Post-turn rehydrates can race the gateway commit: the refreshed page shares the anchor but ends before the just-settled reply. preserveLocalPendingTurnMessages only protected stream-id rows, so a reply that settled onto a non-stream id (interim id, appended assistant-<ts> bubble) was dropped after it already painted. Extend the #70209 only-copy rule to the single newest settled, non-interim, unpersisted assistant row when the refreshed page carries no identical text.
That row is skipped when the refreshed page brings its own assistant row for the same reply ordinal: a rotated or compacted page supersedes it, so keeping the cached copy would render the pre-compression answer next to its replacement.
Closes#121613
ebf1be6527