Installation
Add @sigx/reactivity to your project.
Install the package
pnpm add @sigx/reactivity@sigx/reactivity has no peers of its own. In a web app you rarely add it directly — sigx depends on it and re-exports its API. A library that uses it declares it as a peer ("@sigx/reactivity": "^1.0.0" under peerDependencies) so it resolves to the app's copy; see the install shape.
One copy per page
The tracking context lives in this module, so an app must hold exactly one copy of it: signals written through a second copy never reach effects tracked by the first. A second copy evaluating in the same realm — two installed versions, a bundler that inlined one — throws in development with both versions and both module URLs, and warns once in production:
[sigx] Two copies of @sigx/reactivity are loaded: 0.15.0 at file:///…/.pnpm/…/dist/index.js and 1.0.0 at file:///…/@sigx/reactivity/dist/index.js.The fix is on the install side: install sigx once in the app and keep every @sigx/* library a peer of it, so there is one copy to resolve to. Two @sigx/reactivity entries in the lockfile are the thing to look for. See Stability & versioning.
Verify
import * as Reactivity from '@sigx/reactivity';
console.log(Object.keys(Reactivity));