feat: add historical data

lib/models/remote_command.dart

@@ -59,15 +59,34 @@ class RemoteCommand {
   }
 }
 
+/// A tab event the server refused to store. Re-sending won't help.
+class RejectedEvent {
+  final String? id;
+  final String reason;
+
+  const RejectedEvent({this.id, required this.reason});
+
+  factory RejectedEvent.fromJson(Map<String, dynamic> json) {
+    return RejectedEvent(
+      id: json['id'] as String?,
+      reason: json['reason'] as String? ?? '',
+    );
+  }
+}
+
 class SyncResponse {
   final List<RemoteCommand> commands;
   final String? cursor;
   final List<String> plannedTabNames;
+  final List<String> acknowledgedEventIds;
+  final List<RejectedEvent> rejectedEvents;
 
   const SyncResponse({
     required this.commands,
     this.cursor,
     this.plannedTabNames = const [],
+    this.acknowledgedEventIds = const [],
+    this.rejectedEvents = const [],
   });
 
   factory SyncResponse.fromJson(Map<String, dynamic> json) {
@@ -81,6 +100,14 @@ class SyncResponse {
         for (final name in json['plannedTabNames'] as List<dynamic>? ?? [])
           name as String,
       ],
+      acknowledgedEventIds: [
+        for (final id in json['acknowledgedEventIds'] as List<dynamic>? ?? [])
+          id as String,
+      ],
+      rejectedEvents: [
+        for (final event in json['rejectedEvents'] as List<dynamic>? ?? [])
+          RejectedEvent.fromJson(event as Map<String, dynamic>),
+      ],
     );
   }
 }
@@ -136,16 +163,21 @@ class SyncRequest {
   final String? cursor;
   final List<SnapshotTab> openTabs;
 
+  /// Outbox tab events, oldest first, as their stored JSON objects.
+  final List<Map<String, dynamic>> events;
+
   const SyncRequest({
     required this.deviceId,
     this.cursor,
     required this.openTabs,
+    this.events = const [],
   });
 
   Map<String, dynamic> toJson() => {
     'deviceId': deviceId,
     if (cursor != null) 'cursor': cursor,
     'openTabs': openTabs.map((tab) => tab.toJson()).toList(),
+    'events': events,
   };
 }