Hosts an A2UIPhoenix.Session in a LiveView.

def mount(_params, _session, socket) do
  session = A2UIPhoenix.Session.new([A2UICore.Catalog.Basic.catalog("v1.0")])
  {:ok, A2UIPhoenix.Live.init(socket, session, on_send: &send_to_agent/2)}
end

def handle_info({:agent, payload}, socket) do
  {_result, socket} = A2UIPhoenix.Live.handle_message(socket, payload)
  {:noreply, socket}
end

and render each surface with A2UIPhoenix.Surface:

<.live_component
  :for={surface <- A2UIPhoenix.Session.surfaces(@a2ui)}
  module={A2UIPhoenix.Surface}
  id={"surface-" <> surface.id}
  session={@a2ui}
  surface_id={surface.id}
/>

init/3 assigns the session and attaches a handle_info hook that applies the writes and actions the surfaces report, so the host does not handle those messages itself.

Effects are delivered as they happen:

• {:send, message} goes to the :on_send callback — the host's transport to the agent;
• {:open_url, url} is pushed to the browser as the "a2ui:open_url" event (priv/static/a2ui_phoenix.js opens it in a new tab);
• {:agent_call_sent, call_id, timeout_ms} starts the call's timer, which rejects the call with TIMEOUT if the agent has not answered when it fires (A2UIPhoenix.Session.timeout_agent_call/2), and also goes to the :on_effect callback;
• every other effect goes to the :on_effect callback.

The reply to an embedded MCP App's request is pushed as the "a2ui:mcp_app:reply" event, which the A2UIMcpApp hook relays to the app.