Support connecting debug mode DevTools app to DevTools server

packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart

@@ -46,7 +46,11 @@ class EmbeddedExtensionControllerImpl extends EmbeddedExtensionController
     }
 
     final basePath = devtoolsAssetsBasePath(
-      origin: window.location.origin,
+      // This needs to use the DevTools server URI as the origin because the
+      // extension assets are served through a DevTools server handler. The
+      // DevTools server handler loads them directly from their location in the
+      // user's pub-cache.
+      origin: devToolsServerUriAsString,
       path: window.location.pathname,
     );
     final baseUri = path.join(

packages/devtools_app/lib/src/shared/analytics/_analytics_web.dart

@@ -522,7 +522,8 @@ void cancelTimingOperation(String screenName, String timedOperation) {
   final operation = _timedOperationsInProgress.remove(operationKey);
   assert(
     operation != null,
-    'The operation cannot be cancelled because it does not exist.',
+    'The operation $screenName.$timedOperation cannot be cancelled because it '
+    'does not exist.',
   );
 }
 

packages/devtools_app/lib/src/shared/config_specific/framework_initialize/_framework_initialize_web.dart

@@ -32,9 +32,11 @@ Future<String> initializePlatform() async {
   // Here, we try and initialize the connection between the DevTools web app and
   // its local server. DevTools can be launched without the server however, so
   // establishing this connection is a best-effort.
+  // TODO(kenz): investigate it we can remove the DevToolsServerConnection
+  // code in general. We do not appear to be using the SSE connection.
   final connection = await DevToolsServerConnection.connect();
   if (connection != null) {
-    setGlobal(Storage, ServerConnectionStorage());
+    setGlobal(Storage, server.ServerConnectionStorage());
   } else {
     setGlobal(Storage, BrowserStorage());
   }
@@ -93,19 +95,6 @@ void _sendKeyPressToParent(KeyboardEvent event) {
   );
 }
 
-class ServerConnectionStorage implements Storage {
-  @override
-  Future<String?> getValue(String key) async {
-    final value = await server.getPreferenceValue(key);
-    return value == null ? null : '$value';
-  }
-
-  @override
-  Future<void> setValue(String key, String value) async {
-    await server.setPreferenceValue(key, value);
-  }
-}
-
 class BrowserStorage implements Storage {
   @override
   Future<String?> getValue(String key) async {

packages/devtools_app/lib/src/shared/preferences/preferences.dart

@@ -25,8 +25,8 @@ import '../utils/utils.dart';
 part '_cpu_profiler_preferences.dart';
 part '_extension_preferences.dart';
 part '_inspector_preferences.dart';
-part '_memory_preferences.dart';
 part '_logging_preferences.dart';
+part '_memory_preferences.dart';
 part '_network_preferences.dart';
 part '_performance_preferences.dart';
 
@@ -211,8 +211,17 @@ class PreferencesController extends DisposableController
       return;
     }
 
+    // Whether DevTools was run using the `dt serve --run-app` command, which
+    // runs DevTools in debug mode using `flutter run` and connects it to an
+    // instance of the DevTools server.
+    final usingDebugDevToolsServer =
+        (const String.fromEnvironment('debug_devtools_server')).isNotEmpty &&
+        !kReleaseMode;
     final shouldEnableWasm =
-        (enabledFromStorage || enabledFromQueryParams) && kIsWeb;
+        (enabledFromStorage || enabledFromQueryParams) &&
+        kIsWeb &&
+        // Wasm cannot be enabled if DevTools was built using `flutter run`.
+        !usingDebugDevToolsServer;
     assert(kIsWasm == shouldEnableWasm);
     // This should be a no-op if the flutter_bootstrap.js logic set the
     // renderer properly, but we call this to be safe in case something went

packages/devtools_app/lib/src/shared/server/server.dart

@@ -11,25 +11,49 @@ import 'package:devtools_shared/devtools_shared.dart';
 import 'package:flutter/foundation.dart';
 import 'package:http/http.dart';
 import 'package:logging/logging.dart';
+import 'package:path/path.dart' as path;
 
 import '../development_helpers.dart';
+import '../globals.dart';
+import '../primitives/storage.dart';
 import '../primitives/utils.dart';
 
 part '_analytics_api.dart';
 part '_app_size_api.dart';
 part '_deep_links_api.dart';
+part '_dtd_api.dart';
 part '_extensions_api.dart';
 part '_preferences_api.dart';
 part '_release_notes_api.dart';
 part '_survey_api.dart';
-part '_dtd_api.dart';
 
 final _log = Logger('devtools_server_client');
 
