Who is responsible for ensuring that outputs from multiple teams can be integrated into one Increment?

The responsibility for ensuring that outputs from multiple teams can be integrated into one Increment primarily lies with the developers. In Scrum, the developers are accountable for the delivery and integration of the potentially shippable product Increment at the end of each Sprint. This means they must coordinate their work closely to ensure that the various components developed by different teams can function together seamlessly.

The integration process requires collaboration among the developers to align on shared technical standards, architectures, and practices. It's crucial for them to communicate regularly, conduct integration tests, and address any dependencies or integration challenges throughout the Sprint. By doing so, the developers ensure that the final Increment not only meets the acceptance criteria but is also cohesive and maintainable.

While other roles like the Product Owner and Scrum Master play significant functions within their domains—such as prioritizing the product backlog or facilitating Scrum ceremonies—it's the developers who combine their work into a singular, functional product Increment. Stakeholders can provide feedback and input but do not have a direct role in the actual integration of the output from the teams.