Figma's agent can read guidelines you attach to a published library. Open beta, on Professional, Organization, and Enterprise. You upload markdown: rules, best practices, anti-patterns. When someone prompts with that library on, those files go to the agent in the background.
The lines I would write first are the ones you are tired of saying. Do not detach this. Do not ship the raw hex. This pattern is for the marketing site. The app uses the other one.
We already measured the repo version
An instruction file, AGENTS.md, tied to a +26.1 point lift on open-design-system-bench, across 898 graded generations and four systems. Figma guidelines are a different file, in a different product. I would still write the same rules in both places. Two documents that disagree teach the agent two buttons.
Shorter files cost less. Figma says a prompt can use more AI credits when the library includes guidelines, because that extra context is part of the call. A novel no one maintains is an expensive way to confuse the agent.
If you are outside the code-sources beta, the guidelines file can carry the real prop names this month. Code sources can enforce the list later. The file is the part you can finish before Q1.
I checked the Figma release notes and the Config India 2026 help article on 18 Oct 2026. Plans, betas, and the 4 Nov credit window come from those pages. If your admin console disagrees, trust the console.