`common-path-prefix` is a tiny Node.js utility that, given an array of file‑path strings, returns the longest shared prefix (including the trailing separator) while ignoring the leading base component. It works with both Unix‑style (`/`) and Windows‑style (`\`) separators and lets callers specify a custom delimiter, making it useful for build scripts, templating tools, or any JavaScript project that needs to normalize or compare path hierarchies.