Check a theme's dictionary structure against onepagr's real contract

Validates a theme .typ file's theme and theme-grad exports by actually evaluating them with Typst (typst eval, via Quarto's bundled binary) rather than a hand-rolled text parser, so a theme flagged here is confirmed to fail (or nearly fail) the exact same way it would at real render time, not just suspected to. Checks:

Usage

check_theme(theme = "default", theme_path = NULL)

Arguments

theme: Character. A built-in theme name (e.g. "uk") or a path to a custom theme .typ file. Default "default".
theme_path: Character or NULL. Explicit path override, same as resolve_theme().

Value

Invisibly, a list: ok (logical), path (the resolved theme file), error (character or NULL; set only when the file failed to evaluate at all, in which case every field below is empty/NA), missing / missing_grad (character vectors of required keys not found in theme / theme-grad), type_mismatches / type_mismatches_grad (data frames with key, expected, actual columns), radius_card_missing / radius_card_type_mismatches (same shape, for the nested radius-card dictionary), and unknown (character vector of keys present in theme but outside onepagr's known schema, informational only, not a failure; could be a typo, or a key your own templates read directly).

Details

The file evaluates at all (catches a Typst syntax error, a missing theme/theme-grad export, or any other error Typst itself would raise).
Every key onepagr's shipped templates and components.typ actually dereference is present, in both theme and theme-grad.
Each present key's real Typst-evaluated type matches what onepagr expects (e.g. a color key set to a bare string, or a length key set to a color), exactly the kind of mistake that would otherwise surface as a much less legible Typst error deep inside components.typ, pointing at the component's own code rather than the theme file that actually caused it.

Does not check color contrast or WCAG compliance: a value can be a perfectly well-formed color and still fail WCAG (or vice versa, though a malformed value can never pass it). That's a semantic judgment, not a structural one, and belongs in a separate contrast-checking function, not folded in here.

Callable standalone while developing a new theme (before ever calling render_onepager()), or from another onepagr function or your own test suite that wants to validate a theme up front; nothing about it is tied to a particular call site.

Examples

if (FALSE) { # \dontrun{
# Needs Quarto (bundling Typst) on the system: see check_quarto().
check_theme("uk")
check_theme("default")
} # }