@blackevin/client

The Blackevin SDK: connect, subscribe to channels, publish, and read presence.

import * as Blackevin from "@blackevin/client";

const realtime = new Blackevin.Realtime({ key: "…", clientId: "bob" });
const channel = realtime.channels.get("chat:lobby");

channel.subscribe((message) => console.log(message.data));
await channel.publish("hello", { text: "hi" });

channel.presence.subscribe(["enter", "leave", "update"], async () => {
  console.log("Members:", await channel.presence.get());
});

Browser and Node. Authentication is by publishable key or by a short-lived token your server signs, so an API key secret never reaches a browser.

Where it connects

Nothing to configure: new Blackevin.Realtime({ key }) talks to Blackevin.

endpoint is there for when you need something else — a self-hosted node, a local dev node, a staging environment. It resolves in this order:

1. the endpoint option
2. BLACKEVIN_ENDPOINT, where an environment exists (Node, Bun, Deno)
3. wss://ws.blackevin.com

restEndpoint follows the same order with BLACKEVIN_REST_ENDPOINT, except that an explicitly-given endpoint implies it — a dev or self-hosted node serves both from one origin, so ws://127.0.0.1:3000 yields http://127.0.0.1:3000. Only the default falls through to https://api.blackevin.com, because in production the socket and the API are separate services and swapping the scheme would send REST calls to a host that serves none.

Step 2 needs an actual environment, so it covers Node, Bun and Deno. A browser bundle has none at runtime — if a web app wants to point somewhere else per build, it reads its own env and passes the result:

new Blackevin.Realtime({
  endpoint: import.meta.env.VITE_BLACKEVIN_WS, // unset in prod → the default
  key,
});

Everything exported is public API — see CLAUDE.md before changing a signature.