[foundation] Add basic Universe, only instantiating settings for now

This CL adds the basic scaffolding for what will become bootstrapping
for DevTools foundation.

For now, we instantiate the global Settings instance as this will be
required for nearly everything else.

The CreationOptions are also not final. For now, they are used to
pass in anything "host platform" dependent, but we'll move these
behind better types and interfaces as the migration goes on. For now,
they are a grab bag of host-dependent dependencies required to
instantiate foundation classes.

The CL also adds a unit test running both in Node and the browser
to make sure we can instantiate a Universe in both.

Moving forward, we'll add a DevToolsContext so we can scope these
globals. We'll also have a single global DevToolsContext for
migration purposes.

Bug: 458180550
Change-Id: If1f1b172517ef4e8e3992764cc2f4cf811e24a14
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7124027
Reviewed-by: Philip Pfaffe <[email protected]>
Commit-Queue: Simon Zünd <[email protected]>

Author: szuend

config/gni/devtools_grd_files.gni

@@ -393,6 +393,7 @@ grd_files_bundled_sources = [
   "front_end/entrypoints/wasmparser_worker/wasmparser_worker-entrypoint.js",
   "front_end/entrypoints/wasmparser_worker/wasmparser_worker.js",
   "front_end/entrypoints/worker_app/worker_app.js",
+  "front_end/foundation/foundation.js",
   "front_end/inspector.html",
   "front_end/js_app.html",
   "front_end/models/ai_assistance/ai_assistance.js",
@@ -1021,6 +1022,7 @@ grd_files_unbundled_sources = [
   "front_end/entrypoints/node_app/app/nodeConnectionsPanel.css.js",
   "front_end/entrypoints/wasmparser_worker/WasmParserWorker.js",
   "front_end/entrypoints/worker_app/WorkerMain.js",
+  "front_end/foundation/Universe.js",
   "front_end/generated/ARIAProperties.js",
   "front_end/generated/Deprecation.js",
   "front_end/generated/InspectorBackendCommands.js",

front_end/BUILD.gn

@@ -278,6 +278,7 @@ group("foundation_unittests") {
   deps = [
     "core/common:foundation_unittests",
     "core/i18n:foundation_unittests",
+    "foundation:unittests",
     "models/ai_assistance:foundation_unittests",
     "models/issues_manager:foundation_unittests",
   ]

front_end/Tests.js

@@ -952,7 +952,11 @@
     }
 
     function gotPreferences(prefs) {
-      Main.Main.instanceForTest.createSettings(prefs);
+      Common.Settings.Settings.instance({
+        forceNew: true,
+        ...Main.Main.instanceForTest.createSettingsStorage(prefs),
+        runSettingsMigration: false,
+      });
 
       const localSetting = Common.Settings.Settings.instance().createLocalSetting('local', undefined);
       test.assertEquals('object', typeof localSetting.get());

front_end/entrypoints/main/BUILD.gn

@@ -23,6 +23,7 @@ devtools_module("main") {
     "../../core/platform:bundle",
     "../../core/protocol_client:bundle",
     "../../core/sdk:bundle",
+    "../../foundation:bundle",
     "../../generated:protocol",
     "../../models/ai_assistance:bundle",
     "../../models/autofill_manager:bundle",

front_end/entrypoints/main/MainImpl.ts

@@ -41,6 +41,7 @@ import * as Platform from '../../core/platform/platform.js';
 import * as ProtocolClient from '../../core/protocol_client/protocol_client.js';
 import * as Root from '../../core/root/root.js';
 import * as SDK from '../../core/sdk/sdk.js';
+import * as Foundation from '../../foundation/foundation.js';
 import * as AiAssistanceModel from '../../models/ai_assistance/ai_assistance.js';
 import * as AutofillManager from '../../models/autofill_manager/autofill_manager.js';
 import * as Badges from '../../models/badges/badges.js';
@@ -165,7 +166,14 @@ export class MainImpl {
     console.timeStamp('Main._gotPreferences');
     this.#initializeGlobalsForLayoutTests();
     Object.assign(Root.Runtime.hostConfig, config);
-    this.createSettings(prefs);
+
+    const creationOptions: Foundation.Universe.CreationOptions = {
+      ...this.createSettingsStorage(prefs),
+      logSettingAccess: VisualLogging.logSettingAccess,
+      runSettingsMigration: !Host.InspectorFrontendHost.isUnderTest(),
+    };
+    new Foundation.Universe.Universe(creationOptions);
+
     await this.requestAndRegisterLocaleData();
 
