The current model picker exposes a Manage Models option:

But this UI seems geared towards adding a new model, vs. managing models themselves:

Proposal: Clicking Manage Models should open a model management UI (editor / modal) where I can see all the models I currently have enabled, their provider, their capabilities. From that UI I can show/hide/remove models. In that UI I can also see why certain models aren't available in Agent mode. From that UI I can also add more models. In doing so, I can install new providers (we could automatically discover them from the Marketplace, like we do with our themes picker), or pick an pre-configured provider so I could then choose the models I'd like to add to my collection.

@isidorn