The redesigned notifications page will include a notifications search function. This will not be a free-text search but will, instead, search for notification parameters including: username, topic title, pagename, namespace, date and notification type. Available search parameters will be indicated by autocomplete. Because we want the search to work x-wiki and to find Read messages, it's assumed that users will need to specify the wiki/language when searching (see T132804).
It was suggested that we divide Search into to tickets: This ticket deals with the search functionality proper; T132804 pertains to the interface