feat: make server own products

lib/models/remote_command.dart

@@ -157,6 +157,40 @@ class ServerStock {
   }
 }
 
+/// A product as the website manages it.
+class ServerProduct {
+  final String id;
+  final String name;
+  final String? category;
+  final int priceInCents;
+
+  /// Null: no low stock warning.
+  final int? lowStockThreshold;
+
+  /// Deleted on the website: hidden, kept for open tabs and the history.
+  final bool archived;
+
+  const ServerProduct({
+    required this.id,
+    required this.name,
+    this.category,
+    required this.priceInCents,
+    this.lowStockThreshold,
+    this.archived = false,
+  });
+
+  factory ServerProduct.fromJson(Map<String, dynamic> json) {
+    return ServerProduct(
+      id: json['id'] as String,
+      name: json['name'] as String,
+      category: json['category'] as String?,
+      priceInCents: json['priceInCents'] as int,
+      lowStockThreshold: json['lowStockThreshold'] as int?,
+      archived: json['archived'] as bool? ?? false,
+    );
+  }
+}
+
 class SyncResponse {
   final List<RemoteCommand> commands;
   final String? cursor;
@@ -183,6 +217,10 @@ class SyncResponse {
   /// sales and applies [stockAdjustments] itself.
   final List<ServerStock>? stock;
 
+  /// Every product of the venue, managed on the website. Null from a server
+  /// that doesn't manage the catalog; the tablet then manages its own.
+  final List<ServerProduct>? catalog;
+
   const SyncResponse({
     required this.commands,
     this.cursor,
@@ -196,6 +234,7 @@ class SyncResponse {
     this.settlements = const [],
     this.settlementsCursor,
     this.stock,
+    this.catalog,
   });
 
   factory SyncResponse.fromJson(Map<String, dynamic> json) {
@@ -251,6 +290,13 @@ class SyncResponse {
         ],
         _ => null,
       },
+      catalog: switch (json['catalog']) {
+        final List<dynamic> catalog => [
+          for (final product in catalog)
+            ServerProduct.fromJson(product as Map<String, dynamic>),
+        ],
+        _ => null,
+      },
     );
   }
 
@@ -391,10 +437,15 @@ class RemoteSyncEvent {
   final String? requestedBy;
   final String? message;
 
+  /// A failed sync that only lacked a connection: the bar keeps working and
+  /// everything is sent once it is back.
+  final bool offline;
+
   const RemoteSyncEvent({
     required this.type,
     this.tabCustomerName,
     this.requestedBy,
     this.message,
+    this.offline = false,
   });
 }

lib/models/tab_event.dart

@@ -207,7 +207,9 @@ class TabEventFactory {
       customerName: customerName,
       fields: {
         'lineId': lineId,
-        'productId': productId,
+        // Lines taken over from a tablet's own tabs have no product: the
+        // server then matches them by name and price, and refuses an empty id
+        if (productId.isNotEmpty) 'productId': productId,
         'productName': productName,
         'unitPriceInCents': unitPriceInCents,
         'quantity': quantity,