feat(genui): support functions in prompts and verify rendering

dev_tools/composer/lib/create_tab.dart

@@ -78,7 +78,7 @@ class _CreateTabState extends State<CreateTab> {
         transport: transport,
       );
 
-      final promptBuilder = PromptBuilder.chat(
+      final promptBuilder = await PromptBuilder.createChat(
         catalog: catalog,
         systemPromptFragments: [
           'You are a UI generator. The user will describe a UI they want. '

examples/simple_chat/lib/chat_session.dart

@@ -56,19 +56,20 @@ final Catalog _customCatalog = _basicCatalog.copyWith(
   newItems: [climbingLocationItem],
 );
 
-PromptBuilder _promptBuilderFor(Catalog catalog) => PromptBuilder.chat(
-  catalog: catalog,
-  systemPromptFragments: [
-    Prompts.summary,
-    PromptFragments.acknowledgeUser(),
-    PromptFragments.requireAtLeastOneSubmitElement(
-      prefix: PromptBuilder.defaultImportancePrefix,
-    ),
-    PromptFragments.uiGenerationRestriction(
-      prefix: PromptBuilder.defaultImportancePrefix,
-    ),
-  ],
-);
+Future<PromptBuilder> _promptBuilderFor(Catalog catalog) async =>
+    await PromptBuilder.createChat(
+      catalog: catalog,
+      systemPromptFragments: [
+        Prompts.summary,
+        PromptFragments.acknowledgeUser(),
+        PromptFragments.requireAtLeastOneSubmitElement(
+          prefix: PromptBuilder.defaultImportancePrefix,
+        ),
+        PromptFragments.uiGenerationRestriction(
+          prefix: PromptBuilder.defaultImportancePrefix,
+        ),
+      ],
+    );
 
 sealed class ChatSession extends ChangeNotifier {
   ChatSession._();
@@ -188,7 +189,7 @@ class A2uiChatSession extends ChatSession {
   late final StreamSubscription<ChatMessage> _submitSub;
   late final StreamSubscription<SurfaceUpdate> _surfaceSub;
 
-  void _init() {
+  Future<void> _init() async {
     _messageSub = _transport.incomingMessages.listen(
       _surfaceController.handleMessage,
     );
@@ -198,9 +199,8 @@ class A2uiChatSession extends ChatSession {
     );
     _surfaceSub = _surfaceController.surfaceUpdates.listen(_onSurfaceUpdate);
 
-    _transport.addSystemMessage(
-      _promptBuilderFor(_catalog).systemPromptJoined(),
-    );
+    final PromptBuilder pb = await _promptBuilderFor(_catalog);
+    _transport.addSystemMessage(pb.systemPromptJoined());
   }
 
   void _onSurfaceUpdate(SurfaceUpdate update) {

packages/genui/lib/src/facade/prompt_builder.dart

@@ -5,8 +5,8 @@
 import 'dart:convert';
 
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 
-import '../model/a2ui_message.dart';
 import '../model/catalog.dart';
 import '../primitives/simple_items.dart';
 
@@ -78,38 +78,54 @@ abstract class PromptBuilder {
   /// The builder will generate a prompt for a chat session,
   /// that instructs to create new surfaces for each response
   /// and restrict surface deletion and updates.
-  factory PromptBuilder.chat({
+  static Future<PromptBuilder> createChat({
     required Catalog catalog,
     Iterable<String> systemPromptFragments = const [],
     String importancePrefix = defaultImportancePrefix,
     JsonMap? clientDataModel,
-  }) {
+  }) async {
+    final String commonTypes = await rootBundle.loadString(
+      'packages/genui/submodules/a2ui/specification/v0_9/json/common_types.json',
+    );
+    final String serverToClient = await rootBundle.loadString(
+      'packages/genui/submodules/a2ui/specification/v0_9/json/server_to_client.json',
+    );
     return _BasicPromptBuilder(
       catalog: catalog,
       systemPromptFragments: systemPromptFragments,
       allowedOperations: SurfaceOperations.createOnly(dataModel: false),
       importancePrefix: importancePrefix,
       clientDataModel: clientDataModel,
       technicalPossibilities: const TechnicalPossibilities(),
+      commonTypesSchema: commonTypes,
+      serverToClientSchema: serverToClient,
     );
   }
 
