`book + format: typst`: brand base font (`typography.base` / `mainfont`) not passed to orange-book template — body text falls back to Libertinus Serif (headings OK)

Bug

When rendering a Quarto book (project.type: book) to Typst, the document body font declared by _brand.yml typography.base (or by mainfont) is not applied. The generated book.with(...) call omits the font: argument entirely, so orange-book's font parameter stays at its none default and Typst falls back to its default serif (Libertinus). Headings are unaffected (the brand headings font is emitted via a separate #show heading: set text(...) rule).

This is book-mode specific: a standalone format: typst document with the same _brand.yml correctly emits font: ("Inter",) and embeds Inter.

This is distinct from #14511 / #14517 (which were about font availability — --font-path not passed → headings fell back + unknown font family warning). Here the fonts are available, headings render correctly, no warning is emitted; only the body font request is missing.

Minimal reproduction (no R, brand only)

mybook/
├── _quarto.yml
├── _brand.yml
├── _fonts/Starjedi.ttf      # any local font for headings (optional)
└── index.qmd                # # Préface + one paragraph

_quarto.yml

project:
  type: book
lang: fr
book:
  title: "Anatomie d'une saga"
  subtitle: "Portrait statistique des personnages de Star Wars"
  author: "Mon Mothma"
  chapters:
    - index.qmd
format:
  typst:
    keep-typ: true
    # mainfont: Inter            # <- also tested: IGNORED in book mode
    font-paths: [.quarto/typst/fonts, _fonts]

_brand.yml

typography:
  fonts:
    - { family: "Star Jedi", source: file, files: [ { path: _fonts/Starjedi.ttf, weight: 400 } ] }
    - { family: Inter, source: google, weight: [400, 600, 700] }
  base: Inter
  headings: "Star Jedi"

quarto render → _book/Anatomie-d-une-saga.pdf.

Expected

Body text in Inter (the brand base), same as a standalone format: typst document.

Actual

Body text in Libertinus Serif. No warning (the font is never requested).

Control comparison — same _brand.yml, single doc vs book

	generated .typ	pdffonts (body)
format: typst (single doc, type: default)	font: ("Inter",) passed to template	Inter-Regular embedded
type: book (orange-book)	#show: book.with(title, subtitle, author, lang, main-color, logo, …) — no font:	LibertinusSerif-Regular/Bold/Italic (no Inter)

In book mode the string Inter never appears in the generated index.typ. orange-book's book() does expose a font parameter (default none, applied via set text(font: font) when font != none) — it simply isn't filled. Setting mainfont: Inter explicitly does not help in book mode either (still absent from book.with(...)).

Workaround (verified)

Force the body font with raw Typst injected in the header:

format:
  typst:
    include-in-header:
      - text: |
          #set text(font: "Inter")

After this, pdffonts shows Inter-Regular/Bold (Libertinus gone), headings still Star Jedi.

Root-cause hypothesis

The book → orange-book template generation maps brand/format metadata to book.with(...) arguments (title, subtitle, author, lang, main-color, logo, …) but does not map typography.base / mainfont to the font: argument. For standalone Typst the default template path does emit font: (...), so the mapping exists per-file but is dropped on the book-assembly path — parallel to the earlier font-paths book-mode wiring gap of #14517, which was on the availability side. Likely the same family as the format-state-at-construction-time issue tracked in #14516.

Suggested fix

Pass the resolved base/main font to book.with(font: ...) (orange-book already supports it), or emit a document-level #set text(font: (...)) for books as is done for standalone docs.

Environment

• Quarto 1.10.11 (reproduces) and 1.9.36 (reproduces)
• Typst bundled, orange-book 0.7.1
• _brand.yml typography.base: Inter (source: google), headings local file
• Reproduces with format: typst (auto orange-book); no R, brand only
• Headings render correctly; only the body font is missing → distinct from #14517

Related

• #14517 / #14511 — book brand fonts not passed as --font-path (RESOLVED — headings/availability side)
• #14516 — typst recipe complete callbacks read format state from the captured construction-time format parameter (suspected shared root cause)
• #13548 — Variants fonts from same family with Brand YAML