It would be nice to be able to add a filter to a multi-entity attribute, so user can only select some specific entities from the list.
For instance, we are creating an entity containing several modules. Each modules have a specific use cases
In another entity, we have an attribute which link to the previous one. Except we would like the use to be able to see only the choice of modules which have a specific tag.
I agree that this would be an awesome feature to have. In my case, I'm using a custom entity to represent a directed acyclic graph and another entity to represent a node within that graph. When viewing the details page of the graph entity, I'd like to be able to have grid widgets filter their auto complete results to show only nodes applicable to that graph. This functionality is already available when filtering what is displayed in a grid widget (e.g. <field> <relation> <Current entity> in the filter), so having something similar for auto complete filtering feels like it would be fairly intuitive to use.
