Consider more visual indicator(s) into existing session's harness choice

We have gray placeholder text in the editor and Agents windows that indicates which harness is selected for an existing session (in screenshot below, it's `Copilot`):

But there isn't another (potentially more obvious) visual indicator of the user's harness selection. Is there a way to signify the current harness more clearly to users in existing sessions, without bringing back items we've removed (like the harness Continue In picker, or `Copilot` as a participant name above its chat responses)?