Call genui when url param 'genui=true' is passed. (#3188)

Author: polina-c

pkgs/dart_services/README.md

@@ -29,14 +29,23 @@ dart bin/server.dart
 The server will run from port 8080 and export several JSON APIs, like
 `/api/v3/analyze` and `/api/v3/compile`.
 
-To test Gemini API features on a local machine,
-get an API key from [Google AI Studio](https://aistudio.google.com)
-and set the `GEMINI_API_KEY` environment variable before running:
 
-```
-export GEMINI_API_KEY=<YOUR_API_KEY>
-dart bin/server.dart
-```
+### Enabling code generation
+
+To test code generation features locally:
+
+1. Get needed API keys:
+
+   * Get a GEMINI_API_KEY key from [Google AI Studio](https://aistudio.google.com)
+   * See how to get a GENUI_API_KEY in the internal go/dartpad-manual.
+
+2. Set the needed environment variables before running:
+
+   ```
+   export GEMINI_API_KEY=<YOUR_GEMINI_API_KEY>
+   export GENUI_API_KEY=<YOUR_GENUI_API_KEY>
+   dart bin/server.dart
+   ```
 
 ### Testing
 

pkgs/dart_services/lib/server.dart

@@ -34,14 +34,6 @@ Future<void> main(List<String> args) async {
               'The name of the Cloud Storage bucket for compilation artifacts.',
           defaultsTo: 'nnbd_artifacts',
         )
-        ..addOption(
-          'genui-key',
-          valueHelp: 'key',
-          help:
-              'Genui api key to be passed with request. '
-              'Not needed for hosted instance, just for local development.',
-          defaultsTo: null,
-        )
         ..addFlag(
           'help',
           abbr: 'h',
@@ -79,7 +71,6 @@ Future<void> main(List<String> args) async {
   final redisServerUri = results['redis-url'] as String?;
   final storageBucket =
       results['storage-bucket'] as String? ?? 'nnbd_artifacts';
-  final genUiKey = results['genui-key'] as String?;
 
   final cloudRunEnvVars = Platform.environment.entries
       .where((entry) => entry.key.startsWith('K_'))
@@ -100,7 +91,6 @@ Starting dart-services:
     sdk,
     redisServerUri,
     storageBucket,
-    genUiKey: genUiKey,
   );
 
   _logger.info('Listening on port ${server.port}');
@@ -111,14 +101,12 @@ class EndpointsServer {
     int port,
     Sdk sdk,
     String? redisServerUri,
-    String storageBucket, {
-    String? genUiKey,
-  }) async {
+    String storageBucket,
+  ) async {
     final endpointsServer = EndpointsServer._(
       sdk,
       redisServerUri,
       storageBucket,
-      genUiKey: genUiKey,
     );
     await endpointsServer._init();
 
@@ -137,12 +125,7 @@ class EndpointsServer {
 
   late final CommonServerApi commonServer;
 
-  EndpointsServer._(
-    Sdk sdk,
-    String? redisServerUri,
-    String storageBucket, {
-    String? genUiKey,
-  }) {
+  EndpointsServer._(Sdk sdk, String? redisServerUri, String storageBucket) {
     // The name of the Cloud Run revision being run, for more detail please see:
     // https://cloud.google.com/run/docs/reference/container-contract#env-vars
     final serverVersion = Platform.environment['K_REVISION'];
@@ -153,12 +136,7 @@ class EndpointsServer {
             : RedisCache(redisServerUri, sdk, serverVersion);
 
     commonServer = CommonServerApi(
-      CommonServerImpl(
-        sdk,
-        cache,
-        storageBucket: storageBucket,
-        genUiKey: genUiKey,
-      ),
+      CommonServerImpl(sdk, cache, storageBucket: storageBucket),
     );
 
     final pipeline = const Pipeline()

pkgs/dart_services/lib/src/common_server.dart

@@ -15,6 +15,7 @@ import 'package:shelf_router/shelf_router.dart';
 import 'analysis.dart';
 import 'caching.dart';
 import 'compiling.dart';
+import 'flutter_genui.dart';
 import 'generative_ai.dart';
 import 'project_templates.dart';
 import 'pub.dart';
@@ -38,12 +39,12 @@ class CommonServerImpl {
   late Analyzer analyzer;
   late Compiler compiler;
   final ai = GenerativeAI();
+  final GenUi genui = GenUi();
 
