The currently active tool.
Display name of the session's agent (the pen flyout note: "violet = Sage's").
Whether undo / redo are available (drives nothing visually but kept for a11y).
Selected pen ink color (from WHITEBOARD_PEN_COLORS).
ReadonlyPenSelected pen stroke width.
ReadonlyPenSelected shape kind for drag-create.
ReadonlyShapeA style choice was made — the board applies it to the selected text/sticky item (if any).
Selected text bold state (labels render bold by default).
Selected text color (null = the theme default; palette excludes the agent's violet).
ReadonlyTextSelected text font family.
Selected text font size (curated steps; 12 matches the CSS default).
ReadonlyTextReadonlyTools
The floating left-edge toolbar of the live whiteboard: tool buttons with kbd hints, the pen color/width flyout (with the "violet = agent's" reservation note), the shape flyout, and undo/redo. Pure presentational — all state in/out via bindings.