Arduino language server libraries

I am a bit confused about arduino-language-server… I followed the instructions on the WiKi.

And I get “undeclared identifier” errors, when I use an external Arduino library:

Screenshot from 2023-02-03 20-28-09

I read something about included_libs key on arduino-cli’s documentation - but I think it’s meant for sketch.yaml. More over, this is not even documented on arduino-language-server’s documentation, but on arduino-cli’s docs. Additionally, arduino-cli’s mentions sketch.yaml, and that sketch.json is meant for the Arduino-web-editor, so I wonder - how is that related to arduino-language-server?

So, how can I get completions for my sketch files with those libraries? It’d be nice to have links to full specification of sketch.json in Arduino’s website. I understand that it’s likely that they have documentation missing, but I’m not sure what it is exactly…

Seems like an upstream bug indeed: