Semantic colours invented inline

Every ratio in this section is WCAG 2.1, and that is deliberate — but it is not the whole picture. WCAG 2.1 AA is what these rules enforce and what check fails a build on, because it is what is legally referenced. APCA (the WCAG 3 draft) measures perceptually and scores by size and weight rather than a flat ratio; 02-tokens.md carries its threshold table, and it is worth checking as well, particularly on dark surfaces where WCAG 2's algorithm is weakest.

Two places the difference bites:

• WCAG 2.1 exempts disabled controls entirely, so nothing in this section constrains how faint a disabled label may be. APCA does — Lc 30 is its absolute minimum for disabled button text — and it is the only standard that says anything at all here. --opacity-disabled is held to it.
• The two do not agree on what counts as large text. APCA's thresholds are its own and do not line up with C-17. Each is right inside its own frame; do not mix a score from one with a size rule from the other.

Aim to pass both. Where only one of them has an opinion, that one decides.