feat: add worker factory option for Monaco Editor >= 0.55

Monaco Editor 0.55 changed the createWebWorker API to require a Worker
instance via opts.worker. Additionally, createData is no longer sent
through the worker message protocol.

This adds a `worker` option to `configureMonacoYaml()` that allows
consumers to provide their own Worker factory function. When provided,
the worker manager intercepts the postMessage sequence to inject
createData before the RPC INITIALIZE message, preserving compatibility
with the existing yaml worker protocol.

For Monaco < 0.55, omit the worker option and use MonacoEnvironment as
before. Updated README with usage examples for both Vite and Webpack.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: ttys026

README.md

@@ -31,6 +31,7 @@ offers to configure the YAML language support.
 - [API](#api)
   - [`configureMonacoYaml(monaco, options?)`](#configuremonacoyamlmonaco-options)
 - [FAQ](#faq)
+  - [Using with Monaco Editor >= 0.55](#using-with-monaco-editor--055)
   - [Does this work with the Monaco UMD bundle?](#does-this-work-with-the-monaco-umd-bundle)
   - [Does this work with Monaco Editor from a CDN?](#does-this-work-with-monaco-editor-from-a-cdn)
   - [Does this work with `@monaco-editor/loader` or `@monaco-editor/react`?](#does-this-work-with-monaco-editorloader-or-monaco-editorreact)
@@ -191,6 +192,9 @@ Configure `monaco-yaml`.
 - `schemas` (`object[]`): A list of known schemas and/or associations of schemas to file names.
   (Default: `[]`)
 - `validate` (`boolean`): based validation. (Default: `true`)
+- `worker` (`() => Worker`): A factory function that creates a new `Worker` for the YAML language
+  service. Required for Monaco Editor >= 0.55. See
+  [Using with Monaco Editor >= 0.55](#using-with-monaco-editor--055).
 - `yamlVersion` (`'1.1' | '1.2'`): The YAML version to use for parsing. (Default: `1,2`)
 
 #### Returns
@@ -199,6 +203,66 @@ An object that can be used to dispose or update `monaco-yaml`.
 
 ## FAQ
 
+### Using with Monaco Editor >= 0.55
+
+Monaco Editor **0.55** introduced a breaking change to the `createWebWorker` API: the `Worker`
+instance must now be provided directly by the caller. Previous versions created the worker internally
+via `MonacoEnvironment.getWorker` / `MonacoEnvironment.getWorkerUrl`.
+
+To support Monaco Editor >= 0.55, pass the `worker` option — a factory function that creates a new
+`Worker` — to `configureMonacoYaml`. You no longer need to set up `MonacoEnvironment.getWorker` for
+the `yaml` label.
+
+**Using Vite:**
+
+Create a local worker wrapper (required because Vite's dependency pre-bundling can break the worker
+protocol):
+
+```js
+// yaml.worker.js
+import 'monaco-yaml/yaml.worker.js'
+```
+
+Then pass the worker factory:
+
+```typescript
+import * as monaco from 'monaco-editor'
+import { configureMonacoYaml } from 'monaco-yaml'
+import YamlWorker from './yaml.worker?worker'
+
+configureMonacoYaml(monaco, {
+  worker: () => new YamlWorker(),
+  enableSchemaRequest: true,
+  schemas: [
+    {
+      fileMatch: ['**/.prettierrc.*'],
+      uri: 'https://json.schemastore.org/prettierrc.json'
+    }
+  ]
+})
+```
+
+**Using Webpack 5:**
+
+```typescript
+import * as monaco from 'monaco-editor'
+import { configureMonacoYaml } from 'monaco-yaml'
+
+configureMonacoYaml(monaco, {
+  worker: () => new Worker(new URL('monaco-yaml/yaml.worker', import.meta.url)),
+  enableSchemaRequest: true,
+  schemas: [
+    {
+      fileMatch: ['**/.prettierrc.*'],
+      uri: 'https://json.schemastore.org/prettierrc.json'
+    }
+  ]
+})
+```
+
+For Monaco Editor < 0.55, omit the `worker` option and configure `MonacoEnvironment.getWorker` as
+described in the [Usage](#usage) section above.
+
 ### Does this work with the Monaco UMD bundle?
 
 Yes, starting from version 5.0.0

package-lock.json

@@ -59,7 +59,7 @@
     "@vitest/browser-playwright": "^4.0.0",
     "@vitest/coverage-v8": "^4.0.0",
     "esbuild": "^0.27.0",
-    "monaco-editor": "^0.52.0",
+    "monaco-editor": "^0.55.1",
     "playwright": "^1.0.0",
     "remark-cli": "^12.0.0",
     "remark-preset-remcohaszing": "^3.0.0",