   CommonServerImpl(
     this.sdk,
     this.cache, {
     this.storageBucket = 'nnbd_artifacts',
-    genUiKey,
   });
 
   Future<void> init() async {
@@ -91,6 +92,7 @@ class CommonServerApi {
     router.post(r'/api/<apiVersion>/document', handleDocument);
     router.post(r'/api/<apiVersion>/openInIDX', handleOpenInIdx);
     router.post(r'/api/<apiVersion>/generateCode', generateCode);
+    router.post(r'/api/<apiVersion>/generateUi', generateUi);
     router.post(r'/api/<apiVersion>/updateCode', updateCode);
     router.post(r'/api/<apiVersion>/suggestFix', suggestFix);
     return router;
@@ -329,20 +331,16 @@ class CommonServerApi {
   Future<Response> generateUi(Request request, String apiVersion) async {
     if (apiVersion != api3) return unhandledVersion(apiVersion);
 
-    final generateCodeRequest = api.GenerateCodeRequest.fromJson(
+    final generateUiRequest = api.GenerateUiRequest.fromJson(
       await request.readAsJson(),
     );
 
-    return _streamResponse(
-      'generateUi',
-      Stream.fromIterable([
-        'hello',
-        ' from',
-        ' genui',
-        ' for ',
-        generateCodeRequest.prompt,
-      ]),
-    );
+    final resultStream = Stream.fromIterable([
+      await impl.genui.generateCode(prompt: generateUiRequest.prompt),
+    ]);
+
+    // TODO(polina-c): setup better streaming
+    return _streamResponse('generateUi', resultStream);
   }
 
   Future<Response> updateCode(Request request, String apiVersion) async {

pkgs/dart_services/lib/src/flutter_genui.dart

@@ -0,0 +1,57 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:http/http.dart' as http;
+import 'package:logging/logging.dart';
+
+final _logger = Logger('genui');
+
+class GenUi {
+  static const _apiKeyVarName = 'GENUI_API_KEY';
+  late final String _genuiApiKey;
+
+  GenUi() {
+    _genuiApiKey = Platform.environment[_apiKeyVarName] ?? '';
+    if (_genuiApiKey.isEmpty) {
+      _logger.warning('$_apiKeyVarName not set; genui features DISABLED');
+    } else {
+      _logger.info('$_apiKeyVarName set; genui features ENABLED');
+    }
+  }
+
+  Future<String> generateCode({required String prompt}) async {
+    final response = await _requestGenUI(prompt: prompt);
+
+    if (response.statusCode != 200) {
+      throw Exception('Failed to generate ui: ${response.body}');
+    }
+
+    final decoded = jsonDecode(response.body) as Map<String, dynamic>;
+    final flutterCode = decoded['flutterCode'] as String;
+
+    return flutterCode;
+  }
+
+  Future<http.Response> _requestGenUI({required String prompt}) async {
+    if (_genuiApiKey.isEmpty) {
+      throw Exception('Missing environment variable: $_apiKeyVarName');
+    }
+
+    return http.post(
+      Uri.parse(
+        'https://autopush-devgenui.sandbox.googleapis.com/v1beta1/firstparty/generateidecode?key=$_genuiApiKey',
+      ),
+      headers: <String, String>{
+        'Content-Type': 'application/json; charset=UTF-8',
+      },
+      body: jsonEncode(<String, String>{
+        'userPrompt': prompt,
+        'modelUrl': 'genuigemini://models/gemini-2.0-flash',
+      }),
+    );
+  }
+}

pkgs/dartpad_shared/lib/services.dart

@@ -63,6 +63,9 @@ class ServicesClient {
   Stream<String> generateCode(GenerateCodeRequest request) =>
       _requestPostStream('generateCode', request.toJson());
 
+  Stream<String> generateUi(GenerateUiRequest request) =>
+      _requestPostStream('generateUi', request.toJson());
+
   Stream<String> updateCode(UpdateCodeRequest request) =>
       _requestPostStream('updateCode', request.toJson());
 
