A token name nothing declares
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Rule · bucket: mechanical · severity: error · detector: undeclared-token · since: v0.10.0
Section: Things to avoid
Group: Code-level

Forbidden:
  `font-family: var(--font-body)`, `padding: var(--space-lg)` — in a project whose token layer declares neither

Instead:
  Use the names the token layer declares — `02-tokens.md` lists them, and the token files in the project are the source. If the value you need has no token, that is a finding to report or a value to delete (`H-47`), never a name to make up.

The browser does not warn. A `var()` that cannot resolve makes its whole declaration invalid, so the property falls back to its initial value: the font becomes the browser default serif, padding becomes 0, the border disappears. The page still renders, the source still looks tokenised, and every file-based review passes it. In a live run three of four pages invented their token names this way and shipped mostly unstyled.
`jig check` reads every custom property the project declares — the token layer, its own stylesheets, a Tailwind `@theme`, `style` attributes — and reports each reference to one that is not there. A reference with a fallback, `var(--x, 1rem)`, resolves, and is not reported.