Access to file system from lsp server

[elena-pudovkina]

Hi,
Not having vscode.workspace.fs on the server side of an extension poses quite a challenge.

One way I see to overcome this is the way anycode does it:
Add a handler to the client for fetching file contents:

client.onRequest('persisted/read', async (): Promise<string> => {
  if (!persistUri) {
     return '';
  }
  try {
     const data = await vscode.workspace.fs.readFile(persistUri);
     return decoder.decode(data);
  } catch {
     return '';
  }
});

And send a request from the server whenever you need to read files:

const raw = await this._connection.sendRequest<string>('persisted/read');

But I noticed that anycode only does this in the node runtime. Does it mean that this won’t work in the browser?
Is there a more direct way to allow the server access to the file system or will there be one in the future?

I’m asking because I’m working on migrating the Wake lsp extension to the browser. Its server is compiled from C++ to wasm and it requires access to the file system, so I'm struggling to make the transition.

[dbaeumer]

Dups microsoft/vscode-languageserver-node#782.