The TUI already ships a rich /agents spawn-tree dashboard (live tree,
timeline, per-child tokens/cost/files/tools, kill/pause), but nothing
surfaced it — during delegation the transcript stayed quiet and users
had to already know to type /agents.
Drop a one-time transient activity hint ("subagents working · /agents
to watch live") the first time a turn starts delegating, matching the
existing "· /logs to inspect" house style. Guards keep it unobtrusive:
- fires at most once per turn (resets on message.start)
- silent when the /agents overlay is already open
- gated by display.tui_agents_nudge (default true)
Hooked on subagent.start, not subagent.spawn_requested: the delegate
progress callback in tools/delegate_tool.py only relays start/complete
to the gateway and drops spawn_requested, so start is the first
delegation event the TUI reliably receives. spawn_requested is wired
too for the future case, guarded once-per-turn.
Adds the display.tui_agents_nudge config default and gatewayTypes entry.
5a72e82fd8