Rotation re-inserts the compressor's handoff tail as fresh child rows. Carried
tail dicts arrive without a timestamp, so _insert_message_rows stamped them
with publish-time now(); the parent's durable originals kept their own
timestamps. The two copies then differ in _display_dedupe_key
(role, content, timestamp, tool fields) and _dedupe_display_generations shows
both -> duplicated rows in the ancestor-lineage display read (#59661), once
per segment boundary in a long chain.
publish_compression_child now adopts the durable parent row's timestamp onto
carried rows before insert (best-effort, never overwrites a timestamp the dict
already carries). archive_and_compact gets the same carry for in-place double
compaction, and _insert_message_rows back-stamps the persisted timestamp so
later rotations inherit it. The existing dedupe key and every read path are
unchanged; the collapse happens because identities now agree.
b8b38e55dd