Function setupShellCompletion

src/utils/completionCache.ts:80–139

(theme: ThemeName)

 * shell's rc file. Returns a user-facing status message.
 */
export async function setupShellCompletion(theme: ThemeName): Promise<string> {
  const shell = detectShell()
  if (!shell) {
    return ''
  }

  // Ensure the cache directory exists
  try {
    await mkdir(dirname(shell.cacheFile), { recursive: true })
  } catch (e: unknown) {
    logError(e)
    return `${EOL}${color('warning', theme)(`Could not write ${shell.name} completion cache`)}${EOL}${chalk.dim(`Run manually: ncode completion ${shell.shellFlag} > ${shell.cacheFile}`)}${EOL}`
  }

  // Generate the completion script by writing directly to the cache file.
  // Using --output avoids piping through stdout where process.exit() can
  // truncate output before the pipe buffer drains.
  const ncodeBin = process.argv[1] || 'ncode'
  const result = await execFileNoThrow(ncodeBin, [
    'completion',
    shell.shellFlag,
    '--output',
    shell.cacheFile,
  ])
  if (result.code !== 0) {
    return `${EOL}${color('warning', theme)(`Could not generate ${shell.name} shell completions`)}${EOL}${chalk.dim(`Run manually: ncode completion ${shell.shellFlag} > ${shell.cacheFile}`)}${EOL}`
  }

  // Check if rc file already sources completions
  let existing = ''
  try {
    existing = await readFile(shell.rcFile, { encoding: 'utf-8' })
    if (
      existing.includes('ncode completion') ||
      existing.includes(shell.cacheFile)
    ) {
      return `${EOL}${color('success', theme)(`Shell completions updated for ${shell.name}`)}${EOL}${chalk.dim(`See ${formatPathLink(shell.rcFile)}`)}${EOL}`
    }
  } catch (e: unknown) {
    if (!isENOENT(e)) {
      logError(e)
      return `${EOL}${color('warning', theme)(`Could not install ${shell.name} shell completions`)}${EOL}${chalk.dim(`Add this to ${formatPathLink(shell.rcFile)}:`)}${EOL}${chalk.dim(shell.completionLine)}${EOL}`
    }
  }

  // Append source line to rc file
  try {
    const configDir = dirname(shell.rcFile)
    await mkdir(configDir, { recursive: true })

    const separator = existing && !existing.endsWith('\n') ? '\n' : ''
    const content = `${existing}${separator}\n# NCode shell completions\n${shell.completionLine}\n`
    await writeFile(shell.rcFile, content, { encoding: 'utf-8' })

    return `${EOL}${color('success', theme)(`Installed ${shell.name} shell completions`)}${EOL}${chalk.dim(`Added to ${formatPathLink(shell.rcFile)}`)}${EOL}${chalk.dim(`Run: source ${shell.rcFile}`)}${EOL}`
  } catch (error) {
    logError(error)
    return `${EOL}${color('warning', theme)(`Could not install ${shell.name} shell completions`)}${EOL}${chalk.dim(`Add this to ${formatPathLink(shell.rcFile)}:`)}${EOL}${chalk.dim(shell.completionLine)}${EOL}`