Write a rule. Hardline compiles it into a real logic chip, proves it's correct for every possible case, and mints it on X Layer through TapeOut. Any contract, vault or AI agent can then ask the chip "is this allowed?", and that answer can never be quietly edited.
Yes/no facts your app gives the chip, e.g. "Signer 1 approved".
Your proven chip is taped out through TapeOut on X Layer. After that nobody can edit it, including you. Any contract calls eval(chipId, facts) and gets ALLOW or DENY.
A vault on X Layer that holds OKB. It never decides by itself: before any payment it builds the facts from onchain state (who approved, is it frozen) and asks the chip. Only ALLOW moves money.