break: uses uniform SessionNode abstraction

lib/main.dart

@@ -91,9 +91,12 @@ Future<void> _realMain(SharedPreferences prefs) async {
   // Cloud-sync push hook: after any binding mutation, best-effort push the new
   // state (throttled). Wired via post-construction setter to avoid a circular
   // dependency between ThirdPartyAuthService and SyncService.
-  thirdPartyAuthService.onBindingsChanged = () {
-    return syncService.pushIfDue();
+  thirdPartyAuthService.onBindingsChanged = ({force = false}) {
+    return force ? syncService.forcePush() : syncService.pushIfDue();
   };
+  // Cloud-sync tombstone hook: record a deletion so the next LWW merge does
+  // not resurrect an older remote copy of the unbound platform.
+  thirdPartyAuthService.onUnbind = syncService.recordTombstone;
 
   // Cloud-sync pull hook: after a fresh SSO login, pull cloud bindings onto
   // this device (or surface the master-password restore prompt).
@@ -166,7 +169,7 @@ Future<void> _realMain(SharedPreferences prefs) async {
       );
     }
 
-    if (thirdPartyAuthService.hasEgateBinding) {
+    if (thirdPartyAuthService.hasCpdailyBinding) {
       await scheduleService.fetchAll();
     }
     if (authService.isLoggedIn ||

lib/models/third_party_account.dart

@@ -1,23 +1,37 @@
 enum ThirdPartyPlatform {
   gradescope,
   hydro,
-  egate;
+  cpdaily;
 
+  /// Stable id used for storage keys and cloud-sync payloads. Note: the
+  /// backend bind route for cpdaily is still 'egate' (unrenamed); see
+  /// [apiPath].
   String get id => name;
   String get label => switch (this) {
         ThirdPartyPlatform.gradescope => 'Gradescope',
         ThirdPartyPlatform.hydro => 'Hydro',
-        ThirdPartyPlatform.egate => 'eGate / IDS',
+        ThirdPartyPlatform.cpdaily => 'CpDaily / IDS',
       };
 
+  /// Backend bind/renew route name. cpdaily maps to 'egate' (the backend
+  /// route was not renamed); all others map to their own [id].
+  String get apiPath => switch (this) {
+        ThirdPartyPlatform.cpdaily => 'egate',
+        _ => id,
+      };
+
+  /// Parse a platform id, accepting the legacy 'egate' alias for cpdaily.
   static ThirdPartyPlatform? fromId(String id) {
-    for (final p in ThirdPartyPlatform.values) {
-      if (p.id == id) return p;
-    }
-    return null;
+    return switch (id) {
+      'gradescope' => ThirdPartyPlatform.gradescope,
+      'hydro' => ThirdPartyPlatform.hydro,
+      'cpdaily' || 'egate' => ThirdPartyPlatform.cpdaily,
+      _ => null,
+    };
   }
 }
 
+
 class ThirdPartyAccount {
   final ThirdPartyPlatform platform;
   final String account;
@@ -36,6 +50,20 @@ class ThirdPartyAccount {
   final bool autoRenew;
   final String? password;
 
+  /// Wall-clock timestamp of the most recent local mutation of this account
+  /// (bind / rebind / renew / raw update). Used by the cloud-sync merge to do
+  /// per-account last-writer-wins with [deviceId] as a deterministic
+  /// tie-breaker. Defaults to [boundAt] for accounts created before this
+  /// field existed (back-compat: treated as "ancient" so any newer write
+  /// wins).
+  final DateTime updatedAt;
+
+  /// Stable id of the device that produced the current [updatedAt] bump. Used
+  /// as the LWW tie-breaker so two devices with skewed clocks still converge
+  /// deterministically. Empty for legacy accounts; newer devices always win
+  /// against an empty deviceId.
+  final String deviceId;
+
   const ThirdPartyAccount({
     required this.platform,
     required this.account,
@@ -50,24 +78,36 @@ class ThirdPartyAccount {
     required this.boundAt,
     this.autoRenew = false,
     this.password,
-  });
+    DateTime? updatedAt,
+    String? deviceId,
+  })  : updatedAt = updatedAt ?? boundAt,
+        deviceId = deviceId ?? '';
 
   DateTime? get expireAt => expire == null
       ? null
       : DateTime.fromMillisecondsSinceEpoch(expire! * 1000);
 
-  bool get isExpired {
-    final at = expireAt;
-    return at != null && at.isBefore(DateTime.now());
-  }
+  bool get isExpired =>
+      expireAt != null && DateTime.now().isAfter(expireAt!);
 
