@types/react 19.2.18

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:npm/%40types/react@19.2.18
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40types/react@19.2.18

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:ebaa3562fa246b6a1097b2abb099599cb48305ff5d92f435d42c7dab8f632ec9","contract":["package manifest specifies index.d.ts type declarations, ts5.0 typesVersions fallback, and MIT license","declares useActionState hook signatures supporting synchronous and asynchronous action handlers with optional payload","declares useOptimistic hook signatures with optional state reducer for optimistic UI updates","declares use hook and Usable union type supporting ReactPromise and Context unwrapping","declares Activity component and ActivityProps interface for offscreen and activity boundary rendering","declares cache function and cacheSignal API for per-request memoization and signal tracking"],"goal":"verify pkg:npm/%40types/react@19.2.18","kind":"HOW","packages":["pkg:npm/%40types/react@19.2.18"],"schemaVersion":1},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40types/react@19.2.18"],"schemaVersion":1,"subject":"pkg:npm/%40types/react@19.2.18","verifierAdapter":"node-typescript@1"}

{
  "name": "sample-types-react",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-types-react",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@types/react": "19.2.18"
      }
    },
    "node_modules/@types/react": {
      "version": "19.2.18",
      "resolved": "https://registry.npmjs.org/@types/react/-/react-19.2.18.tgz",
      "integrity": "sha512-AnzbBERsrLKtk2XSfTbYRLjQPdy116Sty4q+T+Bp3IC4l6jNBvreVPAHmpq9qhXQM7CXZPjLVmGMw9sy+hxQ3w==",
      "license": "MIT",
      "dependencies": {
        "csstype": "^3.2.2"
      }
    },
    "node_modules/csstype": {
      "version": "3.2.3",
      "resolved": "https://registry.npmjs.org/csstype/-/csstype-3.2.3.tgz",
      "integrity": "sha512-z1HGKcYy2xA8AGQfwrn0PAy+PB7X/GSj3UVJW9qKyn43xWa+gl5nXmU4qqLMRzWVLFC8KusUX8T/0kCiOYpAIQ==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-types-react",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "@types/react": "19.2.18"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40types/react@19.2.18",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40types/react@19.2.18"
  ]
}

import assert from 'node:assert/strict';
import { createRequire } from 'node:module';
import fs from 'node:fs';
import path from 'node:path';

const require = createRequire(import.meta.url);

// 1. Resolve @types/react package manifest and verify declaration entry points and metadata
const pkgPath = require.resolve('@types/react/package.json');
const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));

assert.equal(pkg.name, '@types/react', 'Package name must be @types/react');
assert.equal(pkg.version, '19.2.18', 'Package version must be 19.2.18');
assert.equal(pkg.types, 'index.d.ts', 'Package types entry must point to index.d.ts');
assert.equal(pkg.license, 'MIT', 'Package license must be MIT');
assert.ok(pkg.typesVersions && pkg.typesVersions['<=5.0'], 'Package must declare typesVersions for TypeScript <= 5.0');
assert.deepEqual(pkg.typesVersions['<=5.0']['*'], ['ts5.0/*'], 'typesVersions <=5.0 fallback path must point to ts5.0/*');

const typesDir = path.dirname(pkgPath);
const indexDts = fs.readFileSync(path.join(typesDir, 'index.d.ts'), 'utf8');

// 2. Verify useActionState hook signatures
assert.ok(
  indexDts.includes('export function useActionState<State>(') &&
  indexDts.includes('action: (state: Awaited<State>) => State | Promise<State>,') &&
  indexDts.includes('initialState: Awaited<State>,') &&
  indexDts.includes('): [state: Awaited<State>, dispatch: () => void, isPending: boolean];'),
  'index.d.ts must declare unary useActionState hook signature'
);

assert.ok(
  indexDts.includes('export function useActionState<State, Payload>(') &&
  indexDts.includes('action: (state: Awaited<State>, payload: Payload) => State | Promise<State>,') &&
  indexDts.includes('): [state: Awaited<State>, dispatch: (payload: Payload) => void, isPending: boolean];'),
  'index.d.ts must declare parameterized useActionState hook signature with payload'
);

// 3. Verify useOptimistic hook signatures
assert.ok(
  indexDts.includes('export function useOptimistic<State>(') &&
  indexDts.includes('passthrough: State,') &&
  indexDts.includes('): [State, (action: State | ((pendingState: State) => State)) => void];'),
  'index.d.ts must declare single-argument useOptimistic hook signature'
);

assert.ok(
  indexDts.includes('export function useOptimistic<State, Action>(') &&
  indexDts.includes('reducer: (state: State, action: Action) => State,') &&
  indexDts.includes('): [State, (action: Action) => void];'),
  'index.d.ts must declare reducer-based useOptimistic hook signature'
);

// 4. Verify use hook and Usable / ReactPromise union types
assert.ok(
  indexDts.includes('export type Usable<T> = ReactPromise<T> | Context<T> | RendererUsable<T>[keyof RendererUsable<T>];') &&
  indexDts.includes('export function use<T>(usable: Usable<T>): T;') &&
  indexDts.includes('export type ReactPromise<T> =') &&
  indexDts.includes('| PendingReactPromise<T>') &&
  indexDts.includes('| FulfilledReactPromise<T>') &&
  indexDts.includes('| RejectedReactPromise<T>;'),
  'index.d.ts must declare use hook function and Usable/ReactPromise type definitions'
);

// 5. Verify Activity component and ActivityProps interface
assert.ok(
  indexDts.includes('export interface ActivityProps {') &&
  indexDts.includes('mode?:') &&
  indexDts.includes('| "hidden"') &&
  indexDts.includes('| "visible"') &&
  indexDts.includes('name?: string | undefined;') &&
  indexDts.includes('children: ReactNode;') &&
  indexDts.includes('export const Activity: ExoticComponent<ActivityProps>;'),
  'index.d.ts must declare Activity component and ActivityProps interface'
);

// 6. Verify cache function and cacheSignal API
assert.ok(
  indexDts.includes('export function cache<CachedFunction extends Function>(fn: CachedFunction): CachedFunction;') &&
  indexDts.includes('export interface CacheSignal {}') &&
  indexDts.includes('export function cacheSignal(): null | CacheSignal;'),
  'index.d.ts must declare cache function and cacheSignal API'
);

console.log('Contract tests passed successfully.');