Function figure_supplement 

fn figure_supplement() -> &'static str

The human-facing supplement word prefixed to a figure’s number in generated reference and caption text; the “Figure” in “Figure 1”.

This is the single localization seam for figure labels: LaTeX localizes it through babel’s \figurename, Typst through figure.supplement under the document text(lang: …). Mosaic captures a document language in metadata but does not yet thread it into the resolver, so this returns the English default; when that plumbing lands, a language-keyed lookup replaces the constant here without touching any call site. Sibling kinds (tables, equations, theorems) grow their own supplements alongside their numbering.