Function expandPath

src/utils/path.ts:40–110

(path: string, baseDir?: string)

 * expandPath('/absolute/path') // '/absolute/path'
 */
export function expandPath(path: string, baseDir?: string): string {
  // Set default baseDir to getCwd() if not provided
  const actualBaseDir = baseDir ?? getCwd() ?? getFsImplementation().cwd()

  // Input validation
  if (typeof path !== 'string') {
    throw new TypeError(`Path must be a string, received ${typeof path}`)
  }

  if (typeof actualBaseDir !== 'string') {
    throw new TypeError(
      `Base directory must be a string, received ${typeof actualBaseDir}`,
    )
  }

  // Security: Check for null bytes
  if (path.includes('\0') || actualBaseDir.includes('\0')) {
    throw new Error('Path contains null bytes')
  }

  const isSyntheticPosixPath = (value: string): boolean =>
    value.includes('/') && !value.includes('\\') && !/^[A-Za-z]:/.test(value)

  // Handle empty or whitespace-only paths
  const trimmedPath = path.trim()
  if (!trimmedPath) {
    if (getPlatform() === 'windows' && isSyntheticPosixPath(actualBaseDir)) {
      return posix.normalize(actualBaseDir).normalize('NFC')
    }
    return normalize(actualBaseDir).normalize('NFC')
  }

  // Handle home directory notation
  if (trimmedPath === '~') {
    return homedir().normalize('NFC')
  }

  if (trimmedPath.startsWith('~/')) {
    return join(homedir(), trimmedPath.slice(2)).normalize('NFC')
  }

  // On Windows, convert POSIX-style paths (e.g., /c/Users/...) to Windows format
  let processedPath = trimmedPath
  if (getPlatform() === 'windows' && trimmedPath.match(/^\/[a-z]\//i)) {
    try {
      processedPath = posixPathToWindowsPath(trimmedPath)
    } catch {
      // If conversion fails, use original path
      processedPath = trimmedPath
    }
  }

  // Handle absolute paths
  if (isAbsolute(processedPath)) {
    if (getPlatform() === 'windows' && isSyntheticPosixPath(processedPath)) {
      return posix.normalize(processedPath).normalize('NFC')
    }
    return normalize(processedPath).normalize('NFC')