Denied actions fail closed.

The enforce pattern

Every action is gated. On denial, enforceAction throws — the agent never reaches the code that would have executed the action. This is fail closed: on denial, the safe default is to stop rather than proceed.

async function enforceAction(input) {
  const result = await behalf.verify({ agentId, ...input });
  if (!result.allowed) {
    throw new Error(`Action blocked by BehalfID: ${result.reason}`);
  }
  return result;
}

// browse_web is allowed — this proceeds.
await enforceAction({ action: "browse_web", vendor: "web" });
console.log("Researching flights...");

// purchase is denied — this throws. The next line never runs.
await enforceAction({ action: "purchase", vendor: "coachella.com", amount: 742 });
console.log("Booking ticket..."); // ← never reached