Function findCommonRootPath

findCommonRootPath(
    files: Iterable<string>,
    baseRoot?: string,
    allowedRoot?: string,
): string
Given a list of file paths, find the longest common parent directory.

Each element is treated as a file path — the last segment is the filename, not a directory. Empty strings are silently ignored.
- On Windows, backslash separators are normalized to forward slashes before comparison.
- If the common prefix is a POSIX root (/), returns "/".
- If no common root exists (e.g. different Windows drives, or all paths are relative with no shared prefix), returns "".
The function performs no I/O and does not call path.resolve — it is a pure string operation. For best results, pass already-resolved absolute paths.
Parameters
- files: Iterable<string>
  File paths to inspect (absolute paths recommended).
- OptionalbaseRoot: string
  When provided, the result is the common ancestor of all file directories AND this path. This prevents the result from being deeper than baseRoot — use it to set a "minimum root" for the computation. Has no effect on which files are included.
- OptionalallowedRoot: string
  When provided, files whose directory is not under this path are silently excluded from the computation. Acts as a security boundary — the result is always this path or a sub-directory of it (assuming at least one file is inside it).
Returns string
The longest common parent directory, or "" if none exists.
- Defined in utils.ts:224