The pane-resize sash's 9px grab band was centered on the split boundary,
so ~4.5px reached into the leading pane and sat exactly on top of the
session list's 4px scrollbar — the pointer always hit the sash (cursor
flipped to col-resize) and the scrollbar thumb was unclickable/undraggable.
Make the grab band asymmetric: 1px into the leading pane, 7px into the
trailing one. The scrollbar regains its full hit area while the sash stays
an easy 8px target; the hairline and hover strip are repositioned onto the
actual boundary.
Fixes#79157
Hermes Agent
7d74375b0b