add email-version hook to override detected Connect version

[juleswg23]

Description

This PR makes embedding pre-releases of quarto into Connect (and vice versa) easier by allowing us to declare the version output Quarto should give, beyond the detected version. This makes it simpler to run Quarto on dev versions of Connect as we make staggered changes to Quarto email support, such as in #13882

closes#14021

---title: email with imageformat:
email:
email-version: 2---
Some of the content in this document makes its way to the rendered
HTML and some of it is destined for a custom email message. The
`email` block customizes the subject and the body of the email
message, while the rendered HTML contains only this paragraph.
::: {.email}
::: {.subject}
Buy groceries
:::
![](image.png)
:::

By setting the above fields, even if Quarto detects that it is running inside an old version of Connect, it will output V2 style email metadata.

When rendered locally, I see V2 output metadata, despite having an old version of connect.

pandoc to: html
output-file: email-with-image.html
standalone: true
section-divs: true
html-math-method: mathjax
wrap: none
default-image-extension: png
variables: {}
metadata
document-css: false
link-citations: true
date-format: long
lang: en
title: email with image
email-version: 2
WARNING: Email format v2 is being forced via 'format.email.version: 2' in YAML. This overrides the Connect version detection.
Output created: email-with-image.html

Checklist

I have (if applicable):

• filed a contributor agreement.
• referenced the GitHub issue this PR closes
• updated the appropriate changelog in the PR
• ensured the present test suite passes
• added new tests
• created a separate documentation PR in Quarto's website repo and linked it to this PR

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[cscheid]

Looks good. Could you run quarto dev-call build-artifacts from your branch and push to this branch the changes you'll see in the schema directory?

[juleswg23]

Thanks @cscheid. I did notice the build step, but wasn't sure if I was meant to run it locally. I pushed all the changes it generated, but none were in the schema directory. Will revert it if that's not what you were looking for.

edit: I must have committed the wrong files.

[cscheid]

(sorry, I gave you the wrong paths. .../schema/... is where the schemas live, but those files are the ones that quarto-cli and the extension use to actually interpret and validate the YAML data)

This is strange. The error we're getting here seems (at least to me) to be unrelated. The files you've pushed are the ones I expected to see...

[cscheid]

I think Christophe just added the necessary changes to main; I wonder if a merge would solve it.

[cscheid]

🎉 If this is working for you within Connect, I'm fine with merging!

[juleswg23]

Super, let's merge!

It's working locally (where I don't have connect v2026.03 since it doesn't exist yet), so I'm as confident as I can be for now.

[cderv]

I think Christophe just added the necessary changes to main; I wonder if a merge would solve it.

Yes sorry. Windows / linux stuff againt

Regarding conflict, a rebase is needed on main (or merging main in the branch) and resolving conflict by building schema artifacts again.

Also, is a changelog entry needed maybe for this?

[cscheid]

Also, is a changelog entry needed maybe for this?

Yes, that's good, and it is. Thank you.

[juleswg23]

Merged and changelog entry added ✅