Replace send/steer/inject with one Agent.send primitive over the (target × wakeup) matrix; followup/steer/inject become fixed-preset alias methods on the now-abstract Agent class. Coalesce context/message into user/message (injected context is a non-user source). Replace agent/queued with agent/inbox/enqueue/dequeue/discard, add cancel keepInbox, and add a FIFO-conservation invariant.