zy666888 Thank you for your feedback. For the time being, we have no plans to introduce a plugin system. While running your own code within Spine would be very powerful, there are often ways to work around this limitation.

It is very useful to write your own application specific tool to load your Spine data. This can be used for many things, such as associating animations and other parts of the skeletons with game or level data, or for visualizing application specific effects, such as particles or sounds.

The Skeleton Viewer is a simple example of such a tool. By monitoring the data file, the tool can automatically reload the data. This allows for a workflow where the animator exports from Spine (shift+ctrl+E repeats the last export) and instantly see the visualization and other information in the tool.

We have answered questions about the plugin system in the past, so you may find the following thread helpful:
https://esotericsoftware.com/forum/d/23924-plugins-/12