What if we want to switch from you to another team mid build?

You can. The codebase is yours, the repository is yours, all documentation is shared as we go (not held back), and there are no exit fees. We have had a small number of startups switch teams mid build (founder priority change, internal hire arriving sooner than expected, etc) and we have always handed over cleanly. We would rather have you leave smoothly than try to retain you through friction, because the small number of clients who leave well sometimes come back later.