Manual /compress wrote the compressed payload into BOTH s.messages (visible) and s.context_messages
(model-facing) + wiped s.tool_calls -> messages vanished from the window. Fix keeps s.messages +
tool history durable, deep-copies compressed only into s.context_messages, anchors off visible msgs.
Co-authored-by: franksong2702 <franksong2702@users.noreply.github.com>
Instead of using len(visible_after)-1 (which points to the last visible
message and gets pushed behind the render window as more turns accumulate),
find the last [CONTEXT COMPACTION] marker in s.messages and compute the
anchor from visible messages before it.
This keeps the compression reference card at the correct boundary even
after 50+ subsequent turns have scrolled the render window past the old
anchor position.
Fixes a bug where the assistant's output message appeared to disappear
after automatic context compression because the reference card was placed
at the wrong position.
