Cross-references from unnumbered chapters lose "Chapter" prefix and ignore bracket syntax

[wryfi]

Bug description

When using @sec- cross-references from within an unnumbered chapter ({.unnumbered}) to a numbered chapter, the reference renders as 1 My Chapter instead of Chapter 1. The same reference renders correctly as Chapter 1 when placed in a numbered chapter.

Additionally, the bracket syntax documented at Book Crossrefs does not work in this context:

• [-@sec-chapter1] should produce just 1 but still produces 1 My Chapter
• [Chapter -@sec-chapter1] should produce Chapter 1 but still produces 1 My Chapter

Minimal reproducible example

_quarto.yml:

project:
  type: book

book:
  title: "Test Book"
  chapters:
    - index.qmd
    - intro.qmd
    - chapter1.qmd

format:
  html:
    theme: cosmo

index.qmd:

# Preface {.unnumbered}

Some preface text.

intro.qmd:

# Introduction {.unnumbered}

See @sec-chapter1 for details.

chapter1.qmd:

# My Chapter {#sec-chapter1}

Chapter content.

Expected behavior

@sec-chapter1 in intro.qmd should render as Chapter 1, consistent with its behavior when placed in a numbered chapter.

Bracket syntax ([-@sec-chapter1], [Chapter -@sec-chapter1]) should also work as documented.

Actual behavior

@sec-chapter1 renders as 1 My Chapter regardless of syntax used.

Quarto version

1.8.27

Related discussions

• Linking to numbered chapters from within an unnumbered chapters #9771 (same issue, acknowledged by maintainer, no tracking issue created)
• Cross-references on unnumbered pages fail (PDF) or are mislabeled (HTML) #5946 (related unnumbered chapter cross-reference issues)