Cards consume the #130 mailbox stream and render live in the transcript:
- DelegateCard: last-3-actions tree for active agent_spawn
- FanoutCard: dot-grid + aggregate stats for agent_swarm / rlm fanout
Sidebar demoted to a navigator (count + role); detail lives in the card.
Engine wires SubAgentRuntime::with_mailbox so the primitive actually flows.
Cards re-bind on session resume via runtime_threads agent_ids.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Hunter Bown
63cb06637b