@westbrook@bkardell this is really interesting. I went down a similar thought process with this "open-stylable" shadow root idea people have suggested and I'm not sure it's the right approach either.
I like your "layer" idea. Would that be a default behavior or would web component authors need to enable that?
@zachleat Great post! I'm not super keen on the DSD (Declarative Shadow DOM) API because of the fact you have to define the template for each component instance, but the DCE (Declarative Custom Elements) API seems promising for scalably SSRing custom elements.
Maybe I'm missing something, but Declarative Shadow DOM kind of feels like a step backwards. Do you have to include the template every time you use the component?