File not found includegraphics in tikz quarto

I am trying to use includegraphics in a TikZ picture in quarto. The following example does not work, I get the error:

LaTeX Warning: File `figTest.png' not found on input line 7.


! Package luatex.def Error: File `figTest.png' not found: using draft setting.

despite the file figTest.png is located in the same folder as my quarto example:

---
title: "A tikz test"
pdf-engine: lualatex
keep-tex: true
filters:
  - diagram
diagram:
  engine:
    tikz:
      execpath: lualatex
      header-includes:
        \usepackage{graphicx}
format:
  pdf:
    include-in-header:
      - text: |
          \usepackage{graphicx}
          \usepackage{tikz}
---

## Test section

See @fig-test below.

::: {#fig-test}

```tikz
\begin{tikzpicture}
    \node (orig) at (0, 0) {\includegraphics{figTest.png}};
\end{tikzpicture}
```

A test figure

:::

Note that to run this example you need the lua filter diagram which can be installed via:

quarto install extension pandoc-ext/diagram

Here is a png image for testing:

Yes, the pandoc-ext/diagram filter builds its TeX in a temp directory. Therefore, relative links do not work.

My workaround has been to adapt the filter and symlink to the project directory from the temp one in the compile function:

os.execute('ln -s $QUARTO_PROJECT_DIR '.. tmpdir .. '/PROJECT')

This way, I can e.g. \input{PROJECT/macros.tex} in my TikZ pictures. In your example, one could write \includegraphics{PROJECT/figTest.png}.

(Would also love to hear if someone found a more elegant way where one doe not need to mess with the filter script...)