Insertion point of include-in-header

[matthiasbaitsch]

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

Code provided to include-in-header is not inserted at the end of the header.

Steps to reproduce

---
format:
    pdf:
        keep-tex: true
        include-in-header: 
            - text: |
                \usepackage{tcolorbox}
                \usepackage{keytheorems}
                \tcbset{definition_style/.style={}}
                \renewkeytheorem{definition}[style=definition,tcolorbox={definition_style}]
---

::: {#def-prime-number}
## Prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers.
:::

Actual behavior

Latex code fails to compile because \renewkeytheorem precedes \newtheorem{definition}{Definition}[section] inserted by quarto.

Expected behavior

Generates PDF document. The attached tex file works since the code in question has been moved to the end of the preamble.

demo-2-edited.tex.zip

Your environment

• OS: macOS Tahoe 26.2

Quarto check output

Quarto 1.8.27
[✓] Checking environment information...
      Quarto cache location: /Users/maba/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.6.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.3.1: OK
      Typst version 0.13.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.8.27
      Path: /Applications/quarto/bin

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

[✓] Checking LaTeX....................OK
      Using: Installation From Path
      Path: /Library/TeX/texbin
      Version: 2025

[✓] 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 Python 3 installation....OK
      Version: 3.12.11
      Path: /Users/maba/usr/python/global-venv/bin/python3
      Jupyter: 5.7.2
      Kernels: python3, julia-1.11, julia-1.10

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

[✓] Checking R installation...........OK
      Version: 4.5.2
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Users/maba/Library/R/arm64/4.5/library
        - /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/library
      knitr: 1.50
      rmarkdown: 2.30

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