@directive-run/react

React hooks for Directive. Built on useSyncExternalStore for tear-free reads with concurrent rendering support.

Install

npm install @directive-run/core @directive-run/react

Quick Start

Define a module in a shared file, then use it in any component:

// system.ts
import { createModule, createSystem, t } from "@directive-run/core";

const counter = createModule("counter", {
  schema: {
    facts: { count: t.number() },
    derivations: { doubled: t.number() },
    events: { increment: {}, decrement: {} },
    requirements: {},
  },
  init: (facts) => {
    facts.count = 0;
  },
  derive: {
    doubled: (facts) => facts.count * 2,
  },
  events: {
    increment: (facts) => { facts.count += 1; },
    decrement: (facts) => { facts.count -= 1; },
  },
});

export const system = createSystem({ module: counter });
system.start();

// Counter.tsx
import { useFact, useDerived, useEvents } from "@directive-run/react";
import { system } from "./system";

export function Counter() {
  const count = useFact(system, "count");
  const doubled = useDerived(system, "doubled");
  const events = useEvents(system);

  return (
    <div>
      <p>Count: {count} (doubled: {doubled})</p>
      <button onClick={() => events.increment()}>+</button>
      <button onClick={() => events.decrement()}>&minus;</button>
    </div>
  );
}

useSelector

Auto-tracking selector over facts and derivations. Subscribes only to the keys your selector reads:

import { useSelector } from "@directive-run/react";
import { system } from "./system";

function Summary() {
  const label = useSelector(system, (state) => {
    return state.count > 10 ? "High" : "Low";
  });

  return <span>{label}</span>;
}

API Reference

Core Hooks

| Hook | Return Type | Description | |------|------------|-------------| | useFact(system, key) | T \| undefined | Subscribe to a single fact value | | useFact(system, [keys]) | Pick<Facts, K> | Subscribe to multiple facts | | useDerived(system, key) | T | Subscribe to a single derivation | | useDerived(system, [keys]) | Pick<Derivations, K> | Subscribe to multiple derivations | | useSelector(system, fn) | R | Auto-tracking selector with optional equality function | | useEvents(system) | Events | Memoized events dispatcher | | useDispatch(system) | (event) => void | Low-level dispatch function |

Advanced Hooks

| Hook | Return Type | Description | |------|------------|-------------| | useWatch(system, key, cb) | void | Side-effect on fact or derivation change (no re-render) | | useInspect(system) | InspectState | Consolidated system state (isSettled, unmet, inflight) | | useRequirementStatus(plugin, type) | RequirementTypeStatus | Requirement loading/error state | | useExplain(system, reqId) | string \| null | Human-readable requirement explanation | | useConstraintStatus(system) | ConstraintInfo[] | All constraint states | | useOptimisticUpdate(system) | { mutate, isPending, error, rollback } | Optimistic mutation with auto-rollback | | useHistory(system) | HistoryState \| null | Undo/redo navigation |

React-Specific

| Export | Description | |--------|-------------| | useDirective(module, options?) | Scoped system with selected facts/derivations | | useDirectiveRef(module) | Scoped system lifecycle (start on mount, destroy on unmount) | | useSuspenseRequirement(plugin, type) | Suspense-compatible requirement status | | useHydratedSystem(module) | Client-side system hydrated from server snapshot | | DirectiveHydrator | SSR/RSC snapshot provider | | shallowEqual | Shallow equality helper for selectors |

Peer Dependencies

• react >= 18
• @directive-run/core

Documentation

• React Adapter Guide
• API Reference

License

MIT