[BUG] Archived Sessions group silently truncates on scroll — no load-more, no count
Description
The auto-generated "Archived Sessions" group in the sidebar does not reliably render its full contents when scrolled. With ~114-140 archived sessions actually in the group (confirmed via the session-management API), scrolling to the visible bottom shows only a fraction, with no "load more" control, no indication more items exist below, and no way to page further.
Steps to reproduce
- Accumulate 100+ archived Code sessions over a few weeks of normal use.
- Open the sidebar, scroll the "Archived Sessions" group to the bottom.
- Compare what's visible against the actual archived session count (e.g. via the session-management MCP tools, or any other way of listing all archived sessions).
Expected behavior
Either the full archived list renders (with virtualized scrolling handling the count transparently), or there's a visible affordance (a "load more" button, a count indicator, pagination) showing that more items exist beyond what's rendered.
Actual behavior
Scrolling simply stops. There's no signal that the list is incomplete — it just looks like you've reached the end. In my case this made ~25–30 archived sessions effectively unreachable through the UI (though they're intact in the underlying data), and initially looked identical to those sessions being permanently lost.
Environment
- Claude Code Desktop
- macOS (Darwin 24.6.0)
- ~160 total Code sessions, ~140 archived, discovered 2026-08-15
Additional context
This is adjacent to the group-reordering requests (#70104, #72126) and the archive-visibility bug (#24534), but is specifically about incomplete rendering within a group, not group placement or the Archive filter. It's a real usability problem for anyone who archives sessions regularly instead of deleting them — the "safe" long-term home for finished work silently becomes unbrowsable past a certain size.