Retire UiChangeEvent and UiEventManager (#254)

Author: polina-c

examples/simple_chat/lib/main.dart

@@ -50,14 +50,14 @@ class _ChatScreenState extends State<ChatScreen> {
     of the user message.
     ''',
     catalog: CoreCatalogItems.asCatalog(),
-    onSurfaceAdded: _onSurfaceAdded,
+    onSurfaceAdded: _handleSurfaceAdded,
     onTextResponse: _onTextResponse,
     // ignore: avoid_print
     onWarning: (value) => print('Warning from UiAgent: $value'),
   );
   final ScrollController _scrollController = ScrollController();
 
-  void _onSurfaceAdded(SurfaceAdded surface) {
+  void _handleSurfaceAdded(SurfaceAdded surface) {
     if (!mounted) return;
     setState(() {
       _messages.add(MessageController(surfaceId: surface.surfaceId));

examples/simple_chat/lib/message.dart

@@ -25,6 +25,6 @@ class MessageView extends StatelessWidget {
 
     if (surfaceId == null) return Text(controller.text ?? '');
 
-    return GenUiSurface(host: host, surfaceId: surfaceId, onEvent: (event) {});
+    return GenUiSurface(host: host, surfaceId: surfaceId);
   }
 }

examples/travel_app/lib/main.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:dart_schema_builder/dart_schema_builder.dart';
 import 'package:firebase_app_check/firebase_app_check.dart';
 import 'package:firebase_core/firebase_core.dart';
@@ -89,7 +91,7 @@ class TravelPlannerPage extends StatefulWidget {
 class _TravelPlannerPageState extends State<TravelPlannerPage> {
   late final GenUiManager _genUiManager;
   late final AiClient _aiClient;
-  late final UiEventManager _eventManager;
+  late final StreamSubscription<UserMessage> _userMessageSubscription;
   final List<ChatMessage> _conversation = [];
   final _textController = TextEditingController();
   final _scrollController = ScrollController();
@@ -108,7 +110,9 @@ class _TravelPlannerPageState extends State<TravelPlannerPage> {
         ),
       ),
     );
-    _eventManager = UiEventManager(callback: _onUiEvents);
+    _userMessageSubscription = _genUiManager.onSubmit.listen(
+      _handleUserMessageFromUi,
+    );
     _aiClient =
         widget.aiClient ??
         FirebaseAiClient(
@@ -146,7 +150,7 @@ class _TravelPlannerPageState extends State<TravelPlannerPage> {
   @override
   void dispose() {
     _genUiManager.dispose();
-    _eventManager.dispose();
+    _userMessageSubscription.cancel();
     _textController.dispose();
     _scrollController.dispose();
     super.dispose();
@@ -206,37 +210,14 @@ class _TravelPlannerPageState extends State<TravelPlannerPage> {
     return;
   }
 
-  void _onUiEvents(String surfaceId, List<UiEvent> events) {
-    final actionEvent = events.firstWhere((e) => e.isAction);
-    final message = StringBuffer(
-      'The user triggered the "${actionEvent.eventType}" event on widget '
-      '"${actionEvent.widgetId}"',
-    );
-    final value = actionEvent.value;
-    if (value is String && value.isNotEmpty) {
-      message.write(' with value "$value"');
-    }
-    message.write('.');
-
-    final changeEvents = events.where((e) => !e.isAction).toList();
-    if (changeEvents.isNotEmpty) {
-      message.writeln(' Current values of other widgets:');
-      for (final event in changeEvents) {
-        message.writeln('- Widget "${event.widgetId}": ${event.value}');
-      }
-    }
-
+  void _handleUserMessageFromUi(UserMessage message) {
     setState(() {
       _conversation.add(UserUiInteractionMessage.text(message.toString()));
     });
     _scrollToBottom();
     _triggerInference();
   }
 
