Broadcasts what happens to files (Storehouse.Notify) on the app's Phoenix.PubSub, as {:storehouse, event, info}.

config :storehouse,
  notify: {Storehouse.Notify.PubSub, :broadcast, [MyApp.PubSub, {MyApp.Files, :topic, []}]}

defmodule MyApp.Files do
  # Every file of an account under "accounts/<id>/": its topic.
  def topic(%{file: %{key: "accounts/" <> rest}}), do: "files:" <> hd(String.split(rest, "/"))
  def topic(%{key: "accounts/" <> rest}), do: "files:" <> hd(String.split(rest, "/"))
  def topic(_info), do: nil
end

The topic is a string, the same for every event, or {module, function, args} called with the event's map first, which gives the topic, or nil to broadcast nothing. In a LiveView:

def mount(_params, _session, socket) do
  if connected?(socket), do: Phoenix.PubSub.subscribe(MyApp.PubSub, "files:42")
  {:ok, socket}
end

def handle_info({:storehouse, :analyzed, %{file: file}}, socket), do: ...