- Rectangle selection via stylus drag in select mode - Visual feedback: dashed selection rect, blue highlight on selected strokes - Operations: delete selection, drag-to-move, copy (toolbar buttons) - Full undo support: DeleteMultipleStrokesAction, MoveStrokesAction, CopyStrokesAction - Preallocated RectF to avoid draw-time allocations (lint) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>