppTextField extends StatefulWidget {
     super.key,
     this.controller,
     this.prefixIcon,
+    this.prefixText,
     this.errorText,
     this.helperText,
     this.enabled = true,
@@ -25,6 +26,10 @@ class AppTextField extends StatefulWidget {
   final String label;
   final TextEditingController? controller;
   final IconData? prefixIcon;
+
+  /// 固定前缀文本（如手机号的 '+86 '），仅展示与拼接语义，不进输入值。
+  final String? prefixText;
+
   final String? errorText;
   final String? helperText;
   final bool enabled;
@@ -62,6 +67,7 @@ class _AppTextFieldState extends State<AppTextField> {
           labelText: widget.label,
           errorText: widget.errorText,
           helperText: widget.helperText,
+          prefixText: widget.prefixText,
           prefixIcon: widget.prefixIcon == null
               ? null
               : Icon(widget.prefixIcon, color: AppColors.muted),
diff --git a/lib/features/auth/register_page.dart b/lib/features/auth/register_page.dart
index 1175e92..51311cf 100644
--- a/lib/features/auth/register_page.dart
+++ b/lib/features/auth/register_page.dart
@@ -147,7 +147,7 @@ class _RegisterPageState extends State<RegisterPage> {
     try {
       await widget.authRepository.register(
         username: _usernameCtrl.text.trim(),
-        phone: _phoneCtrl.text.trim(),
+        phone: '+86${_phoneCtrl.text.trim()}',
         password: _passwordCtrl.text,
       );
       TextInput.finishAutofillContext();
@@ -232,6 +232,7 @@ class _RegisterPageState extends State<RegisterPage> {
                 label: '手机号',
                 controller: _phoneCtrl,
                 prefixIcon: Icons.phone_iphone_rounded,
+                prefixText: '+86 ',
                 errorText: _phoneError,
                 enabled: !_submitting,
                 keyboardType: TextInputType.phone,