On the first open of a session, late async data (most visibly a task/subagent
tool whose nested rows are fetched from the child session after entry) grew the
timeline a beat after the one-shot entry pin, stranding the viewport mid-history.
The steady-state idle gate intentionally ignores that growth, so re-pinning could
not recover it. Add a short, gesture-cancellable entry-stick window that forces
the bottom on every growth until content quiesces (or the user scrolls), covering
both the ResizeObserver and the structural notifyContentChange path.
Bohdan Triapitsyn
9e6d0df942