I absolutely agree with the principle.

In this case, because the directive is used recursively (and instantiated for each node in the catalog tree), it's not easily done (if possible at all).

What I could do is create a container directive as part of the component that will replace the <div> in the index (https://github.com/geoadmin/mf-geoadmin3/blob/7b5b2b1be596231d9b1c0e1dc56ff1d9de137028/src/index.mako.html#L189) and will take care of updating the data. I think that would make sense. What do you think?