archive_and_compact takes the newest tail_count durable rows as the carried tail's superseded
originals (active=0, compacted=0: hidden from display and session_search). The CLI and the gateway
persist a turn's user row only after the turn-start preflight, so at that compaction the row rides
in the carried tail with no durable original of its own. The positional rewind then reached one
row past the tail and flagged the newest summarized message as a superseded duplicate. Each
turn-start compaction hid one more (A5, then A16 in a two-compaction run), on the default config.
The TUI/Desktop are immune because they persist the user row at submit.
tail_count now leaves out this turn's rows that never reached state.db: no persisted marker and
no _row_id, counted within the carried tail window only. That includes the user row and any
unflushed scaffolding. It does so only while the turn holds the session turn lease. Between turns
(a manual /compress, the gateway's pre-turn hygiene) the turn anchor is left over from the last
turn, and a gateway transcript reload is durable but unmarked. Counting those rows would leave
carried originals at compacted=1, the duplicate recall #86366 fixed.
3591bf3bb8