Authentication

Fabric authenticates with a single secret key. You pass it once to the SDK; the SDK attaches it to every request and picks the right environment from it. There is no separate environment parameter and nothing to set per call.

Give the SDK your key

import { Fabric } from "@fabric-messaging/sdk";

const fabric = new Fabric({ apiKey: process.env.FABRIC_API_KEY! });

The key is read from a server-side environment variable and never appears in your code. A key is scoped to one application environment.

The prefix selects the environment

Prefix	`fabric.environment`	Behaviour
`sk_test_`	`sandbox`	Virtual delivery, no real charge.
`sk_live_`	`live`	Real provider delivery, funded wallet required.

The SDK reads the prefix and rejects any other secret-key format with an error before it makes a network request, so a malformed or mis-pasted key fails fast and locally.

const fabric = new Fabric({ apiKey: process.env.FABRIC_API_KEY! });
console.log(fabric.environment); // "sandbox" or "live"

Server-only, by construction

The SDK refuses to run in a browser — constructing it where window and document exist throws. Fabric keys are full-power secrets: never ship one in client JavaScript, a mobile app, a public repository, a log line, or a PUBLIC_-prefixed environment variable. Call Fabric from a trusted server, and if a key may have leaked, revoke it immediately.

Base URL

The SDK targets the correct Fabric endpoint automatically. The baseUrl option is reserved for loopback and private testing only — it must be HTTPS unless it points at localhost, 127.0.0.1, or [::1]. You do not set a base URL for normal use.