Quickstart

In this guide, you will protect a function with Actra and block unsafe execution before it runs.

The example below blocks refunds above 1000.

---

1) Define a Schema

The schema describes the data Actra understands.

version: 1

actions:
  refund:
    fields:
      amount: number

actor:
  fields:
    role: string

snapshot:
  fields:
    fraud_flag: boolean

---

2) Define a Policy

This policy blocks refunds greater than 1000.

version: 1

rules:
  - id: block_large_refund
    scope:
      action: refund
    when:
      subject:
        domain: action
        field: amount
      operator: greater_than
      value:
        literal: 1000
    effect: block

---

3) Compile and Create Runtime

JavaScript

import {
  Actra,
  ActraRuntime,
  ActraPolicyError
} from "@getactra/actra";

const policy = await Actra.fromStrings(schemaYaml, policyYaml);
const runtime = new ActraRuntime(policy);

runtime.setActorResolver(() => ({ role: "support" }));
runtime.setSnapshotResolver(() => ({ fraud_flag: false }));

function refund(amount: number) {
  console.log("Refund executed:", amount);
  return amount;
}

const protectedRefund = runtime.admit("refund", refund);

await protectedRefund(200);   // allowed
await protectedRefund(1500);  // blocked

Python

from actra import Actra, ActraPolicyError
from actra.runtime import ActraRuntime

policy = Actra.from_strings(schema_yaml, policy_yaml)
runtime = ActraRuntime(policy)

runtime.set_actor_resolver(lambda ctx: {"role": "support"})
runtime.set_snapshot_resolver(lambda ctx: {"fraud_flag": False})

@runtime.admit()
def refund(amount: int):
    print("Refund executed:", amount)

refund(amount=200)   # allowed

try:
    refund(amount=1500)  # blocked
except ActraPolicyError as e:
    print("Refund blocked by policy")
    print("Rule:", e.matched_rule)

---

Expected Result

Refunds below 1000 execute normally.

Refunds above 1000 are blocked before execution.

---

Next Steps

• Learn how policies work in First Policy
• Understand DSL blocks in Schema and Policy
• Explore actor and snapshot resolution