The full answer
Source code lives in a repository you control, with its full history, so you can see how the product evolved. Infrastructure runs in cloud accounts set up in your name, along with the credentials for services such as payment gateways, email providers and analytics.
Documentation covers the system architecture, how to set up a development environment, how deployments work, environment configuration and the main integrations. Where we have set up CI/CD pipelines, they are documented and handed over as well.
If you have an in-house team taking over, we run knowledge transfer sessions where our engineers walk them through the codebase, explain key decisions and answer questions. A period of overlap can be arranged so your team is confident before we step back.
Many clients keep us on for post-launch support instead of, or as well as, an internal team. Either way, the handover is designed so you are never dependent on us to access or operate your own product.