How can I make alembic take a new file with a new model into account for a new revision? All the models are in the same directory /models but alembic seems to ignore it. How can it be included and tracked by alembic?
It should be imported one way or another when alembic runs, otherwise it won't know about it. You can for example create a models/__init__.py file and import your models there.
Basically migrations/env.py needs to know about your models. You can import them there as well, but models init is probably easier.