environment variables not substituted with empty title

[aronatkins]

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

This is related to #7754.

When the Quarto website title includes the environment variable shortcode and the (not default) page does not include a title, substitution does not occur.

This is a regression from Quarto 1.4.

Steps to reproduce

project:
  type: website

website:
  title: "{{< env SITE_TITLE >}}"

---
title: "index"
---

this is index.qmd

---
title: ""
---

this is about.qmd

 SITE_TITLE="hiya" ~/quarto/quarto-1.4.557-macos/bin/quarto render --output-dir _site_1.4
 SITE_TITLE="hiya" ~/quarto/quarto-1.5.57-macos/bin/quarto render --output-dir _site_1.5
 SITE_TITLE="hiya" ~/quarto/quarto-1.6.43-macos/bin/quarto render --output-dir _site_1.6
 SITE_TITLE="hiya" ~/quarto/quarto-1.7.34-macos/bin/quarto render --output-dir _site_1.7
 SITE_TITLE="hiya" ~/quarto/quarto-1.8.25-macos/bin/quarto render --output-dir _site_1.8

Looking across all of the generated HTML:

grep '<title' _site*/about.html

Only Quarto 1.4 replaces the environment variable.

_site_1.4/about.html:<title>hiya -</title>
_site_1.5/about.html:<title>about – {{&lt; env SITE_TITLE &gt;}}</title>
_site_1.6/about.html:<title>about – {{&lt; env SITE_TITLE &gt;}}</title>
_site_1.7/about.html:<title>about – {{&lt; env SITE_TITLE &gt;}}</title>
_site_1.8/about.html:<title>about – {{&lt; env SITE_TITLE &gt;}}</title>

To workaround, use title-prefix and pagetitle.

---
title-prefix: ""
pagetitle: '{{< env SITE_TITLE >}} the fix'
---

this is about.qmd

Actual behavior

Environment variables are not substituted.

Expected behavior

Environment variables are not substituted.

Your environment

Tested with multiple Quarto versions (see above).

Quarto check output

Quarto 1.8.25
[✓] Checking environment information...
      Quarto cache location: /Users/aron/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.6.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.3.1: OK
      Typst version 0.13.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.8.25
      Path: /Users/aron/quarto/quarto-1.8.25-macos/bin

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

[✓] Checking LaTeX....................OK
      Using: Installation From Path
      Path: /Library/TeX/texbin
      Version: 2024

[✓] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
      Source: MacOS known location

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

[✓] Checking Python 3 installation....OK
      Version: 3.12.2
      Path: /opt/homebrew/opt/python@3.12/bin/python3.12
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking R installation...........OK
      Version: 4.3.3
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/library
      knitr: 1.50
      rmarkdown: 2.29

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

[cderv]

Looking into that I found

we do retrieve the unprocessed website title to pass it as Pandoc metadata to use in template

quarto-cli/src/project/types/website/website.ts

Lines 173 to 179 in 28d535a

	// title prefix if the project has a title and this isn't the home page
	const title = websiteTitle(project.config);
	if (title) {
	extras.pandoc = {
	[kTitlePrefix]: title,
	};
	}

So we always set a title-prefix. But we do resolve pagetitle later too

quarto-cli/src/command/render/pandoc.ts

Lines 944 to 966 in 28d535a

	// resolve some title variables
	const title = allDefaults?.[kVariables]?.[kTitle] ||
	options.format.metadata[kTitle];
	const pageTitle = allDefaults?.[kVariables]?.[kPageTitle] ||
	options.format.metadata[kPageTitle];
	const titlePrefix = allDefaults?.[kTitlePrefix];
	// provide default page title if necessary
	if (!title && !pageTitle && isHtmlFileOutput(options.format.pandoc)) {
	const [_dir, stem] = dirAndStem(options.source);
	args.push(
	"--metadata",
	`pagetitle:${pandocAutoIdentifier(stem, false)}`,
	);
	}
	// don't ever duplicate pagetite/title and title-prefix
	if (
	(pageTitle !== undefined && pageTitle === titlePrefix) ||
	(pageTitle === undefined && title === titlePrefix)
	) {
	delete allDefaults[kTitlePrefix];
	}

Specifically when there is no title and not pagetitle we do set pagetitle metadata

quarto-cli/src/command/render/pandoc.ts

Lines 951 to 958 in 28d535a

	// provide default page title if necessary
	if (!title && !pageTitle && isHtmlFileOutput(options.format.pandoc)) {
	const [_dir, stem] = dirAndStem(options.source);
	args.push(
	"--metadata",
	`pagetitle:${pandocAutoIdentifier(stem, false)}`,
	);
	}

which I believe will have an impact. However, for both files we have the unprocessed shortcode.

So processing of shortcode in title happens elsewhere. And this is in the Markdown pipeline logic.

The titles metadate are also handled in a Markdown pipeline, prbably so that shortcode is rendered

quarto-cli/src/project/types/website/website-meta.ts

Lines 434 to 435 in 28d535a

	function metaMarkdownPipeline(format: Format, extras: FormatExtras) {
	const resolvedTitle = computePageTitle(format);

This is setup before the previous processing I shared, and the resolved after within this markdownpipeline

quarto-cli/src/project/types/website/website-meta.ts

Lines 453 to 474 in 28d535a

	processRendered(rendered: Record<string, Element>, doc: Document) {
	const renderedEl = rendered[kMetaTitleId];
	if (renderedEl) {
	// Update the document title
	const el = doc.querySelector(
	`head title`,
	);
	if (el && el.innerText === resolvedTitle) {
	if (format.pandoc[kNumberSections] === false) {
	// Remove chapter numbers if not numbered
	const numberEl = renderedEl.querySelector("span.chapter-number");
	if (numberEl) {
	numberEl.remove();
	}
	// Collapse contiguous whitespace
	const collapsed = renderedEl.innerText.replaceAll(/\s+/g, " ");
	el.innerHTML = collapsed;
	} else {
	el.innerHTML = renderedEl.innerText;
	}
	}
	}

The issue seems to be in there.

The first problem I see is at this comparaison

quarto-cli/src/project/types/website/website-meta.ts

Line 460 in 28d535a

if (el && el.innerText === resolvedTitle) {

el.innerText
'about – {{< env SITE_TITLE >}}'
resolvedTitle
' – {{< env SITE_TITLE >}}'

The rendered document as the about pagetitle we added as metadata and that applied in template

quarto-cli/src/resources/formats/html/pandoc/metadata.html

Line 23 in 28d535a

<title>$pagetitle$$if(title-prefix)$ – $title-prefix$$endif$</title>

but the computed is different

quarto-cli/src/project/types/website/website-meta.ts

Line 435 in 28d535a

const resolvedTitle = computePageTitle(format);

So we don't go to replace the shortcode in the HTML by its resolved version from the markdown pipeline

quarto-cli/src/project/types/website/website-meta.ts

Lines 470 to 472 in 28d535a

	} else {
	el.innerHTML = renderedEl.innerText;
	}

renderedEl.innerText
'– hiya'

So at the end this is about the pagetitle handling. we must have modified something in 1.5 that changed this. I'll keep looking

[cderv]

This is the bad commit: c8676ca and change is about exactly the line found

quarto-cli/src/project/types/website/website-meta.ts

Line 460 in 28d535a

if (el && el.innerText === resolvedTitle) {

This was done to fix

• HTML page title in metadata from template partials overridden in websites #7318

So this needs to be fixed while not breaking #7318 fix

[cderv]

So this needs to be fixed while not breaking #7318 fix

I have added a regression test for #7318 in #13576 so that we are covered