An oversized session rebuilt an unbounded runtime repository on every store
update and exhausted the renderer's V8 heap, crash-looping the window. The DOM
budget in thread/list.tsx bounds what PAINTS, but every message was still
normalized into the repository first, so a session only had to be heavy — not
visible — to kill the renderer.
selectTranscriptWindow keeps the tail that fits one render-weight page. Weight,
not message count: measured against a real 1,175-session store, a 400-message
cap disengages on 37 sessions that are heavy but short (one is 133 messages /
1.05MB) while firing on 92 long-but-light sessions that were never at risk.
The cut aligns off branch-group boundaries. useRuntimeMessageRepository records
a group's fork point the first time it sees the group, so a window starting
mid-group would re-parent the surviving branches to whatever happened to
precede them.
Co-authored-by: HexLab <8422520+HexLab98@users.noreply.github.com>
Brooklyn Nicholson
a538b1c989