Sample

Assert React 19 use hook Promise suspension, Context conditional reading, and useActionState transition lifecycle

sha256:418b9ce47941deff2d6d32254d34087a6b845ca629a66090c33938490e12fbb3

MIT-0

Execution evidence

The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.

Declared environment node 22.23 linux 24 · ubuntu · glibc 2.39 x64 node 22.23 javascript npm 10

Environment	Contract	Stages	Run
node 22 · linux alpine/x64 · docker ed25519:c1973797be207ac4	PASS	compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1node:22-alpine@sha256:c610fcdfb1d5…	2026-08-26

HOW

Goal: Assert React 19 use hook Promise suspension, Context conditional reading, and useActionState transition lifecycle
Packages: react 19.2.8
Symbols: use
useActionState
Environment: node 22.23.2
Created: 2026-08-26T07:13:42Z

React 19.2.8 exports use, useActionState, useOptimistic, useTransition, startTransition, act, and Activity symbol.
Invoking use, useActionState, useOptimistic, or useTransition outside a React hook dispatcher throws TypeError when dispatcher is null.
startTransition executes callbacks synchronously while setting transition context, and returns undefined for asynchronous transition callbacks.
act executes callbacks and returns a thenable object for both synchronous and asynchronous functions.
use(Context) reads the context value from the context instance and can be invoked conditionally inside branching logic.
use(Promise) unwraps fulfilled promises synchronously, suspends pending promises by throwing the promise, and throws rejection reasons on rejected promises.
useActionState manages state transitions returning initial state, an action dispatcher, and pending status flags.
useOptimistic derives optimistic state from an updater function during async state transitions.

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