Crash when using inline `#| label: fig-*` syntax with `format: ipynb`

[mcanouil]

Bug Description

Quarto crashes when rendering a document to ipynb format that contains a Python code cell with an inline figure label (#| label: fig-*).
The crash occurs during the Pandoc filter phase with the error: "Block, list of Blocks, or compatible element expected, got table".

The crash does not occur when:

• Using --no-execute flag.
• Using the div syntax (::: {#fig-test}) instead of the inline label.

Steps to Reproduce

---
title: Demo
format: ipynb
---

Inline label (crashes):

```{python}
#| label: fig-test2
print("This renders to part of a Markdown cell.")
```

Run quarto render demo.qmd.

Actual Behaviour

Error running filter /Users/mcanouil/Projects/quarto-dev/quarto-cli/src/resources/filters/main.lua:
Block, list of Blocks, or compatible element expected, got table
	while retrieving function argument content
	while retrieving arguments for function Div
stack traceback:
	...i/src/resources/filters/./customnodes/floatreftarget.lua:936: in field 'render'
	...to-dev/quarto-cli/src/resources/filters/./ast/render.lua:46: in local 'filter_fn'
	...v/quarto-cli/src/resources/filters/./ast/customnodes.lua:168: in function <...v/quarto-cli/src/resources/filters/./ast/customnodes.lua:158>
	(...tail calls...)
	...c/resources/pandoc/datadir/../../filters/modules/jog.lua:34: in upvalue 'run_filter_function'
	...c/resources/pandoc/datadir/../../filters/modules/jog.lua:223: in function <...c/resources/pandoc/datadir/../../filters/modules/jog.lua:202>
	(...tail calls...)
	[C]: in function 'pandoc.List.map'
	...c/resources/pandoc/datadir/../../filters/modules/jog.lua:125: in upvalue 'recurse'
	...c/resources/pandoc/datadir/../../filters/modules/jog.lua:222: in local 'jogger'
	...c/resources/pandoc/datadir/../../filters/modules/jog.lua:171: in upvalue 'recurse'
	...c/resources/pandoc/datadir/../../filters/modules/jog.lua:222: in function <...c/resources/pandoc/datadir/../../filters/modules/jog.lua:202>
	(...tail calls...)
	...v/quarto-cli/src/resources/filters/./ast/customnodes.lua:87: in function <...v/quarto-cli/src/resources/filters/./ast/customnodes.lua:65>
	(...tail calls...)
	.../quarto-cli/src/resources/filters/./ast/runemulation.lua:82: in local 'callback'
	.../quarto-cli/src/resources/filters/./ast/runemulation.lua:100: in upvalue 'run_emulated_filter_chain'
	.../quarto-cli/src/resources/filters/./ast/runemulation.lua:136: in function <.../quarto-cli/src/resources/filters/./ast/runemulation.lua:133>

Expected Behaviour

The document should render successfully to ipynb format, producing a Jupyter notebook with the code cell properly labelled as a figure.

Workaround

Use the div syntax instead of the inline label:

::: {#fig-test}

```{python}
print("This renders to part of a Markdown cell.")
```

:::

Your Environment

• IDE: VSCode
• OS: macOS (Darwin 25.2.0)

Quarto Check Output

Quarto 99.9.9
[✓] Checking environment information...
      Quarto cache location: /Users/mcanouil/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: 99.9.9
      commit: f14ae36813513fb64d8c84c57e511c9321f61736
      Path: /Users/mcanouil/Projects/quarto-dev/quarto-cli/package/dist/bin

[✓] Checking tools....................OK
      TinyTeX: v2026.01
      Chromium: (not installed)
      VeraPDF: (not installed)

[✓] Checking LaTeX....................OK
      Using: TinyTex
      Path: /Users/mcanouil/Library/TinyTeX/bin/universal-darwin
      Version: 2025

[✓] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: /Applications/Brave Browser.app/Contents/MacOS/Brave Browser
      Source: QUARTO_CHROMIUM

[✓] Checking basic markdown render....OK

[✓] Checking R installation...........OK
      Version: 4.5.2
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Users/mcanouil/Projects/quarto-dev/quarto-playground/renv/library/macos/R-4.5/aarch64-apple-darwin20
        - /Users/mcanouil/Library/Caches/org.R-project.R/R/renv/sandbox/macos/R-4.5/aarch64-apple-darwin20/4cd76b74
      knitr: 1.51
      rmarkdown: 2.30

[✓] Checking Knitr engine render......OK

[✓] Checking Python 3 installation....OK
      Version: 3.14.2
      Path: /opt/homebrew/opt/python@3.14/bin/python3.14
      Jupyter: (None)

[✓] Checking Julia installation...

[cderv]

Quick question on this ?

Why using print() inside a cell labelled for figure cross reference ?

Because this does not throw error

---
title: Demo
format: ipynb
keep-md: true
---

Inline label (crashes):

```{python}
#| label: fig-test2
import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 10, 100)
y = np.sin(x)
plt.plot(x, y)
plt.title("Sine Wave")
plt.show()
```

And I bet we have a problem in Lua filter because the markdown structure is NOT a cell output display when you use print

::: {#fig-test2 .cell execution_count=1}
``` {.python .cell-code}
print("This renders to part of a Markdown cell.")
```

::: {.cell-output .cell-output-stdout}
```
This renders to part of a Markdown cell.
```
:::
:::

The div syntax leads to

::: {#fig-test}

::: {#96fcdd6d .cell execution_count=1}
``` {.python .cell-code}
print("This renders to part of a Markdown cell.")
```

::: {.cell-output .cell-output-stdout}
```
This renders to part of a Markdown cell.
```
:::
:::


:::

The problematic syntax is when label is added on the .cell Div directly

::: {#fig-test2 .cell execution_count=1}
``` {.python .cell-code}
print("This renders to part of a Markdown cell.")
```

::: {.cell-output .cell-output-stdout}
```
This renders to part of a Markdown cell.
```
:::
:::

So it should be easy to compare both code path and adapt.

However, what would you expect when using label: fig- and no output display (so no figure really)...

I am asking because I believe execution cell and cross reference is more strict in its content than the Div Syntax (which is more permissive). I bet that knitr engine probably does not like if you use fig- or tbl- and you have no figure or no table. 🤔

[mcanouil]

Quick question on this ?

Why using print() inside a cell labelled for figure cross reference ?

However, what would you expect when using label: fig- and no output display (so no figure really)...

No idea, I don't do that, see:

• https://github.com/orgs/quarto-dev/discussions/13905

[cderv]

thanks I had missed the discussion. So it works for HTML

using same

Inline label (crashes):

```{python}
#| label: fig-test2
print("This renders to part of a Markdown cell.")
```

and having same intermediate

Inline label (crashes):

::: {#fig-test2 .cell execution_count=1}
``` {.python .cell-code}
print("This renders to part of a Markdown cell.")
```

::: {.cell-output .cell-output-stdout}
```
This renders to part of a Markdown cell.
```
:::
:::

So we just need to support it for ipynb I guess - I mean not throwing an error and having same output as using div syntax

    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Demo\n",
        "\n",
        "``` python\n",
        "print(\"This renders to part of a Markdown cell.\")\n",
        "```\n",
        "\n",
        "    This renders to part of a Markdown cell.\n",
        "\n",
        "Figure 1"
      ],
      "id": "f77cf410-b894-4931-b17f-8f8fea9d8db1"
    }