fix(genui): add missing weight property to Component constructor; default TextField width to 1 when nested in a Row

packages/genui/lib/src/catalog/core_widgets/column.dart

@@ -123,7 +123,7 @@ final column = CatalogItem(
                   componentId: componentId,
                   dataContext: dataContext,
                   buildChild: buildChild,
-                  component: getComponent(componentId),
+                  weight: getComponent(componentId)?.weight,
                 ),
               )
               .toList(),
@@ -142,7 +142,7 @@ final column = CatalogItem(
                   DataPath('$dataBinding/$i'),
                 ),
                 buildChild: itemContext.buildChild,
-                component: itemContext.getComponent(componentId),
+                weight: itemContext.getComponent(componentId)?.weight,
               ),
             ],
           ],

packages/genui/lib/src/catalog/core_widgets/row.dart

@@ -8,6 +8,7 @@ import 'package:json_schema_builder/json_schema_builder.dart';
 import '../../model/a2ui_schemas.dart';
 import '../../model/catalog_item.dart';
 import '../../model/data_model.dart';
+import '../../model/ui_models.dart';
 import '../../primitives/simple_items.dart';
 import 'widget_helpers.dart';
 
@@ -123,13 +124,21 @@ final row = CatalogItem(
                   componentId: componentId,
                   dataContext: dataContext,
                   buildChild: buildChild,
-                  component: getComponent(componentId),
+                  weight:
+                      getComponent(componentId)?.weight ??
+                      (getComponent(componentId)?.type == 'TextField'
+                          ? 1
+                          : null),
                 ),
               )
               .toList(),
         );
       },
       templateListWidgetBuilder: (context, list, componentId, dataBinding) {
+        final Component? component = itemContext.getComponent(componentId);
+        final int? weight =
+            component?.weight ?? (component?.type == 'TextField' ? 1 : null);
+
         return Row(
           mainAxisAlignment: _parseMainAxisAlignment(rowData.distribution),
           crossAxisAlignment: _parseCrossAxisAlignment(rowData.alignment),
@@ -142,7 +151,7 @@ final row = CatalogItem(
                   DataPath('$dataBinding/$i'),
                 ),
                 buildChild: itemContext.buildChild,
-                component: itemContext.getComponent(componentId),
+                weight: weight,
               ),
             ],
           ],

packages/genui/lib/src/catalog/core_widgets/text_field.dart

@@ -13,6 +13,7 @@ import '../../model/ui_models.dart';
 import '../../primitives/simple_items.dart';
 
 final _schema = S.object(
+  description: 'A text input field.',
   properties: {
     'text': A2uiSchemas.stringReference(
       description: 'The initial value of the text field.',

packages/genui/lib/src/catalog/core_widgets/widget_helpers.dart

@@ -6,7 +6,6 @@ import 'package:flutter/material.dart';
 
 import '../../model/catalog_item.dart';
 import '../../model/data_model.dart';
-import '../../model/ui_models.dart';
 import '../../primitives/logging.dart';
 import '../../primitives/simple_items.dart';
 
@@ -133,9 +132,8 @@ Widget buildWeightedChild({
   required String componentId,
   required DataContext dataContext,
   required ChildBuilderCallback buildChild,
-  required Component? component,
+  required int? weight,
 }) {
-  final int? weight = component?.weight;
   final Widget childWidget = buildChild(componentId, dataContext);
   if (weight != null) {
     return Flexible(flex: weight, child: childWidget);

packages/genui/lib/src/core/ui_tools.dart

@@ -35,6 +35,7 @@ class SurfaceUpdateTool extends AiTool<JsonMap> {
       return Component(
         id: component['id'] as String,
         componentProperties: component['component'] as JsonMap,
+        weight: (component['weight'] as num?)?.toInt(),
       );
     }).toList();
     handleMessage(SurfaceUpdate(surfaceId: surfaceId, components: components));

