Replace the loose NotificationDefaults intermediate type and 'as NotificationFormData' cast with an exhaustive buildDefaults() helper that narrows each branch of the discriminated union explicitly. TypeScript now infers the return type correctly from the discriminated union without any casts, satisfying strong typing for all channels (email, slack, discord, webhook, pager_duty, teams, matrix, telegram).
This directory contains the client side (frontend) of Checkmate.