-// The DevTools server is only available in release mode right now.
-// TODO(kenz): design a way to run the DevTools server and DevTools app together
-// in debug mode.
-bool get isDevToolsServerAvailable => kReleaseMode;
+/// Whether the DevTools server is available.
+///
+/// Since the DevTools server is a web server, it is only available for the
+/// web platform.
+///
+/// In `framework_initialize_web.dart`, we test the DevTools server connection
+/// by pinging the server and checking the response. If this is successful, we
+/// set the [storage] global to an instance of [ServerConnectionStorage].
+bool get isDevToolsServerAvailable =>
+    kIsWeb && storage is ServerConnectionStorage;
+
+const _debugDevToolsServerFlag = 'debug_devtools_server';
+
+String get devToolsServerUriAsString {
+  const debugDevToolsServerUriAsString = String.fromEnvironment(
+    _debugDevToolsServerFlag,
+  );
+  // Ensure we only use the debug DevTools server URI in non-release
+  // builds. By running `dt serve --run-app`, an instance of DevTools ran
+  // with `flutter run` can be connected to the DevTools server on a
+  // different port.
+  return debugDevToolsServerUriAsString.isNotEmpty && !kReleaseMode
+      ? debugDevToolsServerUriAsString
+      : Uri.base.toString();
+}
 
 /// Helper to catch any server request which could fail.
 ///
@@ -38,8 +62,10 @@ Future<Response?> request(String url) async {
   Response? response;
 
   try {
-    _log.fine('requesting $url');
-    response = await post(Uri.parse(url));
+    // This will be the empty string if this environment declaration was not
+    // set using `--dart-define`.
+    const baseUri = String.fromEnvironment(_debugDevToolsServerFlag);
+    response = await post(Uri.parse(path.join(baseUri, url)));
   } catch (_) {}
 
   return response;
@@ -107,3 +133,16 @@ extension ResponseExtension on Response {
   bool get statusForbidden => statusCode == 403;
   bool get statusError => statusCode == 500;
 }
+
+class ServerConnectionStorage implements Storage {
+  @override
+  Future<String?> getValue(String key) async {
+    final value = await getPreferenceValue(key);
+    return value == null ? null : '$value';
+  }
+
+  @override
+  Future<void> setValue(String key, String value) async {
+    await setPreferenceValue(key, value);
+  }
+}

packages/devtools_app/lib/src/shared/server/server_api_client.dart

@@ -13,6 +13,7 @@ import 'package:logging/logging.dart';
 import '../config_specific/notifications/notifications.dart';
 import '../framework/framework_controller.dart';
 import '../globals.dart';
+import 'server.dart';
 
 final _log = Logger('lib/src/shared/server_api_client');
 
@@ -46,7 +47,8 @@ class DevToolsServerConnection {
           : baseUri.resolve('api/');
 
   static Future<DevToolsServerConnection?> connect() async {
-    final apiUri = apiUriFor(Uri.base);
+    final serverUri = Uri.parse(devToolsServerUriAsString);
+    final apiUri = apiUriFor(serverUri);
     final pingUri = apiUri.resolve('ping');
 
     try {

packages/devtools_app/web/flutter_bootstrap.js

@@ -28,6 +28,10 @@ const wasmQueryParameterKey = 'wasm';
 
 // Calls the DevTools server API to read the user's wasm preference.
 async function getDevToolsWasmPreference() {
+  // Note: when the DevTools server is running on a different port than the
+  // DevTools web app, this request path will be incorrect and the request
+  // will fail. This is okay because DevTools cannot be built with WASM when
+  // running from `flutter run` anyway.
   const request = 'api/getPreferenceValue?key=experiment.wasm';
   try {
     const response = await fetch(request);