-  factory PromptBuilder.custom({
+  static Future<PromptBuilder> createCustom({
     required Catalog catalog,
     required SurfaceOperations allowedOperations,
     Iterable<String> systemPromptFragments = const [],
     String importancePrefix = defaultImportancePrefix,
     TechnicalPossibilities technicalPossibilities =
         const TechnicalPossibilities(),
     JsonMap? clientDataModel,
-  }) {
+  }) async {
+    final String commonTypes = await rootBundle.loadString(
+      'packages/genui/submodules/a2ui/specification/v0_9/json/common_types.json',
+    );
+    final String serverToClient = await rootBundle.loadString(
+      'packages/genui/submodules/a2ui/specification/v0_9/json/server_to_client.json',
+    );
     return _BasicPromptBuilder(
       catalog: catalog,
       systemPromptFragments: systemPromptFragments,
       allowedOperations: allowedOperations,
       importancePrefix: importancePrefix,
       clientDataModel: clientDataModel,
       technicalPossibilities: technicalPossibilities,
+      commonTypesSchema: commonTypes,
+      serverToClientSchema: serverToClient,
     );
   }
 
@@ -332,9 +348,13 @@ final class _BasicPromptBuilder extends PromptBuilder {
     required this.importancePrefix,
     required this.clientDataModel,
     required this.technicalPossibilities,
+    required this.commonTypesSchema,
+    required this.serverToClientSchema,
   }) : super._();
 
   final Catalog catalog;
+  final String commonTypesSchema;
+  final String serverToClientSchema;
 
   final SurfaceOperations allowedOperations;
 
@@ -359,23 +379,84 @@ final class _BasicPromptBuilder extends PromptBuilder {
 
   @override
   Iterable<String> systemPrompt() {
-    final String a2uiSchema = A2uiMessage.a2uiMessageSchema(
-      catalog,
-    ).toJson(indent: '  ');
+    final String catalogSchema = _generateCatalogSchema(catalog);
 
     final fragments = <String>[
       ...systemPromptFragments,
       'Use the provided tools to respond to user using rich UI elements.',
       ...technicalPossibilities.systemPromptFragment(),
       ...catalog.systemPromptFragments,
       ...allowedOperations.systemPromptFragments,
-      _fenced(a2uiSchema, sectionName: 'A2UI JSON SCHEMA'),
+      _fenced(commonTypesSchema, sectionName: 'COMMON TYPES'),
+      _fenced(catalogSchema, sectionName: 'CATALOG SCHEMA'),
+      _fenced(serverToClientSchema, sectionName: 'MESSAGE SCHEMA'),
       ?_encodedDataModel(clientDataModel),
     ];
 
     return _fragmentsToPrompt(fragments);
   }
 
+  String _generateCatalogSchema(Catalog catalog) {
+    final Map<String, dynamic> components = {
+      for (final item in catalog.items)
+        item.name: {
+          'type': 'object',
+          'allOf': [
+            {r'$ref': r'common_types.json#/$defs/ComponentCommon'},
+            {r'$ref': r'#/$defs/CatalogComponentCommon'},
+            {
+              'type': 'object',
+              'properties': {
+                'component': {'const': item.name},
+                ...item.dataSchema.value['properties'] as Map<String, dynamic>,
+              },
+              'required': {
+                'component',
+                ...?item.dataSchema.value['required'] as List?,
+              }.toList(),
+            },
+          ],
+          'unevaluatedProperties': false,
+        },
+    };
+
+    final Map<String, dynamic> functions = {
+      for (final func in catalog.functions)
+        func.name: {
+          'description': func.description,
+          'parameters': func.argumentSchema.value,
+          'returnType': func.returnType.value,
+        },
+    };
+
+    final Map<String, dynamic> catalogJson = {
+      r'$schema': 'https://json-schema.org/draft/2020-12/schema',
+      r'$id': 'https://a2ui.org/specification/v0_9/catalog.json',
+      'title': 'A2UI Catalog',
+      'description': 'Custom catalog of A2UI components and functions.',
+      if (catalog.catalogId != null) 'catalogId': catalog.catalogId,
+      'components': components,
+      if (functions.isNotEmpty) 'functions': functions,
+      r'$defs': {
+        'CatalogComponentCommon': {
+          'type': 'object',
+          'properties': {
+            'id': {
+              'type': 'string',
+              'description':
+                  'A unique identifier for this component instance within '
+                  'the surface. This ID is used to refer to the component '
+                  'in layout children arrays or event handlers.',
+            },
+          },
+          'required': ['id'],
+        },
+      },
+    };
+
+    return const JsonEncoder.withIndent('  ').convert(catalogJson);
+  }
+
   static String? _encodedDataModel(JsonMap? clientDataModel) {
     if (clientDataModel == null) return null;
     final String encodedModel = const JsonEncoder.withIndent(

