set_session_metadata() and advance_compression_session()'s repoint both
stamped entry.updated_at = now. updated_at is the user-activity clock that
drives idle/daily reset policy and the restart-resume freshness gate
(suspend_recently_active, #85709), so a background metadata write (e.g.
Slack thread watermark) or a background compression repoint on a long-idle
session could make it look freshly active and get it falsely resume_pending
after a gateway restart.
These are the last internal stamp sites after 784f733cf (recover) and
5462f689b (touch_activity gating): drop the stamps, keep the durable save.
Follow-up to #85895 (closed) — credit @GodsBoy for the report-side push and
@chelsealong for the analysis on #85709.
3885c1096a