- AgentStepList: an agent's steps down a data_display::Timeline rail,
marked by chat::step_mark, with detail and time
- AgentPlan: items waiting, at work or done, with a count; done items go
quiet and struck through
- chat::step_mark reads motion::changes: a check or cross that arrives pops
in, still on first paint
- AgentStatus: a pill for planning, working, waiting, done or failed
- AgentProgress: the step at work, done of total, the time so far and a
bar split by step; progress past its total fails loud
- SubAgentTree is lists::Tree with each agent's state as its note
- gallery: a plan the button advances, steps, statuses and a tree
