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Weird Bug: mermaid config option breaks OJS #14765
Description
Bug description
Just stumbled upon a weird bug. Maybe I'm missing something. Found this while working on a larger project. Managed to narrow down to a minimal example. I am just reporting my observation -- I didn't investigate further.
When I have config: ... option for mermaid code block, the OJS breaks.
Steps to reproduce
Run this simple test.qmd file
---
title: "Test"
date: "2026-08-10"
format: html
---
```{mermaid}
graph LR
A --> B
```
```{ojs}
//| echo: true
x = 2
x ** 5
```
with quarto preview test.qmd.
Now run it with a config option in the mermaid block (everything else stays same)
---
title: "Test"
date: "2026-08-10"
format: html
---
```{mermaid}
---
config:
look: handDrawn
---
graph LR
A --> B
```
```{ojs}
//| echo: true
x = 2
x ** 5
```
In the second case, the ojs block stops executing -- it becomes just code.
Actual behavior
Left: Without, Right: With the mermaid option
(OJS breaks; although the mermaid option takes correct effect)
There's no error whatsoever.
Expected behavior
The OJS block shouldn't be affected by mermaid's option.
Your environment
Quarto 1.9.38
[✓] Checking environment information...
Quarto cache location: /Users/k2692978/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.8.3: OK
Dart Sass version 1.87.0: OK
Deno version 2.4.5: OK
Typst version 0.14.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.9.38
Path: /Users/k2692978/Applications/quarto/bin
[✓] Checking tools....................OK
TinyTeX: (not installed)
Chromium: (not installed)
Chrome Headless Shell: (not installed)
VeraPDF: (not installed)
[✓] Checking LaTeX....................OK
Tex: (not detected)
[✓] Checking Chrome Headless....................OK
Using: Chrome found on system
Path: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
Source: MacOS known location
[✓] Checking basic markdown render....OK
[✓] Checking R installation...........OK
Version: 4.6.1
Path: /Library/Frameworks/R.framework/Resources
LibPaths:
- /Users/k2692978/Library/R/arm64/4.6/library
- /Library/Frameworks/R.framework/Versions/4.6/Resources/library
knitr: 1.51
rmarkdown: 2.31
[✓] Checking Knitr engine render......OK
[✓] Checking Python 3 installation....OK
Version: 3.9.6
Path: /Library/Developer/CommandLineTools/usr/bin/python3
Jupyter: (None)
Jupyter is not available in this Python installation.
Install with python3 -m pip install jupyter
[✓] Checking Julia installation...
Activity
mcanouil commentedon Aug 12, 2026
That's basically a parsing issue of the mermaid block related to the use of
---.Meanwhile, the workaround is to use inline syntax from mermaid
%%{init: ...}.The issue is unrelated to OJS, whatever comes after is broken.
Adding
keep-md: trueshow the bare and alone---with no empty lines around.mcanouil commentedon Aug 12, 2026
@dasayan05
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mcanouil commentedon Aug 12, 2026
PR is up for the team to review, i.e., enclose mermaid code inside raw HTML block so
---are not treated as markdown.dasayan05 commentedon Aug 13, 2026
ah, I had the same feeling that it was the
---.thanks for the fix.
fix(mermaid): emit mermaid diagrams in a raw html block (quarto-dev#1…