bug: crowded workspace session lists are clipped on desktop and laggy on mobile

Summary

When I run several parallel development sessions inside the same workspace, the current UI becomes difficult to navigate and manage:

• On desktop, the workspace's agent/chat tab list does not provide a usable horizontal overflow or scrolling mechanism. On a narrow window, items beyond the visible area are clipped and I cannot reach all of them.
• The mobile app can expose more of the list, but scrolling and switching between entries often feels sluggish and stutters, especially with many sessions.
• When the daemon/device connection is temporarily lost, previously viewed conversations are not reliably available for immediate local reading. I would like the already-loaded history to remain visible while offline, with synchronization resumed in the background after reconnecting.

This makes it hard to manage multiple parallel developments in one workspace and also makes the app less useful for quickly checking history while a device is offline.

Expected behavior

1. Desktop should provide a clear way to access every agent/chat in a crowded workspace, such as horizontal scrolling, an overflow menu, or another responsive layout that works on narrow windows.
2. Mobile list rendering and tab switching should remain smooth with many sessions, ideally using virtualization and avoiding unnecessary re-renders.
3. Previously loaded workspace and conversation data should be persisted in a bounded local cache. When disconnected, Paseo should show the cached list/history with a clear stale/offline indicator, then reconcile it with the daemon in the background after reconnecting.

Steps to reproduce

1. Open a workspace that contains many parallel agent/chat sessions.
2. Use the desktop app in a narrow window or on a small display.
3. Try to reach the sessions that extend beyond the visible tab/list area.
4. Open the same workspace on mobile and scroll or switch between many sessions.
5. After opening some conversations, temporarily disconnect the daemon/device and try to browse the previously opened history.

Actual behavior

• The desktop list is clipped and cannot be reached by horizontal scrolling.
• Mobile navigation can become noticeably laggy rather than staying fluid.
• During a connection loss, viewing history may wait for a network fetch or show an unavailable/loading state instead of immediately showing previously loaded content.

Environment

• Paseo desktop: 0.5.1
• macOS: 26.5.1 (Apple Silicon)
• Surface: Desktop (Electron); the list/performance concern also affects mobile
• Connection: remote daemon

Related

• #3596 — cache conversation history and avoid re-fetching it after app restart
• #1902 — laggy synchronization on mobile
• #2975 — performance problems when rendering many projects/workspaces

This report combines the symptoms because they affect the same workflow: managing many parallel sessions in one workspace. I can provide a short screen recording with the exact window size and session count if that would help reproduce the UI behavior.