chore(build): add devtools-formatter-worker.ts bundle (#792)

The `devtools-formatter-worker` is a separate entrypoint from the MCP
entrypoint. It is identical to the upstream
`front_end/entrypoints/formatter_worker/formatter_worker-entrypoint.js`
and a required part to make source mapping, formatting and other
AST-based DevTools features work.

The implementation consists of 3 parts:
1) A trivial `devtools-formatter-worker.ts` file that imports the
DevTools entrypoint.
2) A new bundle output, bundling everything that needs to run in the
worker.
3) A call that initializes the `FormatterWorkerPool` with the custom
entrypoint. Otherwise we'd use the unbundled entrypoint from
`chrome-devtools-frontend` not available to us at runtime.

Note that we could improve code splitting in the future as some things
like `core/common` are now bundled twice.

---------

Co-authored-by: Alex Rudenko <OrKoN@users.noreply.github.com>

Author: szuend

rollup.config.mjs

@@ -185,4 +185,11 @@ export default [
       return false;
     },
   ),
+  bundleDependency(
+    './build/src/third_party/devtools-formatter-worker.js',
+    {
+      inlineDynamicImports: true,
+    },
+    (_source, _importer, _isResolved) => false,
+  ),
 ];

src/DevtoolsUtils.ts

@@ -138,6 +138,12 @@ DevTools.I18n.DevToolsLocale.DevToolsLocale.instance({
 });
 DevTools.I18n.i18n.registerLocaleDataForTest('en-US', {});
 
+DevTools.Formatter.FormatterWorkerPool.FormatterWorkerPool.instance({
+  forceNew: true,
+  entrypointURL: import.meta
+    .resolve('./third_party/devtools-formatter-worker.js'),
+});
+
 export interface TargetUniverse {
   /** The DevTools target corresponding to the puppeteer Page */
   target: DevTools.SDKTarget;

src/third_party/devtools-formatter-worker.ts

@@ -0,0 +1,8 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// eslint-disable-next-line no-restricted-imports
+import '../../node_modules/chrome-devtools-frontend/front_end/entrypoints/formatter_worker/formatter_worker-entrypoint.js';

src/third_party/devtools.ts

@@ -18,6 +18,7 @@ export {
   Issue,
   Target as SDKTarget,
   DebuggerModel,
+  Formatter,
   Foundation,
   TargetManager,
   MarkdownIssueDescription,

tsconfig.json

@@ -33,6 +33,7 @@
     "node_modules/chrome-devtools-frontend/front_end/core/protocol_client",
     "node_modules/chrome-devtools-frontend/front_end/core/root",
     "node_modules/chrome-devtools-frontend/front_end/core/sdk",
+    "node_modules/chrome-devtools-frontend/front_end/entrypoints/formatter_worker",
     "node_modules/chrome-devtools-frontend/front_end/foundation/foundation.ts",
     "node_modules/chrome-devtools-frontend/front_end/foundation/Universe.ts",
     "node_modules/chrome-devtools-frontend/front_end/generated",
@@ -60,6 +61,8 @@
     "node_modules/chrome-devtools-frontend/front_end/models/trace",
     "node_modules/chrome-devtools-frontend/front_end/models/workspace",
     "node_modules/chrome-devtools-frontend/front_end/panels/issues/IssueAggregator.ts",
+    "node_modules/chrome-devtools-frontend/front_end/third_party/acorn",
+    "node_modules/chrome-devtools-frontend/front_end/third_party/codemirror",
     "node_modules/chrome-devtools-frontend/front_end/third_party/i18n",
     "node_modules/chrome-devtools-frontend/front_end/third_party/intl-messageformat",
     "node_modules/chrome-devtools-frontend/front_end/third_party/legacy-javascript",
@@ -68,5 +71,8 @@
     "node_modules/chrome-devtools-frontend/front_end/third_party/third-party-web",
     "node_modules/chrome-devtools-frontend/mcp"
   ],
-  "exclude": ["node_modules/chrome-devtools-frontend/**/*.test.ts"]
+  "exclude": ["node_modules/chrome-devtools-frontend/**/*.test.ts"],
+  "files": [
+    "node_modules/chrome-devtools-frontend/front_end/third_party/acorn/package/dist/acorn.mjs"
+  ]
 }