Source the Overlay and Prove It

A successful build does not automatically change every terminal.

You need to expose the built workspace to the shell.

Use a clean terminal

The official tutorial recommends using a separate terminal from the one used to build when testing an overlay.

Open a new terminal:

source /opt/ros/jazzy/setup.bash
cd ~/ros2_ws
source install/local_setup.bash

What changed?

The current shell now has access to packages installed by the overlay.

The tutorial explains that local_setup.bash adds the overlay's packages, while the workspace setup.bash can include the underlay chain captured when the workspace was built.

Prove discovery

Ask ROS 2 for an executable/package that came from the overlay source you built.

For example:

ros2 pkg executables turtlesim

Before/after experiment

Compare two clean terminals:

Terminal A: source only /opt/ros/jazzy/setup.bash.

Terminal B: source Jazzy and the local workspace overlay.

Use package/executable lookup evidence to explain whether the overlay changes what ROS resolves first.

Checkpoint

Finish:

colcon build created the install space, but source install/local_setup.bash...