Command manager is saving the entire attrs object on each attr() call (unexpected behaviour?) about joint

[kumilingus]

This is expected.

The CommandManager makes a snapshot of an attribute value before and after the change (using shallow clone for performance). The snapshot is then applied simply with set() method i.e. without merging.

Even if we would provide a callback, we would have to somehow record the property removal. It would not appear in the diff (and if we record it as undefined it would get lost in the JSON export).

I am not convinced these extra data is an issue. How many data are we talking about?

If this size is an issue, you can also introduce top-level properties such as color or borderWidth (with data-binding to attrs) and record these instead of the attrs object (using cmdBeforeAdd: (eventName) => eventName !== 'change:attrs')).