What: Infrastructure for grouping related sessions (forks/branches with same session ID) in a collapsible tree structure.
Details:
- Currently disabled via feature flag (
xg()returns false) - Groups sessions by session ID with expand/collapse support
- Uses "▼" and "▶" indicators for group state
- Evidence:
QV9()at line 496553,h_3()grouping at line 497146,xg()flag at line 513608 in v2.0.58