Multiple language servers on one language

[Markiewic]

I am working on an extension for Angular support. As you know, Angular does not use any of its own file extensions (like vue, for example), but uses files with the .ts and .html extensions.

So, now Zed correctly recognizes the language of the opened files (HTML and TypeScript).

We specified the following configuration in extension.toml:

[language_servers.angular]
name = "Angular Language Server"
languages = ["TypeScript", "HTML", "Angular"]

[language_servers.angular.language_ids]
"HTML" = "html"
"TypeScript" = "typescript"
"Angular" = "angular"

This means that if the file has the html language selected, then two language servers will work for it: vscode-html-language-server and our angular server. And indeed: functions such as hovering (the textDocument/hover method) work correctly, information is requested from both language servers and combined. Where there is something to tell the vscode-html-language-server server, information from it is displayed, and the same for the angular server.

But there is a problem with the "Go to definition" function. The angular server does not receive the textDocument/definition message at all. If you check what messages vscode-html-language-server receives, these messages are there (and it is logical that it responds with an empty array).

The same situation is with TS files. The vtsls language server receives textDocument/definition messages, but angular does not. Although such functions as auto-completion and hover work correctly.

It is possible to set in the user settings which language servers will be used for a particular language. And what is interesting is that if you set them like this:

{
  "languages": {
    "TypeScript": {
      "code_actions_on_format": {
        "source.fixAll.eslint": true
      },
      "language_servers": ["angular", "vtsls"]
    },
    "HTML": {
      "code_actions_on_format": {
        "source.fixAll.eslint": true
      },
      "language_servers": ["angular", "vscode-html-language-server"]
    }
  },
}

then everything will start working correctly. Yes, now it is the other way around, the vscode-html-language-server and vtsls servers stopped receiving textDocument/definition messages, but angular does.

The same applies to the textDocument/references and textDocument/rename methods. It turns out that these features only work for the language server that is listed first.

In this regard, I have two questions:

1. How can I set the angular language server as a priority using the extension configuration? It is probably incorrect to ask the user to manually set the necessary settings after installation.
2. Is it possible to make features such as defenition search and references search work for all related language servers?