Prerequisite Checkpoint: The Overlay Belongs to the Shell

A package can be built and installed correctly while remaining invisible in a shell that has not sourced the workspace overlay.

Verify both states deliberately:

1. fresh shell without the overlay;
2. shell after sourcing the workspace install setup.

Record the same package lookup in both environments.

Bridge question

What changed?

The package did not suddenly appear on disk. The shell environment changed its search paths and ROS package visibility.

This distinction matters later when a startup failure looks like a missing package but the source/build state is healthy.

Write:

source state: confirmed / unknown
build state: confirmed / unknown
overlay state: sourced / unsourced
package visibility: visible / not visible

Do not diagnose launch or graph behavior until this boundary is clear.