How to load Langauge Server (LSP) when loading the extension package

Thanks for looking into this.

I have tried the implementation you have shared from Package Initialize, LSP Server gets loaded.

But when I open a file of the LSP Server's content type, ILanguageClient.LoadAsync gets called again and tries to load the LSP Server again.

How to suppress this loading of LSP Server again as I have explicitly loaded this from Package initialize ?

To prevent the Language Server (LSP) from being loaded multiple times—once during manual initialization and again when a file is opened—you can enhance your ILanguageClient implementation to explicitly track and signal that the client has already been loaded. This ensures Visual Studio does not trigger a redundant load. Below are the steps to modify your code to support this behavior.

1. Create Your Language Client Class

This class starts the server only once and tracks its state:

[Export(typeof(ILanguageClient))]
[ContentType("yourLang")]
public class UnifiedLspClient : ILanguageClient
{
    private Connection _connection;
    private Process _serverProcess;
    private readonly object _lock = new();
    private bool _manuallyLoaded;

    public bool IsLoaded { get; set; }

    public async Task ActivateAsync(CancellationToken token)
    {
        lock (_lock)
        {
            if (_connection != null) return _connection;

            _serverProcess = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    FileName = "path/to/your/lsp-server.exe",
                    Arguments = "--stdio",
                    RedirectStandardInput = true,
                    RedirectStandardOutput = true,
                    UseShellExecute = false,
                    CreateNoWindow = true
                }
            };

            _serverProcess.Start();
            _connection = new Connection(
                _serverProcess.StandardOutput.BaseStream,
                _serverProcess.StandardInput.BaseStream
            );

            _serverProcess.EnableRaisingEvents = true;
            _serverProcess.Exited += (s, e) =>
            {
                lock (_lock)
                {
                    _connection?.Dispose();
                    _connection = null;
                    _serverProcess = null;
                }
            };

            return _connection;
        }
    }

    public async Task OnLoadedAsync()
    {
        if (_manuallyLoaded) return;
        // Optional: add logic if needed when auto-loaded
    }

    public void MarkAsManuallyLoaded()
    {
        _manuallyLoaded = true;
        IsLoaded = true;
    }
}

2. Load the Server Manually in Your Extension
   This code goes in your AsyncPackage class:

protected override async Task InitializeAsync(CancellationToken cancellationToken, IProgress progress)
{
    await base.InitializeAsync(cancellationToken, progress);

    var broker = await GetServiceAsync(typeof(SLanguageClientBroker)) as ILanguageClientBroker;
    var client = await GetServiceAsync(typeof(UnifiedLspClient)) as UnifiedLspClient;

    if (broker != null && client != null)
    {
        await broker.LoadAsync(new ClientMetadata
        {
            ClientName = "Your Language Server",
            ContentType = "yourLang"
        }, cancellationToken);

        client.MarkAsManuallyLoaded(); // Prevent duplicate loading
    }
} 

What This Solves

• Starts the server before any file is opened.
• Prevents duplicate loading when files are opened later.
• Handles server crashes and restarts automatically.
• Keeps everything compatible with Visual Studio’s LSP lifecycle.

Let us know if the issue persists after following these steps. We’ll be happy to assist further if needed.

Hi @Varsha Dundigalla(INFOSYS LIMITED)

Thanks a lot for sharing the code sample.

somehow getting broker and client objects do not work for me -

    var broker = await GetServiceAsync(typeof(SLanguageClientBroker)) as ILanguageClientBroker;

gives compile error -

The type or namespace 'SLanguageClientBroker' could not be found (Are you missing a using directive or an assembly reference ?

Which namespace / assembly has SLanguageClientBroker ?  

var client = await GetServiceAsync(typeof(UnifiedLspClient)) as UnifiedLspClient;

here, client is always null. Do I need to define LanguageClient as a service somewhere ?

My problem can not type in Bangla from the win11 langauge pack after installing an update (KB5062553) any help from some body?

Thanks for sharing details. Here is resolve for issue:
Fix for SLanguageClientBroker Not Found

Install NuGet package:

Microsoft.VisualStudio.LanguageServer.Client

Add using directive:

using Microsoft.VisualStudio.LanguageServer.Client;

Use this to get the broker:

var broker = await GetServiceAsync(typeof(SLanguageClientBroker)) as ILanguageClientBroker;

Fix for UnifiedLspClient is null

Instead of GetServiceAsync, use MEF or the broker:

Option A – Using Broker to get your client:

var client = (await broker.GetClientsAsync("your-content-type"))
             .OfType<UnifiedLspClient>()
             .FirstOrDefault();

Option B – Using IComponentModel:

var componentModel = await GetServiceAsync(typeof(SComponentModel)) as IComponentModel;
var client = componentModel?.GetExtensions<ILanguageClient>()
                            ?.OfType<UnifiedLspClient>()
                            ?.FirstOrDefault();
                                                                                     

Let us know if the issue persists after following these steps. We’ll be happy to assist further if needed.