@abeyjs/state

Minimal observable value holder: StateCell<T> stores a single value, notifies subscribers on change, and supports functional updates. It is intentionally tiny so views and agents can share UI-facing state without pulling in a full external store.

Uses Object.is to skip no-op writes (same reference or primitive value).

API

StateCell<T>

| Method | Behaviour | |--------|-----------| | get() | Current snapshot. | | set(next) | Replace with next, or resolve next(prev) when **next is a function. No-op if Object.is(resolved, prev). | | update(fn) | Alias for set(fn) with an updater only (clearer at call sites). | | subscribe(listener) | listener() runs after every effective set; returns Unsubscribe (@abeyjs/core). |

Subscriptions are synchronous on set: listeners run in insertion order (Set iteration order in V8). No batching or async scheduling — if you need that, wrap or debounce in the subscriber.

Threading: single-threaded JS; not safe to share one cell across workers without a bridge.

Typical use

• View models passed into @abeyjs/view helpers that call cell.subscribe(() => render…).
• Agents exposing viewState as StateCell (see DynamicCrudAgent in @abeyjs/openapi).

Dependency

@abeyjs/core — Unsubscribe type only.

Build

npm run build -w @abeyjs/state