   String get displayName {
     if (name != null && name!.isNotEmpty) return name!;
-    if (email != null && email!.isNotEmpty) return email!;
-    if (sid != null && sid!.isNotEmpty) return sid!;
     return account;
   }
 
+  /// Comparison key for LWW merge: newer [updatedAt] wins; on a tie the
+  /// lexicographically-larger [deviceId] wins (deterministic, total order).
+  /// An empty deviceId is treated as oldest of all so legacy data loses to
+  /// any real device write.
+  int compareVersionTo(ThirdPartyAccount other) {
+    final c = updatedAt.compareTo(other.updatedAt);
+    if (c != 0) return c;
+    // Empty deviceId always loses.
+    if (deviceId.isEmpty && other.deviceId.isNotEmpty) return -1;
+    if (deviceId.isNotEmpty && other.deviceId.isEmpty) return 1;
+    return deviceId.compareTo(other.deviceId);
+  }
+
   Map<String, dynamic> toJson() => {
         'platform': platform.id,
         'account': account,
@@ -82,9 +122,13 @@ class ThirdPartyAccount {
         'boundAt': boundAt.toIso8601String(),
         'autoRenew': autoRenew,
         if (password != null) 'password': password,
+        'updatedAt': updatedAt.toIso8601String(),
+        'deviceId': deviceId,
       };
 
   factory ThirdPartyAccount.fromJson(Map<String, dynamic> json) {
+    final boundAt =
+        DateTime.tryParse(json['boundAt'] as String? ?? '') ?? DateTime.now();
     return ThirdPartyAccount(
       platform: ThirdPartyPlatform.fromId(json['platform'] as String? ?? '') ??
           ThirdPartyPlatform.gradescope,
@@ -98,10 +142,14 @@ class ThirdPartyAccount {
       hydroOrigin: json['hydroOrigin'] as String?,
       hydroDomains:
           (json['hydroDomains'] as List?)?.map((e) => e as String).toList(),
-      boundAt:
-          DateTime.tryParse(json['boundAt'] as String? ?? '') ?? DateTime.now(),
+      boundAt: boundAt,
       autoRenew: json['autoRenew'] as bool? ?? false,
       password: json['password'] as String?,
+      // Back-compat: pre-v2 blobs had no updatedAt/deviceId. Fall back to
+      // boundAt / empty so they merge as "older than any real write".
+      updatedAt:
+          DateTime.tryParse(json['updatedAt'] as String? ?? '') ?? boundAt,
+      deviceId: json['deviceId'] as String? ?? '',
     );
   }
 
@@ -116,6 +164,8 @@ class ThirdPartyAccount {
     List<String>? hydroDomains,
     bool? autoRenew,
     String? password,
+    DateTime? updatedAt,
+    String? deviceId,
   }) {
     return ThirdPartyAccount(
       platform: platform,
@@ -131,6 +181,8 @@ class ThirdPartyAccount {
       boundAt: boundAt,
       autoRenew: autoRenew ?? this.autoRenew,
       password: password ?? this.password,
+      updatedAt: updatedAt ?? this.updatedAt,
+      deviceId: deviceId ?? this.deviceId,
     );
   }
 }

lib/pages/home_page.dart

@@ -394,17 +394,18 @@ class _HomePageState extends State<HomePage> with TickerProviderStateMixin {
     if (cookieType == null) return cookies;
 
     final sp = ServiceProvider.of(context);
-    // ecourse and student-leave both authenticate against the eGate/IDS
-    // SSO, so they share the eGate binding's CpDaily cookies (which always
-    // include CASTGC via [ThirdPartyAuthService.egateCookies]). Without an
-    // eGate binding there is nothing to inject and the webview opens
-    // unauthenticated — the UI should steer the user to bind eGate first.
-    final String rawCookies = sp.thirdPartyAuthService.egateCookies();
-    if (rawCookies.isEmpty) return cookies;
-
-    final domain = 'ids.shanghaitech.edu.cn';
-
-    for (final part in rawCookies.split(';')) {
+    // ecourse / student-leave / eams webviews all authenticate against the
+    // CpDaily session, whose cookies are exposed by the cpdaily session node
+    // (the CASTGC-bearing cookie set that webviews consume directly). Read
+    // it through the unified [CookieProvider] view so the source is abstracted.
+    final cp = sp.thirdPartyAuthService.cpdailyNode.cookieProvider;
+    if (cp == null || cp.isEmpty) return cookies;
+
+    final domain = cp.domain.isNotEmpty
+        ? cp.domain
+        : 'ids.shanghaitech.edu.cn';
+
+    for (final part in cp.cookies.split(';')) {
       final idx = part.indexOf('=');
       if (idx > 0) {
         final key = part.substring(0, idx).trim();

