Detect Dart web apps via dart:js_interop libraries

packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md

@@ -22,6 +22,10 @@ To learn more about DevTools, check out the
   evaluate expressions and a debug-only screen is unavailable.
   [#4091](https://github.com/flutter/devtools/issues/4091)
 
+* Fixed an issue where Dart and Flutter web apps compiled with WebAssembly
+  (Wasm) or modern web libraries (such as `package:web`) were not recognized as
+  web applications. [#10045](https://github.com/flutter/devtools/pull/10045)
+
 TODO: Remove this section if there are not any updates.
 
 * Improved the readability of ANSI-colored text in the console and logging

packages/devtools_app_shared/CHANGELOG.md

@@ -5,6 +5,10 @@ found in the LICENSE file or at https://developers.google.com/open-source/licens
 -->
 ## 0.5.2-wip
 * Removed redundant argument values.
+* Detect Dart web apps by the presence of `dart:js_interop` in addition to
+  `dart:html`, so dart2wasm and `package:web` apps are recognized without
+  dropping support for older `dart:html` apps. Adds the
+  `dartJsInteropLibraryUri` and `dartWebLibraryUris` constants.
 * Fix `forEachIsolateHelper` to rethrow isolate callback exceptions directly
   using `Future.wait` instead of wrapping them in a `ParallelWaitError`.
 * Fix a `RangeError` thrown by `SplitPane` when the number of children

packages/devtools_app_shared/lib/src/service/connected_app.dart

@@ -15,10 +15,28 @@ final _log = Logger('connected_app');
 
 const flutterLibraryUri = 'package:flutter/src/widgets/binding.dart';
 
-// TODO(kenz): if we want to support debugging dart2wasm web apps, we will need
-// to check for the presence of a different library.
+/// Present in older Dart and Flutter web apps, including google3.
+///
+/// Modern apps may use `package:web` / [dartJsInteropLibraryUri] instead.
 const dartHtmlLibraryUri = 'dart:html';
 
+/// Present in Dart web apps compiled to JavaScript or Wasm.
+///
+/// `package:web` is built on this library, so it is the reliable signal for
+/// modern and dart2wasm apps that no longer import [dartHtmlLibraryUri].
+/// Library URIs are matched by prefix, so this also covers
+/// `dart:js_interop_unsafe`.
+const dartJsInteropLibraryUri = 'dart:js_interop';
+
+/// Libraries whose presence indicates the connected app is a Dart web app.
+///
+/// [dartHtmlLibraryUri] is kept so older apps (including google3) are still
+/// detected.
+const dartWebLibraryUris = [
+  dartHtmlLibraryUri,
+  dartJsInteropLibraryUri,
+];
+
 // TODO(https://github.com/flutter/devtools/issues/6239): try to remove this.
 @sealed
 class ConnectedApp {
@@ -85,8 +103,15 @@ class ConnectedApp {
   bool? _isProfileBuild;
 
   // TODO(kenz): investigate if we can use `libraryUriAvailableNow` instead.
-  Future<bool> get isDartWebApp async => _isDartWebApp ??= await serviceManager!
-      .libraryUriAvailable(dartHtmlLibraryUri);
+  Future<bool> get isDartWebApp async {
+    if (_isDartWebApp != null) return _isDartWebApp!;
+    for (final uri in dartWebLibraryUris) {
+      if (await serviceManager!.libraryUriAvailable(uri)) {
+        return _isDartWebApp = true;
+      }
+    }
+    return _isDartWebApp = false;
+  }
 
   bool? get isDartWebAppNow {
     assert(_isDartWebApp != null);
@@ -230,6 +255,11 @@ final class OfflineConnectedApp extends ConnectedApp {
   @override
   final bool? isDartWebAppNow;
 
