Ruff triggered via jupyterlab-lsp -> python-lsp-server -> python-lsp-ruff chain doesn't recognize that it's checking a Jupyter notebook

[sergey-protserov-uhn]

Description

Hello!

I am not super sure that this is a bug in jupyterlab-lsp, because it may be a bug in python-lsp-server, its Ruff plugin (python-lsp-ruff) or Ruff itself. However, I thought that I will report it here, please let me know if the problem is actually downstream, and I will create another issue there.

Ruff has special handling of some linting rules when it detects that it's checking a Jupyter notebook and not a regular Python file: for example, useless-expression is not triggered for final top-level expression in a cell.

Indeed, when I run ruff check for a Jupyter notebook with such expressions, useless-expression is not triggered. However, it is triggered when I open such a notebook in JupyterLab, it is highlighted and displayed in a diagnostics window. I believe somewhere along the call chain the information that we are checking a notebook is lost, and Ruff interprets it as if it was a regular Python file.

I also get spurious unsorted-imports trigger for the first cell with imports, again only when viewing the notebook in JupyterLab, and not when checking it from command line. While this rule doesn't declare any special handling of notebooks on its page, this may be related.

Here is what I seen when I click on the LSP badge in the status bar:

Thank you!

Context

• Operating System and version: GNU/Linux, Fedora 42
• Browser and version: Firefox 142.0 (64-bit)
• jupyterlab version: 4.4.4 from conda-forge
• jupyterlab-lsp version: 5.1.1 from conda-forge
• python-lsp-server version: 1.12.2 from conda-forge
• python-lsp-ruff version: 2.2.2 from conda-forge
• ruff version: 0.12.1 from conda-forge

Required: installed server extensions

Config dir: /home/user_main/.jupyter
Config dir: /home/user_main/.miniforge3/envs/main/etc/jupyter

jupyter_lsp enabled

- Validating jupyter_lsp...

jupyter_lsp 2.2.5 OK

jupyter_server_mathjax enabled

- Validating jupyter_server_mathjax...

jupyter_server_mathjax  OK

jupyter_server_terminals enabled

- Validating jupyter_server_terminals...

jupyter_server_terminals 0.5.3 OK

jupyterlab enabled

- Validating jupyterlab...

jupyterlab 4.4.4 OK

jupyterlab_git enabled

- Validating jupyterlab_git...

jupyterlab_git 0.51.2 OK

jupyterlab_myst enabled

- Validating jupyterlab_myst...

jupyterlab_myst 2.4.2 OK

nbdime enabled

- Validating nbdime...

nbdime 4.0.2 OK

notebook enabled

- Validating notebook...

notebook 7.4.3 OK

notebook_shim enabled

- Validating notebook_shim...

notebook_shim  OK

panel.io.jupyter_server_extension enabled

- Validating panel.io.jupyter_server_extension...

Extension package panel.io.jupyter_server_extension took 0.5003s to import

panel.io.jupyter_server_extension  OK
Config dir: /usr/local/etc/jupyter

Required: installed lab extensions

Config dir: /home/user_main/.jupyter
Config dir: /home/user_main/.miniforge3/envs/main/etc/jupyter

jupyter_lsp enabled

- Validating jupyter_lsp...

jupyter_lsp 2.2.5 OK

jupyter_server_mathjax enabled

- Validating jupyter_server_mathjax...

jupyter_server_mathjax  OK

jupyter_server_terminals enabled

- Validating jupyter_server_terminals...

jupyter_server_terminals 0.5.3 OK

jupyterlab enabled

- Validating jupyterlab...

jupyterlab 4.4.4 OK

jupyterlab_git enabled

- Validating jupyterlab_git...

jupyterlab_git 0.51.2 OK

jupyterlab_myst enabled

- Validating jupyterlab_myst...

jupyterlab_myst 2.4.2 OK

nbdime enabled

- Validating nbdime...

nbdime 4.0.2 OK

notebook enabled

- Validating notebook...

notebook 7.4.3 OK

notebook_shim enabled

- Validating notebook_shim...

notebook_shim  OK

panel.io.jupyter_server_extension enabled

- Validating panel.io.jupyter_server_extension...

panel.io.jupyter_server_extension  OK
Config dir: /usr/local/etc/jupyter

[sergey-protserov-uhn]

New finding: unsorted-imports doesn't trigger for

but does trigger for