Scrolling up during a running turn broke follow only when the overflow gate
agreed the timeline could scroll. The gate read the last row alone, and a
tool row appended mid-stream has no position until LegendList lays it out,
so the wheel was ignored and the anchored turn still snapped to the end on
tool activity. The gate now falls back to the last positioned row.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>