Installation

Install the portable core, add one host for where your sessions connect, and pin Effect to the release candidate the SDK is built on.

Which packages

Package	What it holds	Runs on
`reactor-effect-client`	`Reactor`, `Session` and `CoordinatorClient`, the `H3` provider, `Playout` with its sources, and `ReactorTest`	Node, Bun and browsers
`reactor-effect-browser`	`BrowserPeer` on the browser’s `RTCPeerConnection`, and `BrowserMedia` to play the session’s tracks	Browsers
`reactor-effect-native`	`NativePeer` on a Node-API addon over Reactor’s `reactor-webrtc` crate (libwebrtc): decoded BGRA frames and 16-bit PCM, in process or in a child process (Node)	Node and Bun, on Linux x64 (glibc) and macOS arm64

Every application installs the client. Then pick a host for where sessions connect:

Tests and offline runs need no host. ReactorTest.layer provides the HTTP client and the peers, so nothing touches the network.
A page that runs its own session adds reactor-effect-browser.
A server or command line that reads frames adds reactor-effect-native.

The packages share one version and are released together. This site follows the repository’s main branch; check npm for the latest published version. The host packages peer on reactor-effect-client at exactly their own version, so install them at the same version.

Install

# The core, which is all tests and offline runs need
npm install --save-exact reactor-effect-client effect@4.0.0-rc.117

# A page that runs its own session
npm install --save-exact reactor-effect-browser

# Node or Bun with decoded frames
npm install --save-exact reactor-effect-native @effect/platform-node@4.0.0-rc.117

# The core, which is all tests and offline runs need
bun add --exact reactor-effect-client effect@4.0.0-rc.117

# A page that runs its own session
bun add --exact reactor-effect-browser

# Node or Bun with decoded frames
bun add --exact reactor-effect-native @effect/platform-node@4.0.0-rc.117

# The core, which is all tests and offline runs need
pnpm add --save-exact reactor-effect-client effect@4.0.0-rc.117

# A page that runs its own session
pnpm add --save-exact reactor-effect-browser

# Node or Bun with decoded frames
pnpm add --save-exact reactor-effect-native @effect/platform-node@4.0.0-rc.117

For tests, add @effect/vitest@4.0.0-rc.117 and vitest 5 as development dependencies. See Test offline.

Modules are flat. Import one by its subpath, or all of them as namespaces from the root:

import * as Playout from "reactor-effect-client/Playout";
import { H3, Reactor, ReactorTest } from "reactor-effect-client";

Subpath imports resolve through the packages’ export maps, so TypeScript needs moduleResolution set to NodeNext or Bundler.

The packages are ES modules only. A Node project runs them from "type": "module", which npm 11’s npm init does not set (it writes "commonjs"): run npm pkg set type=module, or name your files .mts.

The native addon

reactor-effect-native lists one addon package per platform as an exact-version optional dependency, and the package manager installs only the one the host can run:

Platform package	Host
`reactor-effect-native-linux-x64-gnu`	Linux x64 with glibc
`reactor-effect-native-darwin-arm64`	macOS on Apple silicon, macOS 13.0 or later

The addon is prebuilt, so no Rust toolchain is needed. On Linux x64, npm install reactor-effect-native@0.9.0 fetched only the Linux package (an 18.5 MB addon), and NativePeer.layer() then built under Node 24.14 and Bun 1.4.2 (checked 2026-09-30).

Importing reactor-effect-native loads nothing. Building NativePeer.layer() loads the addon, so a host that cannot run it fails there, before any session is allocated: with UnsupportedHost when no platform package is installed (for example after --omit=optional), and with Native when the addon is of another version or cannot load.

The Effect version

Every package peers on Effect 4.0.0-rc.117 exactly. Effect 4 is in release candidates, and a candidate can move modules: 4.0.0-rc.118 moved the effect/unstable/* modules the SDK imports, so a later candidate needs a new SDK release. Install effect and every @effect/* package at exactly 4.0.0-rc.117, with --save-exact as above: under a caret range, a later install without a lockfile takes a later candidate.

Pin `@effect/platform-node-shared`

@effect/platform-node@4.0.0-rc.117 depends on @effect/platform-node-shared with a caret range. npm, Bun and pnpm all resolve that to a later candidate, which fails to load on Effect rc.117 (ERR_MODULE_NOT_FOUND). A project that installs @effect/platform-node pins it in its package.json:

{
  "overrides": {
    "@effect/platform-node-shared": "4.0.0-rc.117"
  }
}

{
  "overrides": {
    "@effect/platform-node-shared": "4.0.0-rc.117"
  }
}

{
  "pnpm": {
    "overrides": {
      "@effect/platform-node-shared": "4.0.0-rc.117"
    }
  }
}

Set it before the first install. Once a lockfile holds the later candidate, delete the lockfile and node_modules and install again. With reactor-effect-native installed, npm alone already resolves the right version through the package’s exact peer; Bun and pnpm still need the override. Checked with npm 11.11, Bun 1.4.2 and pnpm 10.34 on 2026-09-30.

Runtimes

Node 22 or newer. CI runs the portable suites on Node 22.22 and 24.15 on Ubuntu and on Node 24.15 on macOS. Running TypeScript sources directly, as the examples do, needs Node 22.18 or newer.
Bun. CI runs the portable and native suites on Bun 1.4.2 too. The isolated native host, NativePeer.layerIsolated(), needs a Node parent process and refuses to build under Bun.
Browsers with WebRTC (RTCPeerConnection, MediaStream) and Web Crypto, on localhost or HTTPS. BrowserPeer.layer checks for WebRTC when it is built and fails with UnsupportedHost without it.

Quickstart: prompt H3 offline, with no API key.
Going live: the same program on hosted H3.