Local extensions are ignored

[diplfranzhoepfinger]

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

Quarto ignores local extensions totally,
e.g. ....-book_extensions\quarto-ext\orange-book

always using the "global ones"
e.g. C:\Program Files\Quarto\share\extension-subtrees\orange-book_extensions\orange-book

Steps to reproduce

1. make a new Folder,
2. quarto add quarto-ext/orange-book
3. make a project , be sure to read https://github.com/quarto-ext/orange-book?tab=readme-ov-file#usage (type and format must match)
4. make quarto render,
5. modify something in ....-book_extensions\quarto-ext\orange-book

Actual behavior

it takes the global extension, not the local one.

Expected behavior

if extensions of the same name are there,
take the "local" one,
or make this configurable.

Your environment

• OS: Windows
• IDE: Notepad++

Quarto check output

PS C:\Users\franz> quarto check
Quarto 1.9.36
[>] Checking environment information...
      Quarto cache location: C:\Users\franz\AppData\Local\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: 1.9.36
      Path: C:\Program Files\Quarto\bin
      CodePage: 1252

[>] Checking tools....................OK
      TinyTeX: v2026.02
      Chromium: (not installed)
      Chrome Headless Shell: (not installed)
      VeraPDF: (not installed)

[>] Checking LaTeX....................OK
      Using: TinyTex
      Path: C:\Users\franz\AppData\Roaming\TinyTeX\bin\windows\
      Version: 2025

[>] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: C:\Program Files\Google\Chrome\Application\chrome.exe
      Source: Windows Registry

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

[>] Checking R installation...........OK
      Version: 4.5.2
      Path: C:/PROGRA~1/R/R-45~1.2
      LibPaths:
        - C:/Program Files/R/R-4.5.2/library
      knitr: 1.51
      rmarkdown: 2.30

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

[>] Checking Python 3 installation....OK
      Version: 3.13.5
      Path: C:/Program Files/Python313/python.exe
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with py -m pip install jupyter

[>] Checking Julia installation...
PS C:\Users\franz>

[mcanouil]

@diplfranzhoepfinger please don't bypass the bug issue template and provide all the information requested. Without context, steps to reproduce, actual output, and Quarto check output, there is nothing that can be done to help or investigate.

• https://github.com/quarto-dev/quarto-cli/blob/main/.github/ISSUE_TEMPLATE/bug_report.yml

[mcanouil]

Wild guess, you are trying to customise a Typst book in Quarto.
If so, consider looking at the documentation and previous discussions before opening issues.

• https://quarto.org/docs/output-formats/typst-custom.html#book-format-extensions

(Linked in https://quarto.org/docs/books/book-output.html#customizing-typst-books)

[mcanouil]

Could you edit your original post following the template to give clear context?
Maybe share a GitHub repository to help reproduce?

Note that as for any extensions you need to specify the extension format for it to take effect.

[diplfranzhoepfinger]

BTW: @mcanouil

• https://quarto.org/docs/output-formats/typst-custom.html#book-format-extensions

(Linked in https://quarto.org/docs/books/book-output.html#customizing-typst-books)

this does say: The bundled [orange-book extension](https://github.com/quarto-ext/orange-book) provides a complete example of this structure.

and then you click: https://github.com/quarto-ext/orange-book and land:

quarto add quarto-ext/orange-book

then you have again the structure i described in my Original Post.

[mcanouil]

@diplfranzhoepfinger Still, you don't mention changing the format in YAML which is required for any format extension.
Providing all context is important, that's also why there is a bug template to help users ensure they do provide all information and save time to everyone.

---

Here are the steps to reproduce:

1. quarto create book project i14326 i14326
2. quarto add quarto-ext/orange-book
3. Edit _quarto.yml format to: format: orange-book-typst

What seems to happen here is an issue in the extension lookup.
Because Typst book uses an extension "orange-book" and as documented should be format: orange-book-typst, it appears that no local extension with the same name are allowed: _extensions/orange-book or _extensions/<owner>/orange-book.

Deleting the bundled extension while having a local one with the same name works, because internally Quarto sets format: orange-book-typst, then comes the extension discovery which sees the local extension matching the orange-book name.

[diplfranzhoepfinger]

@diplfranzhoepfinger please don't bypass the bug issue template and provide all the information requested. Without context, steps to reproduce, actual output, and Quarto check output, there is nothing that can be done to help or investigate.

• https://github.com/quarto-dev/quarto-cli/blob/main/.github/ISSUE_TEMPLATE/bug_report.yml

Sorry for not using the Template. I did update this issue to use the Template now.

[diplfranzhoepfinger]

Deleting the bundled extension while having a local one with the same name works, because internally Quarto sets format: orange-book-typst, then comes the extension discovery which sees the local extension matching the orange-book name.

YES, this is my current workaround:
after installing/updating Quarto, i delete the bundeled extension.

it is working, but not very nice and dangerous that other team Members have different builds (because of not following this "delete" rule)

[mcanouil]

@gordonwoodhull This raises few issues with the current extension lookup:

1. Should local extension silently override internal extension? A warning?
2. Shouldn't format: orange-book-typst be required regardless of 1?

To me format: typst in book should use internally format: orange-book-typst.
But a user should use format: orange-book-typst explicitly and Quarto should respect that, i.e., use locally installed extension.

---

@diplfranzhoepfinger You don't have to mess with your Quarto installation. Simply change the "orange-book" part to whatever you want and set explicitly the format to use it, i.e., turn your local orange-book extension into _extensions/my-book/_extension.yml and use format: my-book-typst