Fix high CPU usage when encountering non-file URI workspaces

[thecrypticace]

Fixes #1394

There are two issues here:

• Non-file schemes were being treated as if they were file:// URIs and we were getting their filesystem path when ends up being an empty string.
• Neovim, when opening a virtual file (e.g. foo://bar.html), causes the server to be initialized with a file URI of file://. and rootPath of /.. I'd expect them to use the foo:// scheme but that does not happen. I think it's super reasonable to have the server refuse a workspace folder that is the filesystem root. This check is definitely not exhaustive (may not handle network shares, arbitrary mounts, different drives on Windows, etc…) but this is probably "good enough" to detect this situation.

Both of these results in the folder being treated as / and results in a file search from the root causing super high CPU usage. I've also added a check inside getProject so files with non-file schemes are ignored. They'll get a fsPath of empty string as well and as such won't match any project. The VSCode extension already does this at the extension level but we weren't doing it in the language server.

[thecrypticace]

So I just did testing in a new Neovim 0.11 installation. This fix should still be applied to the language server because there is a bug here. But it will NOT fix the Neovim bug listed above. (addressed now)

For a virtual file foo://index.html Neovim is sending this initialization request to the server:

[DEBUG][2025-06-03 11:05:53] .../vim/lsp/rpc.lua:277	"rpc.send"	{
  id = 1,
  jsonrpc = "2.0",
  method = "initialize",
  params = {
    capabilities = { … },
    clientInfo = {
      name = "Neovim",
      version = "0.11.2+ga73904168a"
    },
    processId = 4238,
    rootPath = "/.",
    rootUri = "file://.",
    trace = "off",
    workDoneToken = "1",
    workspaceFolders = { {
        name = ".",
        uri = "file://."
      } }
  }
}

There's three things wrong here:

• rootPath is /. which is wrong. For a non-file url I'm not sure that there is any valid value for this property.
• rootUri should probably be foo://.
• workspaceFolders.0.url should probably be foo://.

I think it's probably wrong for it to be file://. Ultimately this resolves to / according to vscode-uri:

const { URI } = await import("vscode-uri").then(m => m.default);
console.log(URI.parse('file://.').fsPath)
// logs `/`

From a normal initialization we get this:

• Notice how all paths/URIs start in /Users/testing/Applications/test-project

[DEBUG][2025-06-03 11:14:08] .../vim/lsp/rpc.lua:277	"rpc.send"	{
  id = 1,
  jsonrpc = "2.0",
  method = "initialize",
  params = {
    capabilities = { … },
    clientInfo = {
      name = "Neovim",
      version = "0.11.2+ga73904168a"
    },
    processId = 839,
    rootPath = "/Users/testing/Applications/test-project",
    rootUri = "file:///Users/testing/Applications/test-project",
    trace = "off",
    workDoneToken = "1",
    workspaceFolders = { {
        name = "/Users/testing/Applications/test-project",
        uri = "file:///Users/testing/Applications/test-project"
      } }
  }
}

I'm thinking we could maybe check to see if fsPath resolves to / and either:

• Hard fail (throw new Error(…))
• Treat it as if the given workspace folders don't exist

Either way trying to run at a workspace folder root of / is pretty much guaranteed to cause problems.

[igorlfs]

Hey,

There's three things wrong here:

• rootPath is /. which is wrong. For a non-file url I'm not sure that there is any valid value for this property.
• rootUri should probably be foo://.
• workspaceFolders.0.url should probably be foo://.

I think it's probably wrong for it to be file://. Ultimately this resolves to / according to vscode-uri:

Thanks for the info. I'll open an issue in neovim.