preact-sigma

Purpose

preact-sigma is a typed state-model builder for Preact and TypeScript. It keeps top-level public state reactive, derived reads local to the model, writes explicit through actions, and side effects owned by explicit setup.

Installation

npm install preact-sigma @preact/signals immer preact

Quick Example

import { SigmaType } from "preact-sigma";

const Counter = new SigmaType<{ count: number }>("Counter")
  .defaultState({
    count: 0,
  })
  .computed({
    doubled() {
      return this.count * 2;
    },
  })
  .actions({
    increment() {
      this.count += 1;
    },
  });

const counter = new Counter();

counter.increment();

console.log(counter.count); // 1
console.log(counter.doubled); // 2

Documentation Map

• Concepts, lifecycle, invariants, and API selection live in docs/context.md.
• Persistence-specific guidance lives in docs/persist.md.
• Runnable usage patterns live in examples/, starting with examples/basic-counter.ts and examples/command-palette.tsx.
• Exact exported signatures live in dist/*.d.mts after pnpm build.