Function writeIfMissing

src/utils/localInstaller.ts:54–66

* Write `content` to `path` only if the file does not already exist. * Uses O_EXCL ('wx') for atomic create-if-missing.

(
  path: string,
  content: string,
  mode?: number,
)

 * Uses O_EXCL ('wx') for atomic create-if-missing.
 */
async function writeIfMissing(
  path: string,
  content: string,
  mode?: number,
): Promise<boolean> {
  try {
    await writeFile(path, content, { encoding: 'utf8', flag: 'wx', mode })
    return true
  } catch (e) {
    if (getErrnoCode(e) === 'EEXIST') return false
    throw e
  }
}

/**
 * Ensure the local package environment is set up