Can I embed an extension in a custom project type?

[andrewpbray]

Description

Hello!

I've created a custom project type and when I went to embed an extension, I got an unexpected error:

quarto add quarto-ext/fancy-text --embed lexdocs

ERROR: The extension lexdocs does not contribute a format.
You can only embed extensions within an extension which itself contributes a format.

I'm curious: why are extensions not embeddable within custom project types?

Here is a minimal repo that you can use to run the above command and reproduce the error:
https://github.com/andrewpbray/custom-project-type

[cscheid]

(cc @dragonstyle)

[andrewpbray]

A follow-up: it looks like you can fool this check throwing in a blank custom format alongside your custom project type and _extensions.yml:

contributes:
  project:
    project:
      type: website
    website:
      page-footer: |
        "Copyright 2022, Lexcorp, Inc." 
  formats:
    html:
      toc: true

quarto add quarto-ext/fancy-text --embed lexdocs now goes through without an error.

[cscheid]

"don't stand in the way of a sufficiently-motivated power user"

[andrewpbray]

Just to follow-up here: I ran into this problem once more. Should this be flagged as a bug? It seems like the extension embedding code was written after custom formats were devised but before custom project types.

[cderv]

Probably. Is the example shared in OP still not working ? If so I can create an issue from this. Otherwise, you can open one with an example showing this