Introduce A2UI Express package and express_chat example application

coverage_baseline.yaml

@@ -5,12 +5,11 @@
 # Monorepo Coverage High-Water Marks (Auto-generated by test_and_fix --update-baseline)
 dev_tools/catalog_gallery: 52.91
 dev_tools/composer: 20.49
+examples/express_chat: 35.76
+examples/simple_chat: 37.33
 packages/a2ui_core: 76.30
 packages/genai_primitives: 100.00
-packages/genui: 79.71
+packages/genui: 79.72
 packages/genui_a2a: 91.37
-packages/json_schema_builder: 79.09
-tool/e2e: 100.00
-tool/fix_copyright: 89.83
-tool/release: 78.01
-tool/test_and_fix: 94.37
+packages/genui_express: 63.34
+packages/json_schema_builder: 79.27

coverage_policy.yaml

@@ -18,11 +18,14 @@ exclude:
   - "**/*.freezed.dart"
   - "**/*.mocks.dart"
   - "**/generated/**"
+  - "**/*_web.dart"
 
 # Package-specific overrides (paths relative to monorepo root).
 packages:
   packages/genui:
     threshold: 75.0
+  packages/genui_express:
+    threshold: 60.0
   packages/a2ui_core:
     threshold: 75.0
   packages/json_schema_builder:
@@ -36,6 +39,8 @@ packages:
   tool/release:
     threshold: 75.0
   examples/simple_chat:
-    enabled: false
+    threshold: 30.0
+  examples/express_chat:
+    threshold: 30.0
   examples/verdure/client:
     enabled: false

dev_tools/catalog_gallery/linux/flutter/generated_plugins.cmake

@@ -8,6 +8,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)

dev_tools/catalog_gallery/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -12,5 +12,5 @@ import video_player_avfoundation
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   AudioplayersDarwinPlugin.register(with: registry.registrar(forPlugin: "AudioplayersDarwinPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
-  FVPVideoPlayerPlugin.register(with: registry.registrar(forPlugin: "FVPVideoPlayerPlugin"))
+  VideoPlayerPlugin.register(with: registry.registrar(forPlugin: "VideoPlayerPlugin"))
 }

dev_tools/composer/linux/flutter/generated_plugins.cmake

@@ -10,6 +10,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)

dev_tools/composer/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -15,6 +15,6 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   AudioplayersDarwinPlugin.register(with: registry.registrar(forPlugin: "AudioplayersDarwinPlugin"))
   ScreenRetrieverMacosPlugin.register(with: registry.registrar(forPlugin: "ScreenRetrieverMacosPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
-  FVPVideoPlayerPlugin.register(with: registry.registrar(forPlugin: "FVPVideoPlayerPlugin"))
+  VideoPlayerPlugin.register(with: registry.registrar(forPlugin: "VideoPlayerPlugin"))
   WindowManagerPlugin.register(with: registry.registrar(forPlugin: "WindowManagerPlugin"))
 }

dev_tools/composer/windows/flutter/generated_plugins.cmake

@@ -11,6 +11,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)

examples/express_chat/.metadata

@@ -0,0 +1,30 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "adc901062556672b4138e18a4dc62a4be8f4b3c2"
+  channel: "stable"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: adc901062556672b4138e18a4dc62a4be8f4b3c2
+      base_revision: adc901062556672b4138e18a4dc62a4be8f4b3c2
+    - platform: linux
+      create_revision: adc901062556672b4138e18a4dc62a4be8f4b3c2
+      base_revision: adc901062556672b4138e18a4dc62a4be8f4b3c2
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'

examples/express_chat/README.md

@@ -0,0 +1,43 @@
+# Simple Chat Example
+
+This application is a minimal example of how to use the `genui` package to create a simple, conversational chat application.
+
+## Purpose
+
+The main goal of this example is to demonstrate the fundamental concepts of `genui` in a straightforward chat context. It shows how to:
+1. Initialize and use the `SurfaceController`, the core engine for the package.
+2. Provide a simple system prompt to guide the AI's behavior.
+3. Send user messages to the AI and receive responses.
+4. Handle the creation of new UI "surfaces" generated by the AI.
+5. Render these dynamic UI surfaces within a standard chat message list.
+6. Manage a conversation history that interleaves user text messages with AI-generated UI responses.
+
+Unlike more complex examples, this app does not define a custom widget catalog. Instead, it relies on the default `coreCatalog` provided by `genui`, meaning the AI can only respond with basic widgets like `Text`, `Column`, `ElevatedButton`, etc.
+
+## How it Works
+
+The application's logic is contained almost entirely within `lib/chat_session.dart`.
+
+1. **Initialization**: A `SurfaceController` is created to manage the state of UI surfaces.
+2. **User Input**: The user types a message into a `TextField` and hits send.
+3. **Sending the Message**:
+   - The user's text is immediately added to the local message list.
+   - The request is sent to the `AiClient`.
+4. **AI Response**:
+   - The `AiClient` streams `A2uiMessage`s back.
+   - These messages are piped into the `SurfaceController`.
+5. **UI Rendering**:
+   - The UI listens to `SurfaceController.surfaceUpdates` or `A2uiTransportAdapter` streams.
+   - When a surface is added, a `Surface` widget is rendered, dynamically building the UI based on the `UiDefinition` managed by `SurfaceController`.
+
+## Getting Started
+
+Follow the instructions in [Running the app with a Gemini key](../../docs/usage/run_app_with_gemini_key.md).
+
+## Video
+
+https://github.com/user-attachments/assets/469fb2cf-09cf-463c-8c9c-b9c0cb39203b
+
+This video is recorded on May 11, 2026, for [PR#905](https://github.com/flutter/genui/pull/905).
+
+Please update the link if you have a fresher version of the demo.

