Session list stops loading when child-session filtering leaves no scrollbar #350

Reproduction

On Manager v0.17.5, populate a directory with enough sessions that the first page of 25 includes many child sessions and only four root sessions. Keep older root sessions on the next cursor page. Open the session list in a viewport tall enough to fit the four visible cards.

Actual behavior

Child sessions are filtered out after pagination. The remaining cards do not overflow, so no scroll event can request the next page. Automatic pagination only runs when zero visible sessions remain. Older root sessions appear missing, although direct navigation and search still find them.

Expected behavior

Load additional pages while the visible list underfills the scroll viewport, stopping when the list is sufficiently filled or no cursor remains. Preserve child filtering and directory scoping.

Investigation

The relevant code is frontend/src/components/session/SessionList.tsx. A regression fixture with four roots and 21 children reproduces the missing automatic fetch. A local fix adds a scroll-region ref and reuses the existing near-bottom threshold with loading and next-page guards. Focused component tests and the frontend production build pass. Authenticated production-browser verification remains pending.