The model often emits a follow-up batch of tool calls as its own
assistant message with no prose or reasoning. On screen those rows look
like one continuous run, but assistant-ui only groups tool calls within a
single message, so the auto-scrolling tool window never triggered on them
(e.g. two batches of two searches read as 2 + 2, never reaching the
threshold).
Coalesce each settled tool-only assistant message into the preceding
assistant message in the render pipeline so its calls join that message's
tool group. Render-only (never touches the $messages store) and
settle-only (pending messages are skipped) so a live turn is never
merged/un-merged mid-stream; merged results are cached by source identity
so a stable turn yields stable objects with no re-render churn.
Brooklyn Nicholson
6d65210252