-  void _handleUiEvent(UiEvent event) {
-    _eventManager.add(event);
-  }
-
   void _sendPrompt(String text) {
     if (_isThinking || text.trim().isEmpty) return;
     setState(() {
@@ -273,7 +254,6 @@ class _TravelPlannerPageState extends State<TravelPlannerPage> {
                   child: Conversation(
                     messages: _conversation,
                     manager: _genUiManager,
-                    onEvent: _handleUiEvent,
                     scrollController: _scrollController,
                   ),
                 ),
@@ -398,7 +378,7 @@ to the user.
     a Column with the existing OptionsFilterChipInput, a
     ItineraryWithDetails containing the full itinerary, and a Trailhead
     containing some options of specific details to book e.g. "Book accommodation in Kyoto", "Train options from Tokyo to Osaka".
-    
+
     Note that during this step, the user may change their search parameters and
     resubmit, in which case you should regenerate the itinerary to match their
     desires, updating the existing surface.
@@ -450,7 +430,7 @@ When processing a user message or event, you should add or update one surface
 and then call provideFinalOutput to return control to the user. Never continue
 to add or update surfaces until you receive another user event. If the last
 entry in the context is a functionResponse, just call provideFinalOutput
-immediately - don't try to update the UI. 
+immediately - don't try to update the UI.
 
 # UI style
 

examples/travel_app/lib/src/catalog/options_filter_chip_input.dart

@@ -106,9 +106,7 @@ extension type _OptionsFilterChipInputData.fromMap(Map<String, Object?> _json) {
 /// options.
 ///
 /// It is typically used within a [inputGroup] to manage multiple facets of
-/// a user's query. When an option is selected, it dispatches a [UiChangeEvent],
-/// which informs the AI of the user's choice, allowing it to refine its
-/// subsequent responses.
+/// a user's query.
 final optionsFilterChipInput = CatalogItem(
   name: 'OptionsFilterChipInput',
   dataSchema: _schema,
@@ -142,6 +140,7 @@ final optionsFilterChipInput = CatalogItem(
           widgetId: id,
           dispatchEvent: dispatchEvent,
           icon: icon,
+          values: values,
         );
       },
 );
@@ -152,6 +151,7 @@ class _OptionsFilterChip extends StatefulWidget {
     required this.options,
     required this.widgetId,
     required this.dispatchEvent,
+    required this.values,
     this.icon,
   });
 
@@ -160,6 +160,7 @@ class _OptionsFilterChip extends StatefulWidget {
   final String widgetId;
   final IconData? icon;
   final DispatchEventCallback dispatchEvent;
+  final Map<String, Object?> values;
 
   @override
   State<_OptionsFilterChip> createState() => _OptionsFilterChipState();
@@ -201,17 +202,11 @@ class _OptionsFilterChipState extends State<_OptionsFilterChip> {
                         setModalState(() {
                           tempSelectedOption = newValue;
                         });
+                        widget.values[widget.widgetId] = newValue;
                         if (newValue != null) {
                           setState(() {
                             _currentChipLabel = newValue;
                           });
-                          widget.dispatchEvent(
-                            UiChangeEvent(
-                              widgetId: widget.widgetId,
-                              eventType: 'filterOptionSelected',
-                              value: newValue,
-                            ),
-                          );
                           Navigator.pop(context);
                         }
                       },

examples/travel_app/lib/src/catalog/text_input_chip.dart

@@ -50,6 +50,7 @@ final textInputChip = CatalogItem(
           initialValue: textInputChipData.initialValue,
           widgetId: id,
           dispatchEvent: dispatchEvent,
+          values: values,
         );
       },
 );
@@ -60,12 +61,14 @@ class _TextInputChip extends StatefulWidget {
     this.initialValue,
     required this.widgetId,
     required this.dispatchEvent,
+    required this.values,
   });
 
   final String label;
   final String? initialValue;
   final String widgetId;
   final DispatchEventCallback dispatchEvent;
+  final Map<String, Object?> values;
 
   @override
   State<_TextInputChip> createState() => _TextInputChipState();
@@ -106,16 +109,10 @@ class _TextInputChipState extends State<_TextInputChip> {
                     onPressed: () {
                       final newValue = _textController.text;
                       if (newValue.isNotEmpty) {
+                        widget.values[widget.widgetId] = newValue;
                         setState(() {
                           _currentValue = newValue;
                         });
-                        widget.dispatchEvent(
-                          UiChangeEvent(
-                            widgetId: widget.widgetId,
-                            eventType: 'textInputChanged',
-                            value: newValue,
-                          ),
-                        );
                         Navigator.pop(context);
                       }
                     },

examples/travel_app/lib/src/widgets/conversation.dart

@@ -14,14 +14,12 @@ class Conversation extends StatelessWidget {
     super.key,
     required this.messages,
     required this.manager,
-    required this.onEvent,
     this.userPromptBuilder,
     this.showInternalMessages = false,
     this.scrollController,
   });
 
   final List<ChatMessage> messages;
-  final UiEventCallback onEvent;
   final GenUiManager manager;
   final UserPromptBuilder? userPromptBuilder;
   final bool showInternalMessages;
@@ -74,7 +72,6 @@ class Conversation extends StatelessWidget {
                 key: message.uiKey,
                 host: manager,
                 surfaceId: message.surfaceId,
-                onEvent: onEvent,
               ),
             );
           case InternalMessage():

examples/travel_app/test/options_filter_chip_input_test.dart

@@ -20,6 +20,8 @@ void main() {
 
       UiEvent? dispatchedEvent;
 
