Duplicating custom toolbar button from example

If I start with the instructions from Extension Tutorial — JupyterLab 4.1.2 documentation I can get an installed extension.
If I then copy in the src/index.ts and schema/plugin.json from: extension-examples/toolbar-button at main · jupyterlab/extension-examples · GitHub
My extension still installs, but I do not see the toolbar button.
Meanwhile if I run a pip install -ve . from the toolbar button example directory directly it installs the toolbar button example. The only difference that I found of note was in package.json there is a reference to “schemaDir” which wasn’t created from the tutorial. Though duplicating it does not seem to assist.

Any thoughts on where I’m going wrong?

Thank you!