lib/pages/oa_gym_page.dart

@@ -92,7 +92,7 @@ class _OaGymPageState extends State<OaGymPage>
       body: ListenableBuilder(
         listenable: Listenable.merge([auth, tpAuth]),
         builder: (context, _) {
-          final ready = auth.isLoggedIn && tpAuth.hasEgateBinding;
+          final ready = auth.isLoggedIn && tpAuth.hasCpdailyBinding;
           return ready
               ? Column(
                   children: [
@@ -973,15 +973,15 @@ class _ProfileTabState extends State<_ProfileTab> {
   Widget build(BuildContext context) {
     final sp = ServiceProvider.of(context);
     final tpAuth = sp.thirdPartyAuthService;
-    final egate = tpAuth.egateBinding;
+    final cpdaily = tpAuth.cpdailyBinding;
 
-    // Identity card prefers eGate binding (real name + student id) over the
+    // Identity card prefers cpdaily binding (real name + student id) over the
     // primary SSO account, whose userName/userId are Casdoor UUIDs with no
     // meaning in the OA booking context.
-    final displayName = egate?.name?.isNotEmpty == true
-        ? egate!.name!
-        : (egate?.account.isNotEmpty == true ? egate!.account : 'TechPie 用户');
-    final studentId = egate?.sid ?? '';
+    final displayName = cpdaily?.name?.isNotEmpty == true
+        ? cpdaily!.name!
+        : (cpdaily?.account.isNotEmpty == true ? cpdaily!.account : 'TechPie 用户');
+    final studentId = cpdaily?.sid ?? '';
     final avatarText = displayName.characters.firstOrNull ?? 'U';
 
     return ListView(

lib/pages/schedule_page.dart

@@ -729,7 +729,7 @@ class _SchedulePageState extends State<SchedulePage> {
               ? 0
               : adaptiveTopBarHeight() + MediaQuery.viewPaddingOf(context).top,
         ),
-        child: !auth.isLoggedIn || !tpAuth.hasEgateBinding
+        child: !auth.isLoggedIn || !tpAuth.hasCpdailyBinding
             ? Center(
                 child: Column(
                   mainAxisSize: MainAxisSize.min,

lib/pages/settings_page.dart

@@ -106,7 +106,7 @@ class _SettingsPageState extends State<SettingsPage> {
                   ].join(' · '),
                 ),
               ),
-              _EgateBindingTile(tpAuth: tpAuth),
+              _CpdailyBindingTile(tpAuth: tpAuth),
               ListTile(
                 leading: const Icon(Icons.account_tree_outlined),
                 title: const Text('Linked accounts'),
@@ -558,26 +558,26 @@ class _AdaptiveSwitchTile extends StatelessWidget {
   }
 }
 
-class _EgateBindingTile extends StatelessWidget {
+class _CpdailyBindingTile extends StatelessWidget {
   final ThirdPartyAuthService tpAuth;
 
-  const _EgateBindingTile({required this.tpAuth});
+  const _CpdailyBindingTile({required this.tpAuth});
 
   @override
   Widget build(BuildContext context) {
-    final egate = tpAuth.account(ThirdPartyPlatform.egate);
-    final bound = egate != null;
+    final cpdaily = tpAuth.account(ThirdPartyPlatform.cpdaily);
+    final bound = cpdaily != null;
     final theme = Theme.of(context);
 
     return ListTile(
       leading: Icon(
         bound ? Icons.vpn_key : Icons.vpn_key_outlined,
         color: bound ? theme.colorScheme.primary : null,
       ),
-      title: const Text('eGate / IDS'),
+      title: const Text('CpDaily / IDS'),
       subtitle: Text(
         bound
-            ? '已绑定 · ${egate.name ?? egate.sid ?? egate.account}'
+            ? '已绑定 · ${cpdaily.name ?? cpdaily.sid ?? cpdaily.account}'
             : '未绑定 · 需要绑定以启用课表和考试功能',
       ),
       trailing: bound

lib/pages/third_party_accounts_page.dart

@@ -120,7 +120,7 @@ class _ThirdPartyTile extends StatelessWidget {
   IconData get _icon => switch (platform) {
         ThirdPartyPlatform.gradescope => Icons.grading_outlined,
         ThirdPartyPlatform.hydro => Icons.terminal_outlined,
-        ThirdPartyPlatform.egate => Icons.vpn_key_outlined,
+        ThirdPartyPlatform.cpdaily => Icons.vpn_key_outlined,
       };
 
   @override