Codex caught an asymmetry in the first cut: the rebuilt side selected the tail
live segment ([...].pop()) but the preserved side used querySelector() = the
FIRST [data-live-assistant=1] segment. In a multi-live-segment turn (reconnect /
post-tool activity boundaries — see messages.js ensureAssistantRow re-attaching
to the LAST live segment), the smd parser writes into the tail segment, so
swapping the first preserved segment would move the wrong node and leave the
parser-owned tail detached — re-introducing the flicker for multi-segment turns.
Fix: select the preserved segment from querySelectorAll, defaulting to the LAST
(tail), and prefer the one whose data-live-segment-seq matches the rebuilt tail;
compute _preservedLen from that segment. Added a structural regression test
pinning the tail selection.
Verified live: a 2-live-segment turn (seq 1 + seq 2, parser on seq 2) keeps the
parser-owned tail connected across a mid-stream rebuild (was orphaned with the
first-segment selection).
95e874d7be
