Help getting bare csharp language server working (without wrapper)

[ghord]

Hi, I'm trying to get basic csharp language server api working using your GettingStarted. It is a little outdated, but almost working. Here is what I've got so far:

import "@codingame/monaco-vscode-csharp-default-extension";
import "@codingame/monaco-vscode-theme-defaults-default-extension";

import * as monaco from 'monaco-editor';

import "vscode/localExtensionHost";
import { initialize } from '@codingame/monaco-vscode-api'
import { initWebSocketAndStartClient } from "./lsp-client";

import getTextMateServiceOverride from "@codingame/monaco-vscode-textmate-service-override";
import getThemeServiceOverride from "@codingame/monaco-vscode-theme-service-override";
import getLanguagesServiceOverride from "@codingame/monaco-vscode-languages-service-override";

import getConfigurationServiceOverride, {
    updateUserConfiguration
} from '@codingame/monaco-vscode-configuration-service-override';

// this I had to add or textmate is not loading
import "vscode-textmate";
import "vscode-oniguruma";

export type WorkerLoader = () => Worker;
const workerLoaders: Partial<Record<string, WorkerLoader>> = {
    TextEditorWorker: () => new Worker(new URL('monaco-editor/esm/vs/editor/editor.worker.js', import.meta.url), { type: 'module' }),
    TextMateWorker: () => new Worker(new URL('@codingame/monaco-vscode-textmate-service-override/worker', import.meta.url), { type: 'module' })
}

window.MonacoEnvironment = {
    getWorker: function (_workerId, label) {
        console.log(label);
        const workerFactory = workerLoaders[label]
        if (workerFactory != null) {
            return workerFactory()
        }

        console.log("not found: " + label);
        throw new Error(`Worker ${label} not found`)
    }
}

updateUserConfiguration(`{ "workbench.colorTheme": "Default Dark Modern" }`);


// adding services
await initialize({
    ...getTextMateServiceOverride(),
    ...getThemeServiceOverride(),
    ...getLanguagesServiceOverride(),
    ...getConfigurationServiceOverride()
});

const editor = monaco.editor.create(document.getElementById("container")!, {
    language: "csharp",
    automaticLayout: true,
    value: "void Foo() {\n    Console.WriteLine(\"Hello World\");\n}\n"
});

initWebSocketAndStartClient("http://127.0.0.1:1234");

And lsp-client:

export const initWebSocketAndStartClient = (url: string): WebSocket => {
    const webSocket = new WebSocket(url);
    webSocket.onopen = () => {
 
        const socket = toSocket(webSocket);
        const reader = new WebSocketMessageReader(socket);
        const writer = new WebSocketMessageWriter(socket);

        const languageClient = createLanguageClient({
            reader,
            writer
        });
        languageClient.start();
        reader.onClose(() => languageClient.stop());
    };
    return webSocket;
};
const createLanguageClient = (messageTransports: MessageTransports): MonacoLanguageClient => {
    return new MonacoLanguageClient({
        name: 'Sample Language Client',
        clientOptions: {
            // use a language id as a document selector
            documentSelector: ['csharp'],
            // disable the default error handler
            errorHandler: {
                error: () => ({ action: ErrorAction.Continue }),
                closed: () => ({ action: CloseAction.DoNotRestart })
            }
        },
        // this needs to modified in default sample
        messageTransports
    });
};

This is correctly loading dark theme and syntax higlighting is working for csharp, but I have issue with lsp.

When calling initWebSocketAndStartClient from, I'm getting

Uncaught Error: Default api is not ready yet, do not forget to import 'vscode/localExtensionHost' and wait for services initialization
    at Object.get (extension.api.js:25:23)
    at new DidOpenTextDocumentFeature (textSynchronization.js:14:42)
    at MonacoLanguageClient.registerBuiltinFeatures (client.js:1273:30)
    at new _BaseLanguageClient (client.js:270:14)
    at new MonacoLanguageClient (client.ts:19:9)
    at createLanguageClient (lsp-client.ts:26:12)
    at webSocket.onopen (lsp-client.ts:16:32)

This happend whether I import "vscode/localExtensionHost" or not, so my guess is that something changed here in recent versions.

To be precise, error appears because vscode_1.workspace is null here:

class DidOpenTextDocumentFeature extends features_1.TextDocumentEventFeature {
    constructor(client, syncedDocuments) {
        super(client, vscode_1.workspace.onDidOpenTextDocument, vscode_languageserver_protocol_1.DidOpenTextDocumentNotification.type, () => client.middleware.didOpen, (textDocument) => client.code2ProtocolConverter.asOpenTextDocumentParams(textDocument), (data) => data, features_1.TextDocumentEventFeature.textDocumentFilter);
        this._syncedDocuments = syncedDocuments;
    }

Is there any chance you could give me hint what to try next? I've tried waiting some time before initializing client to verify if the issue is with some async loading but it does not seem to matter.

Do you think I should just move to using wrapper?

[CGNonofr]

Can you check that you only have a single version of the library by running find node_modules -name monaco-vscode-api? (how many results?)

btw: you should probably use initUserConfiguration instead of updateUserConfiguration

[ghord]

Thank you very much for response.

I've run npm list @codingame/monaco-vscode-api and here is what i've got:

I have 2 versions of the package:

One is from top level

+-- @codingame/[email protected]

And another one is pulled from languageclient:

`-- [email protected]
  +-- @codingame/[email protected]

I will try to fix this so that I have single version, right?

Btw, my package.json looks like

  "devDependencies": {
    "eslint": "^9.34.0",
    "typescript": "^5.9.2",
    "vite": "^7.1.3"
  },
  "dependencies": {
    "@codingame/esbuild-import-meta-url-plugin": "^1.0.3",
    "@codingame/monaco-vscode-api": "^20.4.0",
    "@codingame/monaco-vscode-configuration-service-override": "^20.4.0",
    "@codingame/monaco-vscode-csharp-default-extension": "^20.4.0",
    "@codingame/monaco-vscode-languages-service-override": "^20.4.0",
    "@codingame/monaco-vscode-textmate-service-override": "^20.4.0",
    "@codingame/monaco-vscode-theme-defaults-default-extension": "^20.4.0",
    "@codingame/monaco-vscode-theme-service-override": "^20.4.0",
    "monaco-editor": "npm:@codingame/monaco-vscode-editor-api@^20.4.0",
    "monaco-languageclient": "^9.11.0",
    "vscode-jsonrpc": "^8.2.1",
    "vscode-languageclient": "^9.0.1",
    "vscode-ws-jsonrpc": "^3.5.0"
  }

I'm a backend dev so npm world is new to me, I would have thought that npm will unify package versions by default.

Thanks for the suggestion with initial config also!.

[CGNonofr]

npm tries to unify, but monaco-languageclient is maybe a bit too specific on the version, `~20.2.1 doesn't match the 20.4.0, so npm just duplicated it, which is a problem here

@kaisalmen any reason for using ~ instead of ^?

[kaisalmen]

Hi @CGNonofr yes, it may be a bit to constrained. Can we be sure that for every montly release / major version of @codingame/monaco-vscode-api minor version changes (e.g 20.2.0 -> 20.3.0) will not break compatibility? WDYT? I could change to a ^21.0.0 pattern with the next major version of monaco-languageclient.

[CGNonofr]

I try to respect the semantic versioning, so a minor change shouldn't have any breaking change