@tybys/wasm-util 0.10.2: Memory, extendMemory, loadSync

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/%40tybys/wasm-util@0.10.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40tybys/wasm-util@0.10.2
Demonstrate these symbols/APIs:
  - Memory
  - extendMemory
  - loadSync

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:sha256:7ae91db174fb232f64638d7ce8ac68d55a653617c89652dfbd8fb8dc21842e58","contract":["loadSync instantiates a WebAssembly binary synchronously from a Uint8Array buffer","extendMemory upgrades a standard WebAssembly.Memory instance to provide typed array getters","Memory instance provides HEAPU8 and DataView access reflecting underlying memory mutations","instantiated WebAssembly module executes exported arithmetic functions correctly","extendMemory is idempotent when called multiple times on the same memory instance"],"goal":"verify pkg:npm/%40tybys/wasm-util@0.10.2","kind":"HOW","packages":["pkg:npm/%40tybys/wasm-util@0.10.2"],"schemaVersion":1,"symbols":["Memory","extendMemory","loadSync"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40tybys/wasm-util@0.10.2"],"schemaVersion":1,"subject":"pkg:npm/%40tybys/wasm-util@0.10.2","symbols":["Memory","extendMemory","loadSync"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-tybys-wasm-util",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-tybys-wasm-util",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@tybys/wasm-util": "0.10.2"
      }
    },
    "node_modules/@tybys/wasm-util": {
      "version": "0.10.2",
      "resolved": "https://registry.npmjs.org/@tybys/wasm-util/-/wasm-util-0.10.2.tgz",
      "integrity": "sha512-RoBvJ2X0wuKlWFIjrwffGw1IqZHKQqzIchKaadZZfnNpsAYp2mM0h36JtPCjNDAHGgYez/15uMBpfGwchhiMgg==",
      "license": "MIT",
      "dependencies": {
        "tslib": "^2.4.0"
      }
    },
    "node_modules/tslib": {
      "version": "2.8.1",
      "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
      "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
      "license": "0BSD"
    }
  }
}

{
  "name": "sample-tybys-wasm-util",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "description": "verify pkg:npm/%40tybys/wasm-util@0.10.2",
  "main": "src/index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@tybys/wasm-util": "0.10.2"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40tybys/wasm-util@0.10.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40tybys/wasm-util@0.10.2"
  ],
  "symbols": [
    "Memory",
    "extendMemory",
    "loadSync"
  ]
}

import { Memory, extendMemory, loadSync } from '@tybys/wasm-util';

export const ADD_WASM_BYTES = new Uint8Array([
  0x00, 0x61, 0x73, 0x6d,
  0x01, 0x00, 0x00, 0x00,
  0x01, 0x07, 0x01, 0x60, 0x02, 0x7f, 0x7f, 0x01, 0x7f,
  0x03, 0x02, 0x01, 0x00,
  0x07, 0x07, 0x01, 0x03, 0x61, 0x64, 0x64, 0x00, 0x00,
  0x0a, 0x09, 0x01, 0x07, 0x00, 0x20, 0x00, 0x20, 0x01, 0x6a, 0x0b
]);

export function createExtendedMemory(descriptor = { initial: 1 }) {
  const mem = new WebAssembly.Memory(descriptor);
  return extendMemory(mem);
}

export function loadModuleSync(bufferSource, imports) {
  return loadSync(bufferSource, imports);
}

export function createAddModule() {
  return loadSync(ADD_WASM_BYTES);
}

export { Memory, extendMemory, loadSync };

import assert from 'node:assert';
import {
  Memory,
  extendMemory,
  loadSync,
  ADD_WASM_BYTES,
  createExtendedMemory,
  loadModuleSync,
  createAddModule
} from '../src/index.mjs';

// 1. loadSync instantiates a WebAssembly binary synchronously from a Uint8Array buffer
const { instance, module } = loadSync(ADD_WASM_BYTES);
assert(instance instanceof WebAssembly.Instance, 'instance should be a WebAssembly.Instance');
assert(module instanceof WebAssembly.Module, 'module should be a WebAssembly.Module');

const helperLoaded = loadModuleSync(ADD_WASM_BYTES);
assert(helperLoaded.instance instanceof WebAssembly.Instance, 'helper loadModuleSync returns an instance');

// 2. extendMemory upgrades a standard WebAssembly.Memory instance to provide typed array getters
const rawMem = new WebAssembly.Memory({ initial: 1 });
const extended = extendMemory(rawMem);
assert.strictEqual(extended, rawMem, 'extendMemory modifies and returns the same memory instance');
assert(extended instanceof Memory, 'extended memory should inherit from Memory');
assert(extended.HEAPU8 instanceof Uint8Array, 'HEAPU8 should be a Uint8Array view');
assert(extended.HEAP32 instanceof Int32Array, 'HEAP32 should be an Int32Array view');
assert(extended.view instanceof DataView, 'view should be a DataView');

const helperMem = createExtendedMemory({ initial: 2 });
assert(helperMem instanceof Memory, 'createExtendedMemory returns Memory instance');
assert.strictEqual(helperMem.HEAPU8.length, 131072, '2 pages should equal 131072 bytes');

// 3. Memory instance provides HEAPU8 and DataView access reflecting underlying memory mutations
extended.HEAPU8[0] = 0xef;
extended.HEAPU8[1] = 0xbe;
extended.HEAPU8[2] = 0xad;
extended.HEAPU8[3] = 0xde;
assert.strictEqual(extended.view.getUint32(0, true), 0xdeadbeef, 'DataView should reflect byte mutations');
assert.strictEqual(extended.HEAP32[0], -559038737, 'HEAP32 should reflect 32-bit integer value');

// 4. instantiated WebAssembly module executes exported arithmetic functions correctly
assert.strictEqual(typeof instance.exports.add, 'function', 'add export should be a callable function');
assert.strictEqual(instance.exports.add(15, 27), 42, 'add(15, 27) should equal 42');

const addModule = createAddModule();
assert.strictEqual(addModule.instance.exports.add(100, 250), 350, 'createAddModule helper executes add correctly');

// 5. extendMemory is idempotent when called multiple times on the same memory instance
const reExtended = extendMemory(extended);
assert.strictEqual(reExtended, extended, 'Calling extendMemory again returns the same instance');
assert(reExtended instanceof Memory, 're-extended instance remains an instance of Memory');

console.log('Contract tests passed successfully.');
process.exit(0);