packages/genui/test/catalog/core_widgets/text_field_test.dart

@@ -0,0 +1,134 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:genui/genui.dart';
+
+void main() {
+  testWidgets('TextField with no weight in Row defaults to weight: 1 '
+      'and expands', (WidgetTester tester) async {
+    final a2uiProcessor = A2uiMessageProcessor(
+      catalogs: [CoreCatalogItems.asCatalog()],
+    );
+    const surfaceId = 'testSurface';
+    final components = [
+      const Component(
+        id: 'row',
+        componentProperties: {
+          'Row': {
+            'children': {
+              'explicitList': ['text_field'],
+            },
+          },
+        },
+      ),
+      const Component(
+        id: 'text_field',
+        componentProperties: {
+          'TextField': {
+            'label': {'literalString': 'Input'},
+          },
+        },
+        // "weight" property is left unset.
+      ),
+    ];
+
+    a2uiProcessor.handleMessage(
+      SurfaceUpdate(surfaceId: surfaceId, components: components),
+    );
+    a2uiProcessor.handleMessage(
+      const BeginRendering(
+        surfaceId: surfaceId,
+        root: 'row',
+        catalogId: 'a2ui.org:standard_catalog_0_8_0',
+      ),
+    );
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: GenUiSurface(host: a2uiProcessor, surfaceId: surfaceId),
+        ),
+      ),
+    );
+
+    expect(find.byType(TextField), findsOneWidget);
+
+    final Flexible flexible = tester.widget(
+      find.ancestor(
+        of: find.byType(TextField),
+        matching: find.byType(Flexible),
+      ),
+    );
+    expect(flexible.flex, 1);
+
+    final Finder textFieldFinder = find.byType(TextField);
+    final Size size = tester.getSize(textFieldFinder);
+    expect(size.width, 800.0);
+  });
+
+  testWidgets('TextField in Row (with weight) expands', (
+    WidgetTester tester,
+  ) async {
+    final manager = A2uiMessageProcessor(
+      catalogs: [CoreCatalogItems.asCatalog()],
+    );
+    const surfaceId = 'testSurface';
+    final components = [
+      const Component(
+        id: 'row',
+        componentProperties: {
+          'Row': {
+            'children': {
+              'explicitList': ['text_field'],
+            },
+          },
+        },
+      ),
+      const Component(
+        id: 'text_field',
+        componentProperties: {
+          'TextField': {
+            'label': {'literalString': 'Input'},
+          },
+        },
+        weight: 1,
+      ),
+    ];
+
+    manager.handleMessage(
+      SurfaceUpdate(surfaceId: surfaceId, components: components),
+    );
+    manager.handleMessage(
+      const BeginRendering(
+        surfaceId: surfaceId,
+        root: 'row',
+        catalogId: 'a2ui.org:standard_catalog_0_8_0',
+      ),
+    );
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: GenUiSurface(host: manager, surfaceId: surfaceId),
+        ),
+      ),
+    );
+
+    expect(find.byType(TextField), findsOneWidget);
+
+    expect(
+      find.ancestor(
+        of: find.byType(TextField),
+        matching: find.byType(Flexible),
+      ),
+      findsOneWidget,
+    );
+
+    // Default test screen width is 800.
+    final Size size = tester.getSize(find.byType(TextField));
+    expect(size.width, 800.0);
+  });
+}

packages/genui/test/core/ui_tools_test.dart

@@ -56,6 +56,57 @@ void main() {
       expect(surfaceUpdate.components[0].componentProperties, {
         'Text': {'text': 'Hello'},
       });
+      expect(surfaceUpdate.components[0].weight, isNull);
+    });
+
+    test('invoke correctly parses int weight', () async {
+      final messages = <A2uiMessage>[];
+      final tool = SurfaceUpdateTool(
+        handleMessage: messages.add,
+        catalog: const Catalog([], catalogId: 'test_catalog'),
+      );
+
+      final Map<String, Object> args = {
+        surfaceIdKey: 'testSurface',
+        'components': [
+          {
+            'id': 'weightedWidget',
+            'component': {'Text': <Object?, Object?>{}},
+            'weight': 1,
+          },
+        ],
+      };
+
+      await tool.invoke(args);
+
+      expect(messages.length, 1);
+      final surfaceUpdate = messages[0] as SurfaceUpdate;
+      expect(surfaceUpdate.components[0].weight, 1);
+    });
+
+    test('invoke correctly parses double weight', () async {
+      final messages = <A2uiMessage>[];
+      final tool = SurfaceUpdateTool(
+        handleMessage: messages.add,
+        catalog: const Catalog([], catalogId: 'test_catalog'),
+      );
+
+      final Map<String, Object> args = {
+        surfaceIdKey: 'testSurface',
+        'components': [
+          {
+            'id': 'weightedWidget',
+            'component': {'Text': <Object?, Object?>{}},
+            'weight': 1.0,
+          },
+        ],
+      };
+
+      await tool.invoke(args);
+
+      expect(messages.length, 1);
+      final surfaceUpdate = messages[0] as SurfaceUpdate;
+      expect(surfaceUpdate.components[0].weight, 1);
     });
   });