Before delivery_mode existed the notifier woke unconditionally when the task
carried a session_id — pre-existing gateway subscriptions had de facto active
wake. The column's 'notify' default alone would silently disable that on
upgrade. Backfill gateway rows to notify+wake on first-add only (tui stays
notify); explicit user downgrades are never overwritten by re-migration.
Sabotage-verified regression tests included.
Teknium