Dismiss Channel Alert

Hide this outage for this operator, until the account recovers.

The row lives until the account reaches 'active' or 'inactive' (the trigger trg_channel_alert_dismissal_end_outage deletes it). dismissed_error_at only records which error the operator saw.

Written only while the account is in 'error'. A banner still on screen for an account that has just recovered would otherwise leave a row the trigger has already passed, and that row would hide the NEXT outage. FOR SHARE serialises this insert against the recovering UPDATE: either the UPDATE waits and its trigger deletes this row, or it committed first and the status check finds 'active' and inserts nothing.