@tybys/wasm-util 0.10.2: extendMemory

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 @tybys/wasm-util.extendMemory in 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:
  - @tybys/wasm-util.extendMemory

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:e2a742622b6529577067a69ea727e44488bfa6bc090197c5ebac461277ac138e","contract":["extendMemory upgrades a standard WebAssembly.Memory instance to provide typed array getters","extendMemory returns the exact same WebAssembly.Memory instance reference","Typed array views and DataView reflect shared buffer byte mutations across representations","extendMemory is idempotent when called multiple times on the same memory instance","Typed array views remain accessible and dynamically re-reference the buffer after memory growth"],"goal":"verify @tybys/wasm-util.extendMemory in pkg:npm/%40tybys/wasm-util@0.10.2","kind":"HOW","packages":["pkg:npm/%40tybys/wasm-util@0.10.2"],"schemaVersion":1,"symbols":["@tybys/wasm-util.extendMemory"]},"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":["@tybys/wasm-util.extendMemory"],"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 @tybys/wasm-util.extendMemory in pkg:npm/@tybys/wasm-util@0.10.2",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@tybys/wasm-util": "0.10.2"
  },
  "license": "MIT-0"
}

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

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

export function wrapMemory(wasmMemory) {
  return extendMemory(wasmMemory);
}

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

export function writeUint32(memory, offset, value, littleEndian = true) {
  memory.view.setUint32(offset, value, littleEndian);
}

export function readUint32(memory, offset, littleEndian = true) {
  return memory.view.getUint32(offset, littleEndian);
}

export { extendMemory, Memory };

import assert from 'node:assert';
import {
  extendMemory,
  Memory,
  wrapMemory,
  createAndExtendMemory,
  writeUint32,
  readUint32
} from '../src/index.mjs';

// 1. extendMemory upgrades a standard WebAssembly.Memory instance to provide typed array getters
const rawMem = new WebAssembly.Memory({ initial: 1 });
assert(!(rawMem instanceof Memory), 'Standard WebAssembly.Memory should not be Memory instance prior to extension');
const extended = extendMemory(rawMem);
assert.strictEqual(extended, rawMem, 'extendMemory returns the exact same WebAssembly.Memory instance reference');
assert(extended instanceof Memory, 'extended memory inherits from Memory');
assert(extended.HEAP8 instanceof Int8Array, 'HEAP8 is an Int8Array view');
assert(extended.HEAPU8 instanceof Uint8Array, 'HEAPU8 is a Uint8Array view');
assert(extended.HEAP16 instanceof Int16Array, 'HEAP16 is an Int16Array view');
assert(extended.HEAPU16 instanceof Uint16Array, 'HEAPU16 is a Uint16Array view');
assert(extended.HEAP32 instanceof Int32Array, 'HEAP32 is an Int32Array view');
assert(extended.HEAPU32 instanceof Uint32Array, 'HEAPU32 is a Uint32Array view');
assert(extended.HEAPF32 instanceof Float32Array, 'HEAPF32 is a Float32Array view');
assert(extended.HEAPF64 instanceof Float64Array, 'HEAPF64 is a Float64Array view');
assert(extended.view instanceof DataView, 'view is a DataView instance');

// 2. extendMemory returns the exact same WebAssembly.Memory instance reference
const mem2 = new WebAssembly.Memory({ initial: 1 });
const wrapped = wrapMemory(mem2);
assert.strictEqual(wrapped, mem2, 'wrapMemory returns the same object reference');

// 3. Typed array views and DataView reflect shared buffer byte mutations across representations
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 reflects byte mutations');
assert.strictEqual(extended.HEAP32[0], -559038737, 'HEAP32 reflects signed 32-bit integer');
writeUint32(extended, 4, 0x12345678, true);
assert.strictEqual(readUint32(extended, 4, true), 0x12345678, 'readUint32 retrieves written value');

// 4. 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 memory remains an instance of Memory');

// 5. Typed array views remain accessible and dynamically re-reference the buffer after memory growth
const grown = createAndExtendMemory({ initial: 1, maximum: 2 });
assert.strictEqual(grown.buffer.byteLength, 65536, 'Initial buffer size is 65536');
assert.strictEqual(grown.grow(1), 1, 'grow should return previous page count');
assert.strictEqual(grown.buffer.byteLength, 131072, 'Buffer size after grow is 131072');
assert.strictEqual(grown.HEAPU8.length, 131072, 'HEAPU8 view dynamically resizes with the buffer');

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