examples/express_chat/android/.gitignore

@@ -0,0 +1,14 @@
+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java
+.cxx/
+
+# Remember to never publicly share your keystore.
+# See https://flutter.dev/to/reference-keystore
+key.properties
+**/*.keystore
+**/*.jks

examples/express_chat/android/app/build.gradle.kts

@@ -0,0 +1,47 @@
+plugins {
+    id("com.android.application")
+    id("kotlin-android")
+    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
+    id("dev.flutter.flutter-gradle-plugin")
+    // START: FlutterFire Configuration
+    id("com.google.gms.google-services")
+    // END: FlutterFire Configuration
+}
+
+android {
+    namespace = "com.example.simple_chat"
+    compileSdk = flutter.compileSdkVersion
+    ndkVersion = flutter.ndkVersion
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_11.toString()
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId = "com.example.simple_chat"
+        // You can update the following values to match your application needs.
+        // For more information, see: https://flutter.dev/to/review-gradle-config.
+        minSdk = flutter.minSdkVersion
+        targetSdk = flutter.targetSdkVersion
+        versionCode = flutter.versionCode
+        versionName = flutter.versionName
+    }
+
+    buildTypes {
+        release {
+            // TODO: Add your own signing config for the release build.
+            // Signing with the debug keys for now, so `flutter run --release` works.
+            signingConfig = signingConfigs.getByName("debug")
+        }
+    }
+}
+
+flutter {
+    source = "../.."
+}

examples/express_chat/android/app/src/debug/AndroidManifest.xml

@@ -0,0 +1,11 @@
+<!-- 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. -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- The INTERNET permission is required for development. Specifically,
+         the Flutter tool needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>

examples/express_chat/android/app/src/main/AndroidManifest.xml

@@ -0,0 +1,49 @@
+<!-- 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. -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <application
+        android:label="simple_chat"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:launchMode="singleTop"
+            android:taskAffinity=""
+            android:theme="@style/LaunchTheme"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize">
+            <!-- Specifies an Android theme to apply to this Activity as soon as
+                 the Android process has started. This theme is visible to the user
+                 while the Flutter UI initializes. After that, this theme continues
+                 to determine the Window background behind the Flutter UI. -->
+            <meta-data
+              android:name="io.flutter.embedding.android.NormalTheme"
+              android:resource="@style/NormalTheme"
+              />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+        <!-- Don't delete the meta-data below.
+             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
+    </application>
+    <!-- Required to query activities that can process text, see:
+         https://developer.android.com/training/package-visibility and
+         https://developer.android.com/reference/android/content/Intent#ACTION_PROCESS_TEXT.
+
+         In particular, this is used by the Flutter engine in io.flutter.plugin.text.ProcessTextPlugin. -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.PROCESS_TEXT"/>
+            <data android:mimeType="text/plain"/>
+        </intent>
+    </queries>
+</manifest>

examples/express_chat/android/app/src/main/kotlin/com/example/simple_chat/MainActivity.kt

@@ -0,0 +1,9 @@
+// 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.
+
+package com.example.simple_chat
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity : FlutterActivity()

examples/express_chat/android/app/src/main/res/drawable-v21/launch_background.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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. -->
+
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="?android:colorBackground" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>

examples/express_chat/android/app/src/main/res/drawable/launch_background.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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. -->
+
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@android:color/white" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>

examples/express_chat/android/app/src/main/res/values-night/styles.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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. -->
+
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is on -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             the Flutter engine draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

examples/express_chat/android/app/src/main/res/values/styles.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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. -->
+
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             the Flutter engine draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

examples/express_chat/android/app/src/profile/AndroidManifest.xml

@@ -0,0 +1,11 @@
+<!-- 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. -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- The INTERNET permission is required for development. Specifically,
+         the Flutter tool needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>