react-19-primitives

Sub-skill of react. Owns the React-19-only hooks and the <Suspense> API surface — what each one accepts, what it returns, what it suspends, and when to reach for it. The dean-stack-specific wiring of <Suspense> + use(idbHydrationPromise) at the app shell is owned by idb (which produces the promise and the Suspense pattern); this skill just describes the API the integration uses.

When to invoke

• Reading a value out of a promise inside render — use(promise).
• Splitting an update into urgent + non-urgent parts — useTransition, useDeferredValue.
• Showing an instant UI update before the real mutation lands — useOptimistic.
• Wiring a form action and reading its pending/result state — useActionState, useFormStatus.
• Authoring or moving a <Suspense> boundary that isn't the dean-stack root one (which idb owns — it produces idbHydrationPromise and the Suspense wiring at the app shell).

Owns

React 19 primitives encouraged by the stack: use(promise), useTransition, useDeferredValue, useOptimistic, useActionState, useFormStatus, and <Suspense> boundaries.

Defers to

• react (parent) — version pin and routing.
• react-compiler-rules — for "no useMemo around a use(promise) read"; the Compiler memoizes already.
• idb — for the dean-stack root <Suspense> + use(idbHydrationPromise) integration. This skill describes what use(promise) does; idb owns the promise itself, the Suspense pattern at the app shell, the debounced write-through, and the BroadcastChannel re-hydration.
• jotai — for the atomWithIDB factory contract that consumes the hydrated state once use(idbHydrationPromise) resolves.
• tanstack-router-routing — for <Suspense> boundaries inside route components / loaders.