What happened?

sync field is undefined for custom preset create by $({}), $$.sync`pwd` throws an exception TypeError: $$.sync is not a function.

Using the example from the document https://google.github.io/zx/api

file test.mjs

const $$ = $({
  verbose: false,
  env: {NODE_ENV: 'production'},
})

// inspect what is in sync
console.log("$.sync ", $.sync)
console.log("$$.sync ", $$.sync)

const env = await $$`node -e 'console.log(process.env.NODE_ENV)'`
const pwd = $$.sync`pwd` // this line throws an exception TypeError: $$.sync is not a function
const hello = $({quiet: true})`echo "Hello!"`

result

$ yarn exec zx test.mjs
$.sync  [Function (anonymous)]
$$.sync  undefined
TypeError: $$.sync is not a function
    at file:///root/workspace/tmp/zx-test/test.mjs:9:20
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

How it should work?

Line: const pwd = $$.syncpwd Shouldn't throw an TypeError: $$.sync is not a function

How to reproduce the bug?

See What happened

Version

8.8.5

What's OS kind?

Linux

What JS runtime is used?

Node.js

Runtime Version

v24.3.0 and v25.2.1

Error stack / relevant log output

$ yarn exec zx test.mjs
TypeError: $$.sync is not a function
    at file:///root/workspace/tmp/zx-test/test.mjs:9:20
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

Code of Conduct

• I agree to follow this project's Code of Conduct