+      final values = <String, Object?>{};
+
       await tester.pumpWidget(
         MaterialApp(
           home: Scaffold(
@@ -33,7 +35,7 @@ void main() {
                     dispatchedEvent = event;
                   },
                   context: context,
-                  values: {},
+                  values: values,
                 );
               },
             ),
@@ -66,12 +68,9 @@ void main() {
       // Check if the chip label is updated.
       expect(find.text('\$\$'), findsOneWidget);
 
-      // Check if the event was dispatched.
-      expect(dispatchedEvent, isA<UiChangeEvent>());
-      final changeEvent = dispatchedEvent as UiChangeEvent;
-      expect(changeEvent.widgetId, 'testId');
-      expect(changeEvent.eventType, 'filterOptionSelected');
-      expect(changeEvent.value, '\$\$');
+      expect(dispatchedEvent, null);
+      final value = values['testId'];
+      expect(value, '\$\$');
     });
 
     testWidgets('renders correctly and handles selection without an icon', (
@@ -83,7 +82,7 @@ void main() {
       };
 
       UiEvent? dispatchedEvent;
-
+      final values = <String, Object?>{};
       await tester.pumpWidget(
         MaterialApp(
           home: Scaffold(
@@ -97,7 +96,7 @@ void main() {
                     dispatchedEvent = event;
                   },
                   context: context,
-                  values: {},
+                  values: values,
                 );
               },
             ),
@@ -121,12 +120,9 @@ void main() {
       // Check if the chip label is updated.
       expect(find.text('\$\$\$'), findsOneWidget);
 
-      // Check if the event was dispatched.
-      expect(dispatchedEvent, isA<UiChangeEvent>());
-      final changeEvent = dispatchedEvent as UiChangeEvent;
-      expect(changeEvent.widgetId, 'testId');
-      expect(changeEvent.eventType, 'filterOptionSelected');
-      expect(changeEvent.value, '\$\$\$');
+      expect(dispatchedEvent, null);
+      final value = values['testId'];
+      expect(value, '\$\$\$');
     });
   });
 }

examples/travel_app/test/widgets/conversation_test.dart

@@ -42,11 +42,7 @@ void main() {
       await tester.pumpWidget(
         MaterialApp(
           home: Scaffold(
-            body: Conversation(
-              messages: messages,
-              manager: manager,
-              onEvent: (_) {},
-            ),
+            body: Conversation(messages: messages, manager: manager),
           ),
         ),
       );
@@ -56,16 +52,12 @@ void main() {
     });
     testWidgets('renders UserPrompt correctly', (WidgetTester tester) async {
       final messages = [
-        const UserMessage([TextPart('Hello')]),
+        UserMessage([const TextPart('Hello')]),
       ];
       await tester.pumpWidget(
         MaterialApp(
           home: Scaffold(
-            body: Conversation(
-              messages: messages,
-              manager: manager,
-              onEvent: (_) {},
-            ),
+            body: Conversation(messages: messages, manager: manager),
           ),
         ),
       );
@@ -95,11 +87,7 @@ void main() {
       await tester.pumpWidget(
         MaterialApp(
           home: Scaffold(
-            body: Conversation(
-              messages: messages,
-              manager: manager,
-              onEvent: (_) {},
-            ),
+            body: Conversation(messages: messages, manager: manager),
           ),
         ),
       );
@@ -109,15 +97,14 @@ void main() {
 
     testWidgets('uses custom userPromptBuilder', (WidgetTester tester) async {
       final messages = [
-        const UserMessage([TextPart('Hello')]),
+        UserMessage(const [TextPart('Hello')]),
       ];
       await tester.pumpWidget(
         MaterialApp(
           home: Scaffold(
             body: Conversation(
               messages: messages,
               manager: manager,
-              onEvent: (_) {},
               userPromptBuilder: (context, message) =>
                   const Text('Custom User Prompt'),
             ),