Where the foundation earns its keep: the action.

The reusable domain pays off at the one boundary that matters: the moment you let the agent act. Put the agent on the action — the boundary is what makes it safe — so you can hand it the consequential route and rely on what it cannot do.

An agent proposes an action. KIFF checks it against the current state of the thing it touches — is this invoice already paid, is this order already refunded — and lets the legitimate action through, refusing only what the state forbids, before it executes. KIFF decides; your system runs the action. Every decision is recorded as evidence.