@modoki/engine / index / StoreHook

Type Alias: StoreHook

StoreHook = () => Record<string, unknown>

Extra store-hook registry for the default game UI layer.

A game registers a React hook via addStoreHook() so its store-derived fields become available to UI bindings (the host's DefaultGameUILayer calls every registered hook and merges the results into storeState).

This lives in the ENGINE (not the app) so game code — including external projects that can't reach into the editor's app/ folder — registers its hooks through the public @modoki/engine/runtime API:

 import { addStoreHook } from '@modoki/engine/runtime';

Each hook MUST be shallow-stable (e.g. return useShallow(selector)) so the assembled storeState keeps referential equality between renders when no bound field changed.

Rules of Hooks: the number of hooks called per render must stay constant. Mutating the registry bumps a version so the consuming layer can remount with the new fixed hook count — subscribeHooksVersion / getHooksVersion back a useSyncExternalStore on the host side.

LIFECYCLE (F9): APP-LIFETIME, NOT scene-scoped — do NOT auto-clear on world swap. Games register their hook ONCE in setup.ts (e.g. chess, llm-test) with no paired removeStoreHook, expecting it to persist for the whole session; resetting on a scene swap would silently drop them on the first scene change and never re-add them. Owners that DO have a teardown (e.g. a per-scene manager) must call removeStoreHook themselves — removal is by hook identity, so it only drops that owner's own hook.

Returns

Record<string, unknown>