Collaborative boards are the canonical Human+ UX surface — a shared canvas where humans sketch, paste, and arrange, and where agents need to drop tiles, draw connectors, and move things around. Every existing whiteboard library either has zero agent affordances or assumes a specific transport.

Board is a controlled, transport-agnostic canvas: sticky notes, freeform pen, connectors, shapes, presence cursors, undo. Every item has a stable id; mutations broadcast AgentActivity events for the presence layer to render.

Hold value in state, pass onChange, render <Board>. For agent operability, register the whiteboard bridge with registerWhiteboardBridge(server, { adapter }) from agent-integrations — the agent gets whiteboard_* tools and the canvas exposes presence in return.