normalize data

packages/z-timeline/lib/state.dart

@@ -1,12 +1,40 @@
+// Bridge data-transfer types deserialized from JSON pushed by the React host.
+//
+// The shape is normalized: groups and items are stored as maps keyed by
+// ID, with groupOrder preserving display ordering.
+//
+// Keep in sync with `apps/web/src/lib/flutter-bridge.ts`.
+
 class TimelineState {
   final TimelineData timeline;
+  final Map<String, TimelineGroupData> groups;
+  final Map<String, TimelineItemData> items;
+  final List<String> groupOrder;
   final String? selectedItemId;
 
-  TimelineState({required this.timeline, this.selectedItemId});
+  TimelineState({
+    required this.timeline,
+    required this.groups,
+    required this.items,
+    required this.groupOrder,
+    this.selectedItemId,
+  });
 
   factory TimelineState.fromJson(Map<String, dynamic> json) {
+    final rawGroups = json['groups'] as Map<String, dynamic>;
+    final rawItems = json['items'] as Map<String, dynamic>;
+
     return TimelineState(
       timeline: TimelineData.fromJson(json['timeline'] as Map<String, dynamic>),
+      groups: rawGroups.map(
+        (k, v) =>
+            MapEntry(k, TimelineGroupData.fromJson(v as Map<String, dynamic>)),
+      ),
+      items: rawItems.map(
+        (k, v) =>
+            MapEntry(k, TimelineItemData.fromJson(v as Map<String, dynamic>)),
+      ),
+      groupOrder: (json['groupOrder'] as List<dynamic>).cast<String>(),
       selectedItemId: json['selectedItemId'] as String?,
     );
   }
@@ -15,17 +43,13 @@ class TimelineState {
 class TimelineData {
   final String id;
   final String title;
-  final List<TimelineGroupData> groups;
 
-  TimelineData({required this.id, required this.title, required this.groups});
+  TimelineData({required this.id, required this.title});
 
   factory TimelineData.fromJson(Map<String, dynamic> json) {
     return TimelineData(
       id: json['id'] as String,
       title: json['title'] as String,
-      groups: (json['groups'] as List<dynamic>)
-          .map((g) => TimelineGroupData.fromJson(g as Map<String, dynamic>))
-          .toList(),
     );
   }
 }
@@ -34,13 +58,11 @@ class TimelineGroupData {
   final String id;
   final String title;
   final int sortOrder;
-  final List<TimelineItemData> items;
 
   TimelineGroupData({
     required this.id,
     required this.title,
     required this.sortOrder,
-    required this.items,
   });
 
   factory TimelineGroupData.fromJson(Map<String, dynamic> json) {
@@ -48,15 +70,13 @@ class TimelineGroupData {
       id: json['id'] as String,
       title: json['title'] as String,
       sortOrder: json['sortOrder'] as int,
-      items: (json['items'] as List<dynamic>)
-          .map((i) => TimelineItemData.fromJson(i as Map<String, dynamic>))
-          .toList(),
     );
   }
 }
 
 class TimelineItemData {
   final String id;
+  final String groupId;
   final String title;
   final String? description;
   final String start;
@@ -65,6 +85,7 @@ class TimelineItemData {
 
   TimelineItemData({
     required this.id,
+    required this.groupId,
     required this.title,
     this.description,
     required this.start,
@@ -75,6 +96,7 @@ class TimelineItemData {
   factory TimelineItemData.fromJson(Map<String, dynamic> json) {
     return TimelineItemData(
       id: json['id'] as String,
+      groupId: json['groupId'] as String,
       title: json['title'] as String,
       description: json['description'] as String?,
       start: json['start'] as String,