Under "On next message" folding, a Turn woken by a notice (settled
subagent, goal round, schedule, background job) advanced the bottom Turn
and folded the finished Turn without an own-input driver, so the generic
fold room left a following reader looking at blank space.
Chat Nodes now declare a group-tree position (`groupTree`, ordered
`exchange` > `turn` > `process`). Human input claimed in Step 1 marks its
Turn as opening an exchange; notices and later steering carry no
position. `GroupTreeSegments` splits the loaded Turns at opening Turns,
and `bottomSource` covers the whole latest exchange, so notice-woken
Turns no longer fold earlier ones while the next human message folds the
exchange through the own-input path. Only `exchange` is read today; the
`turn` and `process` positions are reserved for the existing kind lists.
imccyu