Should `book` support "Website Drafts"?

The 1.5 Website Drafts feature adds drafts and draft-mode to the website key.

Since book inherits the base-website schema you can add drafts and draft-mode to book without any warnings, but those options aren't currently respected by books (more details on this below).

I think there are two options:

• Support drafts and draft-mode for book
• Make drafts and draft-mode a website only thing, and explicitly disallow for books.

Issues with book and Website Drafts

Set Up:

quarto create book book-drafts
quarto render --to html

draft-mode isn't respected

Set draft: true in intro.qmd:

---
draft: true
---

And draft-mode: visible in _quarto.yml

book:
  draft-mode: visible
  ...

Expected: _book/intro.html should be in book sidebar navigation.
Actual: _book/intro.html isn't in book sidebar navigation.

Try draft-mode: gone in _quarto.yml

book:
  draft-mode: gone
  ...

Expected: _book/intro.html should be empty.
Actual: _book/intro.html has full content (along with Draft banner).

drafts isn't respected

Remove draft: true from intro.qmd and instead add drafts to _quarto.yml:

book:
  drafts:
    - intro.qmd

Expected: Should be the same behavior as having the draft: true option in intro.qmd
Actual: With draft-mode: gone, intro.html appears as though it isn't a draft at all.

Start by reproducing the behavior with quarto create book book-drafts and quarto render --to html, using _quarto.yml and intro.qmd. Trace how book rendering handles draft-mode and drafts, comparing the existing website behavior; done means the chosen support or rejection is consistent for book navigation, empty output, and draft listing.