**alien‑signals** is a ultra‑lightweight, high‑performance JavaScript signal library that implements a push‑pull reactivity algorithm (similar to Vue 3, Preact, Svelte, etc.) without using collections or recursion. It provides primitives like `signal`, `computed`, `effect`, and scopes for building fast, framework‑agnostic reactive state, and is used by projects such as Vue core, XState, and various language‑tooling ecosystems. The library is aimed at frontend developers and library authors who need a minimal, fast reactive core for UI state management or custom reactive APIs.