     Host.userMetrics.syncSetting(Common.Settings.Settings.instance().moduleSetting<boolean>('sync-preferences').get());
@@ -243,7 +251,11 @@ export class MainImpl {
     }
   }
 
-  createSettings(prefs: Record<string, string>): void {
+  createSettingsStorage(prefs: Record<string, string>): {
+    syncedStorage: Common.Settings.SettingsStorage,
+    globalStorage: Common.Settings.SettingsStorage,
+    localStorage: Common.Settings.SettingsStorage,
+  } {
     this.#initializeExperiments();
     let storagePrefix = '';
     if (Host.Platform.isCustomDevtoolsFrontend()) {
@@ -287,14 +299,8 @@ export class MainImpl {
     // setting can't change storage buckets during a single DevTools session.
     const syncedStorage = new Common.Settings.SettingsStorage(prefs, hostSyncedStorage, storagePrefix);
     const globalStorage = new Common.Settings.SettingsStorage(prefs, hostUnsyncedStorage, storagePrefix);
-    Common.Settings.Settings.instance({
-      forceNew: true,
-      syncedStorage,
-      globalStorage,
-      localStorage,
-      logSettingAccess: VisualLogging.logSettingAccess,
-      runSettingsMigration: !Host.InspectorFrontendHost.isUnderTest()
-    });
+
+    return {syncedStorage, globalStorage, localStorage};
   }
 
   #initializeExperiments(): void {

front_end/foundation/BUILD.gn

@@ -0,0 +1,39 @@
+# Copyright 2025 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("../../scripts/build/ninja/devtools_entrypoint.gni")
+import("../../scripts/build/ninja/devtools_module.gni")
+
+devtools_foundation_module("foundation") {
+  sources = [ "Universe.ts" ]
+
+  deps = [ "../core/common:bundle" ]
+}
+
+devtools_entrypoint("bundle") {
+  entrypoint = "foundation.ts"
+
+  deps = [ ":foundation" ]
+
+  # IMPORTANT: core/ or models/ must not be added here.
+  visibility = [
+    "../../mcp/*",
+    "../entrypoints/*",
+    "../panels/*",
+    "../testing/*",
+    "../ui/*",
+    "./*",
+  ]
+}
+
+devtools_foundation_module("unittests") {
+  testonly = true
+
+  sources = [ "Universe.test.ts" ]
+
+  deps = [
+    ":bundle",
+    "../core/common:bundle",
+  ]
+}

front_end/foundation/README.md

@@ -0,0 +1,10 @@
+# DevTools foundation
+
+DevTools foundation is the core business logic of DevTools: mainly core/ and models/.
+The difference between "foundation" and the rest of DevTools is
+that the code is targeted not just for the browser, but also the Node.js runtime.
+As such, allowed use of APIs is restricted to what is available in both runtimes.
+
+A `DevToolsUniverse` is a concrete, encapsulated instance of "foundation" scoped
+to a single root CDP target. It is valid to create multiple `DevToolsUniverse`
+instances simultaneously.

front_end/foundation/Universe.test.ts

@@ -0,0 +1,17 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import * as Common from '../core/common/common.js';
+
+import * as Foundation from './foundation.js';
+
+describe('Universe', () => {
+  it('can be instantiated', () => {
+    new Foundation.Universe.Universe({
+      syncedStorage: new Common.Settings.SettingsStorage({}),
+      globalStorage: new Common.Settings.SettingsStorage({}),
+      localStorage: new Common.Settings.SettingsStorage({}),
+    });
+  });
+});

front_end/foundation/Universe.ts

@@ -0,0 +1,29 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import * as Common from '../core/common/common.js';
+
+export interface CreationOptions {
+  // Settings things
+  syncedStorage: Common.Settings.SettingsStorage;
+  globalStorage: Common.Settings.SettingsStorage;
+  localStorage: Common.Settings.SettingsStorage;
+  logSettingAccess?: (name: string, value: number|string|boolean) => Promise<void>;
+  runSettingsMigration?: boolean;
+}
+
+export class Universe {
+  constructor(options: CreationOptions) {
+    // TODO(crbug.com/458180550): Store instance on a "DevToolsContext" instead.
+    //                            For now the global is fine as we don't anticipate the MCP server to change settings.
+    Common.Settings.Settings.instance({
+      forceNew: true,
+      syncedStorage: options.syncedStorage,
+      globalStorage: options.globalStorage,
+      localStorage: options.localStorage,
+      logSettingAccess: options.logSettingAccess,
+      runSettingsMigration: options.runSettingsMigration,
+    });
+  }
+}

front_end/foundation/foundation.ts

@@ -0,0 +1,7 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import * as Universe from './Universe.js';
+
+export {Universe};