UI view state
Source: src/app/ui/view_state
This package holds transient interaction state rather than persisted session data: selected bounding boxes, preview tool mode, box-mutation/selection history, and key filtering for the frame table. Annotation actions update the active editable layer through Application workflows; the UI state tracks which items and interactions are active, not the canonical box data.
The distinction matters when saving and restoring projects: domain settings, playback, and layer contents belong to session/project data, while the window's current interaction belongs here. Handlers coordinate these states with preview widgets.