Incorrect `editor.suggest.showWords` replacements for completion items if an LSP response takes too long

[atscott]

Does this issue occur when all extensions are disabled?:

Yes and No. The issue occurs when a single LSP extension takes a while to return completion results (even if those results are empty). I have disabled all installed extensions other than the modified lsp-sample from vscode-extension-samples

Version: 1.100.2 (Universal)
Commit: 848b80aeb52026648a8ff9f7c45a9b0a80641e2e
Date: 2025-05-14T21:47:40.416Z
Electron: 34.5.1
ElectronBuildId: 11369351
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.5.0

Steps to Reproduce:

1. Clone https://github.com/atscott/lsp-example-completions. This is the lsp-sample with small edits to demonstrate the behavior
2. Install dependencies: npm i
3. compile: 'npm run compile'
4. Launch the client
5. Open an HTML file and make its contents be:

<div class="something"></div>
<div class="something"></div>

6. Go to the second "something" text and ctrl+backspace it and type "so" in quick succession
7. Accept the "something" completion item when it appears and notice that the editor clobbers the closing quote

characterClobberDemo.mov

If this is expected for some reason, I would expect that at least the documentation needs to be updated to describe how to handle this correctly in the extension. I would not expect to reproduce this so easily with the lsp sample.

[atscott]

I have only observed this issue with the built in word completions and can prevent these types of problems with

 "[html]": {
  "editor.suggest.showWords": false,
  },

Though of course, I then don't ever have word completions.

[jrieken]

Can you press cmd+/ while the something suggestion shows. I wanna double check that is from the word-based completions provider. Iff so (which it very much looks like) then your LSP extension shouldn't have any impact. Word-based completions are computed on an independent worker thread, totally isolated from extensions and LSP. The only thing that would affect this is the word definition, e.g the regex that defines what a word is. Wrt can you check the editor.suggest.insertMode setting esp if that's redefined for some language?

[atscott]

Here's the screenshot for when I do the typing quickly:

And this is what shows when I pause 1 second between each keystroke (including the ctrl+backspace to delete the word):

I'm not sure that difference matters. I notice the index changes as a hit backspace or retype letters in both cases, but the result is always the same for the initial quick typing where characters at the end of the completion are clobbered.

editor.suggest.insertMode is insert in both user and workspace settings