Where a host's boards live: a DynamicSupervisor the host adds to its own tree (spec/15 §8.1, D-146).

The library starts no process of its own. A host places this supervisor, names it, and starts each board under it with Visualize.Board.Server.start/2:

children = [
  {Visualize.Board.Supervisor, name: MyApp.Boards},
  MyAppWeb.Endpoint
]

{:ok, board} =
  Visualize.Board.Server.start(MyApp.Boards,
    board: board, store: store, binding: binding, feeds: feeds)

Visualize.Board.Server.start/2 takes any DynamicSupervisor, so a host that has one already starts boards under it, and Visualize.Board.Server.child_spec/1 places one board under a supervisor of any kind. A board is :transient: one that crashes is started again with its start options, and one stopped with Visualize.Board.Server.stop/1 is not.