@@ -120,7 +123,12 @@ class ServicesClient {
     httpRequest.body = json.encode(request);
     final response = await client.send(httpRequest);
 
-    if (response.statusCode != 200) throw ApiRequestError(action, '');
+    if (response.statusCode != 200) {
+      throw ApiRequestError(
+        action,
+        '${response.statusCode}: ${response.reasonPhrase}',
+      );
+    }
 
     try {
       yield* response.stream.transform(utf8.decoder);

pkgs/dartpad_ui/lib/enable_gen_ai.dart

@@ -4,3 +4,18 @@
 
 // Turn on or off gen-ai features in the client.
 const bool genAiEnabled = false;
+
+/*
+
+To use GenUI locally:
+
+1. Set genAiEnabled to true above.
+
+2. See go/dartpad-manual-genui for instructions on how to start backend with GENUI_API_KEY.
+
+3. Use this command to run UI:
+
+flutter run -d chrome --web-port 8888 --web-browser-flag "--disable-web-security" \
+  --web-launch-url="http://localhost:8888/?channel=localhost&genui=true"
+
+*/

pkgs/dartpad_ui/lib/main.dart

@@ -130,6 +130,7 @@ class _DartPadAppState extends State<DartPadApp> {
     final channelParam = state.uri.queryParameters['channel'];
     final embedMode = state.uri.queryParameters['embed'] == 'true';
     final runOnLoad = state.uri.queryParameters['run'] == 'true';
+    final useGenui = state.uri.queryParameters['genui'] == 'true';
 
     return DartPadMainPage(
       initialChannel: channelParam,
@@ -139,6 +140,7 @@ class _DartPadAppState extends State<DartPadApp> {
       builtinSampleId: builtinSampleId,
       flutterSampleId: flutterSampleId,
       handleBrightnessChanged: handleBrightnessChanged,
+      useGenui: useGenui,
     );
   }
 
@@ -206,6 +208,7 @@ class DartPadMainPage extends StatefulWidget {
   final String? gistId;
   final String? builtinSampleId;
   final String? flutterSampleId;
+  final bool useGenui;
 
   DartPadMainPage({
     required this.initialChannel,
@@ -215,6 +218,7 @@ class DartPadMainPage extends StatefulWidget {
     this.gistId,
     this.builtinSampleId,
     this.flutterSampleId,
+    this.useGenui = false,
   }) : super(
          key: ValueKey(
            'sample:$builtinSampleId gist:$gistId flutter:$flutterSampleId',
@@ -298,6 +302,10 @@ class _DartPadMainPageState extends State<DartPadMainPage>
           }
         });
     appModel.compilingState.addListener(_handleRunStarted);
+
+    debugPrint(
+      'initialized: useGenui = ${widget.useGenui}, channel = $channel.',
+    );
   }
 
   @override
@@ -697,13 +705,20 @@ class DartPadAppBar extends StatelessWidget implements PreferredSizeWidget {
     LocalStorage.instance.saveLastCreateCodePrompt(promptResponse.prompt);
 
     try {
-      final stream = appServices.generateCode(
-        GenerateCodeRequest(
-          appType: promptResponse.appType,
-          prompt: promptResponse.prompt,
-          attachments: promptResponse.attachments,
-        ),
-      );
+      final Stream<String> stream;
+      if (widget.useGenui) {
+        stream = appServices.generateUi(
+          GenerateUiRequest(prompt: promptResponse.prompt),
+        );
+      } else {
+        stream = appServices.generateCode(
+          GenerateCodeRequest(
+            appType: promptResponse.appType,
+            prompt: promptResponse.prompt,
+            attachments: promptResponse.attachments,
+          ),
+        );
+      }
 
       final generateResponse = await showDialog<String>(
         context: context,

pkgs/dartpad_ui/lib/model.dart

@@ -464,6 +464,10 @@ class AppServices {
     return services.generateCode(request);
   }
 
+  Stream<String> generateUi(GenerateUiRequest request) {
+    return services.generateUi(request);
+  }
+
   Stream<String> updateCode(UpdateCodeRequest request) {
     return services.updateCode(request);
   }