- Match View() and getItemAndLineAtY() row counts for empty items so
streaming-reasoning placeholders no longer offset hit-testing by one
row each (exposed when extension widgets like subagent-monitor shrink
the scrollback).
- Honor IsLineInRange's endCol=-1 'to end of line' sentinel in
HighlightLine and ExtractText so the start row of a multi-line drag
actually renders highlighted and is included in clipboard copies.
- Add regression tests for both invariants in scrolllist and selection.
- Lock viewport scroll while a drag-select is active so highlighted
content stays under the cursor (SetItems, appendStreamingChunk,
MouseWheelDown all now honor IsMouseDown).
- HandleMouseDrag defensively clears autoScroll on every update so a
racy re-enable can't shift the row mid-drag.
- Recompute scrollback yOffset/viewport height on each mouse event
via currentScrollbackBounds() instead of relying on stale values
cached during the previous View() pass.
- Account for canceling/ctrlCPressedOnce warning rows in
distributeHeight and mark layoutDirty when those flags toggle so
the height budget and mouse origin stay in sync.
- Add ScrollList regression tests covering the three invariants.
Ed Zynda