Load as a script extension under Editor in the Asset List. The @namespace link is a sample project.
■ Overview
This is a user script that can be used to create Editor extensions in the PlayCanvas Editor.
When this script is enabled, the script under "Assets" -> "Editor" file will be loaded as an extension.
■ Usage
The project in @namespace is a sample project.
Please see here for how to create it.
Sample project
https://playcanvas.com/editor/scene/1636573
Using the Editor API of PlayCanvas (ja )
https://zenn.dev/yushimatenjin/books/5877730dbc05a7
