A LiveView in a room: the same session as a browser's channel or an agent's process, in the LiveView's own process. Presence, awareness, the room's documents and the policy work the same; the room's events reach the LiveView's components with send_update/2, or the LiveView itself.

live_session :default, on_mount: [Issho.Live] do

# In a LiveView or one of its components, once connected:
{:ok, _session} = Issho.Live.join(MyApp.Issho, current_user, "board:42")
{:ok, snapshot} = Issho.Live.open("board:42", "board:42", notify: {MyComponent, "board"})

A component named in notify gets update/2 with an :issho assign for each event, {event, key, payload}:

• {"tx", document_id, accepted_transaction}: a transaction accepted in a document it opened;
• {"aware", room, frame}: the others' awareness;
• {"presence_diff", room, diff}: people who came and went;
• {"bye", room, reason}: the session ended (revoked, refused).

notify: :self sends them to the LiveView as {Issho.Live, event, key, payload} messages instead.

Grants: rooms the browser joins

A component whose browser half joins the room itself (a text editor, which applies its own changes in the browser) needs a grant: a short token for the room, signed by the LiveView for the actor it authenticated. grant/4 signs it and remembers it, and the hook renews it when the browser asks (the "issho:grant" event, with the room), after asking the policy again, so that a person whose access went away gets no new grant. One grant serves every component of the page in that room.

grant = Issho.Live.grant(MyApp.Issho, current_user, "notebook:7", can: :write)

The components of a LiveView share one session per room: joining a room the LiveView is in already gives the same session.

Join only in a connected LiveView (connected?(socket)): the static render has no process that lasts.