Feature request: Keep multiple chats open side by side #20008

Problem

When working on related tasks, switching back and forth between threads makes it hard to compare answers and keep context visible.

Proposed feature

Add a way to keep two or more chats open at once in a side-by-side or split view. It would be useful to compare responses, reference one thread while working in another, and move between parallel tasks without losing the current view.

A first version could allow opening a second thread in a pane, resizing or closing that pane, and choosing which thread each pane shows.

Question for maintainers

Would a contribution for this feature be welcome? The README says contributions are mostly not being accepted yet, so I’d appreciate guidance on whether this is in scope and the preferred design before starting a PR.