When I launch my application Python throws a “backend is not a package” style import error, preventing the whole project from boot-strapping. The setup is straightforward: a FastAPI backend sits in the root of the repo, complete with an __init__.py file, yet the interpreter still refuses to treat the folder as a package. I need a Python expert who can: • Inspect the project layout, startup script and PYTHONPATH interaction • Pinpoint the exact cause of the mis-recognition—whether it is a circular import, relative-path issue, or environment quirk • Supply a concise code or configuration fix and walk me through the reasoning so I understand the change You’re free to choose any diagnostic approach—virtualenv tweaking, module re-organisation, or clever use of sys.path—as long as the final result is a clean “uvicorn main:app” (or equivalent) run with no import errors. A short note outlining the root cause and the solution is part of the deliverable.