Function performVersionUpdate

src/utils/nativeInstaller/installer.ts:429–476

* Performs the core update operation: download (if needed), install, and update symlink. * Returns whether a new install was performed (vs just updating symlink).

(
  version: string,
  forceReinstall: boolean,
)

 * Returns whether a new install was performed (vs just updating symlink).
 */
async function performVersionUpdate(
  version: string,
  forceReinstall: boolean,
): Promise<boolean> {
  const { stagingPath: baseStagingPath, installPath } =
    await getVersionPaths(version)
  const { executable: executablePath } = getBaseDirectories()

  // For lockless updates, use a unique staging path to avoid conflicts between concurrent downloads
  const stagingPath = isEnvTruthy(process.env.ENABLE_LOCKLESS_UPDATES)
    ? `${baseStagingPath}.${process.pid}.${Date.now()}`
    : baseStagingPath

  // Only download if not already installed (or if force reinstall)
  const needsInstall = !(await versionIsAvailable(version)) || forceReinstall
  if (needsInstall) {
    logForDebugging(
      forceReinstall
        ? `Force reinstalling native installer version ${version}`
        : `Downloading native installer version ${version}`,
    )
    const downloadType = await downloadVersion(version, stagingPath)
    await installVersion(stagingPath, installPath, downloadType)
  } else {
    logForDebugging(`Version ${version} already installed, updating symlink`)
  }

  // Create direct symlink from ~/.local/bin/ncode to the version binary
  await removeDirectoryIfEmpty(executablePath)
  await updateSymlink(executablePath, installPath)

  // Verify the executable was actually created/updated
  if (!(await isPossibleNcodeBinary(executablePath))) {
    let installPathExists = false
    try {
      await stat(installPath)
      installPathExists = true
    } catch {
      // installPath doesn't exist
    }
    throw new Error(
      `Failed to create executable at ${executablePath}. ` +
        `Source file exists: ${installPathExists}. ` +
        `Check write permissions to ${executablePath}.`,
    )
  }
  return needsInstall
}

async function versionIsAvailable(version: string): Promise<boolean> {
  const { installPath } = await getVersionPaths(version)