packages/genui/lib/src/model/a2ui_schemas.dart

@@ -280,17 +280,9 @@ abstract final class A2uiSchemas {
 
   /// Schema for a validation check, including logic and an error message.
   static Schema validationCheck({String? description}) {
-    return S.object(
+    return S.combined(
+      $ref: r'common_types.json#/$defs/CheckRule',
       description: description,
-      properties: {
-        'message': S.string(description: 'Error message if validation fails.'),
-        'condition': S.any(
-          description:
-              'DynamicBoolean condition (FunctionCall, DataBinding, or '
-              'literal).',
-        ),
-      },
-      required: ['message', 'condition'],
     );
   }
 
@@ -300,44 +292,40 @@ abstract final class A2uiSchemas {
     String? description,
     List<String>? enumValues,
   }) {
-    final literal = S.string(
-      description: 'A literal string value.',
-      enumValues: enumValues,
-    );
-    final Schema binding = dataBindingSchema(
-      description: 'A path to a string.',
-    );
-    final Schema function = functionCall();
+    if (enumValues != null) {
+      final literal = S.string(
+        description: 'A literal string value.',
+        enumValues: enumValues,
+      );
+      final Schema binding = dataBindingSchema(
+        description: 'A path to a string.',
+      );
+      final Schema function = functionCall();
+      return S.combined(
+        oneOf: [literal, binding, function],
+        description: description,
+      );
+    }
     return S.combined(
-      oneOf: [literal, binding, function],
+      $ref: r'common_types.json#/$defs/DynamicString',
       description: description,
     );
   }
 
   /// Schema for a value that can be either a literal number or a
   /// data-bound path to a number in the DataModel.
   static Schema numberReference({String? description}) {
-    final literal = S.number(description: 'A literal number value.');
-    final Schema binding = dataBindingSchema(
-      description: 'A path to a number.',
-    );
-    final Schema function = functionCall();
     return S.combined(
-      oneOf: [literal, binding, function],
+      $ref: r'common_types.json#/$defs/DynamicNumber',
       description: description,
     );
   }
 
   /// Schema for a value that can be either a literal boolean or a
   /// data-bound path to a boolean in the DataModel.
   static Schema booleanReference({String? description}) {
-    final literal = S.boolean(description: 'A literal boolean value.');
-    final Schema binding = dataBindingSchema(
-      description: 'A path to a boolean.',
-    );
-    final Schema function = functionCall();
     return S.combined(
-      oneOf: [literal, binding, function],
+      $ref: r'common_types.json#/$defs/DynamicBoolean',
       description: description,
     );
   }
@@ -383,46 +371,17 @@ abstract final class A2uiSchemas {
   ///
   /// Can be either a server-side event or a client-side function call.
   static Schema action({String? description}) {
-    final eventSchema = S.object(
-      properties: {
-        'event': S.object(
-          properties: {
-            'name': S.string(
-              description:
-                  'The name of the action to be dispatched to the server.',
-            ),
-            'context': S.object(
-              description: 'Arbitrary context data to send with the action.',
-              additionalProperties: true,
-            ),
-          },
-          required: ['name'],
-        ),
-      },
-      required: ['event'],
-    );
-
-    final functionCallSchema = S.object(
-      properties: {'functionCall': functionCall()},
-      required: ['functionCall'],
-    );
-
     return S.combined(
+      $ref: r'common_types.json#/$defs/Action',
       description: description,
-      oneOf: [eventSchema, functionCallSchema],
     );
   }
 
   /// Schema for a value that can be either a literal array of strings or a
   /// data-bound path to an array of strings.
   static Schema stringArrayReference({String? description}) {
-    final literal = S.list(items: S.string());
-    final Schema binding = dataBindingSchema(
-      description: 'A path to a string list.',
-    );
-    final Schema function = functionCall();
     return S.combined(
-      oneOf: [literal, binding, function],
+      $ref: r'common_types.json#/$defs/DynamicStringList',
       description: description,
     );
   }

packages/genui/pubspec.yaml

@@ -38,3 +38,8 @@ dev_dependencies:
     sdk: flutter
   network_image_mock: ^2.1.1
   test: ^1.26.2
+
+flutter:
+  assets:
+    - submodules/a2ui/specification/v0_9/json/common_types.json
+    - submodules/a2ui/specification/v0_9/json/server_to_client.json