No turtlesim running.
Start one in a terminal:ros2 run turtlesim turtlesim_node
No nodes are running.
Nodes and the topics connecting them appear here live.
Open a file from the tree, use a lesson’s Open in editor button, or type code <file> in a terminal.
Files live in /home/user inside your browser and are kept between visits.
Starting the ROS 2 simulation in your browser…
The first visit downloads Python (~13 MB). After that it comes from the browser cache and starts in seconds.