Unique-key Registry mapping session IDs to running Nous.AgentServer processes.

This is one of the two processes Nous starts in its own supervision tree (see Nous.Application): the registry names agents, and Nous.AgentDynamicSupervisor owns their lifecycle. Nothing registers here directly — Nous.AgentDynamicSupervisor.start_agent/3 passes via_tuple(session_id) as the child's :name, so an AgentServer is registered by Registry at start and unregistered automatically when it exits. Keys are :unique, so a session ID can only ever have one live agent; starting a second one for the same ID returns {:error, {:already_started, pid}}.

The registry is partitioned across System.schedulers_online/0, because the read path is a hot one: a LiveView fan-in resolves the session's agent on every event, from a different process each time.

Examples

config = %{model: "openai:gpt-4o-mini", instructions: "You are helpful."}
{:ok, _pid} = Nous.AgentDynamicSupervisor.start_agent("session-42", config)

# Resolve the pid when you need it
{:ok, pid} = Nous.AgentRegistry.lookup("session-42")
Nous.AgentServer.send_message(pid, "Hello")

# ...or let Registry route a GenServer call for you
GenServer.call(Nous.AgentRegistry.via_tuple("session-42"), :get_history)

Nous.AgentRegistry.lookup("no-such-session")
#=> {:error, :not_found}