Python code cells will separate `#` and `|` after formatting in quarto

[psychelzh]

System details:

Positron and OS details:

Positron Version: 2025.09.0 (user setup) build 139
Code - OSS Version: 1.103.0
Commit: 30e3d0a74e09a0f6640929822cb57a326671360e
Date: 2025-08-29T18:50:28.998Z
Electron: 37.2.3
Chromium: 138.0.7204.100
Node.js: 22.17.0
V8: 13.8.500258-electron.0
OS: Windows_NT x64 10.0.26100

Session details:

Python 3.13.7

Describe the issue:

In Quarto document, Python code cells will separate # and | after formatting, which then causes the chunk header not working.

Steps to reproduce the issue:

1. Create a new quarto document, say test.qmd.
2. Input these lines and save

```{python}
#| label: test
#| echo: false

print("Hello, World!")
```

3. Then you will find the header formatting is wrong:

But for R code cells, it is normal:

Expected or desired behavior:

Do not separate # and |

Were there any error messages in the UI, Output panel, or Developer Tools console?

None for now.

[midleman]

Hello! Thank you for reporting this issue.

I was able to repro this issue by following these steps:

1. Create empty .qmd
2. Paste into file:

```{python}
#| label: test
#| echo: false

print("Hello, World!")
```

3. Right click and select to Format Cell
4. Verify #| are properly formatted - FAIL

Expected: the #| remain formatted together.
Actual: the # and | separated

I’ll go ahead and move this to triage so the team can review. Thanks again for taking the time to file this!

[juliasilge]

This is happening because ruff will format this:

#Apple
#| Banana
## Cherry

to this:

# Apple
# | Banana
## Cherry

I think we'd need to somehow have the Quarto extension strip out comments before formatting, or to identify special Quarto comments and not put them in the virtual doc? I suppose the dream would be to not have ruff treat Quarto comments like this.

[juliasilge]

There are several issues on the Quarto extension about this (quarto-dev/quarto#368) and actually a fix is in flight!

• fix: protect code cell options from formatting quarto-dev/quarto#655