What is the right course of action here?

In this scenario, you are approaching a cyclist who is completing a turn. The correct action is to wait until the cyclist has finished their maneuver before proceeding. This is in accordance with German traffic regulations, which prioritize the safety of all road users, especially vulnerable ones like cyclists.

By waiting for the cyclist, you ensure that you do not interfere with their path, reducing the risk of an accident. Sounding the horn or taking priority would not be appropriate, as it could discourage safe driving behavior and increase the likelihood of a collision. Understanding this principle is crucial for promoting safety and compliance with traffic laws.