+  /// There is no [serviceManager] to query for an offline app, so this
+  /// returns the value that was recorded when the app was exported.
+  @override
+  Future<bool> get isDartWebApp async => isDartWebAppNow ?? false;
+
   @override
   final bool? isRunningOnDartVM;
 

packages/devtools_app_shared/test/service/connected_app_test.dart

@@ -0,0 +1,127 @@
+// Copyright 2026 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file or at https://developers.google.com/open-source/licenses/bsd.
+
+import 'package:devtools_app_shared/service.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('ConnectedApp', () {
+    test('isDartWebApp is true when dart:html is available', () async {
+      final serviceManager = _FakeServiceManager(
+        availableLibraries: ['dart:html'],
+      );
+      final app = ConnectedApp(serviceManager);
+      expect(await app.isDartWebApp, isTrue);
+      expect(app.isDartWebAppNow, isTrue);
+    });
+
+    test('isDartWebApp is true when dart:js_interop is available', () async {
+      final serviceManager = _FakeServiceManager(
+        availableLibraries: ['dart:js_interop'],
+      );
+      final app = ConnectedApp(serviceManager);
+      expect(await app.isDartWebApp, isTrue);
+      expect(app.isDartWebAppNow, isTrue);
+    });
+
+    test('isDartWebApp is false when no web libraries are available', () async {
+      final serviceManager = _FakeServiceManager(
+        availableLibraries: [
+          'dart:io',
+          'package:flutter/src/widgets/binding.dart',
+        ],
+      );
+      final app = ConnectedApp(serviceManager);
+      expect(await app.isDartWebApp, isFalse);
+      expect(app.isDartWebAppNow, isFalse);
+    });
+
+    test('isDartWebApp short-circuits on first matching library', () async {
+      final queriedLibraries = <String>[];
+      final serviceManager = _FakeServiceManager(
+        availableLibraries: ['dart:html', 'dart:js_interop'],
+        onLibraryUriAvailable: queriedLibraries.add,
+      );
+      final app = ConnectedApp(serviceManager);
+
+      expect(await app.isDartWebApp, isTrue);
+      expect(queriedLibraries, equals(['dart:html']));
+    });
+
+    test('isDartWebApp caches results', () async {
+      var callCount = 0;
+      final serviceManager = _FakeServiceManager(
+        availableLibraries: ['dart:js_interop'],
+        onLibraryUriAvailable: (_) => callCount++,
+      );
+      final app = ConnectedApp(serviceManager);
+
+      expect(await app.isDartWebApp, isTrue);
+      final callsAfterFirst = callCount;
+      expect(callsAfterFirst, greaterThan(0));
+
+      expect(await app.isDartWebApp, isTrue);
+      expect(callCount, equals(callsAfterFirst));
+    });
+
+    test('isDartWebAppNow asserts when not initialized', () {
+      final serviceManager = _FakeServiceManager();
+      final app = ConnectedApp(serviceManager);
+      expect(() => app.isDartWebAppNow, throwsAssertionError);
+    });
+
+    test(
+      'isFlutterWebAppNow is true and isFlutterNativeAppNow is false for modern Flutter web apps',
+      () async {
+        final serviceManager = _FakeServiceManager(
+          availableLibraries: [flutterLibraryUri, 'dart:js_interop'],
+        );
+        final app = ConnectedApp(serviceManager);
+        expect(await app.isFlutterApp, isTrue);
+        expect(await app.isDartWebApp, isTrue);
+        expect(app.isFlutterWebAppNow, isTrue);
+        expect(app.isFlutterNativeAppNow, isFalse);
+      },
+    );
+  });
+
+  group('OfflineConnectedApp', () {
+    test(
+      'isDartWebApp returns the recorded value without a service manager',
+      () async {
+        expect(
+          await OfflineConnectedApp(isDartWebAppNow: true).isDartWebApp,
+          isTrue,
+        );
+        expect(
+          await OfflineConnectedApp(isDartWebAppNow: false).isDartWebApp,
+          isFalse,
+        );
+        expect(await OfflineConnectedApp().isDartWebApp, isFalse);
+      },
+    );
+  });
+}
+
+class _FakeServiceManager extends Fake implements ServiceManager {
+  _FakeServiceManager({
+    this.availableLibraries = const [],
+    this.onLibraryUriAvailable,
+  });
+
+  final List<String> availableLibraries;
+  final void Function(String uri)? onLibraryUriAvailable;
+
+  @override
+  bool libraryUriAvailableNow(String? uri) {
+    if (uri == null) return false;
+    onLibraryUriAvailable?.call(uri);
+    return availableLibraries.any((u) => u.startsWith(uri));
+  }
+
+  @override
+  Future<bool> libraryUriAvailable(String uri) async {
+    return libraryUriAvailableNow(uri);
+  }
+}