Split view for two sessions side by side on desktop

On desktop I can only see one session at a time — the sidebar shows the list, but opening a session replaces the current view instead of adding beside it.

Would love a way to open two sessions side by side, so I can watch one agent work while checking on another without tabbing back and forth (or opening a second browser tab as a workaround).

┌────────────┬────────────────────────┬────────────────────────┐
│  Sidebar   │  Session A             │  Session B              │
└────────────┴────────────────────────┴────────────────────────┘

Happy 1.2.3, macOS.