@lite-fsm/core

Framework-agnostic runtime for lite-fsm: typed machine configs, MachineManager, effects, actor templates, snapshots, hydration, middleware contracts, and core TypeScript types.

Use this package when you want the FSM runtime without React or any UI dependency.

Install

npm install @lite-fsm/core

For Immer-style reducers that mutate draft state, also install middleware:

npm install @lite-fsm/middleware immer

Quick Example

import { MachineManager, createMachine, type FSMEvent } from "@lite-fsm/core";

type ToggleEvent = FSMEvent<"TOGGLE"> | FSMEvent<"RESET">;

const toggle = createMachine<ToggleEvent>({
  config: {
    OFF: { TOGGLE: "ON", RESET: "OFF" },
    ON: { TOGGLE: "OFF", RESET: "OFF" },
  },
  initialState: "OFF",
  initialContext: { count: 0 },
  reducer: (slice, event, { nextState }) => ({
    state: nextState,
    context: {
      count: event.type === "RESET" ? 0 : slice.context.count + 1,
    },
  }),
});

const manager = MachineManager({ toggle });

manager.transition({ type: "TOGGLE" });

console.log(manager.getState().toggle);
// { state: "ON", context: { count: 1 } }

Main Exports

• createMachine - typed machine config factory.
• MachineManager - runtime store for coordinating multiple machines.
• createEffect - effect wrapper with every or latest semantics.
• createConfig and createReducer - helpers for reusable typed config and reducer definitions.
• Machine and defineMachine - standalone machine APIs.
• Snapshot and hydration types for dehydrate() / hydrate() workflows.
• Middleware, actor, event, state, and manager types.

Documentation

• Full documentation
• Core package guide
• Core API reference