Haven't tried personally but README.md mentions that you need to specify the plugin location also:

I believe it's a location of a directory and not the plugin itself.
The location corresponds to --pluginProbeLocations tsserver option so you could try to google that further if you still have problems.

Having plugins in tsconfig.json shouldn't work, right?

I tried using name as location and yarn's location like this:

  init_options = {
    plugins = {
      {
        name = "typescript-svelte-plugin";
        location = "./.yarn/unplugged/typescript-svelte-plugin-npm-0.2.5-0efec0bddd/node_modules/typescript-svelte-plugin/";
      };
    };
  };

No success. Even with direct path to index.js as a location.

Googled pluginProbeLocations, results don't seem to be straightforward to use. 🤔

Can you provide a simple project that I can test this on?

try ./.yarn/unplugged/typescript-svelte-plugin-npm-0.2.5-0efec0bddd/ @non25

Both plugins work fine in simple project which I made for testing.
And tsconfig.json is enough to start them. No explicit configuration in the editor for LS is needed.
Actually removing init_options from neovim configuration stopped plugins from working. Strange stuff.
The interesting part is that location is pointing to non-existing directory, and that make both plugins work somehow.
Even more interesting part is that I don't specify css-modules plugin in both neovim config and tsconfig.json and somehow it picks it up. 😮
Will post an update once I realize why it doesn't work in regular projects. 🤷‍♂️

Here's my testbench: https://github.com/non25/typescript-ls-testbench
I feel like there's something fishy going on with tsconfig.json and editor-passed init_options. 🤔

My observation is that tsconfig.json plugins section works only if init_options.plugins is populated with at least one object like this:

{
  name: "anything-non-empty",
  location: "anything-non-empty"
}

Language server plugin can also work without being specified in tsconfig.json, name should be correctly specified and location can be any non-empty string.
I guess it looks it up using node's resolution.

I gues you've probably seen the code handling this in this server but if not I'll just mention that it passes names of the plugins through the --globalPlugins option and the locations through the --pluginProbeLocations option. So I would guess that some non-existing location might be OK if typescript anyway does some default lookup in node_modules.

Here is relevant typescript's code for loading the plugins: https://github.com/microsoft/TypeScript/blob/39ff1568e9676d40cf545477e9fd04077eff9b78/src/server/project.ts#L2277-L2295

With your example project, it works for me without having any plugin specified in init_options.

For example here is with only typescript-svelte-plugin enable in tsconfig.json:

And with typescript-plugin-css-modules enabled I also get an error on style.class2 line.

It is really strange that plugins stop working once I remove init_options, or even location with garbage path from neovim config:

lspconfig.tsserver.setup{
  handlers = {
    ["textDocument/definition"] = require('tsreact').handle_gtd
  };
  cmd = { "yarn", "typescript-language-server", "--stdio" };
  on_attach = ts_utils_on_attach;

  -- these guys
  init_options = {
    plugins = {
      {
        name = "anything";
        location = "anything";
      };
    };
  };
  --

}

https://asciinema.org/a/CLmXeVsYki4X5EJPlKwkwV7yW 🤷‍♂️

Feel free to close I guess, thanks for the help.
Will go with this strange workaround, at least it works for me now. 🙂

If there is a way to log the whole LSP communication with the server then that might reveal something.

Might be useful to log both the logs with and without init_options. Or at least without.

I don't use neovim but I did make an effort to set it up and test with your project and it's working for me even without init_options defined so I will close this issue.

For reference, I've tried with the options below. Tried both with and without init_options but removed the handlers configuration since I was missing some reference there.

syntax on

" Specify a directory for plugins
" - For Neovim: stdpath('data') . '/plugged'
" - Avoid using standard Vim directory names like 'plugin'
call plug#begin('~/.vim/plugged')

" Make sure you use single quotes

Plug 'neovim/nvim-lspconfig'

" Initialize plugin system
call plug#end()

lua << EOF
require'lspconfig'.tsserver.setup{}

vim.lsp.set_log_level("debug")

local lspconfig = require('lspconfig')

lspconfig.tsserver.setup{
  cmd = { "yarn", "typescript-language-server", "--stdio" };
  on_attach = ts_utils_on_attach;

  -- these guys
  init_options = {
    plugins = {
      {
        name = "anything";
        location = "anything";
      };
    };
  };
  --

}

EOF