Listing YAML breaks headers when included with no newline

[seragunn]

Bug description

I don't know if this is a regression or if it was never the intended behaviour to put a listing definition in an included file.

Starting in v1.7.4, if you have the listing YAML definition in an included file, it is echoed when it's included (but is still processed)

Steps to reproduce

_quarto.yml:

project:
  type: website
  title: "listing-issue"

index.qmd

# News
{{< include news.qmd >}}

news.qmd

---
listing:
  contents: news
  id: news
---

::: {#news}
:::

news/newsitem.qmd

---
title: sample news
---

# Test

News content

Expected behavior

v1.7.3:

Actual behavior

v1.7.4:

Your environment

No response

Quarto check output

`quarto check` output

Quarto 1.7.4
[✓] Checking environment information...
      Quarto cache location: /home/sera/.cache/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.4.0: OK
      Dart Sass version 1.70.0: OK
      Deno version 1.46.3: OK
      Typst version 0.11.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.7.4
      Path: /opt/quarto/bin

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

[✓] Checking LaTeX....................OK
      Using: Installation From Path
      Path: /usr/bin
      Version: undefined

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

[✓] Checking Python 3 installation....OK
      Version: 3.13.1
      Path: /usr/bin/python3
      Jupyter: 5.7.2
      Kernels: julia-1.11, ir, python3, sagemath

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

[✓] Checking R installation...........OK
      Version: 4.4.2
      Path: /usr/lib64/R
      LibPaths:
        - /home/sera/.R
        - /home/sera/R/x86_64-pc-linux-gnu-library/4.4
        - /usr/lib/R/library
      knitr: 1.48
      rmarkdown: 2.28

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

[mcanouil]

Did you try the latest pre-release? When using pre-release, please always use the latest and avoid making comparisons with past versions before trying out the latest version first.

What's the use case where you need to include a file with a YAML frontmatter such as a listing to a page, instead of defining the listing directly in that page?
Beside the possible bug you are reporting, you put yourself in a position where metadata can be overwritten by each include you make.

[mcanouil]

I've created a default blog project and cannot reproduce the issue:

[seragunn]

Thanks for the response. I looked into this more and I narrowed down the issue:

It happens when you have a section heading directly above your include (with no line in between)

---
title: "demo"
---

# Blog content
{{< include _index.qmd >}}

And sorry I should have specified. I noticed the issue on the latest pre-release (1.7.13) but I did a bifurcation to track the issue down to the 1.7.4 update. This screenshot is with 1.7.13.

Use case: me and my colleague are trying to rebuild our website in Quarto and to help modularize the homepage, he put the news listing in a subfile. It's easy enough to avoid this issue by either defining the listing in the main file or to, it appears, put a newline after the heading.

[mcanouil]

Note that having empty lines surrounding headers, lists, and code blocks is one of the rule shared by all markdown linters to precisely avoid these issues.

Because in your case you end up with a very weird markdown.

---
title: "demo"
---

# Blog content
---
listing:
  ...
---

Which obviously will confuse markdown readers, since "underlined" text is a header, and you can use both header syntax at the same time.

See GitHub for instance:

Input	Output
## Header using `#` Header using `---` below --- ## Header using `#` AND `---` below ---	Header using # Header using --- below Header using # AND --- below

[seragunn]

Gotcha, that makes sense. Thanks for your time. I'm going to close this issue now since everything is behaving as expected.

[mcanouil]

I'm reopening because the lead maintainer might want to either ensure empty lines are added by the "include shortcode" and/or keep this for future linting, etc.
CC @cscheid