Documentation

Guard the actions your agents can't take back.

Arc is the guardrail between your AI agents and production. Define what an action is allowed to do, hold the risky ones for a human, and let the rest run only as a signed request your own app verifies — with a spend cap so a loop can't quietly burn the budget. These docs take you from npm install to a blocked over-budget action in five minutes.

Start the quickstart → What is Arc?

Free to start — run the local Arc stack and guard your first action.

src/actions.ts @geostack/arc

// one action, one decision
export const actions = arc.defineActions({
  issue_refund: {
    risk: "high",
    defaultDecision: "ask",  // hold for a human
  },
});

read_invoice allow

issue_refund ask

delete_account block

Start here

Zero to a blocked agent action. The quickstart is the fastest path — it takes you from npm install to a blocked over-budget action against a local Arc server.

Concepts

One quotable explainer per primitive. The glossary defines them; the product walk-through shows each in the flow.

Guides

Task-oriented and copy-paste. Each step in the quickstart ends with something working.