Getting started — dvar Documentation

dvar documentation

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Dvar is a policy firewall for AI agents. It evaluates tool actions before side effects occur and returns a deterministic allow, deny, or require_approval decision.

Dvar complements application authorization, IAM, sandboxing, secrets management, database permissions, and network policy. It does not replace those controls, and it only protects actions that pass through its interception boundary.

Status

The current release is pre-stable. Review package release notes before upgrading and test policy behaviour before enabling enforcement in production.

Install

bash

npm install @rokadhq/dvar

Initialize a policy

bash

npx dvar init
npx dvar validate
npx dvar test-policy

The generated policy starts in monitor mode. Monitor mode allows actions to execute while recording the decision Dvar would have enforced.

Protect a tool

import { createDvar } from "@rokadhq/dvar";

const dvar = await createDvar({ policyPath: "dvar.yaml" });

const readCustomer = dvar.protectTool({
  name: "crm.read_customer",
  capabilities: ["data.read"],
  inputSchema: {
    type: "object",
    additionalProperties: false,
    required: ["customerId"],
    properties: {
      customerId: { type: "string", minLength: 1 },
    },
  },
  execute: async ({ customerId }: { customerId: string }) => ({
    customerId,
    status: "active",
  }),
});

Call the protected tool with execution context:

const customer = await readCustomer(
  { customerId: "customer-1" },
  {
    principal: { id: "user-1", type: "user" },
    agent: { id: "support-agent" },
    tenant: { id: "tenant-a" },
    environment: "production",
  },
);

Operating modes

Mode	Behaviour
`monitor`	Executes the action and records `would_allow`, `would_deny`, or `would_require_approval`.
`enforce`	Blocks denied and approval-gated actions before the executor runs.
`strict`	Applies the strongest configured enforcement behaviour.
`off`	Disables Dvar evaluation for the configured boundary.

Current capabilities

Declarative YAML and JSON policies
Deterministic precedence
Generic JavaScript and TypeScript tool wrappers
JSON Schema argument validation
Stable reason codes
Privacy-conscious audit events
Embedded policy tests
JSONL replay that never invokes tools
CLI commands for initialization, validation, diagnostics, testing, replay, and version inspection

Production rollout

Define the tools and capabilities that cross the Dvar boundary.
Start in monitor mode.
Review audit events and policy-test results.
Correct unexpected decisions before enforcement.
Enable enforcement gradually for high-risk actions.
Keep application authorization, IAM, sandboxing, secrets, and infrastructure policy in place.