How a File Named types.py Broke a Python Server While Local Tests Passed

A developer refactoring Python code used an AI model to extract dataclasses into a new file, which was named types.py — a name that conflicts with Python's standard library module. Local tests passed without issue, but the same code on a remote server began failing on imports that had never been modified, because the server's working directory placed the new file ahead of the standard library in sys.path. The root cause was that Python's import system resolves module names relative to sys.path[0], which changed between environments due to a different working directory. Attempts to fix the issue by manipulating sys.path made both environments fail consistently, which was described as the first honest diagnostic result of the incident. The actual solution was straightforward: rename the helper file to avoid shadowing a built-in module name.